Lg958l Training Material 10070

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LG958L Training Material
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Structure and Overview of Complete Machine
CONTENTS
Overall Structure of Complete Machine
Definition of Loader Model
Meaning of Loader Ordering Number
Performance Characteristics of LG958L (E5816215A3601)
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Product Configuration
Optional Configuration
Optional Attachments
Specification of Complete Machine

Section I Structure and Overview of Complete Machine
Chapter I Overview of LG958L Loader
I. Overall Structure of Complete Machine
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LG958L wheel loader is SDLG's 4th generation loader product built elaborately by
SDLG in response to
medium- and high-end markets both home and abroad, featuring European style, lon
g wheelbase,
and high breakout force. This product adopts the world s leading technologies and
is fitted with
fixed shaft electro-hydraulic shift transmission and single-lever pilot control.
Featuring outstanding
characteristics of high working efficiency, light and flexible operations, high
boom lifting force, and
good stability of complete machine, it s especially suitable for operations under
harsh working
conditions, including mines and sedendary soils.

II. Definition of Loader Model
1. Numbering Rule for Loader Model
In accordance with the requirements of standard QJ/LGJ QJ/LGJ 02.03-2006, the pr
oduct
model is composed of enterprise logo, characteristic code, product category code
, main
parameter code, platform code, and upgrade code.
LG 9 5 8
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Enterprise logo (LG denotes SDLG)
Characteristic code
Product category code
Main parameter code
Platform code
Upgrade code

(1) The characteristic code is expressed by 1~3 Latin letters in upper case.
Articulated steering wheel loader Track loader Skid steering wheel loader
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Product category Characteristic name Characteristic
code Note
Earthmoving
machinery
Articulated steering wheel loader
Track loader C
Skid steering wheel loader S

(2) Product category code
9 denotes earthmoving machinery 6 denotes excavation machinery
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8 denotes road machinery 7 denotes mining truck

(3) The main parameter code of the product is expressed by the Arabic
numbers and shall be chosen as per the following regulations:
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The loaders with rated carrying
capacity no less than 2 tons are
expressed by rounded value of
rated carrying capacity. For
instance, the rated carrying
capacity of LG958L is 5 tons and
therefore the main parameter code
is 5.
The loaders with rated carrying capacity
less than 2 tons are expressed by
rounded value of rated carrying capacity
(unit: ton) multiplied by 10. If the value
obtained is only one digit, suffix 0 to
the value obtained. For instance, the
rated carrying capacity of LG918 is 1.8
tons and therefore the main parameter
code is 18.

(4) Platform code
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The product platform is determined depending on the product status,
technical specification, and main structural configuration. Generally, the
product platform is classified into 5 levels, namely economic level,
medium level, medium and high level, and high level, which are
expressed by number 2, 3,6 , 8, and 9 respectively.

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No platform code is used for the loaders less than 2 tons, in which case a
letter is used to denote the drive mode. M denotes mechanical drive mode, H
denotes static hydraulic drive mode, and no letter is used for hydraulic drive
mode.

(5) Upgrade code
In event of major change in product
structure or performance, which
requires the redesign, prototype
build, or authentication, the upgrade
code shall be given. The upgrade
code is expressed by Arabic number
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in succession. The - after the
main parameter code shall be
removed if no upgrade code is
available.
For instance, for the medium-end
wheel load product with rated
carrying capacity of 5 tons that is
upgraded for the 2nd time, the
product model is LG953-2.

2. Meaning of Ordering Number
In accordance with the numbering method for ordering number of loader
product (abstract from QG/LGJ03.07 2006), the format and composition of
ordering number for wheel roader is as below:
Manufacture code
Identification code
Engine code
Main parameter and
upgrade code
Operating
environment code
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Transmission code
Drive axle code
Hydraulic
configuration code
Multifunctional
configuration code
Composite
configuration code
Cab code

(1) The first letter denotes operating environment code
E Export model
Export model Underground model CE model Domestic model
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C CE model
T Underground model
None Domestic model
(2) The first and second numbers denote main parameter. For instance, 58
denotes LG958 and 36 denotes LG936. The third number denotes upgrade
number.

1.6-2.0t 3.0t 4.5t 5.0t 6.0t 7.0t 8.0t
1 Yuchai YC6J125ZT21
Shangchai
SC11CB240.1G2B1
2
Weichai
WD10G220E23
Weichai
WD10G240E21
3 Weichai Deutz
WP6G125E22
Weichai
WP6G160E201
Shangchai
SC11CB220G2B1
Weichai
WD12G31
0E221
4
5 Weichai YC4D80T20
Dongfeng
Cummins 6BT5.9
Yangzhou Diesel
(3) The 4th number denotes engine model.
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6
Engine Co., Ltd.
WP3.9G65E2
DDE BF6M2012 DDE BF6M1013
7
8
VOLVO
D13
VOLVO
D13
9 Weifang Huafeng
ZHBG44
A
B Deutz
Deutz

(4) The 5th number denotes transmission model.
SDLG transmission ZF transmission VRT200
transmission
Hangzhou Advance
transmission
Shantui
transmission
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1.6-2.0t 3.0t 4.5t 5.0t 6.0t 7.0t 8.0t
1 SDLG transmission SDLG transmission SDLG transmission
2 Shantui
transmission
Hangzhou
Advance/Shantui/ZF
transmission
VRT200
transmission/
ZF transmission
VRT200 transmission
/
ZF transmission
VOLVO
transmissio
n
VOLVO
transmission

(5) The 6th number denotes drive axle.
ZF axle SDLG axle Feicheng axle
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1.6-2.0t 3.0t 4.5t 5.0t 6.0t 7.0t 8.0t
1 SDLG axle /
Feicheng axle SDLG axle SDLG axle SDLG axle SDLG axle SDLG
axle
SDLG
axle
2
ZF axle ZF axle

1.6-2.0t 3.0t 4.5t 5.0t 6.0t 7.0t 8.0t
0
Dual swing arm
mechanical control
Single regulator
constant flow
Mechanical control
(6) The 7th number denotes configuration of hydraulic system.
Pilot control Mechanical
control
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1
Single regulator
constant flow
2
3
Pilot control
Flow amplification
4
Mechanical
control
Load sensing
Mechanical
control
Load sensing
Mechanical
control
Load sensing
Mechanical control
Load sensing
5 Pilot control
Load sensing
Pilot control
Load sensing
Pilot control
Load sensing
Pilot control
Load sensing
Pilot control
Load sensing
Pilot control
Load sensing
Pilot control
Load
sensing

(7) The 8th number denotes boom type.
Standard Ultralong-Wheelbase Long-Wheelbase
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1.6-2.0t 3.0t 4.5t 5.0t 6.0t 7.0t 8.0t
A Standard Standard Standard Standard Standard Standard Standard
G LongWheelbase Long-Wheelbase LongWheelbase Long-Wheelbase LongWheelbase
Q UltralongWheelbase
UltralongWheelbase
R
Short boom dual
swing arm Short boom

(8) The 9th number denotes multi-functional configuration code
Duplex valve Triple valve Rapid coupling device
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1.6-2.0t 3.0t 4.5t 5.0t 6.0t 7.0t 8.0t
2 Duplex valve Duplex valve Duplex valve Duplex valve Duplex valve Duplex
valve
Duplex
valve
3 Triple valve Triple valve Triple valve Triple valve Triple valve Triple
valve
k Rapid coupling
device
Rapid coupling
device Rapid coupling
device

(9) The 10th number denotes cab model.
Underground cab Standard cab ROPS cab
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1.6-2.0t 3.0t 4.5t 5.0t 6.0t 7.0t 8.0t
0
Underground
cab
Underground
cab
Underground
cab
Underground
cab
6 ROPS ROPS
ROPS ROPS ROPS ROPS
9 Standard Standard Standard Standard Standard

3. Performance Characteristics of LG958L (E5816215A3601)
Item Performance
(1) With
8.079m
body
length, the
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complete
machine
features
outstanding
stability.

Item Performance
(2) Ultra-high
breakout
force and
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ultra-high
lifting force.

Item Performance
(3) 6.4s boom
lifting time
(fully
loaded) and
Start
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=11.3s total
cycling time
feature high
working
efficiency. End

Item Performance
(4) retraction
angle of
bucket
achieves
high
loading
coefficient,
solving the
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industry s
common
existed
problem of
incomplete
loading
Large of
bucket.

Item Performance
(5) SDLG s
patented
dual-seal
hydraulic oil
pipe
connectors
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completely
eliminate
the oil
leakage.
Photo of
seal ring

Item Performance
(6) KD function
Neutral start
interlocking
2F 2R 1F 2F
Press KD
button
Pull
backward
To reverse
gear
Push
forward
To forward
gear
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function

Item Performance
(7) The DDE
BF6M1013
Euro-III
emission
compliant
engine
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features
strong
power, high
torque, and
low fuel
consumption
and noise.

Item Performance
(8) ZF
transmission
features
power cutoff
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function.
Change photo

Item Performance
(9) SDLG s selfmade
heavyduty
drive
axle boasts
best
reliability in
the industry.
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The external
dry type
brake
features easy
maintenance
and lower
cost.

Item Performance
(10) High
strength
frame
passes
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100,000
cycles of
enhanced
fatigue
test.

Item Performance
(11) New steel
structure
cab boasts
luxury
upholstery,
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front air
vents, large
space, and
shock
absorbing
seat.

Item Performance
(12) The pilot
control
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features
lightweight
and
flexibility.

Item Performance
(13) Widened
engine
hood
makes the
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heat
radiation
and repair
easier.

Section II Product Configuration
I. Optional Configuration
Ordering
number Engine Transmissio
n Operations Cab
Quick
coupling
device
Bucket
capacity
E5812215A39 Weichai
WD10.G220
ZF Single-lever
Conventional
cab /
2.7 m3
E5813215A39 Shangchai C6121 Conventional
cab /
E5814215A36
Dongfeng
Cummins ROPS cab /
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transmissio
n
LG drive
axle
pilot control
Load-sensing
system
Triple valve
m
3.0 m3
3.6 m3 4.2
m3
4.5 m3
6CT8.3
E5814215A39
Dongfeng
Cummins
6CT8.3
Conventional
cab /
E5812215AK6 Weichai
WD10.G220 ROPS cab Optional
E5814215AK6 Dongfeng
Cummins 6CT8.3 ROPS cab Optional

Snow bucket Rock bucket Fork
I. Optional Attachments
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Bale grab Timber grab Multifunctional bucket
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Section III Technical Specification of Complete Machine
I. Main Parameters (E5816215A3601)
Item Parameter
Bucket capacity (m3) 3.0
Item Parameter
Tipping load(kN) =110.0
1. Main Parameters
Complete Machine
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Rated load(kg) 5000
Overall weight(kg) 16900
L×W×H (mm) 8079×3024×3382
Maximum traction force(kN) =155.0
Maximum breakout
force(kN) =180.0
Maximum gradeability (º) 30

2. Main Parameters
Traveling Speed
Item Parameter
Gear Forward Reverse
1st (km/h) 0~6.5 0~6.5
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2nd (km/h) 0~11.5 0~11.5
3rd (km/h) 0~23 0~23
4th (km/h) 0~38 /

3. Main Parameters - Engine
Item Parameter
Model BF6M1013
Type
Inline, water-cooled,
turbocharged, direct
Item Parameter
Number of cylinders 6
Cylinder bore/stroke (mm) 108/130
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injection
Rated power
(/kW ) 169
Rated speed
(r/min) 2200
Displacement (L) 7.146
Minimum fuel
consumption (g/kW.h) =210
Top torque(N.m) 925
Emission standard Chinese Stage-III

3. Main Parameters
Torque Converter
Item Parameter
Type Single-stage, three-way, single turbine,
hydraulic torque converter
Torque conversion coefficient 2.55
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Oil cooling mode Recirculated water-cooling
Inlet oil pressure of torque converter
(MPa) 0.85
Outlet oil pressure of torque converter
(MPa) 0.5

4. Main Parameters
Transmission
Item Parameter
Model ZF
Type Fixed shaft electro-hydraulic shift
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Number of gears Four forward and three reverse
Transmission pump model Transmission built-in
Gearshift working pressure (MPa) 1.6 1.8

5. Main Parameters
Drive Axle
Item Parameter
Type Full-time 4-wheel drive
Tire specification 23.5-25
Pressure of front tires (MPa) 0.39±0.01
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Pressure of rear tires (MPa) 0.33±0.01
Type of wheel reducer 1-stage planetary reduction
Wheel reduction ratio 4.4
Main drive reduction ratio 5.286

6. Main Parameters - Brake
Item Parameter
Type of service brake Air-assisted hydraulic caliper disc brake
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Braking pressure (MPa) 0.784
Type of parking brake Electro-pneumatic internal expanding shoe brake

7. Main Parameters Steering Hydraulic
Item Parameter
Type Load-sensing fully hydraulic articulated steering
Priority valve YXL-250-16
Steering pump JHP2100/Gj0010C-XF
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Steering gear BZZ6-800
Steering angle (º) 38°
Steering pressure (MPa) 16

8. Main Parameters
Working Hydraulic
Item Parameter
Type Hydraulic pilot control
Working pump JHP3160
Multi-way valve D32-17.5, pressure: 17.5MPa, flow: 250L/min
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Total cycling time (s) =11.3
System working pressure (MPa) 17.5

9. Main Parameters
Filling Capacity (Recommended Oils)
Item Recommendation Parameter
Engine (L) 19
Transmission (L) 35
Drive axle (L) 2X16
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Brake system (L) 4
Fuel (L) 300
Hydraulic oil (L) 210

Operation Specification of Complete Machine
CONTENTS
Maintenance Specification of Complete Machine
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Checking of Complete Machine

Section I Operation Specification of Complete Machine
Chapter II Operations, Maintenances, and Checking of Complete Machine
I. Preparations before Start
1. Get familiar with and master safety operation practice of loader
Only the specially trained and approved personnel can
operate and maintain the machine.
Operate and maintain the machine under good
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physical state.
Properly wear all labor protection appliances. Abide by the instructions and coo
perate with each
other.

2. Get familiar with the safety signs of complete vehicle.
Starter switch warning sign,
located above the starter switch.
High temperature warning, located on
engine hood and at exhaust pipe Fuel tank sign, located on fuel tank.
Rotate key to
neutral position
after parking
Warning
Take cautions
against scalding by
hot portions.
Recommended scope
Recommended scope
Caution
The driver must have official driver s license
Caution
1. Guard your hands against
squeezing.
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Hydraulic oil tank sign, located on
hydraulic oil tank.
Parking brake sign, located on right
operating panel.
Hoisting sign, located at hoisting
position of frame.
Operation caution sign, located on left
front window within cab.
Cab door caution sign, located on
outer side of cab door.
and fulfill the maintenance as per the
requirements in the operation and
maintenance manual of this machine.
Before start, check the machine and fulfill the
preparation works as per the specified
requirements.
Before the startup or backup of the machine,
observe the surrounding area for presence of
pedestrian and obstacle and sound the horn
for signaling.
The engine water temperature must be higher
than 55ºC, the oil temperature must be higher
than 45ºC, and the air pressure must be
higher than 0.45MPa before the machine is
put into high speed and full load operations.
The engine water temperature shall not
exceed 95ºC and the oil temperature shall not
exceed 120ºC.
2. Make sure to lock the doors
during traveling.

Loader traveling caution sign, located on right
front window of cab.
Lifting boom safety sign, located on both sides of
boom.
Caution
It s prohibited to get on or off the machine during
the traveling. No person is allowed to sit in any
place of the machine, except the driver seat.
The bucket or other working device shall load the
material as even as possible and prevent the
excessive offset towards one side.
It s prohibited to travel at high speed under
loaded condition.
Make sure to slow down during steering and
avoid the sudden steering and sudden braking.
Do not travel at high speed under rainy or snowy
weathers and avoid the steering on slopes as far
as possible.
Pay attention to observe the readings of the
instruments and park the machine away from fire
source.
While parking the machine on a slope, tightly set
the parking brake and block the wheels with
triangle woods.
Avoid the checking and maintenance with the
engine running.
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Under-boom danger sign, located on both sides of boom.
There is injury danger at articulations during
steering. The sign is located at front and rear frame
articulations.
Warning
Never stand
beneath the
boom.

Antifreeze sign, located on left cab door and
engine hood water tank filler port. Hot water caution sign, located at engine ho
od water
tank cap.
This machine is
filled with (-25#)
antifreeze.
Note: The antifreeze is glycol
engine coolant.
While adding the antifreeze,
operate as per the operation
instructions of the antifreeze
purchased in accordance with the
required environment conditions,
or it will impair the antifreeze
effect.
Recommended operation scope:
-25#: For use under = -15º
environment condition.
-35#: For use under = -25º
environment condition.
-45#: For use under = -35º
environment condition.
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Safety distance warning sign, located on both sides of
engine hood.
Machine contact warning sign, located on both sides of
engine hood.

3. Get familiar with information of instrument panel
Left turn indicator Right Central warning lamp turn indicator Engine speedometer
Warning indicator Warning indicator
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Torque converter oil
temperature gauge
Instrument panel
Brake pressure gauge Fuel level gauge Working hourmeter
Engine water
temperature gauge

Low fuel level warning
Safety locking indicator
Handbrake indicator
Seat belt
High beam indicator
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Gear indicator (FNR1234) Low brake pressure warning

Transmission oil filter blockage
warning
High coolant
temperature warning
Air cleaner blockage warning
Power cutoff indicator
Low transmission oil
Charging indicator warning pressure warning
Low engine oil pressure
warning
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Preheating indicator
Mute indicator
Fuel-water separator
warning
Engine malfunction
warning
Fuel strainer warning

4.1 Engine oil level;
4.2 Transmission oil level;
4.3 Hydraulic oil level;
4.4 Coolant level;
4.5 Brake fluid level;
4. Checking items before start:
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4.6 Checking of lubrication status at lubricating points;
4.7 Checking of battery;
4.8 Checking of tire air pressure;
4.9 Water drainage from fuel-water separator and air reservoir;
4.10 Checking of hydraulic pipeline;

Parking:
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Before the checking, park the machine on a level and solid ground, shift the gea
rshift
operating lever to neutral position, press the parking brake switch, lower the b
ucket
level onto the ground, align the front and rear frames without any angle, place
the
blocks before and after the tires, and leave the complete machine still for 15mi
n.

4.1 Engine oil level;
H L
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(1) Pull out the oil dipstick and wipe clean the lubricating oil on the oil dips
tick with clean
lint-free paper.
(2) Re-insert the oil dipstick into the engine and pull it out and then observe
the mark of
lubricating oil on the dipstick. If the mark is between L and H, it indicates th
at the
lubricating oil level is normal. If the mark is below L, add lubricating oil to
specified
level. If the mark is above H, find out the cause and operate for 2~3 times.
(3) Ensure that the oil level is within normal range and the oil dipstick is rei
nstalled
properly.

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If the engine is short of lubricating oil, the poor lubricating oil
is used, or the lubricating oil is not replaced for a long period,
it will probably lead to seizure of bushing or scuffing of
cylinder.
Seizure of bushing Scuffing of cylinder
Warning!

4.2 Check the transmission oil level.
Transmission oil
dipstick
Oil level under hot Filler port
state
Oil level under
cold state Upper mark
Lower mark
Middle mark
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(1) Star the engine and idle run (approximate 1,000r/min). Loosen and withdraw t
he
transmission oil dipstick and wipe clean the oil from the oil dipstick with clea
n lint-free paper.
(2) Re-insert the oil dipstick into the transmission, tighten and withdraw and t
hen observe the
oil mark on the oil dipstick.
(3) When the oil temperature is approximate 40ºC, the oil level shall be between l
ower mark and
middle mark. When the oil temperature is approximate 80ºC, the oil level shall be
between
upper mark and middle mark. If out of above range, add transmission oil as speci
fied.
(4) Ensure that the oil level is within normal range and the oil dipstick is rei
nstalled properly.

4.3 Check the hydraulic oil level.
The scale of oil dipstick is 8~12
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(1) Shift the gearshift operating lever to neutral position, start the complete
machine, lift the boom to highest position, tilt forward the bucket to
level state by means of bucket leveling mechanism, and stop the engine.
Then operate the pilot lever to slowly lower the boom and place level the
bucket, shift the operating lever to neutral position, and stop the engine.
(2) Observe the oil dipstick on the left side of the hydraulic oil tank. The oil
level shall be within 8~12. If insufficient, add to specified level.

4.4 Check the coolant level.
4.5 Check the brake fluid level.
(1) Open the water tank cap under
cold state of engine.
(2) Observe
the coolant amount
within radiator and ensure that
the radiator is full of coolant. If
insufficient, add coolant timely.
(3) Install the water tank cap.
(1) Open the access cap of booster pump
assembly oil cup.
(2) Observe the brake fluid amount in the oil
cup. The fluid amount shall be 3/4 of oil
cup capacity. Add brake fluid if insufficient.
(3)
Observe the oil cup filter screen for
presence of impurity and clean if any.
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(4) Install the oil cup cap.

4.6 Check the lubrication status at lubricating points;
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Check the lubrication status at lubricating points and timely add the lubricatin
g
grease. The adding method of lubricating method is as below:
(1) Remove oil dirt from vicinity of lubricating points.
(2) Connect grease gun to the grease nipple and operate the grease gun to add th
e
lubricating grease. Observe the articulated surfaces, till the used grease is
completely squeezed out and the new grease just overflows.
(3) Remove over-flown used grease and properly protect the grease nipple with a
small amount of new grease.

4.7 Check the battery;
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(1) Remove foreign material from the top of battery and observe the battery for
presence of
damage or leakage.
(2) Check the battery charge indicator. It indicates good battery if the indicto
r is green. If the
indicator is black, it s necessary to charge the battery. If white, it s necessary t
o replace
battery.
(3) Check the connection of wiring posts. In event of looseness, timely tighten.

4.7 Check the tire air pressure;
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(1) Screw off the tire valve protective cap and check the intactness of tire val
ve. Remove the
impurity and dirt from the vicinity of the valve, connect the pressure gauge to
the tire
valve, and observe the reading of pressure gauge.
(2) The pressure shall be 0.333~0.353MPa for front tires and 0.275~0.294MPa for
rear tires. If
the measurement is out of above range, inflate or deflate the compressed air (Th
is
standard is applicable for the tires with 16 ply rating. For tires with 18 ply r
ating, add
0.05MPa on the basis of above standard for the tire pressure).
(3) At completion of checking, properly preserve the pressure gauge and install
the valve
protective cap.
caution: While checking the air pressure and inflating the tire, do not face you
r body towards
straightly to the tire and pressure gauge.

4.7.1 Hazard of over-high or under-low pressure to tires:
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While the loader is traveling with
over-high tire pressure, the
contact area of the tire crown is
reduced and the partial load is
increased, which will accelerate
the wear and lead to tire burst
under worse cases.
While the loader is traveling with
under-low tire pressure, the wear is
accelerated and the overheating is
caused for the tire shoulder, which
will lead to separation between
sidewall rubber and cord ply and
lead to burst under worse cases.
Over-high air pressure Under-low air pressure

4.9 Drain water from fuel-water separator and air reservoir;
(1) Place an oil container beneath the water (1) Open the water drainage valve o
f
Water
drainage
valve
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drainage valve of the fuel-water
separator.
(2) Remove the dirt from the vicinity of the
water drainage valve of the fuel-water
separator and loosen the water drainage
valve of fuel-water separator, till the
water flows out.
(3) Observe the water drainage status.
When the clean fuel flows out, close the
water drainage valve. Properly dispose
the drained water.
the air reservoir.
(2) Close the water drainage plug
when the water in the reservoir is
fully drained.

4.10 Check the hydraulic pipeline;
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Before the start, carefully check all hydraulic pipelines and air pipelines for
presence of leakage. If any, tighten timely. Check the pipelines for presence
of damage and timely replace if any.

II. Start Requirements
Position Position STOP ON Position START
1. Before start, shift the gear operating lever to neutral gear.
2. Rotate the starter key to position ON, observe the power-on status of the ins
trument
panel, and check that all instruments display normally and there is no alarmed m
alfunction
lamp. At the same time, sound the horn for warning purpose.
67 RELIABILITY IN ACTION
3. Rotate the starter key to position START. In such case, the starter will driv
e the rotation of
engine. When the engine is started, immediately release the key. The starter key
will
automatically return to position ON. If the engine fails to start, wait for at l
east 1min
before retry. If the engine fails to start after three consecutive attempts, che
ck for the
cause.
4. After the engine is started, do not operate under high load immediately. Idle
run the
engine for 3~5min, gradually increase the engine speed, and operate the boom cyl
inder
and bucket cylinder for 3~5 cycles of recirculation actions.

III. Checking after Start
1. Check the readings of instruments. No malfunction warning lamp shall light up
.
Water temperature gauge, normal if pointer is
within green zone (60~100 .)
Torque converter oil temperature gauge,
normal if pointer is within green zone
(60~120 .)
RELIABILITY 68 IN ACTION
Transmission pressure gauge, normal if
pointer is within green zone
(1.5~1.8MPa)
Brake air pressure gauge, normal if
pointer is within green zone
(0.4~0.8MPa)

2. Check the functional actions:
2.1 Check the steering flexibility; 2.2 Check the service braking effect.
RELIABILITY 69 IN ACTION
Operate the loader for left and right turns
while the engine is running at moderate
speed. The steering shall be flexible
without stagnation.
While the loader is traveling at 24km/h on a
dry and level cement road, the braking
distance shall not exceed 9m.

2.3 Check the running status of engine.
RELIABILITY 70 IN ACTION
(1) The fuel lines and air lines shall be free of leakage during the running of
engine.
(2) Listen to the engine sound and ensure that there is no abnormal sound such
as noise.
(3) Observe the exhaust gas color of the engine. The exhaust gas shall be free o
f
clear black, blue, or white smoke. In event of continual abnormal smoke, stop
the engine for checking.

IV. Operation Specification
1. Startup
RELIABILITY 71 71 IN ACTION
(1) To prevent accidents, ensure that
there is no irrelevant person on
the loader or in the vicinity of the
loader and keep the loader away
from the obstacles, high voltage
wires, and cables before the
traveling.
(2) Lift the boom, tilt backward
the bucket, and maintain
the traveling state. The
lower articulated point of
boom shall be
400~500mm off the
ground.

RELIABILITY 72 IN ACTION
(3) Shift the gearshift operating
lever to 1st forward gear or 1st
reverse gear, depress the brake
pedal, and lightly rotate the
parking brake switch to pop up
to release the parking brake.
(4) Release the brake pedal and
slowly depress the throttle
pedal to drive forward or
backward the loader.

2. Stop
RELIABILITY 73 IN ACTION
(1) Release the throttle pedal, depress the brake pedal to stop steadily the
loader, and shift the gearshift operating lever to neutral position.
(2) Push down the parking brake switch.
(3) Lower the bucket or other working device onto the ground.
(4) Idle run the engine for approximate 5min, rotate the starter key to
position OFF to stop the engine, and withdraw and properly preserve the
key.

3. Operation Method
Rock pile
RELIABILITY 74 IN ACTION
(1) To load the rock material, the bucket shall have a downward tilting angle.
To load the earthwork, the bucket shall place horizontally onto the
ground and shovel straightly perpendicular to the material.
(2) After the bucket is fully loaded, make sure to retract the bucket before
lifting the boom.
(3) Do not lower the boom at the position FLOAT .

4. Loading and Unloading Method
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(1) Cross loading/unloading
Align the loader with the stockpile,
load the material, and travel
rearward. Then, the dump truck
drives in between the loader and the
stockpile. This loading/unloading
method features shortest cycle time.
(2) V-shaped loading/unloading
Position the dump truck so that the dump
truck forms an approximate 60º angle
with the backward direction of the loader.
After the bucket is fully loaded with
material, the loader travels backward,
steers for certain angle, and drives
towards the dump truck. The smaller the
V-shape angle is, the higher the working
efficiency of the loader is.

5. Safety Precautions
It s prohibited to lift the boom without retracting
the bucket during the loading of material.
It s prohibited to load or unload the material
during steering.
RELIABILITY 76 IN ACTION
It s prohibited to lift the boom to highest
position for excavation operations.
Lower the gravity center while driving up a slope.

It s prohibited to travel laterally on a slope. Travel slowly to
drive down a slope. It s prohibited to coast with engine
stopped. While traveling down a slope under heavily loaded
condition, travel the loader under backup mode.
The maximum water depth shall not reach the drive axle housing
and brake disc.
RELIABILITY 77 IN ACTION
Make sure to keep good ventilation during compartment
(and underground) operations. The engine must be fitted
with exhaust gas treatment device.
Do not operate the operating lever further after the cylinder
reaches limit position and operate slowly at uniform speed
during unloading.

Section II Maintenance Specification of Complete Machine
I. Safety Rules
(1) At the maintenance of the machine, affix a
maintenance label to the steering wheel,
which shall indicate the name of
maintenance operator, date, and time.
(2) No one is allowed to remove this label,
except the one who affixed this label.
(3) The operator who affixed this label shall also
preserve the starter key.
(4) Operate on a solid and level ground.
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(5) Close the working device to the ground and
place level the bucket.
(6) Shift all operating levers to neutral positions.
(7) Pull up the parking brake lever.
(8) Place blocks before and after the tires.
(9) Lock the front and rear frames with frame
locking levers.
(10) Pay attention to high temperature oil and
coolant, in order to guard against scalding.

II. Mandatory Maintenance Contents
No. Mandatory Maintenance Description 50100h
500600h
10001200h
1 Determine whether the customer fulfilled the maintenance as per the Operation
and Maintenance
Manual. v v v
2 Check and tighten the connecting bolts of all drive shafts, wheel rims, and br
ake calipers; v v v
3 Check and fasten connecting bolts of bucket blades or anti-wearing plate. v v
v
4 Check the throttle control, parking brake, and gearshift control systems. v v
v
5 Check whether the circuits and electric units of the electric system are norma
l. v v v
6 Check the fuel tank and radiator for normal levels. v v v
7 Check the sealing performance, reliability, and flexibility of the brake syste
m. v v v
8 Check the brake booster pump for normal level. v
9 Check all portions of brake system for presence of leakage, clean booster pump
oil cup filter screen,
clean breather port, and check brake fluid and add if insufficient. v v v
10 Check and clean breather port of transmission. v v v
RELIABILITY 79 IN ACTION
11 Check the sealing performance of hydraulic and steering systems of working de
vice. v v v
12 Check all portions of hydraulic system for presence of leakage and check oil
level of hydraulic oil tank. v v v
13 Clean breather port of hydraulic oil tank and check and clean oil return filt
er element of hydraulic oil
tank. v v
14 Add lubricating oil or grease to all lubricating points, including all articu
lated points of working device,
fan shaft, frame articulated points, drive shaft, and rear axle swing articulate
d points. v v v
15 Check for presence of other abnormality. v v v
16 Conduct the maintenance for the diesel engine strictly as per the requirement
s of Operation and
Maintenance Manual of Diesel Engine. v v v
17 Strictly follow the regulations of ZF AG for the maintenance of ZF axles and
transmissions. v v v
18 Check and adjust other portions as required, such as drain residual fluid fro
m bottom of air reservoir
and drain water from oil line. v v v

19 Clean the transmission oil sump and replace the oil suction filter element of
transmission oil sump. v v v
20 Replace the filter element in the torque converter
transmission oil line syst
em. v v v
21 Replace transmission oil. v v v
22 Replace the gear oil of front and rear axles. v v
23 Check the battery, clean the battery surfaces and wiring terminals, and apply
a film of Vaseline to the
surfaces of wiring terminals. v v
24 Clean the muffler of brake solenoid valve. v v
25 Check and fasten the connecting bolts between front and rear axles, diesel en
gine, transmission, and the
frame. v v
26 Check the working device and frame for cracked welds and loose connecting bol
ts. v v
27 Check the tire pressure. v v
28 Check and adjust the braking gap of the handbrake system. v v
RELIABILITY 80 IN ACTION
29 Check the wear status of the brake disc and frication plate of the foot brake
system and when necessary
replace. v v
30 Open the water drainage valve of the air reservoir to drain the water. v v
31 Replace the brake fluid v v
32 Replace oil return filter element of hydraulic oil tank. v v
33 Replace pilot oil filter element. v v
34 Check the hydraulic oil amount and cleanliness and filter if possible, add if
insufficient, and replace if
necessary. v
35 Check the gap and wear status between hinge pin and sleeve at all articulated
points. v
36 Check and clean the breather port of hydraulic oil tank and clean hydraulic o
il tank. v
37 Replace oil suction filter element of hydraulic oil tank. v

III. Mandatory Maintenance Method
By taking 1,000~1,200h maintenance for instance, the section below describes
the mandatory maintenance method. The operation method to stop the
machine is same with that of checking before stop.
1. Check and tighten the connecting bolts of all drive shafts, wheel rims, and
brake calipers
RELIABILITY 81 IN ACTION
(1) Remove the mud and sundries from the vicinity of the fastening bolts of
drive shafts, wheel rims, and brake calipers.
(2) Lightly rotate every bolt with wrench to check for presence of looseness
and tighten any loose bolt to specified torque.

2. Check and fasten connecting bolts of bucket blades or anti-wearing plate.
RELIABILITY 82 IN ACTION
(1) Remove mud and sundries from the vicinity of the connecting bolts of
bucket blades or anti-wearing plate.
(2) Lightly rotate every bolt with wrench to check for presence of looseness
and tighten any loose bolt to specified torque.

3. Check the throttle control, parking brake, and gearshift control systems.
RELIABILITY 83 IN ACTION
(1) Check the throttle operating pedal for flexible movement without any
stagnation and check whether the engine speed rises steadily and
uniformly following the depressing of the pedal.
(2) Check all pipelines of the parking brake system for presence of air
leakage, check brake buttons for flexible operations, check brake air
chamber spring for normal return, and check for clear braking effect.
(3) The gearshift operating lever shall be free of stagnation and all gears shal
l
work normally.

4. Check whether the circuits and electric units of the electric system are
normal.
RELIABILITY 84 IN ACTION
(1) Check the connectors of all harnesses for secure connections and ensure
that the harnesses are free of damage.
(2) Check all instruments for normal functioning and check all electric units
for normal functioning without any damage.
(3) Check all switches of electric system for flexible functioning and good
contact.

5. Check the fuel tank and radiator for normal levels.
Filler cap
Level gauge
RELIABILITY 85 IN ACTION
(1) Park the loader on a level ground and observe the level gauge from the
outside of the fuel tank. If the reading of level gauge is below the
marking 0, add fuel through filler port of fuel tank.
(2) Under the cold state of the engine, open the water tank cap and
observe the coolant amount in the radiator. Ensure that the radiator is
full of coolant. If insufficient, add coolant timely.

6. Check the sealing performance, reliability, and flexibility of the brake syst
em.
Water
drainage
plug
(1) Check all pipelines of brake system for presence of damage and check pipelin
e
connections for presence of leakage.
(2) The brake system shall operate flexibly and reliably during the traveling. W
hile
traveling at 24km/h on a dry and even cement road, the braking distance shall
not be more than 9m.
RELIABILITYINACTION86 86

7. Clean booster pump oil cup filter screen, clean breather port, and check brak
e
fluid and add if insufficient.
Breather hole
(1) Open the booster pump oil cup cap and take out the filter screen. Ensure tha
t
the filter screen is free of damage, remove foreign materials from filter screen
,
and clean breather hole.
(2) Check and ensure that the brake fluid in the oil cup is above 2/3 of the oil
cup
RELIABILITYINACTION87
capacity. If insufficient, add brake fluid to the specified amount.

8. Check and clean breather port of transmission.
(1) Remove the foreign materials and oil dirt from the vicinity of the breather
port.
(2) Disassemble the transmission breather port and clean with clean gear oil.
(3) At completion of cleaning, install breather port to the transmission.
RELIABILITYINACTION88

9. Check the sealing performance of hydraulic and steering systems of working de
vice.
(1) Check the pipelines of working device hydraulic system for presence of damag
e
and, if damaged, replace timely.
(2) Check the connections between all pipelines for presence of leakage and, upo
n
detection of leakage, find out cause and timely repair.
RELIABILITYINACTION89

10. Check the hydraulic oil tank level.
Scale range of oil dipstick
RELIABILITY 90 IN ACTION
Observe the oil dipstick on the left side of the hydraulic oil tank. The oil lev
el
shall be within 8~12. If insufficient, add to specified level.
is within 8~12.

11. Add lubricating oil or grease to all lubricating points, including all artic
ulated points
of working device, fan shaft, frame articulated points, and drive shaft.
RELIABILITY 91 IN ACTION
Adding method of lubricating grease:
(1) Remove oil dirt from vicinity of lubricating points.
(2) Connect grease gun to the grease nipple and operate the grease gun to add th
e
lubricating grease. Observe the articulated surfaces, till the used grease is
completely squeezed out and the new grease just overflows.
(3) Remove over-flown used grease and properly protect the grease nipple with a
small
amount of new grease.

12. Conduct the maintenance for the diesel engine strictly as per the requiremen
ts of
Operation and Maintenance Manual of Diesel Engine.
12.1 Maintenance of air cleaner
RELIABILITY 92 IN ACTION
Main cleaner Auxiliary cleaner
(1) Replace or clean once every 2,000 hours or when the maintenance indicator tu
rns red.
(2) The main cleaner must be replaced after being cleaned for up to 6 times and
the
auxiliary cleaner is a one-off part.
(3) If the maintenance indicator is still red after the cleaning, make sure to r
eplace the
cleaner.
(4) The damaged cleaner shall be replaced as well.
(5) The interval for replace of cleaner depends on the working environment. The
worse the
environment is, the more frequent the replacement shall be.

Cleaning and checking method of main cleaner:
(1) Mechanical cleaning:
Lean against the surface of a soft and clean
object and slap the end of main cleaner lightly.
(2) Clean with compressed air:
. Blow clean the cleaner from inside to outside
along the wrinkles of the cleaner.
. Use clean and dry compressed air with
pressure no more than 500kPa.
. Maintain at least 3~5cm spacing between
nozzle and cleaner.
(3) Check the cleaner.
RELIABILITY 93 IN ACTION
. Check the cleaner by illumination method. Place a light source within the
cleaner. If the lighting is visible from the outside, replace the cleaner.
. Upon detection of pinhole, scratch, cracking or other damage, make sure to
replace the cleaner.
. At the replacement of the main cleaner, make sure to replace the auxiliary
cleaner.
. If the filter indicator lights up though the main cleaner is replaced or ever
cleaned, it indicates that the auxiliary cleaner is blocked.

12.2 Replace the engine oil filter.
Engine oil filter
RELIABILITY 94 94 IN ACTION
(1) Remove the impurities and oil dirt from the vicinity of the filter and place
an oil container beneath the filter.
(2) Disassemble the used filter and place properly. Apply a small amount of
engine oil to the seal ring of new filter and install to the filter seat.
(3) Clean the splashed oil dirt.

12.3 Replace the engine oil
Filler
port
H L
RELIABILITY 95 IN ACTION
(1) Place an oil container beneath the oil drainage port of the engine, disassem
ble the
oil drainage plug to fully drain the oil from oil sump, and then install the oil
drainage plug.
(2) Open the filler cap and add engine oil to the engine. The filling amount sha
ll be
between L and H of the oil dipstick. Please refer to the Checking of Engine Oil
Level
in Checking before Start for specific operation method.
(3) Install the filler cap, clean the splashed oil dirt, and properly dispose th
e used oil.

12.3 Replace fuel-water separator element.
Fuel-water separator
element
RELIABILITY 96 IN ACTION
(1) Remove the dirt form the vicinity of the separator element, place an contain
er beneath the
separator element, and use wrench to disassemble the separator element along wit
h fuel
cup.
(2) Disassemble the fuel cup from the used element and install to new element. T
op up new
element with fuel, apply a film of fuel uniformly to the seal ring of element, a
nd install the
element to the element seat.
(3) Clean the splashed dirt and properly dispose the used fuel and element.

12.4 Replace fuel filter element.
Fuel filter element
RELIABILITY 97 IN ACTION
(1) Clean the dirt from the vicinity of the fuel filter and place a container
beneath the fuel filter.
(2) Disassemble the used filter and place properly. Apply fuel uniformly to the
seal ring of new filter and install to the filter seat.
(3) Clean the splashed dirt.

12.5 Check the engine belt tension.
(1) Push the belt with a
10kg force after the
belt is tensioned. The
vertical deflection shall
be approximate
5~8mm. If the
deflection exceeds
RELIABILITY 98 IN ACTION
15mm, please adjust
the tensioner or replace
with new belt.
(2) Check the belt once
every 250h or when the
belt noise is high.

13. Replace the filter element in the torque converter
system.
(1) Remove the oil dirt and
foreign material from the
vicinity of the filter and
place an oil container
beneath the transmission.
(2) Disassemble the used filter
element, apply uniformly a
film of lubricating oil to
RELIABILITY 99 IN ACTION
the seal ring of new filter
element, and install new
filter element to the
transmission.
(3) Clean the oil dirt splashed
on the transmission.

transmission oil line

14. Replace transmission oil.
(1) Remove the oil dirt from the
vicinity of the oil drainage
plug, place an oil container
beneath the oil drainage
port, and disassemble the oil
drainage plug to drain the
used oil. Thoroughly remove
the oil dirt from the oil
drainage plug, housing
sealing surface, and
transmission body and install
RELIABILITY 100 IN ACTION
Oil
drainage
plug
Filler
port
the oil drainage plug with
new seal ring.
(2) Add transmission oil into the
transmission through filler
port to the specified level
and install the oil dipstick.
(3) Clean the splashed oil dirt.

15. Replace the gear oil of front and rear axles.
RELIABILITY 101 IN ACTION
Replace the gear oil of wheel reducer:
(1) While parking the machine, adjust the oil drainage plug of wheel reducer to
the lowest position, place an oil container beneath the oil drainage port,
and disassemble the oil drainage plug to fully drain the used oil. Then
install the oil drainage plug.
(2) Disassemble the oil filler plug, add gear oil into the wheel reducer till th
e
gear oil overflows from the filler port, and then install the oil filler plug.
(3) Clean the splashed gear oil.

Axle housing
oil filler plug
Axle housing
oil drainage
plug
RELIABILITY 102 IN ACTION
Replace the axle housing gear oil:
(1) Place an oil container beneath the oil drainage plug, disassemble the oil dr
ainage
plug to fully drain the used oil, and then install the oil drainage plug.
(2) Disassemble the oil filler plug, add gear oil to the axle housing till the g
ear oil
overflows from the filler port, and then install the oil filler plug.
(3) Clean the over-flown gear oil.

16. Check the battery, clean the battery surfaces and wiring terminals, and
apply a film of Vaseline to the surfaces of wiring terminals.
RELIABILITY 103 IN ACTION
(1) Remove the foreign materials from the surfaces of the battery.
(2) Check the cables and wiring posts for secure connections and timely
tighten any loose connection.
(2) Uniformly apply a film of Vaseline to the surfaces of wiring posts and
install the fire-proof caps.

17. Check and fasten the connecting bolts between front and rear axles, diesel
engine, transmission, and the frame.
Check the connecting bolts between the front and rear axles, diesel engine, and
transmission and the frame for presence of looseness and timely tighten any loos
e
bolt to specified torque.
RELIABILITYINACTION104

18. Check the working device and frame for cracked welds and loose
connecting bolts.
RELIABILITY 105 IN ACTION
(1) Check the welds of structural parts, such as working device and frame,
for presence of cracking and, upon detection of cracking, repair timely.
(2) Check the fastening bolts of all portions for presence of looseness and,
upon detection of any loose bolt, tighten to specified torque.

19. Check and adjust the braking gap of the handbrake system.
Adjustment nut
Linked with
brake
RELIABILITY 106 IN ACTION
(1) Park the vehicle on a level ground, start the engine, release the parking br
ake, and
adjust the adjustment nut to a moderate gap between brake shoe and brake drum.
(2) Checking criterion: Park the vehicle with properly adjusted gap on a slope w
ith 1/4
gradient, stop the engine, and apply the parking brake. If the vehicle can hold
on
the slope, it indicates that the gap is moderately adjusted. If not, the re-adju
stment
is required.

20. Check the wear status of the brake disc and frication plate of the foot
brake system and when necessary replace.
RELIABILITY 107 IN ACTION
Check the wear status of brake disc and friction plate. If the braking effect is
impaired due to serious wear, the replacement is required.

21. Open the water drainage valve of the air reservoir to drain the water.
Water
drainage plug
RELIABILITY 108 IN ACTION
(1) Open the water drainage valve of the air reservoir to drain the water.
(2) Close the water drainage plug after the water in the air reservoir is fully
drained.

22. Replace the brake fluid.
Air bleeding
valve
RELIABILITY 109 IN ACTION
(1) Drive the loader to a level ground, shift the gearshift operating lever to
neutral gear (N) , stop the loader, and push down the parking brake
switch to guard the loader against movement. Open the air bleeding
valves of all brake calipers with open-end wrench to fully drain the used
brake fluid into a container.
(2) Add new brake fluid, start the engine, apply the braking for several
times to flush the entire system pipeline with new brake fluid, and then
drain the brake fluid.

(3) Close the air bleeding valves of rear axle brake and front axle left brake a
nd top up
the oil cup with brake fluid.
Filler port Oil cup Brake pedal
RELIABILITY 110 IN ACTION
(4) Apply the braking for several times (ensure that the air reservoir has suffi
cient
pressure. In event of pressure alarm, slightly depress the throttle pedal furthe
r till
the pressure is normal, before the application of braking) , till the brake flui
d flows
continually at the air bleeding valve.
(5) While maintaining the oil level of booster pump oil cup, depress and hold th
e brake
pedal. When the brake fluid flows out continually under spurting state, close th
e air
bleeding valve of front axle right brake.
(6) Repeat above step to bleed the air from the front axle left brake, rear axle
left brake,
and rear axle right brake respectively.
(7) Top up the booster pump oil cup with oil, apply the braking for several time
s, and
add oil till the oil level reaches 2/3 of oil cup capacity.

Brake
pedal
Brake
pressure
RELIABILITY 111 IN ACTION
(6) Repeat above step to bleed the air from the front axle left brake, rear axle
left
brake, and rear axle right brake respectively.
(7) Top up the booster pump oil cup with oil, apply the braking for several time
s,
and add oil till the oil level reaches 2/3 of oil cup capacity.

23. Replace the hydraulic oil tank return filter element and suction filter
element and clean the breather port of hydraulic oil tank.
(1) Remove the dirt from vicinity of return flange, disassemble the return
Suction flange
cap
Filler cap Return flange cap
Breather cap
Breather filter
RELIABILITY 112 IN ACTION
flange, take out the return filter element, properly install new filter
element, clean the flange mounting surface, and properly install the
flange.
(2) Remove the dirt from vicinity of suction flange, disassemble the suction
flange, take out the suction filter element, properly install new suction
filter element, clean the flange mounting surface, and properly install
the flange.
(3) Disassemble and clean the breather cap and reinstall to original
position.

24. Replace pilot oil filter element.
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(1) Remove the dirt from the pilot filter housing and place an oil container
beneath.
(2) Disassemble the filter housing, take out the used filter element, replace
with new filter element, and install the filter housing.
(3) Clean the splashed hydraulic oil and properly dispose the used filter
element.

25. Check the gap and wear status between hinge pin and sleeve at all
articulated points.
RELIABILITY 114 IN ACTION
(1) Check the gap between hinge pin and sleeve. If over-sized, repair timely.
(2) Check for looseness and gap between bushing and structural part and
repair if necessary.

Section III Checking of Complete Machine
I. Safety precautions
1. The operator shall understand and abide by the governing national and local s
afety regulations.
2. Most of the accidents are caused by the failure of abiding by the operation a
nd maintenance
regulations of the machine. To prevent the accidents, before the operations, ple
ase read,
understand, and abide by all warnings and precautions in the operation and maint
enance manual
and on the machine.
3. Pay attention to the safety during the testing, in order to prevent harming y
ourself or others.
4. While adjusting the working pressure of hydraulic system, make sure to stop t
he engine, operate
the operating lever to lower the boom, and wait for the hydraulic system to unlo
ad before the
pressure adjustment.
5. During the pressure measurement, do not directly conduct the pressure adjustm
ent when the
pressure reading is low, or it will easily lead to over-high pressure of hydraul
ic system and cause
RELIABILITY 115 IN ACTION
danger.
6. During the testing, make sure to hang a label of NO OPERATION on the working de
vice
operating lever of the loader or appoint a special person to guard the machine,
in order to
prevent the operation errors of the non-testing personnel from causing danger.
7. As it s impossible to forecast all possible dangers, the safety instructions in
this manual and on
the machine can't include all safety precautions. While using the procedures and
operations not
recommended in this manual, ensure the safety of yourself and other persons and
make sure not
to damage the machine. If it s unsure of the safety of certain operations, please
consult with our
company. We company will not be liable for any safety obligations for the safety
accidents arising
from the improper operations and the safety obligations for such operations will
be solely borne
by the user and the operator.

II. Instructions of Testing Tools and Applications
1. List of testing tools
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No. Code Name Specification and model Application
1 6900000436 One-off packing carton Packing carton
2 4030000369 Pressure gauge
213.53.063/60G1/4 0 6MPa For measurement of pilot pressure
and gearshift pressure
3 4030000370 Pressure gauge
213.53.063/400G1/4 0 40MPa For measurement of system pressure
(working/steering)
4 4030000368 Testing hose SMS20/M1/4-3000A Assorted with pressure
5 6430000379 Pressure gauge 213.53.063/600G1/4 For measurement of
vibration pressure
6 6430000205 Tire pressure gauge 0 0.6MPa For measurement of tire
7 6430000423 Tire pressure gauge extension rod Assorted with tire

gauge
road roller
pressure
pressure gauge

8 6430000204 Infrared thermometer Infrared thermometer Non-contact infrared ther
mometer
9 6430000206 Multimeter For measurement of all kinds of
electric units and circuits
RELIABILITY 117 IN ACTION
Note: The actual storage places of the testing connectors and pressure gauges wi
thin the toolbox may differ
from the places shown in the figure. Please carefully observe at the choice of t
esting tools, in order to prevent
the use of wrong tool.
10 6430000203 Battery tester HBV200 For measurement of battery voltage
and discharging
11 6410004204 Measuring connector smk20m14*1.5-PE smk20-m14*1.5-PE Assorted with pressure gauge
12 6410003035 Measuring connector smk20m14*1.5-pc smk20-m14*1.5-pc Assorted with pressure gauge
13 4120002381 Testing connector SMK20-G1/4-PC smk20-G1/4-PC Assorted with pressu
re gauge
14 6430000556 Tachometer DT-207L For measurement of engine speed or
related speeds

III. Testing Method
1. Operation Method of Pressure Gauge
1.1 Testing specification of pressure gauges:
(1) Pay attention to maintain the cleanliness during testing, in order to
prevent the ingress of dirt into the hydraulic system.
(2) While switching from one testing medium to another testing medium,
pay attention to thoroughly clean the connectors of testing hoses, in
order to prevent contaminating the oil or fluid to be tested.
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(3) Use pressure gauge of appropriate measuring range strictly as per the
requirements.
(4) Ensure the operation safety during the testing.

1.2 Measure the pressure of working hydraulic system.
(1) Park the loader on a level and solid ground, lower the working device onto t
he ground, apply the
parking brake, place an oil container beneath the pressure measurement port, and
connect the
Multi-way
valve
Pressure
measurement port
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pressure measurement pipeline, on which the pressure gauge is already connected,
to the pressure
measurement port. Choose the measuring range of 40MPa for the pressure gage (The
rated pressure
of the working hydraulic system for LG958L is 17.5MPa and the working hydraulic
system may contain
reserved pressure. Pay attention to the safety while connecting the pressure mea
surement pipeline and
loosen the pressure measurement port firstly to relieve the pressure) .
(2) Start the engine and operate the working device for a while. After the oil t
emperature reaches
approximate 60ºC~90ºC, operate the throttle pedal to run the engine at rated speed a
nd operate the
boom cylinder to the end of rodless chamber. Under the system overflow status, r
ead the reading of
pressure gauge (The boom cylinder is at the end of rod chamber and the bucket cy
linder may at the
end of rodless or rod chamber) .
(3) After the measurement, park steadily the machine, stop the engine, disassemb
le the measuring tools,
and remove the flown hydraulic oil.

1.3 Measure the pressure of steering hydraulic system.
Oil inlet pipe B
of steering
cylinder
Oil inlet pipe A
of steering
cylinder
Pressure
measurement
port
Measuring connector Testing result
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(1) Park the loader on a level and solid ground, lower the working device onto t
he ground, apply the
parking brake, place an oil container beneath the pressure measurement port, and
connect the
pressure measurement pipeline, on which the pressure gauge is already connected,
to the pressure
measurement port. Choose the measuring range of 40MPa for the pressure gage (The
rated
pressure of the steering hydraulic system for LG958L is 16MPa and the steering h
ydraulic system
may contain reserved pressure. Pay attention to the safety while connecting the
pressure
measurement pipeline and loosen the pressure measurement port firstly to relieve
the pressure) .
(2) Start the engine and operate the working device for a while. After the oil t
emperature reaches
approximate 60ºC~90ºC, operate the throttle pedal to run the engine at rated speed,
rotate the
steering to one limit position, and read the reading of pressure gauge.
(3) After the measurement, park steadily the machine, stop the engine, disassemb
le the measuring
tools, and remove the flown hydraulic oil.

2. Operation of battery tester
2.1 Structural characteristics:
This product is composed of the DC voltmeter, load resistors, circuits, and
switches, casing made of imported steel, and copper plated clamps. There is
battery capacity status indicator on the instrument panel.
2.2 Technical Specification:
Testing range: The battery is 6V and 12V in rated voltage, 32~500A in rated
capacity, and 100~120A in discharging current.
Indication method: Indicated by surface colors and characters.
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Measurement method: Manual momentary contact type, with testing time no
more than 5s each time.
Accuracy of gauge outfit: With grade 2.0 gauge outfit and 0~16V measuring
limit, the delivery products meet the enterprise standard (Q/ILPW-02-98) .
Measure the open-circuit voltage of battery before the testing. If the voltage i
s
=12.4V, the test can be conducted. If the voltage is <12.4V, charge the battery
firstly and then conduct the testing and judgment. The loading time of battery
shall not exceed 10s.

2.3 Test the battery.
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Load switch
(1) While testing the battery, test in a ventilated place. No smoking is allowed
for the operator and no
open fire is allowed in the surrounding area. Clean the testing terminals of the
battery and check the
battery casing for presence of rupture and destruction.
(2) Check whether the pointer of the tester is at the zero position on the left
side of the dial. If not,
rotate the zero setter in the rear cap hole to adjust the pointer to straight ze
ro position.
(3) Clamp the testing clamps to the wiring posts of the battery. If the surface
indicator lights up, it
indicates the positive pole. The test may be conducted disregarding the positive
and negative poles.
If the indicator fails to light up, check whether the clamps are securely connec
ted.
(4) Depress the load switch, till the pointer is stable. The testing time is not
allowed to last for 10s.
Observe the surface pointer and the test result is good if within green zone, lo
w if within red zone,
and weak if within yellow zone.

2.3 Test the charging system.
(1) Connect the tester as per the method for measurement of battery.
(2) Start the engine and run the engine, till the normal working temperature is
reached.
(3) Increase the engine speed to 1,200~1,500r/min. Pay attention to keep clean t
he
engine and at the same time do not depress the load switch.
(4) If the pointer is within red zone, it indicates that the charging system is
malfunctioned and the battery will be insufficiently charged. If the pointer is
within green zone, it indicates that the charging system is normal and the
battery can be charged.
2.4 Measure the missing cell of battery:
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(1) Connect the red rubber clamp of the battery tester to the positive post of
battery. Note: It's absolutely prohibited to use the black rubber clamp, in orde
r
to prevent danger.
(2) Insert the wire testing probe into the lower socket of the gauge body to tes
t
the missing cell in turn. If there is no reaction in surface indicator for one c
ell
(ensure the good contact during testing) , it indicates that the battery has
missing cell.
(3) The conventional testing is 2V per cell, which indicates that the battery is
normal.

3. Operations of multimeter
3.1 Overview
MY-65 is a handheld 4 ½ digital multimeter with stable performances and high
accuracy. The design of overall circuits is based on large scale integrated circ
uit and
dual-integral A/D converter, supplemented by all-functional over-load protection
. It
can be used to measure the DC and AC voltages, DC and AC currents, resistances,
capacitances, diodes, frequencies, and circuit continuity and non-continuity.
3.2 Characteristics
(1) 10 functions and 32 measuring ranges.
(2) LCD display, with character height at 22mm.
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(3) Display of 1 if out of current measuring range.
(4) Over-load protection in full measuring range.
(5) Automatic power-on/power-off
(6) Working temperature range: 0ºC 40ºC
(7) Storage temperature range: -10.~50.
(8) Display of low battery power: Display of battery symbol on left top corner o
f
LCD.
(9) Overall dimensions: 189*91*31.5mm

3.3 Specifications
(1) DC voltage
Measuring range Resolution Accuracy
200mV 0.01mV ± (0.05%+5)
2V 0.1mV ± (0.1%+5)
20V 1mV ± (0.1%+5)
200V 10mV ± (0.1%+5)
1000V 0.1V ± (0.15%+5)
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Input resistance: 10MO for all measuring ranges.
Overload protection: DC or AC 250V effective voltage for 200mV measuring
range and 700V effective voltage of 1,000V peak voltage for other measuring
ranges.

(2) AC voltage
Measuring
range Resolution Accuracy (50~60Hz) Accuracy
(40~400Hz)
2V 0.1mV ± (0.5%+15) ± (1.0%+15)
20V 1mV ± (0.8%+15) ± (1%+50)
200V 10mV ± (0.8%+15) ± (1%+50)
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700V 0.1V ± (1.0%+15) ± (1.2%+50)
Input resistance: 2MO for all measuring ranges.
Overload protection: 700V effective voltage or 1,000 peak voltage for all
measuring ranges.
Display: Average value (converted to sine effective value).

(3) DC current
Measuring range Resolution Accuracy
2mA 0.1µA ± (0.5%+10)
20mA 1µA ± (0.5%+10)
200mA 10µA ± (0.8%+10)
20A 1mA ± (2.0%+20)
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Overload protection: 200mA/250V fuse (no fuse protection for 20A measuring
range)
Maximum input current: continual current for 10A current and no more than
15s for 20A.

Measuring range Resolution Accuracy
2mA 0.1µA ± (0.8%+20)
20mA 1µA ± (0.8%+20)
200mA 10µA ± (1.2%+20)
20A 1mA ± (2.5%+50)
(4) AC current
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Overload protection: 200mA/250V fuse (no fuse protection for 20A measuring
range)
Maximum input current: continual current for 10A current and no more than
15s for 20A.
Frequency range: 40Hz~400Hz
Display: Average value (converted to sine effective value).

(5) Resistance
Measuring range Resolution Accuracy
200O 0.01O ± (0.5%+10)
2kO 0.1O ± (0.5%+5)
20kO 1O ± (0.5%+5)
200kO 10O ± (0.5%+5)
2MO 100O ± (0.5%+5)
20MO 1kO ± (0.5%+5)
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200MO 10kO ±.5.0% (Reading -1000) +20.
Overload protection: 250V AC effective voltage.
Note: Under the 200MO measuring range, it s normal that the 1000 is
displayed on the LCD when two measuring probes are short-circuited,
which shall be subtracted from the reading.

(6) Capacitance
Measuring range Resolution Accuracy
2000pF 0.1pF ± (4.0%+20)
20nF 1pF ± (4.0%+20)
200nF 10pF ± (4.0%+20)
2µF 100pF ± (4.0%+20)
20µF 1nF ± (4.0%+20)
(7) Frequency
Measuring range Resolution Accuracy
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20kHz 1Hz ± (1.5%+15)
(8) Audio continuity/non-continuity
Measuring range Description
. The built-in buzzer will sound when the
measured resistance is less than 70O

3.4 Measurement method
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3.4.1 Measure the voltage.
(1) Insert the black measuring probe into the jack COM and insert the red probe
into
jack VO or VOHz.
(2) To measure the DC voltage, rotate the functional switch to DC voltage measur
ing
range. (To measure the AC voltage, rotate the functional switch to AC voltage
measuring range). Estimate the maximum voltage to be measured, choose an
appropriate measuring range, and connect the measuring probes to two ends of the
circuit to be measured. The multimeter will display the measured voltage and at
the
same time indicate the polarity of the red probe.

3.4.2 Measure the current.
(1) Insert the black measuring probe into the jack COM and insert the red
probe into the jack mA if the current to be measured is less than 200mA or
into the jack 20A if the current to be measured is within 200mA~20A.
(2) Rotate the switch to DCA current measurement range, estimate the
maximum current to be measured, choose an appropriate measuring
range, and connect the probes to the circuit to be measured.
Measure the resistance:
(1) Insert the black measuring probe into the jack COM and insert the red
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probe into jack VO or VOHz.
(2) Rotate the functional switch to position O, choose an appropriate
measuring range, connect the probes to the pins of the resistor to be
measured, and read the data from the LCD.
(3) If the 1 is displayed on the LCD during measurement, it indicates that
the resistance shall be measured with a higher measuring range.

3.5 Infrared thermometer
3.5.1 Main technical specification
(1) Laser aiming guidance
(2) ./. conversion
(3) Display resolution: 0.1ºC
(4) Storage temperature: -21.~50.
(7) Preset emissivity: 0.95
(8) Power: 9V battery
(9) Battery life: Approximate 12h
(10) Measurement accuracy: ±2% or ±2.
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(5) Measurement time: 0.8S
(6) Distance coefficient: 12:1
(11) Working temperature: 0.~50.

3.5.2 Operation Method
Key Measure of
Infrared thermometer
Temperature
display
Laser irradiation
point
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(1) Power-on Press the key measure . The infrared thermometer powers on for self
examination and automatically measures and displays the temperature.
(2) Measurement
Point the probe to the target and press the key Measure for single
measurement or press and hold the key Measure for continual measurement (Note: At
the time of measurement, press and hold the key Measure for no less than
approximate 0.8s)
(3) Power-off After powered on, the infrared thermometer will automatically powe
r off if no
operation is made for more than 15s.
(4) Auxiliary function Press the key C to display the temperature in ºC . Press the key
F to display the temperature in ºF". Press the key Backlight to turn on/off the
display backlight. Press the key Laser to turn on/off the aiming of laser.

3.5.3 Precautions
(1) 30min transition period is required for high variation of environment temper
ature. High
variation of environment temperature will influence the measurement accuracy of
the
infrared thermometer. It will temporarily impair the accuracy of the infrared th
ermometer
when it s carried from one environment to another environment with high temperatur
e
difference for measurement. To achieve most ideal measurement result, in event o
f
variation of environment temperature in which the infrared thermometer is to be
used,
leave the infrared thermometer in the environment temperature for a period for b
alance
purpose before use.
(2) Most of the organic materials and the painted or oxidized surfaces contain 0
.95 emissivity
so that the 0.95 emissivity is preset in the infrared thermometer. It will lead
to inaccurate
measurement while measuring shining or polished metal surfaces. The solution is
to cover
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the surface to be measured with black tape or black paint. When the tape tempera
ture
reaches the same temperature of the material being covered, measure the surface
temperature of the tape or paint.
(3) The infrared thermometer features compactness and easy operations. Aim it at
the target
and push the key Measure to read out the surface temperature of the object within
1s.
It can measure the temperature of hot, dangerous, and inaccessible object under
the noncontact
condition.
(4) Special precautions for operation of infrared thermometer: It s absolutely pro
hibited to aim
the laser directly at the eyes or reflective surfaces, in order to prevent causi
ng personal
injuries!

3.6 Operations of speedometer
(1) Place a small piece of reflective tape to the moving part to be tested, such
as shaft, disc,
and pulley. If the part to be tested contains high reflection rate, apply the da
rk paint to
Measurement of engine
speed
Reflective tape
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ensure reliable measurement.
(2) Press and hold the power switch for several seconds and observe the display
whether the
reading varies continually along with the speed of the rotating part. Once the l
aser
irradiates to the reflective tape, the speedometer starts to display the speed.
If the laser
aims at the target, the speed is flashed on the top of the display. If no speed
is flashed, it
indicates that it s already detached (the adjustment of focus is required).
(3) Before the speedometer detaches from the testing position, loosen the power
switch to
keep the reading at completion of observation.
(4) The last reading can be displayed for 5min. Press the key Save to display for
further
5min. The key Save can be pressed repeatedly.

3.7 Measure the tire pressure.
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(1) Measurement method: Stop the vehicle and wait for the tire temperature to dr
op to
ambient temperature before the measurement.
(2) Application in malfunction judgment: The abnormal wear in the middle of tire
tread
is caused by over-high tire pressure. The overheating of tire, ply separation of
tire
shoulder, or even tire burst is caused by under-low tire pressure or overloaded
operations.
(3) Standard air pressure:
Front tires: 0.333~0.353MPa
Rear tires: 0.275~0.294MPa
Note: For the tires with 18 ply rating, add 0.05MPa on the basis of above standa
rd air
pressure.

Overview of Engine System
CONTENTS
Basic Structural Principle of DDE Engine
Engine block group
Crank-link mechanism
Valve mechanism
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Fuel system
Cooling system
Lubrication system
Electronic control system
Cause Judgment and Troubleshooting for Common
Malfunctions of Engine System

Section I Overview of Engine System
Chapter III Structural Theory of LG958L Engine System (DDE)
I. Introduction of Main Parameters
I. Model Explanation
BF6M1013-22 T3-0268
B Turbocharged model M Water cooling system
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LG958L is equipped with Dalian Deutz BF6M1013-22T3 engine. 1KW=1.36HP
F High speed 4-stroke 10 Upgrade number
6 Number of cylinders: 6 13 Stroke: 130mm
22 10X horsepower T3 Euro-III model
0268 Ordering number

2. Introduction of Main Parameters
Engine type
6-cylinder, inline, water-cooled,
turbocharged and inter-cooled,
direct injection, and .-shaped
combustion chamber
Minimum idling speed
rpm 600
Engine power (kw) 169 Compression ratio 18:1
Fuel type Diesel Cylinder pressure bar 30-38
Engine rated speed 2200 r/min Working sequence of
cylinders 1-5-3-6-2-4
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Cylinder bore/ stroke 108/130mm Fuel injection pump Electronically controlled
monoblock pump
Minimum fuel
consumption =210g/kW h Fuel injector Opening pressure of 210230bar
Oil cooling mode Recirculating water cooled Thermostat opening
temperature 83.
Displacement 7.146 Thermostat full open
temperature 95.
Rotation direction Counter-clockwise, when
observed towards flywheel Cylinder sleeve type Wet cylinder sleeve

II. Product Characteristics
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1. The monoblock pump structure adopted is proved by European market for 12 year
s,
featuring good product continuity and stable performance.
The electronically controlled monoblock pump is directly arranged on the cylinde
r block and
is directly driven by camshaft so that the high pressure is established instantl
y within the
pump. The short high pressure oil pipes feature universality and easy repair.

2. With compact structure and small volume, it s lighter by 100~150kg compared
with like products and features simple structure and easy repair as the repair
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and maintenance points are arranged on the same side of the engine.

3.
With minimum fuel consumption under full load in the world s leading level, it s
lower by 5g/KWh and saves fuel by 3~5L per 100km compared with like
products.
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Ambient noise curve of
engines from industry
benchmark competitors
Ambient noise curve of
BF6M1013 engine
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4. The engine adopts monoblock pump structure, which is located within
the cylinder block and is directly driven by the camshaft. With good
rigidity and low noise (only 96dB under full load), it s the model with
lowest noise among the domestic industry benchmark competitors.
Internal noise of cab: The internal noise meets the standard ISO 6396
and is comparable with passenger cars.

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5. The parts feature good universality, high serialization level, and easy match
ing of complete
vehicle. The oil sump adopts symmetric design so that positions can be swapped.
The water
pump and fan are separated against mutual interference. There are multiple arran
gement
schemes available for the turbocharger, such as middle upward arrangement, middl
e
downward arrangement, and rear arrangement, depending on the user s needs.

Section II Basic Structural Principle of DDE Engine
I. Engine Block Group
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The engine block group includes cylinder block, cylinder sleeve, cylinder head,
valve chamber
cover cap, and oil sump.
Function of engine block group: The engine block is the primary assembly structu
re for engine.
It bears the moving parts of the engine and the internal and external acting for
ces during the
working of the engine and is fitted with all kinds of accessories. Therefore, th
e engine block must
have enough strength to bear all kinds of acting forces under rated load or even
a certain
overload. It must have enough strength to minimize the deformations of all parts
during the
working of engine and have good anti-corrosion performance against coolant, lubr
icating oil,
and flammable gas.

1. Cylinder head
The DDE engine cylinder head adopts integral structure. The cylinder head is ins
talled
on the top of the cylinder block to seal the cylinder from the top and constitut
e the
combustion chamber. As it comes into frequent contact with high temperature and
high
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pressure combusted gas, the cylinder head is subject to high thermal load and
mechanical load. The cylinder head is also fitted with intake and exhaust valve
seats and
valve pipe bore for installation of intake and exhaust valves and intake and exh
aust
pipelines.
The cylinder is fixed onto the cylinder block by 18 bolts (for 4-cylinder engine
s) and 26
bolts (for 6-cylinder engines). The cylinder head bolts must be tightened as per
specified
sequence, in order to ensure the uniform force application on the cylinder head.
Before tightening the cylinder head bolts, apply engine oil onto the threaded pa
rts.
Tightening torque for cylinder head bolts: 30N.m for 1st step, 80N.m for 2nd ste
p, and
90º angle for final step.

Intake manifold
Exhaust manifold
Exhaust valve
Intake valve
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The cylinder head is cast with intake and exhaust ports, of which the intake
ports are connected with intake pipes and the exhaust ports are connected
with exhaust pipes. The intake and exhaust valve for every cylinder can be
determined depending on the positions of the intake and exhaust ports.

2. Cylinder block
The engine block is the basic framework for the engine. It not only bears the
acting force of high pressure and high temperature gas, but also it's fitted wit
h
almost all engine parts. Therefore, the cylinder block must have sufficient stre
ngth
and rigidity.
(1) Depending the different mounting planes of the cylinder block and oil sump,
the cylinder block is commonly classified into following three types:
Gantry cylinder block
General cylinder block
Tunnel cylinder block
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The DDE engine adopts gantry cylinder block.

(2) Advantages of DDE cylinder block
The DDE cylinder block adopts German standard high strength gray cast iron. With
integral noise and
vibration reduction design, it reduces the noise by 3dB(A) compared with like pr
oducts. The design of
cylinder block takes the easy repair and maintenance into sufficient considerati
on. It s built through
best optimized design via finite element method. The cylinder block is cast with
low pressure fuel line,
which is functioned as fuel inlet line of monoblock pump for non-electronically
controlled engine and
as fuel return line of monoblock pump for electronically controlled engine, to a
chieve more reasonable
layout of complete unit, prevent leakage, and preheat the fuel.
The design of cylinder block takes the easy repair and maintenance into sufficie
nt consideration so
RELIABILITYINACTIONthat all external accessories, except the starter and turboch
arger, are arranged on the same side of
the engine.

(3) Structure of cylinder block
This place is the
fuel line on the
cylinder block
and is the fuel
return line of
monoblock
pump for
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electronically
controlled
engine.
1. Cylinder block 2. Main bearing bolts 3. Locating pin 4. Screw plug 5. Sealing
gasket
6. Screw plug 7. Screw plug 8. Screw plug 9. Bushing 10. Bushing 11. Water jacke
t plug
13. Screw plug 14. Guide bushing 23. Guide bushing 24. Screw plug

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The 1013 main oil line regulator valve is installed on the lower plane of the cy
linder
block. To replace the regulator valve, tap a threaded hole with M8 screw tap and
screw in puller to take out the regulator valve at the time of disassembly. Ther
e is an
opening extent of regulator valve when no engine oil pressure is available. The
higher
the engine oil pressure is, the larger the opening extent is.

3. Cylinder sleeve
The cylinder structure in which the cylinder is directly bored in the cylinder b
lock is
referred to integral cylinder. The integral cylinder features good strength and
rigidity and
is capable of bearing high load. However, the integral cylinder features high ma
terial
requirements and high cost. If the cylinder is manufactured into independent cyl
indrical
parts (namely cylinder sleeve) and then installed into cylinder block.
(1) Classification of cylinder sleeve
For water-cooled engines, depending on whether the cylinder sleeve comes into co
ntact
with coolant, the cylinder sleeve is classified into dry type and wet type.
Characteristics of dry type cylinder sleeve:
After the cylinder sleeve is installed into the cylinder
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block, its outer walls do not come into contact with the
coolant directly. Instead, its outer walls come into direct
contact with the walls of cylinder block, with thin wall
thickness (generally 1~3mm). It features the
advantages of integral cylinder block, namely good
strength and rigidity. However, the machining is
relatively complicated, as the finish machining is
required for both inner and outer surfaces, and it
brings about inconvenient disassembly and assembly
and poor heat radiation.

Characteristics of wet type cylinder sleeve
:

After the cylinder sleeve is installed into the cylinder block, its outer
walls come into direct contact with the coolant and the cylinder
sleeve only comes into contact with the cylinder block by a belt on
the top and bottom respectively, with the wall thickness generally at
5~9mm. It features good heat radiation, uniform cooling, and easy
machining. Generally, the finish machining is required only for inner
surface and no machining is required for the outer surface coming
into contact with the coolant, featuring easy disassembly and
assembly. However, its disadvantages include lower strength and
rigidity against dry type cylinder sleeve and easy occurrence of
water leakage. Therefore, some leak-proof measures shall be taken.
Th The engine i fitted fi d on LG958L adopts d wet type cylinder d sleevel .
LG958L li
(2) Measures for wear reduction of cylinder sleeve
Correct start and startup. At the cold start of diesel engine, rotate the engine
for several times
to lubricate the friction surfaces before start. Then, idle run the engine for w
arm-up and do not
depress the throttle pedal. Do not start up the machine when the coolant tempera
ture is less
than 40ºC. During the running, try to maintain the diesel engine within normal tem
perature
range and travel at moderate speed. Correct choice and use of lubricating oil. C
hoose the
lubricating oil with best viscosity depending on the seasons and performance req
uirements of
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diesel engine. Enhance the maintenance works for fuel filter, oil filter, and ai
r cleaner to
minimize the ingress of mechanical impurity into the cylinder.

4. Cylinder gasket
(1) The cylinder gasket is installed between cylinder head and cylinder block an
d is
functioned to seal the contact surface between cylinder head and cylinder block
to prevent leakage of air, water, and oil. In addition, the gap between the plan
e
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of piston crown and cylinder block is generally 1±0.1mm and can be adjusted by
adding or removing cylinder gasket.
(2) Structure characteristics: The material of cylinder gasket must have certain
elasticity to compensate the unevenness of the fitting surface and ensure the
sealing. In addition, the cylinder gasket must have good heat resistance and
pressure resistance against ablation and deformation under high temperature
and high pressure. At present, the copper sheet
cotton structure cylinder
gasket is mostly applied. Some engines adopt the cylinder gasket with woven
wire net or perforated steel plate framework and asbestos and rubber adhesive
pressed on both sides.

(3) Calculation method for thickness of cylinder gasket for DDE engine
The DDE engine adopts metal cylinder gasket, which is classified into three
thickness classes identified by the number of bores at the edge of the cylinder
gasket. To choose appropriate cylinder gasket, it s required to measure the piston
protrusion. Based on the maximum measurement of piston protrusion, choose the
cylinder gasket of corresponding thickness.
Piston protrusion Mark of cylinder
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gasket
[0.28-0.54mm) one bore
[0.54-0.64mm) two bores
[0.64-0.75mm) Three bores

Measurement method for piston protrusion
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[1] Remove the oil dirt from the surfaces of cylinder block, place the
measurement bar and cushion block on the sealing surface of
crankcase, on which the cylinder sleeve is installed, and set the pointer
of dial gauge to mark 0 .

[2] Place the dial gauge and measurement tool at the measuring points of piston,
rotate the
engine to move upward the piston, and observe the variation of dial gauge pointe
r. When
the pointer reaches maximum reading and starts to reduce, stop the rotation of e
ngine
and read the reading of the dial gauge. In such case, the reading is the piston
production.
[3] At the time of measurement, choose the Ø95mm circle on the piston as the measu
ring
point and keep the measuring point consistent with the direction of piston pin.
All pistons
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shall be measured and the maximum value shall be chosen.

The height difference between the
cylinder block plane and the piston
crown is used as the basis to determine
the thickness of the cylinder gasket. At
the replacement of piston, measure the
value of each piston in turn. Take the
maximum value and look up the required
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cylinder gasket thickness S as per the
diagram above.
At the time of measurement, the piston
must at the absolute top dead center.
The height difference between cylinder
gasket plane and piston crown = .-.
(The range of top gap . is 0.9~1.1mm.)

5. Oil sump
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The oil sump of DDE engine adopts symmetric design to ensure easy installation.
Two
oil drainage plugs are fitted to ensure easy oil drainage, as the oil can be dra
ined from
both left and right sides. With the application of really low force, the oil sum
p is
generally is stamped from thin steel sheet and its shape depends on the overall
arrangement of the engine and the capacity of the engine oil. The oil drainage p
lug is
fitted on the bottom of the oil sump. Generally, the oil drainage plug is fitted
with
permanent magnet to absorb the metal particles from the lubricating oil and redu
ce
the engine wear. The gasket is fitted on between upper and lower crankcase fitti
ng
surfaces to prevent the leakage of lubricating oil.

5. Gear chamber cover
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DEUTZ engine adopts the design thinking of separated gear chamber cover (includi
ng
rear oil seal) and flywheel housing. The flywheel housing is functioned for conn
ection
with complete vehicle and the gear chamber cover is functioned to seal the gear
chamber and prevent the leakage of engine oil and is also functioned for ventila
tion of
crankcase. This structure greatly reduces the weight and types of flywheel housi
ng and
feature good universality. The flywheel housing is fitted with two locating slee
ves (21)
for orientation purpose at the installation of gear chamber cover.

II. Crank-link mechanism
1. Brief
Crankshaft timing
1st compression ring
2nd compression ring
Oil control ring
Piston
Connecting rod bolt
Flywheel
Speed sensor pulse gear
Connecting rod large end
lower bushing
Connecting rod cap
Piston pin
Circlip
Connecting rod small
end bushing
Connecting rod
Connecting rod large
end upper bushing
Main bearing upper
bushing
Crankshaft
Crankshaft sprocket
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The crank-link mechanism is the main part for the engine to generate and output
the
power.
Function: It converts the force applied by the combusted gas onto the piston cro
wn to
the torque of crankshaft and outputs the mechanical energy.
Structure: It s composed of the piston rod group and crankshaft flywheel group.
Crankshaft and main bushing: The DEUTZ engine adopts fully balanced cast steel
crankshaft, with full support.
toothed belt pulley
Connecting rod nut
Main bearing lower bushing
Crankshaft pulley
Thrust plate

2. Piston rod group
Piston ring
Piston
Rod
Piston pin
Circlip
Connecting rod
bearing bushing
cap
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Rod bushing
Bolt
The piston rod group includes piston, piston rings, piston pin, rod, and rod
crankshaft.
Function: It transmits the power acquired from the combustion process to the
crankshaft.

(1) Piston top surface
Printed drawing number
Flywheel end mark
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Printed manufacture date
Weight group mark
The manufacture date is in
format of Year-Month-Day
year code year code month code
2001 1 2013 D 1 A
2002 2 2014 E 2 B
2003 3 2015 F 3 C
2004 4 2016 G 4 D
2005 5 2017 H 5 E
2006 6 2018 J 6 F
2007 7 2019 K 7 G
2008 8 2020 L 8 H
2009 9 2021 M 9 G
2010 A 2022 N 10 K
2011 B 2023 P 11 L
2012 C 2024 R 12 M
team
weight of the
piston(g)
A (986,994]
B (994,1002]
C (1002,1010]

(2) Piston rings
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The piston rings include the 1st compression ring, 2nd compression ring, and oil
control ring in turn from the top to bottom. Two compression rings are mainly
functioned to seal the cylinder and the oil control ring is only functioned to
uniformly apply the lubricating oil to the cylinder walls for lubrication during
the
vertical movement of the piston and at the same time scrape the excessive
lubricating oil into the oil sump.

Two compression rings have the
directionality. During the installation,
the compression ring marked with top
shall face towards the piston crown.
During the installation, the openings of
three piston rings shall stagger for a
certain angle with each other and shall
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avoid the ±45º range in the direction
of the piston pin.

(3) Connecting rod
The mass of the connecting rod assembly (connecting
rod, connecting rod small end bushing, and connecting
rod bolts) shall be controlled within 1865~1965g. The
connecting rod assembly is grouped by mass into 10
groups, with the mass difference no more than 10g
between any two neighboring groups.
Group
mark
Mass (g) Group
mark
Mass (g)
A 1865~1875 F 1915~1925
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B 1875~1885 G 1925~1935
C 1885~1895 H 1935~1945
D 1895~1905 I 1945~1955
E 1905~1915 J 1955~1965

(3) Precautions for assembly of connecting rod
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(1) The fracture-splitting process is adopted for the parting surface of connect
ing rod body cap. The fracturesplitting
surface shall be free of cracking or loose metal particles. It's disallowed to r
eversely install the
connecting rod body and cap, or it will impair the indented junction surface.
(2) While assembling the connecting rod, the boss on the connecting rod shall fa
ce towards the flywheel end.
(3) The connecting rod is stamped with number. During the assembly, pay attentio
n to align properly to
prevent reverse installation. Once reversely installed, the indented junction su
rface will be impaired.
(4) There is a boss on one end of the connecting rod bushing. During the assembl
y, align with the bushing
cap to prevent reverse installation.

3. Crankshaft flywheel group
(1) Brief
Main
journal
Connecting rod
journal
Counterbalance Crankshaft flange
Front of
crankshaft
Rear of
crankshaft
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Main journal Crankshaft gear
Lubricating orifice
Connecting rod journal
lubricating orifice
The crankshaft flywheel group includes the crankshaft, flywheel, and all parts
installed on the crankshaft (crankshaft timing gear, bushing, thrust plate, and
pulley).
Function: It transmits the power to the engine oil pump, water pump, air
compressor, fuel pump, fan impellor, and flywheel and outputs the power.

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Crankshaft and main bushing: The DEUTZ engine adopts fully balanced
cast steel crankshaft, with full support.

(2) Precautions for Assembly
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[1] There are total 7 crankshaft bushing caps, which are marked with numbers
1, 2, 3, 4, 5, 6, and 7 respectively counting from the flywheel end. Pay
attention to the sequence and do not wrongly install at the time of
installation.

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[2] The crankcase is fitted with
guide posts to ensure the
smooth installation of
crankshaft bushing caps.
[3] The crankshaft bushing caps are fitted
with reverse installation proof boss so that
the caps can t be properly assembled
once reversely installed.

[4] The 2nd crankshaft bushing cap is fitted with 2 pairs of thrust plates (tota
l 4 plates) to
prevent the axial runout of crankshaft. The axial runout range of crankshaft is
0.1~0.3mm. At the installation of the thrust plates, the oil line shall face tow
ards the
crankshaft. The other two thrust plates shall be installed on the crankshaft in
spacing of 180º from the above two thrust plates.
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Oil groove
Pay attention to prevent
reverse installation
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[5] There are two oil grooves on the crankshaft bushings so that the
lubricating oil lubricates the bushings via oil grooves. While installing the
bushings, pay attention to align the external boss of bushing with the
bushing cap to prevent the reverse installation.

[6] During the installation of engine oil pump, pay attention to correspond the
key
within engine oil pump to the key slot of the crankshaft and keep level the
mounting plane of engine oil pump with the cylinder block plane.
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[7] While assembling the crankshaft, align the timing mark on the crankshaft
gear with the timing mark on the camshaft. The timing mark of camshaft is
on the top of camshaft gear and the timing mark of crankshaft is at the
tooth space of the crankshaft gear. When it s properly timed, the tooth
top with timing mark is engaged with the tooth space with timing mark.

III. Valve mechanism
1. Brief
The rocker subassembly of engine is mainly composed of tappets, push rods, intak
e
and exhaust valves, and rockers.
1. Push rod 2. Tappet 3. Rocker fastening bolts 4. Rocker seat 5. Rocker 7. Wash
er
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8. Retainer 9. Fastening nut 10. Adjustment screw 11. Rocker group 12. Rocker se
at
13. Spring 14. Washer 15. Intake valve 16. Exhaust valve 17. Spring seat 18. Val
ve pipe
19. Intake valve seat 20. Exhaust valve seat

2. Camshaft
1. Camshaft 2. Camshaft bushing 3. Sensing pin 4. Camshaft gear 5. Bushing 6. Id
ler
7. Idler 8. Guide sleeve
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The valve tappets of the Deutz engine are directly driven by camshaft and
the camshaft also drives the monoblock pump. The camshaft of Deutz
engine is fully supported. The BF6M engine is fitted with 6+1 bushings and
BF4M engine is fitted with 4+1 bushings. All bushings are same, except the
bushing near the flywheel end.

Valve Rocker and push rod
3. Main parts
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Intake manifold and preheating plug Tappet

4. Arrangement of valves
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The cylinder at the flywheel end is the 1st cylinder and there are 1st cylinder
exhaust valve, 1st
cylinder intake valve, 2nd cylinder exhaust valve, 2nd cylinder intake valve, 3r
d cylinder exhaust valve,
3rd cylinder intake valve, 4th cylinder exhaust valve, 4th cylinder intake valve
, 5th cylinder exhaust
valve, 5th cylinder intake valve, 6th cylinder exhaust valve, and 6th cylinder i
ntake valve in turn from
left to right.
As the engine equipped on 958L incorporates the EGR function, while adjusting th
e valve
clearance, it s necessary to find out the compression top dead center for valve ad
justment
cylinder by cylinder. The intake valve clearance is 0.3mm and the exhaust valve
clearance is 0.5mm.

IV. Fuel System
1. Brief
The fuel line pressure measuring point for low pressure chamber shall be the
downstream of fine filter outlet. The fuel pressure shall be 4.2bar at 1,500~1,8
99rpm,
5bar at 1,900~2,300rpm, and 5bar at 2,300rpm. When measured at the cylinder bloc
k
outlet, the measurement shall be lower than normal pressure by 1bar. When measur
ed
at inlet of fuel delivery pump, the fuel pressure shall be no higher than -0.3ba
r. The
temperature of return fuel shall not exceed 80ºC and the amount of return fuel sha
ll be
more than 8L. 1. Fuel tank
2. Fuel line to diesel pump
3. Diesel pump
4. Fuel line to diesel filter
5. Diesel filter
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6. Fuel line to fuel injection pump
7. Fuel injection pump
8. Fuel line to fuel injector
9. Fuel injector
10. Fuel return pipe
11. Fuel pipe bolt with pressure control valve
12. Fuel line of fuel return tank
13. This distance shall be as large as possible.

Fuel operation diagram
Fuel tank
Fuel-water separator
Fuel delivery pump
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Fuel fine filter
Monoblock pump
Fuel injector

Fuel delivery pump Fuel return check valve
2. Main parts
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Electronically controlled monoblock pump Fuel injector

3. Low pressure fuel line
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The diesel from the diesel tank flows to the fuel delivery pump via fuel-water s
eparator and,
after being filtered by diesel filter, flows via external connector into the met
al low pressure fuel
line that is connected with the electronically controlled monoblock pump. Each p
ump is
connected with external fuel inlet pipe separately. The fuel return passage is c
ast on the
cylinder block.
As the fuel supply amount of the fuel delivery pump is more than 10 times of the
fuel outlet
amount of the monoblock pump, a great amount of excessive fuel flows back to the
diesel
tank via fuel return check valve and return pipe to completely bleed the air fro
m the fuel line
by a great amount of returning fuel and radiate the monoblock pump by a great am
ount of
returning fuel flowing through the monoblock pump.

3. High pressure fuel line
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The fuel in the low pressure fuel line enters into the monoblock pump. Under the
action of the monoblock pump, the high pressure fuel is formed from the
monoblock pump to the fuel injector via really short high pressure fuel pipe. Wh
en
the pressure reaches 220bar, the fuel injector opens to inject the atomized fuel
into
the combustion chamber, which mixes with the air to form flammable air mixture.

4. Electronically controlled monoblock pump
(1) Brief
Advantages: The monoblock pump is one of the latest
technologies, which ensures that the combustion is more
adaptable to the needs of working condition to achieve more
sufficient combustion and higher efficiency and lower the
exhaust contamination and fuel consumption. It also boast
following advantages:
 Compact structure and good rigidity, as it s directly driven
by camshaft via tappets.
 Up to 1,600bar fuel injection pressure.
 Smaller installation space.
 Short and standardized high pressure fuel pipe.
Good and freely adjustable speed regulation performance
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 and applicability for engines of different applications.
 Easy replacement of pump.
Function: Under different working conditions of the engine, it
supplies high pressure fuel at fixed timing and fixed quantity as
per the requirements of complete unit so that all cylinders can
function normally to output the required power and torque and
at the same time meet the emission standard. It plays a vital role
for the performance, working reliability, and durability of the
engine and is the core part of the fuel supply system.

(2) Working Principle
Injection module
1 - Fuel injector body
2 Transition connecting high
pressure pipe
3 High pressure fuel pipe
4 High pressure fuel pipe connector
5 Travel stop
6 Solenoid valve needle valve
7 Disc
8 Pump body
9 High pressure chamber
10 Fuel pump plunger
15 Solenoid valve spring
16 Valve housing with coil and
magnetic iron core
17 Output disc
18 Intermediate disc
19 Seal ring
20 Fuel inlet (low pressure)
21 Fuel return
22 Fixed part of fuel pump plunger
23 Plunger return spring
24 Tappet body
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When the solenoid valve is cut off, the fuel return passage opens and the monobl
ock pump can t establish
high pressure. The fuel return passage closes and the fuel pressure can rise rap
idly only when the solenoid
valve is turned on. The high pressure fuel flows into the fuel injector through
a really short high pressure fuel
pipe for fuel injection. When the solenoid valve is cut off, the fuel return pas
sage opens for rapid pressure
relief and the fuel injection is stopped. The power-on duration of the solenoid
valve determines the
recirculating fuel supply amount. The working process of electronically controll
ed monoblock pump is
mainly classified into four stages: fuel injection process, bypass process, inje
ction process, and unloading
process.
11 Engine block
12 Roller pin
13 Cam
14 Spring seat
25 Spring seat
26 Roller body
27 Roller

[2] Bypass process: When the plunger moves
[1] Fuel suction process: The solenoid valve
is not powered on. When the plunger
moves downward, the fuel pressure
within the pump chamber is less than
the fuel pressure of low pressure fuel
line. In such case, the fuel of low
pressure system enters into the high
pressure injection system via the fuel
inlet on the plunger sleeve.
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upward, the fuel in the plunger chamber is
compressed. However, if the solenoid
valve is still under cut-off state, the fuel
pressure within the plunger chamber
depends on the opening pressure of the
fuel return check valve, which is far lower
than the opening pressure of fuel injector,
so that the fuel will return to the fuel tank
via fuel return passage.

[3] Fuel injection process: During the fuel supply
stroke of the plunger, when the electronic
control issues the fuel injection control pulse
at a specific moment, based on the sensor
signals collected, and powers on the
electromagnet via drive circuit. In such case,
the fuel inlet and return passages are closed
and an enclosed volume is formed within the
plunger chamber. Following the rise of the
plunger, the fuel within the enclosed volume
is compressed and the pressure rises rapidly.
When the pressure is higher than the opening
pressure of the fuel injector, the needle valve
opens and the fuel is injected into the
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cylinder.
Note: The resistance of the solenoid coil for the
solenoid valve of monoblock valve is approximate
0.9O. If less than 0.4O, the coil is probably short
circuited. The fuel injection timing is controlled by
the power-on moment and the fuel injection
amount is calculated by the power-on duration to
realize the control of fuel injection amount.

[4] Unloading process: When the control
pulse is terminated, the electromagnet is
cut off and the fuel return passage
opens so that the fuel overflows via fuel
return passage, the high pressure fuel
unloads to the low pressure system via
valve port, and the pressure of high
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pressure fuel line drops. When the
pressure drops to the opening pressure
of needle valve, the fuel injection is
completed.

V. Cooling system
1. Brief
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(1) The integral cooling system is adopted, featuring compact structure and easy
installation.
(2) High reliability and low operation cost.
(3) High cooling efficiency and low required power
(4) 1.5bar pressure in cooling system after the running of engine. The antifreez
e must
be used as the normal coolant temperature is above 100ºC. In addition, as the
thinnest cast thickness of engine block water passage is only 4mm, the use of
antifreeze can prevent he blockage of water passage due to water scale.

2. Thermostat
The thermostat is functioned to change the recirculation strength of the water (
route
and flow rate) depending on the engine load and water temperature. In addition,
it
can shorten the hot start time of engine and reduce the fuel consumption and wea
r
of engine parts.
The DDE engine adopts paraffin thermostat, with opening temperature at 83ºC and
full opening temperature at 95ºC.
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(1) Minor recirculation
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Before the hot start of the cold engine, the water temperature is below 83ºC. In s
uch case, the main
valve closes and the bypass valve opens so that the coolant can directly flow ba
ck to the water inlet
of water pump via bypass pipe and is compressed into the water jacket by the wat
er pump. In such
case, the water only recirculates in a small scale between water jacket and wate
r pump without
flowing through the radiator. In such case, as the cooling strength is low, the
water temperature can
rise rapidly to ensure that all parts of the engine can warm up uniformly and ra
pidly or prevent the
under-cooling of the engine. Due to short flow route and low flow rate of the co
olant, this
recirculation is referred to as minor recirculation, namely thermostat . water p
ump . engine
radiator . water jacket . thermostat.

(2) Major recirculation
When the water temperature within the engine rises to 95ºC, the main valve opens f
ully and the bypass
valve fully closes so that the coolant flows completely into the radiator. In su
ch case, the cooling strength
is increased to drive down the water temperature or keep it from being too high.
In such case, as the
coolant flow route is long with high flow rate, it s referred to as major recircul
ation, namely thermostat
water pump
.
engine oil radiator
.
water jacket
.
radiator
.
thermostat.
When the coolant within the engine is between two above-mentioned temperatures,
both the main valve
and bypass valve partially opens so that the major recirculation and minor recir
culation of coolant coexist.
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In such case, the coolant recirculation is referred to as mixed recirculation.

Engine block
water passage
3
Minor
recirculation inlet
1
Water return
port 2
(3) Major and minor recirculation routes
Water pump water
inlet 5
Major
recirculation
water port 4
Water pump
water inlet 6
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Water passage 7 from
water pump to engine
block

Minor recirculation route
Minor recirculation
inlet 1
Water
pump
Water pump outlet
5
Water passage 7 to
engine block
Engine block water Engine oil radiator
passage 3
Cylinder
head
Water return port 2 196 RELIABILITY IN ACTION
Major recirculation route
Water pump inlet 6 Water
pump
Water pump outlet
5
Water passage 7 to
engine block
Engine oil radiator
Engine block water
passage 3
Cylinder
head
Water
return port
2
Major recirculation
water port 4

VI. Lubrication System
1. Brief
Structure of lubrication system: Oil sump, engine oil pump, engine oil
radiator, engine oil filter, pressure limiting valve, main oil passage, and
engine oil pump suction pipe.
Function of lubrication system: The lubrication system is functioned to
continually convey a sufficient amount of clean engine oil at appropriate
temperature to the friction surfaces of all drive parts during the running of
the engine and form an oil film between friction surfaces to realize fluid
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friction, in order to reduce the friction resistance, lower the power
consumption, and relieve the wear of engine parts and promote the
working reliability and durability of the engine.
Lubrication mode: Pressure lubrication, splash lubrication, and lubrication
by lubricating grease.
Functions of lubricating oil: Lubrication, cooling, cleaning, sealing, and
rusting-proof.

Diagram of lubricating oil circuit
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1. Oil sump 2. Intake manifold 3. Engine oil pump 3a. Oil return valve 3b. Relie
f valve 4. Engine oil radiator
4b. Engine oil radiator bypass valve 5. Engine oil filter 6. Main oil line 7. Ma
in bearing 8. Connecting rod
bearing 9. Camshaft bearing 10. Oil passage to fuel injector orifice 11. Fuel in
jection orifice for cooling of
piston 12. Tappet control orifice for rocker pulse 13. Push rod 14. Rocker 15. O
il return passage to oil sump
16. Engine oil sensor 17. Oil passage to exhaust turbocharger 18. Exhaust turboc
harger 19. Oil passage to
compressor or hydraulic pump 20. Compressor 21. Hydraulic pump 22. Oil return pa
ssage of compressor or
hydraulic pump 23. To oil sump 24. From turbocharger to crankcase

2. Engine oil pump
DEUTZ engine oil pump is of rotor type. Installed within front hood of engine
and directly driven by crankshaft, it features as below:
. Installed within front hood to ease the disassembly.
. Directly driven by crankshaft, without additional drive parts.
. Small installation space.
. Large diameter, more teeth, and stable oil supply of pump.
. The rotor of oil pump is installed onto the crankshaft by three unevenly
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distributed keys and the pumped oil amount is controlled by the tooth
width of oil pump rotor. The oil supply amount of the oil pump is 50L/min
for 4-cylinder engine and 75L/min for 6-cylinder engine. The oil supply
amount is 90L/min for oil delivery pump of BF6M1013ECP.
Upon detection of low engine oil pressure during normal running of vehicle,
check the engine oil pump. Upon detection of clear internal wear or scratch,
replace the engine oil pump.

Oil pressure chamber
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Oil suction chamber Oil inlet

Radiator
The engine oil radiator is built in the
coolant circuit and is under series
connection on the upstream of the main
oil line to control the temperature of
lubricating oil by means of the
temperature of coolant. As the coolant
temperature can be controlled
automatically, the engine oil temperature
can also be controlled to a certain extent.
3. Engine oil radiator
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Radiator cap
Therefore, the engine oil temperature can
be controlled within normal range. When
the engine oil temperature is high, the
engine oil is cooled by the coolant. When
the oil temperature is low at the start and
warm-up of the engine, the engine oil
absorbs heat from the coolant to rapidly
increase the engine oil temperature, lower
the flow resistance, and help the
lubrication.

4. Route of lubricating oil
1. Oil sump
2. Engine oil radiator bypass
valve
3. Engine oil filter bypass
valve
4. Engine oil collector
Fan end
Engine
oil filter
Engine oil
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5. Engine oil pump
6. Supercharger
7. Main oil passage pressure
limiting valve
radiator

1
2 3
4
1
2 34
67
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5
8

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Lubricating
oil from
engine oil
pump
Oil passage
1
Oil
passage 2
Radiator Engine oil
filter element
Oil passage
3
Main Oil
passage 4
Oil passage 5, for lubrication of camshaft
Oil passage 6 for lubrication of
Route of lubricating oil circuit
205 RELIABILITY IN ACTION
crankshaft and oil passage 7 for
lubrication of connecting rod and
piston
8 Oil passage for tappet
and push rod
Rocker

VII. Electronic control system
1. Composition of electronic control system
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Sensor Electronic control unit (ECU) Electronically controlled
monoblock pump

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2. Sensors
(1) In the level of complete unit, ensure that the crankshaft sensor, camshaft
sensor, and engine oil pressure sensor work normally, or the complete
unit can t be started.
Crankshaft speed
sensor
Camshaft speed sensor
Coolant
temperature
sensor
Turbocharge
d air
temperature
sensor
Fuel
temperat
ure sensor
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Air pressure
sensor, within
ECU
Turbocharge
d air pressure
sensor
Engine oil
pressure
sensor
Throttle pedal position sensor

(2) Function of camshaft speed sensor:
The
crankshaft
sensor needs
15s to find
out the top
dead center.
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At the time of start, the determination of the 1st cylinder compression top dead
center
can be taken as the reserved function of crankshaft speed sensor.

(3) Crankshaft speed sensor
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The crankshaft speed sensor is installed on the front of the engine.
By measuring the tooth signal on the engine flywheel, it provides instant
speed of engine to the ECU for accurate timing and fuel amount control on
the engine.

(4) Fuel temperature/water temperature sensor
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The water temperature/fuel temperature sensor provides the engine
coolant/fuel temperature signal to the ECU and its sensing unit is a negative
temperature coefficient thermistor. The ECU continually collects the real-time
water temperature and fuel temperature to correct the fuel injection amount.

(4) Fuel temperature/water temperature sensor
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The intake pressure temperature sensor provides to the ECU the intake
temperature and intake pressure information at the downstream of enginecooler.
The pressure sensing unit is a silicone diaphragm and the temperature
sensing unit is a negative temperature coefficient thermistor. The ECU collects
the intake pressure and temperature information to correct the fuel injection
amount.

(5) Engine oil pressure sensor
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This sensor real-time detects the engine oil pressure information and
transmits to the ECU. When the engine oil pressure is out of normal range,
the ECU will restrain the engine power or control the flameout of the engine.

3. Main functions of ECU
(1) Start control
For an engine, to ensure the start reliability and
start smoke number emission requirements,
the fuel injection timing and start torque must
be set as per the method below:
Fuel injection timing = f (speed, fuel injection
amount, and coolant temperature)
Start torque = f (speed, coolant temperature,
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and start time).
The start control function is under activated
state, till the engine speed exceeds the start
end speed and the engine enters idling control.
The driver can operate the engine only under
the idling control state. The start end speed is
subject to the coolant temperature and
atmospheric pressure.

(2) Fuel injection timing adjustment
The adjustment of fuel injection timing is intended to meet the emission
regulations and fuel economy requirements as well as consider the cold start
and low noise. The adjustment of fuel injection timing is related to the
engine performance and additional correction.
Fuel injection timing = f (speed, fuel injection amount, cooling temperature,
intake pressure, and atmospheric pressure)
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(3) Malfunction Diagnosis
The electronic control unit incorporates the real-time self-diagnosis function.
Upon detection of malfunction, the ECU will save the malfunction
information and current environmental information into the ECU. At the
same time, the malfunction indicator lamp on the instrument panel flashes
to remind the driver of getting repaired by the service station. At the service
station, the repair personnel will connect special diagnostic tool to the ECU
and read out the malfunction information.

(4) Cold start auxiliary control
Under cold temperature, to improve the cold start performance of the
engine, the ECU will determine whether the intake preheating is required
and the required preheating duration depending on the current engine
temperature, which is realized through the control on the intake preheating
relay.
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(5) Engine protection function
It s intended to protect the engine under certain extreme conditions.
Under the working conditions such as over-high coolant temperature and
under-low engine oil pressure, the engine power will be lowered or it will
even lead to engine flameout, in order to protect the engine.

Section III Cause Judgment and Troubleshooting for Common
Malfunctions of Engine System
I. Diagnosis and troubleshooting procedure for malfunctions of DDE engine
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1. Thoroughly consider the malfunction cause by considering the engine as an int
egral
unit.
2. Thoroughly understand the information from the operator: Abnormal noise, work
ing
condition and environment, change of oil pressure or water temperature, abnormal
dust or smoke at occurrence of malfunction, consumptions of engine oil, fuel, an
d
coolant and their recent changes, smoke density, fuel in use, presence of engine
surge during idling or full speed running, presence of long-term idling, recent
temporary repair and repair information, previous occurrence of similar malfunct
ion,
information of part replacement, and status after previous treatment.

3. Conduct necessary checking: Engine
cleanliness, belt tension, presence
of external leakage of engine oil,
fuel, or water, levels of engine oil,
water, and fuel, engine sound,
presence of jitter, and presence of
smell, carbon deposit, oil mud, and
other abnormality beneath the
rocker cap at the time of
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disassembly.
4. Conduct correct analysis.
5. Conduct correct repairs.
6. Verify whether the repairs fulfilled
actually solve the malfunction.

II. Diagnosis and troubleshooting principle for malfunctions of engine
1. Upon detection of malfunction, firstly check whether the operation and
maintenance instructions are strictly followed and check for presence of
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substituting the maintenance with repair.
2. Poorly manufactured parts (such as hollow filter element), especially the
counterfeit products procured due to temptation of cheap prices, will greatly
shorten the service life of diesel engine.
3. At the occurrence of malfunction, exclude one by one
from simpleness to difficulty.
4. Do not replace any part easily before the malfunction
cause is found.
5. Pay attention to disconnect the battery during repair, in
order to prevent the start of engine.

III. Analysis of malfunction cases
1. Cause for difficult start or start failure
(1) Malfunction of starter electric lock
(2) The temperature is less than start limit temperature
(3) Malfunction of starter interlock
(4) Blockage of fuel delivery pump inlet passage
(5) Working failure of cooling fan/broken or loose belt (belt-driven fuel delive
ry pump)
(6) Battery depletion or malfunction (7) Loose or oxidized wires of starter moto
r
(8) Damage or engagement failure of starter motor
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(9) Incorrect valve clearance (10) Leakage of high pressure fuel pipe
(11) Malfunction of preheating plug (12) Damage of fuel injector
(13) Air content in diesel system (14) Dirty diesel filter and diesel strainer
(15) Incorrect engine oil grade or viscosity (16) Disqualified diesel
(16) No signal from sensor to ECU (18) Malfunction of starter relay
(19) ECU malfunction

Sensor input:
1. Crankshaft position
2. Camshaft position
3. Coolant temperature
4. Intake temperature
and pressure
5. Engine oil pressure
Electronic
control unit
ECU
Setting point:
Foot throttle position
sensor
Hand throttle position
sensor
Functional selection switch
Port:
Power supply
Function block
diagram of system
[1] Functional block diagram of starter system
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Actuator:
Electronically controlled
monoblock pump
Diagnostic port
CAN bus
Display functions:
Speed
Torque
Warning signal
Malfunction indicator
lamp

[2] Fuel line judgment
Malfunction symptom: While driving the rotation of engine with starter, there is
no
exhaust gas or start symptom of the engine.
Judgment method: Cylinder interruption method.
1. Outflow of diesel: It indicates that the malfunction occurs at the high press
ure
fuel line.
2. Air in out-flown diesel: The malfunction occurs in low pressure fuel line or
fuel
return line.
3. No outflow of diesel: The malfunction occurs at low pressure fuel line.
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No outflow of diesel
after cylinder
interruption
Check fan belt
Observe fuel
amount
Leakage of low
pressure fuel line
Blocked
Replace if broken
Adjust if loose
Normal
Replace if no rotation
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Check fuel delivery pump pulley
Normal
Repair

Check fuel delivery pump Outflow of fuel after cylinder
interruption
No pressure
Low fuel supply of fuel delivery pump
Pressure of manual fuel supply
Check and adjust regulator valve
Wear of housing
Soft check valve spring
Stagnation of fuel return check valve
Broken check valve spring
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II. Unstable running or start failure
(1) Working failure of cooling fan/broken or loose belt (belt-driven fuel
delivery pump)
(2) Incorrect valve clearance
(3) Leakage of high pressure fuel pipe
(4) Damage of fuel injector
(5) Air content in diesel system
(6) Blockage of diesel filter and diesel strainer
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(7) Disqualified diesel
(8) ECU malfunction
(9) Malfunction of speed sensor

III. Insufficient engine power
(1) Check the maximum idling speed with speedometer
Depending on the configuration of the engine, the maximum idling speed shall be
higher than the rated speed by 6~8%. The basic calculation equation is as below:
Maximum idling speed = Rated speed × 1.07
If the maximum idling speed is insufficient, check whether the throttle pedal ca
n reach
the maximum throttle position.
(2) Check the fuel injector for presence of leak through or cavitation due to in
sufficient
primary fuel line pressure.
(3) Check the low pressure fuel line system. The insufficient pressure of low pr
essure
fuel line will directly lead to insufficient power or ablation of fuel injector.
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The minimum fuel supply pressure of low pressure fuel line in 5bar system (unloa
ded):
1500-1899/min >4.2bar 1900-2500/min > 5.0bar
>2500/min >5.3bar
The pressure measuring point of the low pressure fuel line shall be the downstre
am of
the fuel outlet of the fine filter (namely at the fuel inlet of crankcase). If n
o
measurement space is available in this point, measure at the upstream of the fue
l
return valve (namely at the fuel outlet of the crankcase). Caution: Under rated
speed,
the pressure measured at the fuel outlet of crankcase is lower than the fuel pre
ssure at
fuel inlet of crankcase by approximate 1.0bar.

Causes for insufficient pressure of low
pressure fuel line:
- Blockage of fuel strainer and fine filter.
- Failure of fuel return valve.
- Over-high flow resistance in fuel delivery
pipeline from fuel tank to fuel delivery
pump.
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- Sufficient fuel supply pressure in fuel delivery pump.
- Excessive flow resistance in fuel delivery pipeline from fuel return valve
to fuel tank. In event of excessive resistance, the fuel return amount will
be insufficient and the fuel temperature will rise (the fuel temperature
shall not exceed 80ºC).

Checking Method:
(1) Provided that the filter element is not blocked, if the fuel pressure can t
be reached, check or replace fuel return valve.
(2) If the pressure is still insufficient, check the fuel delivery line for pres
ence
of over-high flow resistance. Method:
Supply the fuel on the upstream of fuel delivery pump directly with a fuel
barrel, in order to determine the over-high resistance due to fuel supply
pipeline and strainer from the fuel tank to fuel delivery pump.
Requirement: The fuel pipe inside diameter on the upstream of the fuel
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delivery pump shall be no less than 12mm and the fuel pressure at the inlet
of fuel delivery pump during the maximum idling speed shall be more than 0.5bar (or -0.35bar for Euro-II compliant engines).
(3) If the pressure is still insufficient, check the fuel return amount. Method:
Disassemble the fuel return end of the fuel return pipe from the fuel tank and
insert into an empty barrel. Measure the fuel return amount of the engine
under the maximum idling speed for 1min. The amount shall be above 8L.

IV. Black smoke
Root cause: Due to incomplete combustion of diesel, the incompletely
combusted carbon forms free carbon, which is floating within the combusted
gas and is exhausted along with the exhaust gas to form black smoke.
Malfunction Cause:
(1) Blockage of air cleaner and excessive intake
resistance. .
(2) Excessive fuel supply amount of fuel injection
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pump or over-high uneven fuel supply among
cylinders.
(3) Blockage of inter-cooler.
(4) Poor injection of fuel injector
(5) Low cylinder pressure.
(6) Poor quality of diesel.
(7) Insufficient cylinder pressure.

(2) If the air cleaner is normal and the black smoke is present during idling of
the
diesel engine, it indicates excessive fuel supply amount under idling condition.
Check the fuel injection pump.
(3) If the fuel supply of the fuel injection pump is normal, check the fuel supp
ly
timing of the fuel injection pump.
Diagnosis and troubleshooting method for black smoke:
(1) Disassemble the air cleaner and check and clean the
inter-cooler.
If the black smoke of diesel engine disappears, it
indicates that the air cleaner is too dirty and shall be
cleaned.
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(4) If the fuel supply timing is correct, check the working condition of cylinde
rs by
single cylinder interruption method. If the speed variation is not obvious and
the black smoke symptom disappears after the fuel interruption of certain
cylinder, it indicates the poor working of this cylinder, probably the excessive
fuel supply amount of branch pump, poor mist injection quality of fuel injector,
or under-low cylinder pressure. After the cause is determined, resolve the
cause.
(5) If no problem is detected in above-mentioned items, the diesel quality is
probably too bad, which leads to incomplete combustion. Replace the diesel.

V. White smoke
1. Cause: The diesel within the combustion chamber is vaporized and not
combusted and is drained in milk white from the exhaust pipe or the water
content in the diesel is vaporized in the cylinder to form steam, which is
exhausted in white from the exhaust pipe.
Malfunction Cause
(1) Water content in diesel or water leakage due to burst cylinder gasket or
cracked cylinder head or cylinder block, leading to water ingress of cylinder.
(2) Low cylinder pressure.
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(3) Under-low working temperature.
(4) Poor injection quality of fuel injector.
(5) Poor diesel quality.
(6) Late fuel supply moment of fuel injection
pump.

Diagnosis and troubleshooting method for while smoke:
(1) During the running of diesel engine, loosen the air bleeding screw or high p
ressure fuel
pipe connector on the monoblock pump and check the fuel flow for presence of wat
er
drops. IF no water drop is present, it indicates that the white smoke in exhaust
pipe is
caused by the water content in diesel. Fully drain the water from fuel tank, die
sel filter,
and high and low pressure fuel lines.
(2) If there is no water in diesel, open the water tank and observe the water ta
nk for
presence of air bubble. If the air bubble is present, it indicates the ingress o
f coolant into
the cylinder. Disassemble the cylinder head, find out the malfunction portion, a
nd repair
or replace.
(3) If there is no ingress of water into cylinder, check the cylinder pressure.
If the cylinder
pressure is too low, check and repair.
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(4) While traveling in winter, if the diesel engine is frequently working under
low
temperature, it will lead to presence of white smoke in exhaust pipe. Check whet
her the
shutters are closed securely and the insulation sleeve is good. Otherwise, the r
epair is
required.
(5) If no problem is detected in above-mentioned items, check the fuel injection
quality of
the fuel injector.
(6) If the fuel injection quality meets the requirements, check the fuel supply
timing and
adjust as specified. The diesel quality is of certain influence on the white smo
ke of diesel
engine exhaust pipe. If necessary, replace with new fuel for comparison testing.

VI. Blue smoke
A great amount of engine oil that enters into the combustion chamber is
vaporized to oil gas and exhausted from exhaust pipe before being combusted.
Malfunction Cause:
(1) Excessive engine oil in oil sump.
(2) Penetration of engine oil into combustion chamber due to damaged oil seal
of turbocharger.
(3) Serious permeation of engine oil in cylinder.
(4) Wear of valve stem and pipe, leading to excessive gap and failure of valve
pipe seal.
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Diagnosis and troubleshooting method for blue smoke:
(1) Check the engine oil level in oil sump. If above specified level, drain the
excessive engine oil.
(2) If the engine oil level is normal, disassemble the fuel injector and check
the oil dirt and carbon deposit of the fuel injector. In event of serious oil
dirt and carbon deposit, it indicates the serious permeation of engine oil
on cylinder or excessive gap of valve stem and pipe. Disassemble the
cylinder head to find out the cause and resolve the malfunction.
(3) Check the working status of seal rings of intake and exhaust valve pipes.
(4) Check the sealing status of turbocharger.
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VII. Engine oil pressure warning
Step 1 Check the oil sump for under-low (over-high) oil level or shortage of oil
and
check for qualified engine oil trademark. ;
Step 2 Check the engine oil filter and cooler for excessive resistance.
Step 3 Check for over-high water temperature of cooling system and check for
over-high engine oil temperature.
Check turbocharger, strainer, engine oil pipeline, and connector gasket for
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Step 4 presence of blockage or rupture.
Step 5 Check the pressure limiting valve of main oil line for excessive or insuf
ficient
adjustment.
Step 6
Check the bushings for excessive gap or damage, check whether the engine
working hours reach the overhaul period, and check the parts for serious
wear.

VIII. Over-high water temperature
Step 1
The water temperature is high when the diesel engine runs under high load.
Check whether the oil sump level, water tank level, and water pump belt are
normal.
Step 2 Check whether the thermostat and connecting water pipes are normal.
Step 3 Check the water temperature gauge and water temperature sensor for
normal functioning.
Step 4 The checking of fan found out that the external surfaces of the water tan
k are
really dirty and the radiator port is completely blocked by dirt. ;
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IX. Oil-water mixture
1. Damage of engine oil radiator sealing
gasket or engine oil radiator.
2. Damage of cylinder gasket.
3. Cracking and blister of cylinder block.

CONTENTS
Structure and Principle of Torque Converter
Structure and Principle of Transmission
Oil Supply and Lubrication System of ZF Transmission
Electric Control System of ZF Transmission
Operation and Maintenance of ZF Transmission
Common Malfunctions and Troubleshooting of ZF
Transmission
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1
Section I Structure and Principle of Torque Converter
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Figure 4-1 Diagram of Transmission System for LG958L Loader
1. Torque converter 2. Rear drive axle 3. Transmission 4. Drive shaft 5. Front d
rive axle
2 3 4 5
The hydraulic torque converter is installed between the engine and transmission
and is mainly function to change the torque outputted by the engine so that the
torque output of the turbine will probably exceed the input torque of engine via
pump impellor so as to improve the power performance of loader and ensure the
stable transmission.

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Figure 4-2 Internal Structure Diagram of ZF Torque Converter
Torque converter: It s mainly composed of pump impellor, turbine, idler pulley (co
mmonly referred
to as three-element part. The torque converter manufactured by Hangzhou Advance
incorporates
two turbines, namely tier-1 and tier-2 turbines, so that it's referred to as fou
r-element part), and
housing and it s capable of automatically regulating the torque output and speed o
utput of the
engine.

Working principle of torque converter: Some blades are uniformly arranged within
each working
Pump impellor
Guide pulley
Turbine
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impellor of the torque converter. These blades work together with each other to
form an
enclosed annular space, in which the fluid can recirculate. When the engine flyw
heel drives the
rotation of pump impellor, the blades of the pump impellor drives the rotation o
f fluid. Under the
action of the centrifugal force, the fluid flows from the inner edges of blades
to the outer edges
to impact the turbine blades and drive the rotation of turbine for torque output
. The flowing fluid
flows from the outer edges of blades to the inner edges of blades within the tur
bine to impact
the blades of guide pulley and then returns to the pump impellor along the blade
s of guide
pulley for next cycle. The torque conversion of the hydraulic torque converter i
s attributed to the
presence of guide pulley. The guide pulley is connected with the torque converte
r housing via
fixed guide pulley seat and the torque converter is connected with engine flywhe
el via elastic
plate.

1. Characteristics of ZF transmission:
. 4 forward gears and 3 reverse gears
. High working efficiency
. Low repair rate
. Ultra-long service life
. Low fuel consumption
. Low noise
Section II Structure and Principle of Transmission
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Structural diagram of ZF
transmission

Connecting
flange with
torque converter
and engine
ZF
transmission
Torque
converter
2. Structure of ZF
transmission
The ZF transmission is
mainly composed of
electronic control units
(gearshift operating
lever, electric control
box, and gearshift ZF
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valve) and mechanical
gearshift transmission
(6 clutches and drive
gears and output
shaft).
transmission
Transmission
ZF transmission
Gearshift
operating lever
ZF transmission

Rear view of transmission
Oil filter
1st power
takeoff port
Output speed
Optional
emergency
pump port
Clutch K1
Clutch KV
Clutch KR
2nd power
takeoff
port
1st power
takeoff port
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sensor
Transmissio
n filler port
Output
flange, fitted
with parking
brake
Clutch K2
Clutch K3
Clutch K4
Clutch KV
Removed part
on right side of
transmission

Press once KD button
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Use of KD button function of ZF transmission in actual applications

Electric control box of ZF
transmission
Gearshift valve of ZF transmission
(including pressure measuring point)
Clutch K3
Two-stage
pressure control
valve
1Mpa
reducing valve
M4 Oil pipe to twostage
pressure pilot
control valve
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Solenoid valve
(resistance: 90±10Ohm)
During electric welding of
main unit for repair, unplug
the connector of electric
control box
Forward
clutch KV
Reverse
clutch KR
Clutch K2 K4 clutch
System
pressure
Clutch K1

Clutch
KV
Clutch
K1
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Clutch KV and K1 of ZF transmission
Power
drive
gear
Schematic diagram of clutch

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Clutch KV and K1 of ZF transmission

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Clutch KR and K2 of ZF transmission

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Clutch K3 and K4 of ZF transmission

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The travel for pistons of various clutches is 1.8~2.4mm.

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The axial clearance is 0.1~0.3mm after assembly of various shafts.

Route diagram for various gears of ZF transmission
(4 forward gears and 3 reverse gears)
Internal structural diagram of ZF transmission
3. Route diagram for various gears of ZF transmission
1st forward
Output gear
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Route diagram for various gears of ZF transmission (4 forward gears and 3 revers
e gears)
3rd forward
2nd forward gear
gear
Output
Output
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Route diagram for various gears of ZF transmission (4 forward gears and 3 revers
e gears)
4th forward
gear
1st
reverse
gear
Output
Output Countershaft
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Route diagram for various gears of ZF transmission (4 forward gears and 3 revers
e gears)
2nd reverse
gear
3rd reverse
Output gear
Output
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Section III Oil Supply and Lubrication System of ZF Transmission
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Oil recirculation schematic diagram of transmission with two-stage pressure cont
rol valve

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Cast aluminum gearshift control valve with 5 solenoid valves and two-stage press
ure control valve

Section IV Electric Control System of ZF Transmission
1. ZF built-in electric system
1. Electric control
box EST-17T
2. Transmission
3. Gearshift
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operating lever
DW-2
4. Connecting port to
circuits of
complete machine
5. To transmission
solenoid valve
6. To output speed
sensor

2. ZF built-in harnesses and connectors
Cable electric control
box connector
Complete machine wire connector
Gearshift operating
lever connector
Sensor 2
Sensor 1
Lever 5
Yellow
Green
Pink
Blue Purple
Black
Red
Grey
(I)
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Solenoid valve connector Starter interlocker 584
Pressure switch 600
Lever 8
Lever 6
Lever 2
Lever 7
Lever 9
Lever 10
Lever 4

3. ZF peripheral electric system
To electric control box
Intermediate relay
(power cutoff)
Intermediate
relay
(reversing)
Intermediate relay
(starter interlocker)
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To instrument panel electric control
box working indicator
Parking brake indicator switch
Brake switch (left)
Brake switch (right)
To brake lamp
To starter relay
signal terminal
To brake
lamp
To starter relay terminal G2

. Neutral start interlocking
function
. Neutral locking function.
Rotate the red neutral
gear locking switch.
. Power cutoff function
during braking at 1st gear
Lock direction
KD button
4. Gear selector
The gear selector is the gear signal input device of the ECU. Its normal
functioning directly influences the normal functioning of the system. Use
the multimeter for measurement and judgment.
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or 2nd gear.
. Kick-down function (KD
button)
Gearshift operating lever of ZF transmission
Neutral gear locking switch

The continuity and logic relationships between the red wire in the harness
of gear selector and other wires and various gears are as below:
With red FI F2 F3 F4 R1 R2 R3
Blue v × × v v × ×
Green × × v v × × v
Black v v v v v v v
Yellow v v v v × × ×
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Grey × × × × × × ×
Pink × × × × v v v
Purple × × × × × × ×
If the grey wire is under continuity state, the complete machine can t be started.
The purple
is the KD function, the pink is the control of reverse gear, and the yellow is t
he forward gear.

5. Electric control box
As the main control part for judgment of gear, the electric control box analyzes
the
signal of selector and issues command to the solenoid valve.
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6. Gearshift valve
The gearshift valve is the actuator unit that engages and disengages the
control gear of the solenoid valve as per the command of ECU.
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1) Sequence of solenoid valve: 4, 3, 5, 2, and 1 from top to bottom.
2) If the O-ring is not properly seated, it will easily cause oil leakage at
side cap.
3) The resistance of solenoid valve is 90±10O.

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Clutch for
various gears KV K1 K2 K3 K4 KR
Control
solenoid valve M3 M2 and
M4 M4 \ M5 M1

7. Speed sensor
Transmission speed sensor
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Resistance of speed sensor:
1020±100O

1. Operation Precautions
(1) To check the transmission oil level, the engine shall idle run (at approxima
te
1,000r/min) and the oil temperature shall be at normal working temperature.
(2) When the oil temperature is at 40ºC, the oil level shall be between the middle
mark and lower mark of the oil dipstick.
When the oil temperature is at 80ºC, the oil level shall be between the middle
mark and upper mark of the oil dipstick.
Section V Operation and Maintenance of ZF Transmission
Hot oil level zone
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(3) Periodically replace the transmission oil and replace the filter strictly as
per the
maintenance schedule.
(4) Before starting the engine, ensure that the operating lever is at neutral ge
ar.
(5) Before starting up the machine each time, release the parking brake.
Cold oil level zone

(6) When it's necessary to hoist the transmission to fit the engine with transmi
ssion or
separate the engine from the transmission, avoid the fall-off of the torque conv
erter.
(7) While parking the machine, the gearshift operating lever shall be at neutral
gear.
(8) The normal working oil temperature shall be within 80~110ºC. Under heavy load,
the oil
temperature is allowed to rise to 120ºC for a short time. Pay special attention to
the
controlling oil pressure of the transmission. Upon detection of any abnormality
in the
transmission during operation, immediately stop the machine for checking.
(9) When the electric welding is required for repair in event of the machine mal
function, make
sure to disconnect the cable connector from the EST
electronic control unit (to
cut off
the current to the electronic control unit), or the impact current during the el
ectric
welding will probably burn out the electronic control unit.
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2. Operations
(1) Preparations and maintenance before driving
Before the operation of the transmission, make sure to add an
appropriate amount of lubricating oil as per the specified specification
of lubricating oil. While adding oil to the transmission for the first
time, make sure to take into consideration that the oil radiator, filter,
and connecting pipeline must be fully filled with oil. Therefore, the
lubricating oil amount to be added for the first time will be much
more than the lubricating oil amount to be added during normal
maintenances.
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The oil level can be checked only when the operating level is at
neutral gear. While checking the oil level, insert the oil dipstick to the
dead end of the dipstick tube. While cleaning the filter of main oil line,
pay attention to prevent the ingress of dirt and sediments into the oil
circuit. Therefore, place a cover plate to guard the parking brake
against being dipped by the oil.
While installing the filter, pay attention not to tighten excessively.

(2) Driving and gearshift
To start the engine, make sure that the gearshift operating lever is at neutral
gear.
For the purpose of safety, before starting the engine, the parking brake shall b
e
under braked state to prevent the startup of machine due to the start of engine.
After
the engine is started, release the parking brake, select the driving direction a
nd gear,
and depress the throttle slowly to start up the machine. During the traveling of
the
machine, the torque converter substitutes the function of main clutch. When the
road
condition is good, it s possible to travel at higher gear.
If the machine stops traveling, but the engine is still running and the transmis
sion is
shifted to a gear other than neutral gear, the engine will not stop at that time
. On a
straight road, the machine will probably crawl, as the idling of engine will gen
erate a
certain traction force via the torque converter. The appropriate method is to pl
ace
the parking brake at braked state whenever the machine is parked.
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To park the machine for a long period, make sure to shift the operating lever to
neutral gear. During the traveling of the machine, make sure to release the park
ing
brake. Due to the influence of the torque converter, while shifting from a high
speed
gear to a low speed gear, the engine speed will increase, especially at the time
of
gear jump. Therefore, whenever the condition permits, while shifting from a high
speed gear to a low speed gear, depress the foot brake for slow deceleration bef
ore
the gearshift. When the machine is traveling at high speed or changing driving
direction, lower the engine speed.

(3) Driving and gearshift
The maximum oil temperature at outlet of torque converter shall not exceed 120ºC.
For non-malfunctioned control subassembly and transmission with sufficient
traveling mileage, the temperature shall not be too high. If the oil temperature
exceeds 120ºC, make sure to stop the machine and check for presence of external
oil leakage. At the same time, shift the transmission to neutral gear and run th
e
engine at 1,200~1,500rpm. In such case, the oil temperature will lower rapidly t
o
the normal value (approximate within 2~3min). If the oil temperature fails to dr
op,
certain portion within the system is malfunctioned. Make sure to resolve the
malfunction before proceeding the operations.
Normal range for gearshift oil pressure: 1.6~1.8MPa (16~18bar).Normal range for g
earshift oil pressure: 1.6 1.8MPa (16 18bar). To monitor the To monitor the
control pressure, make sure to install a pressure gauge or pressure monitoring
unit. If the pressure drops to below the specified minimum pressure after a cert
ain
gear is engaged and the clutch is depressed (though the pressure at moment of
gearshift will drop automatically temporarily), make sure to resolve the cause o
f
pressure drop. The under-low control pressure will lead to damage of clutch, as
the
clutch is short of sufficient contact pressure and the continual skid of frictio
n plate
leads to over-heating.
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3. Maintenance
(1) Check the oil level.
- Park the machine on a level place.
- Shift the gearshift operating lever of the transmission to neutral gear N and
set the parking brake at braked position.
- Idle run the engine at approximate 1,000r/min.
- Counterclockwise the oil dipstick and take out and wipe clean the oil dipstick
.
- Insert the oil dipstick into the oil dipstick tube and tighten to place. Wait
for 3s
and take it out (measure for at least two times).
- When the oil temperature is at 40ºC, the oil level shall be between the middle
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mark and lower mark "Cold of the oil dipstick.
- When the oil temperature is at 80ºC, the oil level shall be between the middle
mark and upper mark "Hot of the oil dipstick.
Caution: Checking the oil level under cold state is to ensure sufficient
recirculation flow for transmission and torque converter and the decisive criter
ion
for oil level is to meet the oil level requirement under hot state.

(2) Replace the oil.
Make sure to replace the oil for the first time after the
for the first 100 hours. Afterwards, replace the oil once
hours or once a year. At the replacement of oil, park the
place. Under the working temperature of the transmission,
drainage plug and seal ring and fully drain the used oil.
- Start the engine and idle run the engine.
- Shift the transmission operating lever to neutral gear
- Add oil to the upper mark of the oil range Cold .
- Set the parking brake at safe place.
- Shift to every gear for once.
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- Check the oil level and when necessary add the oil.
Part Name Initial oil
replacement
Normal oil
replacement Oil specification Checking of oil
level
Transmission
(4WG200)
After 100
working hours.
Replace filter
as well.
At interval of
1,000 working
hours, but no
more than 1 year.
Replace filter as
well.
Mobil Delvac 1300
SAEl5W40 or Titan
universal oil HD15W-40
(manufactured by
Shanghai Desi Oils Co.,
Ltd.)
Before
operation each
day

machine is working
every 1,000 working
vehicle at a level
take out the oil
N .

(3) Replace oil filter.
Make sure to replace ZF fine filter at the replacement of oil
each time. Replace as per the following requirements:
- Apply a thin film of oil onto the seal ring.
- Push in the filter, till it comes into contact with the sealing
surface on the transmission, and then tighten for approximate
1/3~1/2 turn with hand.
- Add oil.
- Start the engine.
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- Idle run the engine (at approximate 1,000r/min). When the
transmission oil temperature reaches working temperature,
check the transmission oil level.
- Check whether the filter is tightened. If necessary, tighten again
with hand.

(4) Assembly precautions for ZF transmission:
I. Fitting and connection between ZF transmission and engine
1. Wipe clean the anti-rusting oil from the engine flywheel and the inside of
flywheel housing to be fitted.
2. Place the transmission at the fitting station and disassemble the fixing wood
plate from the torque converter middle flange on the transmission (It's
absolutely prohibited to slide outward the torque converter and its middle
flange).
3. While fitting and connecting the transmission with engine, without moving the
transmission, fit the flywheel housing of engine with the torque converter
connecting housing on the transmission and ensure that the middle flange of
torque converter enters into the junction surface of the engine flywheel.
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Fall-off of torque
converter

4. Completely fit and fix the connecting housing of torque converter and
flywheel housing of engine with three bolts and then tighten the connecting
bolts of torque converter middle flange and engine flywheel in turn.
5. Finally tighten all connecting bolts of torque converter connecting flange an
d
engine flywheel housing.
6. Through the square observation port on the connecting housing of the
torque converter, check the connecting elastic plate between torque
converter and its middle flange for presence of squeezed deformation
(Under normal status, the plane of elastic plate shall be perpendicular to the
axis of middle flange).
7. Control size for connecting the connecting housing of transmission with
engine flywheel housing: 39.6±0.5.
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II. Precautions for installation from transmission and radiator oil pipe
The tightening depth for the connection between pipe connector and
transmission shall not come into contact with the core of the backpressure valve
.
If the insertion depth exceeds 21mm, it will cause working failure of the
backpressure valve due to blockage of core and obstruct the recirculation oil li
ne
between transmission torque converter and radiator so that the working oil of th
e
torque converter can t be sufficiently recirculated for heat radiation to cause
over-high oil temperature of the torque converter.

III
.
Installation of torque converter temperature sensor
1.
While installing the temperature sensor at the oil temperature measuring
point of the torque converter, upon detection that the top of the sensor is
pushed against the core of backpressure valve, do not forcibly screw in the
sensor. Please timely notify the technician to solve the malfunction, in order
to prevent the damage of sensor and valve core due to interference.
IV.
Fluid within side cap of gearshift operating valve
1.
After the engine is started, a part of oil in the gearshift operating oil system
will ill overflow fl and return t to t th the tank k vivia the oil il li line wi
thin ithi th the side sid cap of f the
d tth
th
gearshift operating valve. Therefore, when the side cap is opened during the
running of the engine, the oil will spray from the valve body. Therefore, while
installing the side cap, make sure properly seat the O-ring of side cap and
clamp the hoop to the required place, in order to prevent the so-called valve
leakage symptom.
2.
Do not open the side cap of gearshift operating valve at will.
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V. Speed sensor
1. The gap between the end of speed sensor and the tooth top of gear is
0.5~0.8mm. The disassembly of sensor without prior consent and the
incorrect installation will lead to damage of the sensor.
Do not disassemble the speed sensor without prior consent.
2. The service personnel is disallowed to add or remove the adjustment
washer at the time of assembly.
Speed
sensor
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VI. ZF cables
1. While arranging the cables, ensure that the cables at all positions
are free of friction with any other part.
2. The cables at all positions shall be correctly fixed.
VII. Electric control box
1. At the time of electric welding, unplug the connector of electric
control box to disconnect the electric control box from circuits and
prevent the burnout of electric control box.
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2. Guard the electric control box against moisture and rainfall.

Section VI Cause Judgment and Troubleshooting
for Common Malfunctions of ZF Transmission
1. No gear, though the complete machine can be started.
 Check oil level
 Check the cable for presence of worn damage.
 Check the connectors and fuses
 Check whether the power voltage is at a stable normal value.
 Check the parking brake for normal functioning.
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 Check for normal power connection between engine and torque
converter.
 Check for normal gearshift oil pressure.
 Check for normal functioning of gearshift operating lever.
 Check for normal functioning of solenoid valve.

2. No 3rd gear or 4th gear is available, though the 1st gear and
2nd gears are available in complete machine.
» Check oil level
» Check cable connectors for normal connections.
» Check cables for worn damage.
» Check speed sensor for normal functioning.
» Check lever for normal functioning.
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3. No 1st gear or 2nd gear is available, though the 3rd gear and
4th gears are available in complete machine.
» Check the cables for normal connection.
» Check pressure sensor for normal functioning.

4. Noise of transmission
» Check oil level
» Check the connecting bolts between transmission and frame
and engine for presence of looseness.
» Check the drive shaft and its support for normal functioning.
» Check the hydraulic pump for abnormality.
» Check the articulations for normal functioning.
5. Weak complete machine
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» Check oil level
» Check whether the gearshift pressure is at 1.6~1.8MPa.
» Check for normal power of engine.
» Check the oil for improper trademark, deterioration, and
presence of air bubble.

Overview of LG958L Drive Axle
CONTENTS
Structure of LG Drive Axle
Structure and Principle of Main Drive
Structure and Principle of Differential
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Half Shaft
Wheel Reducer
Cause Analysis of Common Malfunctions of Drive Axle

The drive axle of the wheel loader is located at the end of the transmission sys
tem
and is the general term for all transmission mechanism between the drive shaft a
nd
the drive wheels. It s mainly functioned to transmit the torque from the drive sha
ft
to the drive wheels to reduce the output speed of the transmission and increase
the
torque and realize the differential function between the wheels on two sides. In
addition, the drive axle housing also plays a role for load carrying and power
transmission.
The wheel loader generally adopts drive mode of both front and rear axles, namel
y
4-wheel drive.
The LG958L loader adopts A510A drive axles. The front axle is fixed on the front
frame and the rear axle is of swing type drive axle and is installed on the rear
frame
Chapter V Drive Axle
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via rear axle bracket. The rear axle is capable of vertical swing of ±11º with respe
ct to
the rear frame, with the purpose of guaranteeing the stable ground touch of four
wheels and improving the trafficability of loader while the complete machine is
traveling on a rough road.
In addition to the different installation modes, another difference between the
front
axle and rear axle is the main drive. For the main drives of the front and rear
drive
axles, the spiral direction of the spiral bevel gear pair is different. The main
drive of
the front axle is in left-handed direction and the driven spiral bevel gear is i
n righthanded
direction. The spiral direction of the rear axle is in opposite direction of the
front axle.

Section I Structure of Drive Axle
The drive axle of the loader is
mainly composed of axle
housing, main drive (including
differential), half shaft, wheel
reducer, tire, and wheel rim
assemblies. Its structure is
shown in Figure 5-1.
The drive axle is installed on
the frame to carry the load
transmitted from the frame
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and convey to the wheels. The
housing of the drive axle is the
mounting carrier for main
drive, half shaft, and wheel
reducer.
Figure 5-1 Structure of Drive Axle
1 Tire 2
Wheel rim assembly 3
aft
6 Planetary gear 7
Sun gear 8
12 Axle housing wheel support 13

Planetary carrier 4

Inner gear ring 5

Planetary sh

Wheel rim nut 9
Bearing 10 Bearing 11
Oil seal
Half shaft 14
Breather hole 15
Main drive

Section II Main Drive
1. Structure of main drive
The main drive is functioned to further reduce the speed and increase the torque
for the power transmitted from the transmission and alters the rotating axis of
input shaft by 90º and transmits to the wheel reducer via differential and half
shaft.
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The structure of main drive is shown in Figure 5-2.
The main drive is mainly composed of differential and main reducer that is
composed of one pair of spiral bevel gears.
Figure 5-2 Main Drive

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Cylindrical
roller bearing
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To ensure sufficient carrying rigidity of the drive spiral bevel gear, the drive
spiral bevel gear is integrated with the shaft. Its front support is on two
tapered roller bearings that come into close contact by small ends and its rear
support is on the cylindrical roller bearing to form transversal support.
Tapered roller
bearing

Differential
right housing
Differential
left housing
Tapered roller
bearing
Carrier
Tapered roller
bearing
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The annular driven bevel gear is fixed on the flange on the right housing of
the differential by bolts. The differential housing is supported by two
tapered roller bearings within the seat bores on two ends of the carrier.
Driven bevel
gear
Bolt

Tapered roller
bearing
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While assembling the main reducer, the tapered roller bearings shall have certai
n
assembly preload, namely the tapered roller bearings shall be applied with certa
in
preload on the basis of eliminating the bearing gap. To adjust the preload of
tapered roller bearings, the adjustment washer is installed on one end of the sp
acer
bushing between the bearing inner races. If too tight, increase the total thickn
ess of
washer. Otherwise, reduce the total thickness of washer.
Spacer
bushing

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It s intended to reduce the axial movement of gear shaft due to the
axial force generated during the transmission of bevel gears, in order to
promote the support rigidity of the shaft and guarantee the normal
engagement of bevel gear pair. However, the gear shaft can t be too
tight, or it will easily accelerate the wear of tapered roller bearing.
The pre-tightened torque of the tapered roller bearing can be obtained
by measuring the rotating torque of the drive bevel gear (as shown in
Figure 5-3). Generally, the rotating torque is 1.5~2.6N.m.
Figure 5-3 Measurement of bearing rotating torque

Thrust bolt
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To guarantee the sufficient support rigidity of the drive bevel gear, the thrust
bolt is
installed on the back of the driven spiral bevel gear to restrain the deformatio
n of
the driven spiral bevel gear, in order to prevent the excessive deformation of d
riven
spiral bevel gear from impairing the normal working. During the assembly and
debugging, pay attention to generally adjust the gap between the back of the
driven spiral bevel gear and the end of thrust bolt to 0.2~0.4mm.
Adjustment method: Screw in the thrust bolt, till it comes into contact with the
large spiral back. Then, screw out by 1/4 turn and lock the thrust bolt.

Tapered roller
bearing
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The preload for the tapered roller bearings supporting the differential housing
is adjusted
by rotating the adjustment nuts on two ends. At the time of adjustment, rotate t
he drive
bevel gear with hand to position the bearing rollers to correct places.
After the proper adjustment, the differential subassembly shall be capable of be
ing rotated
by a torque of 2.9~3.9N.m.
It must be pointed out that the adjustment of preload for tapered roller bearing
shall be
conducted before the engagement of the gears.
Adjustment
nut

2. Adjustment of engagement status for spiral bevel gears
The adjustment of engagement status for spiral bevel gear refers to the adjustme
nt
of backlash and engagement contact area.
While adjusting the backlash of spiral bevel gear pair, press the probe of dial
gauge
against the tooth face at large end edge of driven spiral bevel gear and then ro
tate
the driven spiral bevel gear to directly measure the backlash, as shown in Figur
e 5-4.
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Specific measurement method of backlash:
Fix the stand of dial gauge on the bracket, place the probe of dial gauge
perpendicular to the tooth face of driven spiral bevel gear, rotate the driven s
piral
bevel gear back and forth with hand, and observe the variation amplitude of the
dial gauge, which is the measured backlash. Generally, it s required to measure at
3~4 different places along the circumference. The backlash shall be 0.20~0.35mm.
Figure 5-4 Measurement of Backlash

Measurement method of engagement contact area:
While measuring the engagement contact area of bevel gear pair, firstly
apply red paint (such as red lead) to the teeth (generally three teeth) of the
driven spiral bevel gear, rotate the driven spiral bevel gear repeatedly with
hand, and check the contact trace. The correct engagement status is as
below: The contact area shall be no less than 60% in both tooth length and
tooth height directions and the engagement trace shall be in the middle
with slight offset towards small end in tooth height direction and shall
slightly close to the small end in tooth length direction, as shown in Figure
5-5. Forward carrying face Large end
297 RELIABILITY IN ACTION
Figure 5-5 Correct engagement trace
Reverse carrying face
Contact area closes to center Contact area closes to large end and tooth top

Adjustment of backlash:
The backlash is adjusted by rotating the adjustment nut to change the position o
f driven
spiral bevel gear (when necessary, adjust by moving the drive spiral bevel gear
assembly).
If the gap is above the specified value, close the driven spiral bevel gear towa
rds the drive
spiral bevel gear. Otherwise, move it away from the drive spiral bevel gear. To
maintain the
properly adjusted preload for the differential tapered roller bearings, the numb
er of turns
the adjustment nut on one end is screwed in shall be equal to the number of the
turns the
adjustment nut on the other end is screwed out.
Adjustment method for engagement contact area:
a. When the engagement trace closes to the large end or small end of the gear, f
irstly
move the axial position of driven spiral bevel gear. If there is no change of ba
cklash,
adjust the axial mounting position of the drive spiral bevel gear.
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b. When the engagement trace closes to the tooth top or tooth root of the gear,
firstly
move the axial position of drive spiral bevel gear. If there is no change of bac
klash,
adjust the axial mounting position of the driven spiral bevel gear.
. The position of drive spiral bevel gear is changed by adjusting the thickness
of
adjustment washer.
. The position of driven spiral bevel gear is changed by moving the adjustment n
ut. To
prevent impairing the tension of the tapered roller bearings on two ends of
differential, the number of turns the adjustment nut on one end is screwed out s
hall
be equal to the number of the turns the adjustment nut on the other end is screw
ed
in.

Contact area of
driven bevel gear tooth
face
Adjustment method Movement direction of
gear
Move the driven gear towards
drive gear. If the backlash is too
small, move outward the drive
gear.
Move the driven gear away from
drive gear. If the backlash is too
large, move inward the drive
gear.
Table 5-1 Adjustment of Contact Area and Backlash during Installation of Spiral
Bevel Gears
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The adjustment of contact area is of great influence on the operation performanc
e
and service life and must be conducted carefully.
Move the drive gear towards
driven gear. If the backlash is too
small, move outward the driven
gear.
Move the drive gear away from
driven gear. If the backlash is too
large, move inward the driven
gear.

3. Judgment method for rotation direction of spiral bevel gear
The spiral direction of the spiral bevel gear is expressed by the tooth trace di
rection,
for which the judgment method is as below:
Observed towards the tooth face of bevel gear, the spiral bevel gear is left-han
ded if
the tooth trace is in counterclockwise direction from small end to large end,
otherwise the spiral bevel gear is right-handed.
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Right-handed gear Left-handed gear

Front axle drive spiral bevel gear,
left-handed
Front axle driven spiral bevel gear,
right-handed
Judgment examples
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Rear axle drive spiral bevel gear,
right-handed
Rear axle driven spiral bevel gear,
left-handed

1. Structure of differential
The drive axle differential of the wheel loader adopts symmetric bevel gear
differential. It s mainly composed of differential left and right housings, cross
shaft, four planetary bevel gears, and two half shaft gears (as shown in Figure
56).
Section III Structure and Principle of Differential
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1 Bearing 2
Left housing 3 Gasket 4
Half shaft gear 5
Washer 6 Planetary
gear 7 Driven gear 8
Right housing 9
Cross shaft 10
Bolt
5-6 Breakdown diagram of differential constituent parts

The differential left and right housings are fitted by bolts. The driven spiral
bevel gear
of the main drive is fixed on the flange of differential right housing by bolts.
The
journal of the cross shaft is embedded in the bore formed by corresponding slots
on
the parting surface between left and right housings. Each journal is attached wi
th a
straight bevel gear (planetary gear) under floating state, which is engaged with
two
straight bevel half shaft gears. The journals of two half shaft gears are suppor
ted in
corresponding left and right seat bores of the differential housings respectivel
y and
are connected with half shaft via inner spline.
The differential is mainly functioned for differential function against the uneq
ual speed
between left and right wheels, in order to reduce the wear of tires.
While traveling linearly under same road condition, there is no relative movemen
t
between planetary gear and half shaft gear and two shaft shafts rotate under sam
e
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speed. The differential starts to act under the following conditions:
. While traveling on rough road.
. While making a turn: The inner and outer wheels on one same axle have differen
t
traveled distances and speeds and the left and right half shafts rotate under
different speeds. In such case, there is a relative rotation between planetary g
ear
and half shaft gear to adapt to two unequal rotation speeds.
. While changing the rotation travels of left and right wheels under unequal air
pressure between left and right wheels.

The back of the differential planetary gear and the inner surface of
corresponding place of differential housing are made spherical surfaces to
ensure that the planetary gear is centered to help the correct engagement
with two half shaft gears. As the planetary gear and half shaft gear are of
straight bevel gear, while transmitting the torque, a high axial force is
applied along the axis direction of planetary gear and half shaft gear and
there is relative movement between gear and differential housing. To
reduce the wear between gear and differential housing, the anti-wear plain
washer is installed between the half shaft gear and differential housing and
the anti-wear spherical washer is installed between the planetary gear and
differential housing. The anti-wear washers are generally made of steel.
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When the washer is worn after certain service time of the loader, replace
with new anti-wear washer to prolong the service life of differential.
The gears in the differential are lubricated by the gear oil within the
differential housing. The differential housing is machined with port for inlet
and outlet of lubricating oil. To guarantee good lubrication between
planetary gear and cross shaft journal, a plane is milled on the cross shaft
journal and the orifices are drilled between teeth of planetary gear as oil
passages.

2. Working principle of differential
Kinetic characteristic
The symmetric bevel gear differential adopted by the drive axle of
wheel loader is a planetary gear mechanism. The differential housings
and planetary gear shaft (cross shaft) are integrated to form the
planetary carrier. In addition, the differential is functioned as a drive
part as the differential housings are rigidly connected with the driven
spiral bevel gear of the main drive.
The power is transmitted from the drive spiral bevel gear of main
reducer to the driven spiral bevel gear and is transmitted to the drive
wheels in turn through differential housings, cross shaft, planetary gear,
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half shaft gear, and half shaft.
When the wheels on two sides are rotating at same speed, the
planetary gears rotate around the axis of half shaft
the revolution. If
the resistance is different between wheels on two sides, the planetary
gear rotates around its axis the autogiration, while performing the
above-mentioned revolution. Therefore, two half shaft gears drive the
wheels on two sides for rotation at different speeds.

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5-7 Schematic diagram for common bevel gear differential
Assuming that the rotating angular speed is . (n0 in revolution per minute) and
the
angular speeds of half shaft gears are .l and .2 respectively (n1 and n2 in revo
lution
per minute respectively), then the following equation is established:
2.=.l+.2
2n0=n1+n2

The above equation is the kinetic characteristic equation for symmetric
type bevel gear differential with equal diameters of two half shaft gears.
It indicates that the sum from the speeds of left and right half shaft gears
is equal to two times of the speed of the differential housing and is
relevant to the speed of planetary gear. Therefore, while the loader is
making a turn or is running under other working condition, by means of
the autogirations of planetary gears at corresponding speeds, the drive
wheels on two sides can roll, instead of slide, at different speeds on the
ground. This equation also indicates:
. When the speed of half shaft gear on one side is zero, the speed of
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the half shaft gear on the other side is two times of the differential
housing speed.
. When the speed of differential housing is zero, if the half shaft gear
on one side is rotating under the application of other external
torque, the half shaft gear on the other side will rotate at same
speed in opposite direction.

It can be learnt from the above equation:
1.
When the resistance torque is unequal between the left and right half
shafts, its difference enables the torque applied on the planetary gear to
overcome the friction resistance torque Mr within the differential so that the
planetary gears rotate for differential function.
2.
When there is a speed difference between left and right wheels, the torque
will be non-uniformly distributed onto the left and right half shafts so that a
higher torque is distributed onto the half shaft with lower speed and a lower
torque is distributed onto the half shaft with faster speed.
sum of torques applied onto two half shafts is equal to the torque
33.. The The sum of torques applied onto two half shafts is equal to the torque
applied onto the differential.
As the symmetric type bevel gear differential that is extensively applied at
present features really low friction torque, it can be considered that the torqu
e
is always uniformly distributed, no matter whether the left and right drive
wheels are under same speed or not, which is the transmission characteristic
of different speeds without different torques for common differentials. This
characteristic can meet the traveling and operating needs of loader on
common roads. However, when the loader is operating under extremely poor
ground, it will seriously impair the trafficability of the loader.
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3. Working principle of differential
Distribution of torque
For symmetric type bevel gear differential, assuming that the torque
from the main reducer is Mo, the torques distributed to the inner and
outer half shafts by the differential are M2 and M1 respectively, and the
friction resistance torque within differential is Mr, then:
M2+M1=Mo M2-M1=Mr
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5-8 Diagram for torque distribution of differential
1 Half shaft gear 2
Half shaft gear 3
Planetary gear shaft 4 Planetary gear

Section IV Half Shaft
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The half shaft is the solid shaft for transmission of power between differential
and
wheel reducer. Its inner end is connected with the half shaft gear of differenti
al via
spline and its outer end is connected with the sun gear of wheel reducer via spl
ine
and retainer. The left and right half shafts of the loader drive axle adopt full
floating
structure. This structure enables two ends of half shaft to carry only the torqu
e,
without any counterforce or bending torque. To prevent the axial play of half sh
aft
under the application of the lateral force, the engagement end with the sun gear
of
wheel reducer is limited by pillar (or steel ball). The torque and movement from
the
main drive is transmitted to the half shaft via differential and then is transmi
tted to
the wheel reducer via half shaft.

Section V Wheel Reducer
The wheel reducer is the final torque enhancement and speed reduction mechanism
in
the transmission system. It can increase the reduction ratio of transmission to
meet the
traveling and working requirements of the complete machine. In addition, as it c
an
accordingly reduce the speed ratios of main drive and transmission, it reduces t
he
transmitted torques of these parts and reduces their structural sizes.
The wheel reducer adopts planetary transmission mechanism. The entire mechanism
is
composed of drive sun gear, fixed gear ring, driven planetary carrier, and plane
tary gear,
of which the working principle is shown in the figure.
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5-9 Working principle of wheel reducer
1 Gear ring 2
Planetary carrier 3
Half shaft 4 Planetary gear 5
Wheel hub 6
gear

Sun

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The sun gear and half shaft are connected together by spline. The gear ring
is fixed on the wheel support on two ends of the drive axle housing via
spline and it s stationary. The planetary gear that engages with the sun
gear and gear ring is installed on the planetary carrier via roller bearing and
planetary gear shaft. The planetary carrier and wheel rim are fixed together
by wheel rim bolts and therefore the wheel rim rotates along with the
planetary carrier.
The power from the main drive is transmitted to planetary gear via half
shaft and sun gear so that the planetary gear rolls along the stationary
inner gear ring and drives the rotation of planetary carrier and drive wheels.
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To improve the engagement conditions of sun gear and planetary gear and
ensure uniform distribution of engagement load, the half shaft is under
floating state, instead of being under stationary support.
The lubrication system of the wheel reducer is an independent system and
the oil level access hole and screw plug are fitted on the end cap of the
planetary carrier. The filler port and screw plug are fitted on the end face of
the planetary carrier.

Section VI Tire-Wheel Rim Assembly
The tire-wheel rim assemblies of the loader are the main traveling parts and
are functioned to carry the weight of complete machine, relieve the impact
force from the ground, and generate drive force and braking force by means of
the adhesion between tires and road.
1. Wheel rim
The wheel rim is composed of wheel rim body, retainer, and lock ring. After
being installed onto the wheel rim, the tire is restrained by the wheel rim body
and retainer and is locked by lock ring.
The wheel rim is fixed onto the planetary carrier of drive axle wheel reducer
and the power is transmitted to the wheel rim and tire via the planetary carrier
.
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2. Tire
The wheel loader generally adopts low pressure wide tires, featuring large
sectional size, good elasticity, and low ground pressure. While traveling or
operating on soft foundation, the tire features low sink, high adhesion, and
good traction and trafficability. While traveling or operating on rough road, th
e
tire can ensure the good damping and shock absorption performance of the
loader.

1. Normally, the front axle is subject to higher force and the rear
axle is subject to lower force. Why is the rear axle main drive
malfunctioned earlier?
This is mainly caused by the improper operations of the operator.
When the insertion angle of the bucket is too large, the front
wheels of the loader will be off the ground and all insertion force
will be carried by the rear axle so that the rear axle will be damaged
due to overload.
Section VII Analysis of Common Malfunctions of Drive Axle
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2. What is the cause for full permeation of gear oil in the drive
axle brake disc? How to solve this problem?
The oil permeation of the brake disc is generally caused by the
damaged dual-lip framework oil seal at the final drive, which causes
external leakage of gear oil and oil contamination on brake disc
and impairs the braking effects. This is really dangerous. Timely
disassemble the tire, planetary carrier, and wheel hub for repair and
replacement.

3. What is the cause for abnormal sound within the axle casing?
(1) Incorrect operations. If the insertion angle of the bucket is too high
during the working, the front wheels will be off the ground and the
rear axle main drive will be easily damaged. If the bucket load is too
high, the rear wheels will be off the ground and the front axle main
drive will be easily damaged. Once the gears are damaged, it will
generate abnormal sound.
(2) Noise due to improper backlash between drive and driven gears. The
excessive backlash will lead to impact between teeth of gears. The
under-size backlash will lead to squeezing between teeth of gears,
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accelerate the wear, and cause heating of drive axle.
(3) Improper adjustment of assembly gap, leading to over-size or
under-size bearing gap and causing noise.
(4) The stagnation of differential planetary gear and cross shaft and the
wear of adjustment washer will lead to excessive backlash of bevel
gears and cause noise.

4. How to solve the leakage of main drive oil seal? What are
the precautions for installation of new oil seal?
Troubleshooting:
Disassemble the drive shaft, disassemble the lock nut with special
socket, take out the flange, disassemble the oil seal seat and oil
seal, and replace with new oil seal.
Caution:
Check the oil seal for presence of aging, cracking, and damage. Do
not expand the oil seal too forcible, in order to prevent plastic
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deformation. Immerse the oil seal into the fluid at the temperature
closing to the working temperature as close as possible and then
install the oil seal. Use special tool.

Overview of Working Hydraulic System
CONTENTS
Pilot Controlled Working Hydraulic System
Working Principle for Hydraulic Units of Working Hydraulic System
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Cause Judgment and Troubleshooting for Common Malfunctions
of Working Hydraulic System

Section I Overview of Working Hydraulic System
The common working hydraulic systems include the following types:
1. Mechanically controlled working hydraulic system
It s mainly composed of hydraulic pump, multi-way reversing valve, boom
cylinder, bucket cylinder, hydraulic oil tank, operating mechanism, and
pipelines.
Our LG933 and LG953 products adopt this type, in which the multi-way
reversing valve is controlled via flexible shaft.
2. Pilot controlled working hydraulic system
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It s mainly composed of hydraulic pump, pilot valve, pressure selector valve,
hydraulically controlled multi-way reversing valve, boom cylinder, bucket
cylinder, hydraulic oil tank, and pipelines.
Our LG938L and LG958L products adopt this type, in which the high pressure
and high flow main oil lines are controlled by the low pressure and low flow
pilot oil lines.

Section II Pilot Controlled Working Hydraulic System
1. System characteristics
The working hydraulic system of LG958L loader adopts pilot controlled working hy
draulic
system, in which the high pressure and high flow main oil lines are controlled b
y low pressure
and low flow pilot oil lines. Compared with mechanically controlled hydraulic sy
stem, this
working hydraulic system features the following characteristics:
1) Light, flexible, and efficient pilot control, capable of realizing finger ope
rations.
2) Control of pressure reducing proportional pilot valve, greatly reducing the r
eversing
operating force.
3) The safety valve, overload valve, oil refilling valve, and check valve adopt
plug-in structure,
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featuring good university and easy repair.
4) The pilot valve adopts integral structure, featuring low volume and easy arra
ngement.
5) Under the stopped state of the engine, the pressure selector valve and pilot
valve can be
used to realize the drop of the boom and forward tilting of the bucket.
6) The pilot valve sets the positioning electromagnet for the lifting of boom an
d rearward
tilting of bucket to realize the vertical lifting limit of boom and the automati
c leveling
control of bucket at any position, which simplify the operation procedure, relie
ve the labor
strength, and prevent the energy loss and pressure impact due to frequent action
s of the
safety valve.

2. Schematic diagram for working device hydraulic system of LG958L loader
Steering oil tank
Multi-way valve
Pilot valve
Boom cylinder
Legend
Combination
valve block
Steering gear
Working oil zone
Oil return zone
Pilot control oil zone
Steering control oil zone
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Bucket cylinder
Working pump
Oil return filter
Oil tank
Priority valve
Hydraulic oil
radiator
Pilot pump Steering pump
Pressure
Boom piston selector valve
Piston rod
extending
Bucket rearward
tilting
Piston rod
extending
Boom piston
Piston rod retracting
Bucket forward
tilting
Piston rod
retracting
Pressure of relief valve
MPa
Nominal
displacement ml/r
Rated speed r/min
Rated pressure MPa
Pressure of relief valve
MPa
Nominal
displacement ml/r
Rated speed r/min
Rated pressure MPa
Pressure of relief valve
MPa
Nominal
displacement ml/r
Rated speed r/min
Rated pressure MPa

Section III Working Principle for Hydraulic Units of Working Hydraulic System
1. Working pump
Drive gear shaft
Drive gear shaft
Working pump is mainly
composed of housing
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The working pump is mainly composed of housing, drive gear shaft, driven gear sh
aft, side plate, and front cap.
Side plate
Side plate
Front cap

The working pump conveys the fluid by means of the change and movement of the wo
rking
Rotate along with gear to bring oil to compression chamber
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volume formed by the housing and the engaged gears and converts the mechanic ene
rgy to
hydraulic energy. While the working pump is running, many enclosed working chamb
ers are
formed between the tooth spaces of the gears and the housing and end cap. When t
he gears
are rotating in the direction shown in the figure, within the oil suction zone,
as the engaged
teeth of the gears gradually disengage so that the volume of the enclosed workin
g chamber is
increased gradually to suck in the oil from the oil tank and full fill the tooth
space. Along the
further rotation of the gears, the oil is conveyed to the oil compression chambe
r. Within the oil
compression zone, as the teeth of gears gradually engage, the volume of enclosed
working
chamber gradually reduces so that the oil is squeezed out. The oil suction zone
and the oil
compression zone are separated by the engaged teeth of gears and the pump body.
Under the
variation of volume, the continually inputted oil is pumped out by the gears to
form pressure
oil.

2. Multi-way valve
Main safety
valve
Rodless chamber
overload valve
Boom valve
lever
Auxiliary valve
lever
Bucket valve
lever
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The multi-way reversing valve is mainly composed of the valve body, boom valve l
ever
subassembly, bucket valve lever subassembly, auxiliary valve lever subassembly,
bucket cylinder
rodless chamber overload valve subassembly, bucket cylinder rod chamber overload
valve
subassembly, logic valve subassembly, and check valve.
It s mainly functioned to control the different opening directions of the valve co
re as per the oil
control signal of the pilot valve, in order to control the oil direction, flow,
and pressure of the
working pump, realize different movement directions of the boom cylinder and buc
ket cylinder,
and hold the bucket and boom at certain positions to meet the needs of the loade
r for different
operation actions.
Rod chamber
overload valve

The multi-way valve of LG958L loader is a triple valve. The first line is the bu
cket line (the middle
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line shown in the figure), in which the ports A1 and B1 are connected with the r
odless chamber
and rod chamber of the bucket cylinder respectively and the ports a1 and b1 are
connected with
the bucket retraction and unloading control ports of pilot valve respectively to
control the lines
A1 and B1.
The second line is the boom line, in which the ports A2 and B2 are connected wit
h rodless
chamber and rod chamber of the boom cylinder respectively and the ports a2 and b
2 are
connected with the lifting and lowering control ports of pilot valve to control
the lines A2 and B2.
The third line is the auxiliary line and is to be used at the addition of third
line connectors. For
other models, the ports A3 and B3 are sealed and the ports a3 and b3 are connect
ed by a hose
for reserved use.

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1. Neutral position
When the pilot lever is at the neutral position, both the core of boom reversing
valve
and the core of bucket reversing valve are at the neutral position under the act
ion of
the spring. The cores seal the chambers A1, A2, B1, and B2, the oils of the cham
bers of
the boom cylinder and bucket cylinder stop flowing, and the oil inlet port P and
oil
outlet port T of the multi-way valve are directly connected so that the oil from
the
working pump returns to the oil tank directly through multi-way valve.

a1 b1
B1 A1
Check valve
P
T
a1 b1
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2. Rearward tilting of bucket (upward tilting)
While shifting the pilot lever leftward to the bucket rearward tilting position,
the pilot
oil line a1 is fed with oil to drive the movement of the bucket valve core towar
ds
direction b1. In such case, the valve core closes the passage between the chambe
r P
and chamber T and opens the passage between chamber P and chamber A1 and
between chamber T and chamber B1. The high pressure oil enters into the rodless
chamber A1 of bucket cylinder through chamber P and the oil in the rod chamber B
1 of
bucket cylinder returns to hydraulic oil tank through chamber T oil line to real
ize the
bucket backward tilting action (bucket retraction action).

a1 b1
B1 A1
Check valve
B1 T P
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3. Forward tilting of bucket (downward tilting)
While shifting the pilot lever rightward to the bucket forward tilting position,
the pilot
oil line b1 is fed with oil to drive the movement of the bucket valve core towar
ds
direction a1. In such case, the valve core closes the passage between the chambe
r P
and chamber T and opens the passage between chamber P and chamber B1 and
between chamber T and chamber A1. The high pressure oil enters into the rod
chamber B1 of bucket cylinder through chamber P and the oil in the rodless chamb
er
A1 of bucket cylinder returns to hydraulic oil tank through chamber T oil line t
o
realize the bucket forward tilting action (bucket unloading action).

a2 b2
B2 A2
P
Check valve
A2
T
T P B2
Oil from pilot lever enters boom lifting inlet port to drive rightward
Movement of boom reversing slide valve
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4. Lifting of boom
While shifting the pilot lever backward to the bucket lifting position, the pilo
t oil line a2
is fed with oil to drive the movement of boom valve core towards direction b2. I
n such
case, the valve core closes the passage between chamber P and chamber T and open
s
the passages between chamber P and chamber A2 and between chamber T and chamber
B2. The high pressure oil enters into the rodless chamber A2 of boom cylinder th
rough
chamber P and the oil in the rod chamber B2 of boom cylinder returns to hydrauli
c oil
tank through chamber T oil passage to realize the bucket lifting action.

a2 b2
B2 A2
P
Check valve
A2
T
B2
T P
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5. Lowering of boom
While shifting the pilot lever forward to the bucket lowering position, the pilo
t oil line b2
is fed with oil to drive the movement of boom valve core towards direction a2. I
n such
case, the valve core closes the passage between chamber P and chamber T and open
s the
passages between chamber P and chamber B2 and between chamber T and chamber A2.
The high pressure oil enters into the rod chamber B2 of boom cylinder through ch
amber
P and the oil in the rodless chamber A2 of boom cylinder returns to hydraulic oi
l tank
through chamber T oil passage to realize the bucket lowering action.

a2 b2
A2
T
T B2 P
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6. Floating of boom
While shifting forward further the pilot lever from the boom lowering position t
o the floating
position, the logic valve opens and the chamber B2 and chamber T are connected.
In such
case, the position of boom valve core is completely same with that of boom lower
ing position
and the ports P, A2, B2, and T are interconnected so that the boom cylinder pist
on is floating
freely under the action of external force.
Logic valve k Check valve

7. Main safety valve
During the working of the multi-way valve, the system
pressure is adjusted by the safety valve. When the oil
from the working pump reaches the oil inlet of safety
valve, a part of the pilot oil enters into the middle oil
chamber through the central orifice of the valve body.
Under the action of the oil pressure and spring, the
valve body is pressed tightly to the oil inlet to block the
pressure relief passage. When the system pressure
exceeds 17.5MPa, the oil pressure overcomes the spring
force of the pilot valve core and pushes away the
poppet so that the pressure of the middle oil chamber
reduces accordingly. In such case, the oil from the oil
inlet overcomes the spring force of the valve body and
pushes open the valve body so that the oil inlet is
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connected with the oil return chamber for pressure
relief. The oil drainage amount for the pressure
regulation is subject to three annular oil ports on the
outside of the valve housing, which are classified into
large, medium, and small sizes. When the system
pressure exceeds the pressure setting, the safety valve
will open for relief by grade to restrain the system
working pressure within the pressure setting range and
protect the system.
Large
Medium
Small
Large
Small
Medium

8. Overload valves for rodless chamber and rod chamber
of bucket cylinder
The overload valves for rodless chamber and rod chamber
of bucket cylinder are of direct-acting safety valve and are
installed between the rodless chamber of bucket line and
chamber T and between the rod chamber and chamber T.
The pressure settings for the overload valves for rodless
chamber and rod chamber are 20MPa and 12MPa
respectively. Adjust the adjustment screw on the top to
adjust the spring preload and change the pressure setting.
Main functions of the overload valves are:
1) When the bucket line is at the neutral position, both
the front and rear chambers of the bucket cylinder are
closed. In such case, if the bucket is subject to the
Rodless
chamber A1
Oil return
chamber T
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external impact load, it can effectively prevent the
surge of partial pressure.
2) During the lifting and lowering of the boom, it can
drain the oil automatically.
When the boom is lifted to a certain position so that the
piston rod of the bucket cylinder is pulled outward to
cause sharp pressure rise in front chamber of bucket
cylinder, the overload valve can enable the oil entrapped in
the front chamber of hydraulic cylinder to return to
hydraulic oil tank through safety valve and prevent the
damage of cylinder or hydraulic pipeline due to high
pressure.
Rod chamber
B1
Oil return
chamber T

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9. Check Valve
The check valve is set at the oil inlet for bucket line, boom line, and auxiliar
y line of multi-way valve.
The oil refilling valve, which is also a check valve, is set between rodless cha
mber B1 and oil return
chamber T of the bucket line. Its main function is to supplement oil to the rod
chamber of bucket
cylinder. For instance, during the rapid downward tilting of bucket for unloadin
g of the loader, when
the gravity center of the bucket is beyond the lower articulation point, the buc
ket accelerates the
downward tilting under the action of gravity center. However, the movement speed
of the bucket
cylinder is subject to the oil supply speed of the hydraulic oil pump. This chec
k valve can timely
supplement the oil to the front chamber of bucket cylinder so that the bucket ca
n tilt downward
rapidly and impact the limit block to realize the impact unloading.

3. Pilot valve
Positioning electromagnet
subassembly
Lifting positioning electromagnet
Rearward tilting positioning
electromagnet
Floating positioning
electromagnet
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The pilot valve is mainly composed of valve body, electromagnet subassembly, met
ering valve subassembly, and
sequence valve subassembly.
Metering valve subassembly Sequence valve subassembly

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The pilot valve is fitted with operating lever. There are three operating positi
ons, namely forward
tilting, neutral, and backward tilting, for the bucket and there are four operat
ing positions,
namely lifting, neutral, lowering, and floating, for the boom. The positioning e
lectromagnet is set
for the lifting, floating, and backward tilting positions.
When the operating lever of pilot valve is shifted to full lifting position or f
ull bucket retraction
position, the operating lever is locked and positioned, till the boom or bucket
reaches the
limiting limit height or bucket limit angle and the proximity switch acts. In su
ch case, the solenoid
coil is powered off to lose the magnetic force so that the operating lever autom
atically returns to
neutral position under the action of the reset spring.

Lifting
Lowering
Unloading
Bucket
retracting
Port T
Port K
Port P
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The oil inlet port P, oil return port T, and floating port K of the pilot valve
are connected with the oil outlet port of pilot pump, hydraulic oil tank
return block, and port K of multi-way valve respectively. The oil control
ports for the lifting, lowering, bucket retraction, and unloading of pilot
valve are connected with the oil control ports for lifting, lowering, bucket
retraction, and unloading of the boom line and bucket line of the multiway
valve.
Bucket retracting Unloading Lowering Lifting

P
T
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When the operating lever of pilot valve is at neutral position, the slide valve
is at start
position, the oil inlet chamber P is disconnected from oil control port and oil
return
chamber T, the oil control port is connected with oil return chamber T, and the
valve levers
of the multi-way valve are at neutral position under the action of spring.

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While shifting the operating lever to lowering position, the pressure pin drives
the
downward movement of the pressure rod so that the metering spring drives the dow
nward
movement of metering valve core to cut off the passage between control chamber a
nd oil
return chamber and connect the control oil chamber with oil inlet chamber. The p
ilot
pressure oil reaches one end of multi-way valve to drive the movement of multi-w
ay valve
slide valve and realize corresponding reversing action. At the same time, the oi
l pressure of
the control chamber is applied to the lower end of metering valve core, which is
balanced
with the metering spring force.
Connect the oil inlet chamber with
control oil chamber

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While shifting further the operating lever from the lowering position to the flo
ating position,
as the positioning electromagnet is set for this position, the pilot valve will
be locked. In
such case, the oil pressure at the control port is increased to open the sequenc
e valve in the
pilot valve, the hydraulic oil of the drainage orifice passage K within the mult
i-way valve
returns to the oil tank through drainage port T within pilot valve, the oil refi
lling valve for
the rod chamber of boom cylinder opens (the logic valve moves downward), and the
ports P,
A2, B2, and T are interconnected to realize the floating of boom. When the pilot
valve is
pulled out of the floating position and released, the reset spring drives the up
ward
movement of pressure rod so that the operating lever returns to neutral position
.
To oil tank through drainage port of pilot valve

This pilot valve adopts pressure reducing proportional pilot control mode, in
which the travel of the multi-way valve lever is proportional to the operating
angle of the operating lever. When the operating lever is hold at certain place,
the spring force is fixed and the corresponding pressure of control chamber is
also fixed. The spring force varies along with the variation of the operating le
ver
swing angle: High swing angle brings about high spring force, high pressure of
control chamber, and accordingly increased push force onto the multi-way
valve core, namely the travel of main valve core is proportional to the swing
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angle of pilot valve operating lever, in order to realize the proportional pilot
control.

4. Hydraulic cylinder
The hydraulic cylinder is the hydraulic actuator that converts the fluid
pressure energy to mechanical pressure to drive the working mechanism
for linear reciprocating movement or reciprocating swing movement.
The hydraulic cylinder can be classified by acting mode into single-acting
type and dual-acting type.
The single-acting hydraulic cylinder only has one oil port, of which the
piston rod or plunger is extended under the action of pressure oil and is
returned by means of the gravity or spring force.
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The dual-acting hydraulic cylinder has two oil ports, in which the
reciprocating movement of the piston is realized under the action of the
pressure oil.
The hydraulic cylinder can be classified by structural type into piston type,
plunger type, swing type, and telescoping type, of which the piston type
hydraulic cylinder is mostly applied.
The hydraulic cylinders applied in the LG958L loader are mostly of dualacting
piston type cylinder.

Dual-acting single-rod piston type hydraulic cylinder
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The dual-acting piston type hydraulic cylinder is generally composed of cylinder
body 10,
piston 5, piston rod 14, and the guide sleeve 12 for guiding function. To ease t
he analysis of
problems, conventionally the cylinder is composed of rod chamber (the chamber wi
th piston
rod) and rodless chamber. The pressure oil enters into the left chamber of hydra
ulic cylinder
through port A to drive the rightward movement of the piston and the hydraulic o
il in the
right chamber is drained through port B.
1 Cylinder bottom 2
Spring retainer 3
Collar 4 Circlip 5
Piston 6
O-ring 7 Supp
rt ring 8
Retainer 9 Yx seal ring 10
Cylinder block 11
Pipe connector 12
Guide sleeve 13
C
ylinder head
14 Dust ring 15
Piston rod 16
Locating screw 17
Lifting eye 18 Damping plunger

Piston rod
Cylinder
head
Piston
Cylinder
bottom
Connec
ting
yoke
Breakdown Diagram of Hydraulic Cylinder
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Cylinder
head bolts
Cylinder
body
Cylinder head

5. Pressure selector valve
Valve body
Check valve
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The pressure selector valve is installed in the pilot oil line and is mainly com
posed
of the valve body, check valve, valve core, and spring.
Valve core
Spring

Pr
P2
P1
L
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The port P1 is connected with pilot pump, the port Pr is connected with rodless
chamber of boom cylinder, the port P2 is the oil outlet port connected with pilo
t
valve, and the port L is the oil return port connected with hydraulic oil tank.
The pressure selector valve is functioned to supply pressure oil at certain pres
sure
to the pilot valve and, after the diesel engine is stopped, ensure that the boom
can
be placed onto the ground or the bucket can fulfill the unloading operation.

T il l
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During the working, the oil
ers into
pilot valve through central
To pilot valve T il l
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During the working, the oil
ers into
pilot valve through central
To pilot valve

from pilot pump enters into the port P1 and then ent
orifice of valve core and oil outlet port P2.
from pilot pump enters into the port P1 and then ent
orifice of valve core and oil outlet port P2.

Check valve
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When the pressure at oil outlet port P2 is above 1.5MPa, the valve core moves le
ftward to stagger the
port P1 from port Pr and cut off the passage between oil inlet port P1 and oil p
ort Pr (rodless chamber
of boom cylinder). The check valve is fitted at the port Pr to prevent the backf
low of the oil.
Cut off passage between oil inlet port and rodless chamber of boom
cylinder

Operating lever is at neutral position Operating lever is at neutral position
When the diesel engine is stopped, there is no pressure oil at the port P1 so th
at the valve core
returns to the position at which the port P1 is connected with port Pr. In such
case, if the boom
is lifted and the operating lever is at neutral position, the hydraulic oil in t
he rodless chamber of
the boom cylinder is sealed within the pipeline.
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In such case, when the operating lever is shifted to boom lowering
position, the hydraulic oil in the rodless chamber of boom cylinder
enters into the check valve and port Pr, then enters into the pilot valve
through valve core and oil outlet port P2, and then enters into the
multi-way revering valve through pilot valve to position the boom
valve core at lowering position to lower the boom. During above
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process, the valve core controls the pressure from port Pr to pilot
valve at approximate 1.5MPa. The pressure at oil outlet port P2 is
increased to move leftward the valve core, reduce the flow of port P1,
and thus reduce the pressure at oil outlet port P2 and realize the
control of pressure.

Section IV Cause Judgment and Troubleshooting for
Common Malfunctions of Working Hydraulic System
1. What are the causes for damage or working failure of gear pump? How to
prevent such problems?
Cause: (1) The ingress of hard particles (such as iron chipping and sand) in the
hydraulic oil will scratch or damage the side plate and various motion parts of
the
gear pump.
(2) The fitting gap of the spline slot between the pump shaft and drive shaft is
impaired due to excessive wear, leading to occasional interruption of pump.
(3) The serious wear between gear side face and side plate will lead to ablation
of
gear pump.
(4) The blockage or poor sealing of oil suction pipe leads to insufficient oil s
uction of
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pump and burns the pump due to cavitation.
(5) The non-uniformly tightened connecting bolts of flange disc leads to damage
of
pump during working.
Preventative measure: A. Check the drive shaft of gear pump.
B. Check the bearings of drive shaft and eliminate any axial play.
C. Check the tightening torque for the fastening bolts of pump cover and pump
body to ensure uniform tightening torque.
D. Check the oil suction pipe to prevent ingress of air into the system.
E. Ensure the cleanliness of oil.

2. What are the causes for weak bucket and easy drop or floating of
bucket?
(1) Damage of bucket cylinder piston oil seal, leading to oil permeation.
(2) Scuffing, scratch, or wear of bucket valve stem and valve bore, leading
to high leakage of hydraulic oil.
(3) Damage or gap of cone valve cone and cone valve seat on overload
valve of bucket valve, leading to leakage due to poor contact.
3. What are the causes for easy burst of working pump and easy leakage
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at end face?
The cause is the blockage of main safety valve in the multi-way valve, which
leads to unlimited rise of system pressure and finally leads to the burst of
working pump, as the system oil line is under enclosed state.
There are following causes for the oil leakage at end face:
The long-term internal high pressure of working pump lengthens the connecting
bolts between the pump cover and pump body and leads to looseness and oil
leakage; the radial cracking or scratch trace of pump cover and pump body.

4. What is the cylinder pulling-out symptom? What is the harm? How to
prevent?
(1) Cylinder pulling-out: When the bucket is at the downward tilting limit
position, the piston rod of the bucket cylinder has the shortest extension
length. When the boom is lifted to a certain height, the limit point of the
boom comes into contact with the bottom face of the bucket. When the
boom is lifted further, the bucket will not tilt downward along with the lifting
of boom. In such case, the relative positions of the support points on two
sides of bucket cylinder will change along the further lifting of the boom,
which drives the outward extension of the bucket cylinder piston rod. As the
front and rear chambers of the bucket cylinder are under enclosed state
during the lifting of the boom, the outward extension of the piston rod will
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surely lead to the surge of pressure in front chamber. This symptom for
outward extension of bucket piston rod when the boom is lifted under the
fully unloaded state of bucket is referred to as cylinder pulling-out
symptom.
(2) Hazard: Bending deformation of bucket arm; damage of knuckle bearings at
hinge of bucket cylinder; Thread failure of lock nut for bucket cylinder piston.
(3) Preventative measure: After the bucket is unloaded, firstly retract the buck
et
and then lift the boom.

5. What is the cause for the occasional nodding symptom (namely
firstly drop and then lift) when the boom is being lifted?
As the boom control valve of the multi-way valve adopts vacuum enclosed
mode, there will be a floating state in which the oil inlet port and oil return
port are connected with working oil port at certain moment of reversing.
Under the action of the dead weights of the boom and bucket, the boom
firstly drops. After the vacuum enclosed state is reached, the floating state
in which the oil inlet port and oil return port are connected with working
oil port is ended and then the boom is lifted.
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6. What are the causes for slow and weak lifting and tilting of bucket?
The seals of the bucket lifting and tilting cylinders are damaged to cause
internal leakage of hydraulic cylinder and lead to weak actions.
The symptoms include oil permeation at surface joint of hydraulic cylinder,
fast pressure drop, and oil permeation noise during working.

7. Common malfunctions of multi-way valve:
(1) The dirt within multi-way valve, blockage of valve, or blocked valve chamber
oil
passage leads to obstructed oil flow. The symptoms include high operating
resistance of multi-way valve lever, inflexible movement of valve lever, and res
et
failure of valve lever.
(2) Excessive wear of multi-way valve and excessive fitting gap between valve le
ver
and valve body lead to internal leakage and insufficient working flow.
(3) Malfunction of safety valve. The opening pressure of the pilot safety valve
is too
low. In such case, do not blindly tighten the pressure regulation screw of the
safety valve. Disassemble the safety valve and observe the pilot relief valve
spring for breakage, check the guide valve for good sealing, check the main
valve core for blockage, and check the main valve core damping hole for
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blockage. If no problem is found from above items, adjust the opening pressure
of safety valve.
(4) High internal leakage of working pump, insufficient output flow of pump, and
reduced return pressure lead to weak lifting and tilting of bucket. The symptoms
include high working noise of hydraulic pump (the internal leakage noise of the
pump can be heard), increased engine speed and higher hydraulic pump noise,
and many copper chippings in oil filter and tiny copper chippings in oil.
(5) Blockage of oil suction pipe and oil filter or the aging, distortion, or poo
r sealing
of the oil suction pipe leads to insufficient flow.

8. What are the causes for vibration during the lifting and rotation
of bucket?
The specific malfunction causes and troubleshooting are as below:
(1) Insufficient oil amount, leading to unstable working pressure. Add
sufficient hydraulic oil.
(2) Poor sealing of oil suction hose port, leading to ingress of air into
system and unstable working pressure. Check the air-tightness.
(3) Air content in oil. The oil is mixed with a great amount of tiny air
bubbles to form compressible object. Eliminate the poorly sealed
portions in the low pressure oil line and bleed the air from the oil.
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(4) Loose hydraulic cylinder piston, leading to play of piston rod within
hydraulic cylinder. Disassemble the hydraulic cylinder and find out
the cause.
(5) Unstable opening pressure of safety valve, leading to variation of
high oil pressure and vibration. Check the pressure regulation spring
of valve and adjust the opening pressure.
(6) Unequal leakage between bucket cylinder and boom cylinder, leading
to flow variation and vibration. Check the cylinders respectively and
take measures for the defective cylinder.

9. What are the causes for the slow and weak tilting of bucket, though the
boom is working normally?
(1) Abnormal regulated pressure for two overload valves of bucket cylinder. Chec
k
the pressure and set normal value.
(2) The impurity particles in the main core of bucket cylinder overload valve bl
ock
the main core and position the overload valve under normally open state.
Remove the impurities and at the same time check the spring for breakage and
failure, check the seal ring for aging, and check the valve core and valve body
for appropriate fitting gap (the normal fitting gap is 0.006~0.012mm).
(3) Internal leakage of bucket cylinder. Check and resolve.
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10. What are the causes for over-high oil temperature of the hydraulic system?
Provided that the system factors are excluded, the over-high oil temperature is
mainly caused by:
(1) Wear of hydraulic pump gear pair, side plate, and pump body and damage of
pump internal seals, leading to reduced volume efficiency of pump.
(2) Disqualified oil trademark in use, leading to poor cleanliness or deteriorat
ion of
mixed oil.

Overview of Steering System
CONTENTS
Load-Sensing Fully Hydraulic Steering System
Working Principle for Hydraulic Units of Steering System
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Cause Analysis and Troubleshooting for Common
Malfunctions of Steering System

I. Classification of steering system
The steering system of the wheel loader is functioned to control the traveling
direction of the loader. It can stably maintain the linear traveling of the
loader and can flexibly change the traveling direction as required.
By steering mode, the wheel loader can be classified into deflection wheel
steering mode, skid steering mode, and articulated steering mode.
For the loader with articulated steering mode, the working device is installed
on the front frame. When the frame is swinging, the direction of the working
Section I Overview of Steering Hydraulic System
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device is always consistent with the direction of the front frame, which can
enable the working device to rapidly aim at the working face during the
operations, in order to reduce the travel and time of working cycles and
improve the working efficiency of the loader. Therefore, the articulated
steering mode has become the mostly applied steering mode in modern
loaders.

II. Requirements of steering system
The good steering performance is one important factor to guarantee the
traveling safety of the loader, relieve the labor strength of driver, and improv
e
the working efficiency. The basic requirements on the steering system include
light and flexible operations, stable and reliable working, and good durability.
The steering oil line requires relatively stable supply of oil flow. However, th
e
steering system commonly adopts fixed displacement pump. As the flow of
fixed displacement pump varies along with the speed, the flow of the steering
oil line is reduced when the engine runs at low speed, which will cause
delayed response of steering speed and easily lead to accidents. If the high
flow pump is adopted, when the engine runs at high speed, the excessive oil
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flow will be relieved through the relief valve, which is not economical due to
high power loss and easy heating of oil.
A relatively appropriate method is to choose auxiliary pump and flow changeover
valve. The pressure oil of the auxiliary pump varies along with the engine
speed under the control of the flow change-over valve to fully or partially flow
into the steering oil line, in order to guarantee the flow of steering oil line.
The
remaining oil flows into the working oil line.

III. Types of steering system
There are many types of steering system and the different types of
steering system represent the development levels of different hydraulic
technologies respectively.
At present, the types of the steering system applied in the wheel loader
are as below:
. Fully hydraulic steering system composed of single stabilizer valve
and open center no-reaction steering gear.
. Load-sensing fully hydraulic steering system composed of priority
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valve and loading sensing steering gear.
. Load-sensing fully hydraulic steering system composed of priority
valve and coaxial flow amplifying steering gear.
. Flow amplifying steering system.

The steering system of LG958L loader is a load-sensing fully hydraulic steering
system
composed of priority valve and coaxial flow amplifying steering gear.
This system is mainly composed of steering pump, coaxial flow amplifying fully h
ydraulic
steering gear, steering cylinder, hydraulic oil tank, and pipelines and accessor
ies, as shown
in Figure 6-1.
This steering system features the following characteristics:
1. Compact structure and small size for constituent units.
2. Automatic lubrication and long service life for all units.
Section II Load-Sensing Fully Hydraulic Steering System
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3. Reliable steering and light and flexible operations.
4. It can realize the converging with the hydraulic system of working device to
reduce the
power loss and improve the system efficiency.
At the time of steering, the system supplies oil preferentially to the steering
hydraulic
system and the remaining oil converges with the return oil of steering system to
return to
oil tank through radiator.
The safety valve is set on the priority valve, with the regulated system pressur
e at 16MPa.

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7-1 Schematic diagram of LG958L steering system
1. Priority valve 2. Steering pump 3. Oil suction filter element 4. Steering cyl
inder
5. Coaxial flow amplifying steering gear 6. Radiator 7. Oil return filter elemen
t
8. Hydraulic oil tank

Steering Gear BZZ6-800
I. Steering gear
1. Meaning of steering gear model
Section III Structure and Working Principle of Steering System Hydraulic Units
Model of steering
gear Type of steering gear
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Displacemen
t: 800ml/r
BZZ1 Open center no-reaction fully hydraulic steering
gear
BZZ2 Open center reaction fully hydraulic steering gear
BZZ3 Closed center no-reaction fully hydraulic
steering gear
BZZ4 Multi-functional no-reaction fully hydraulic
steering gear
BZZ5 Load-sensing fully hydraulic steering gear
BZZ6 Load-sensing flow amplifying fully hydraulic
steering gear

2. Types of fully hydraulic steering gear:
1) The BZZ fully hydraulic steering gear
is mainly classified into:
Open center no-reaction type (BZZ1);
Open center reaction type (BZZ2);
Closed center no-reaction type (BZZ3);
Load-sensing type (BZZ5);
Coaxial flow amplifying type (BZZ6);
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Type symbols of BZZ
and other types.
The functionality symbols are shown in
the left figure:

2) Corresponding types of steering gears for specific loader models
NO. Applied model Name of steering
gear Type of steering gear
1 952/952H/952L Steering gear
BZZ1-800
Open center no-reaction fully
hydraulic steering gear
2 968/969 Steering gear
BZZ3-100
Closed center no-reaction fully
hydraulic steering gear
3 916/918 Steering gear
BZZ5-320
Dynamic signal load-sensing fully
hydraulic steering gear
Steering gear Static signal load-sensing fully
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4 936/938 BZZ5-500
hydraulic steering gear
5 946L Steering gear
BZZ6-500
Static load-sensing flow amplifying
fully hydraulic steering gear
6 933L Steering gear
BZZ6-630
Static load-sensing flow amplifying
fully hydraulic steering gear
7 953/956/958 Steering gear
BZZ6-800
Static signal flow amplifying fully
hydraulic steering gear

3. Structural composition of steering gear
As shown in Figure 5-2 (a) and (b), the structure of the BZZ6 fully hydraulic st
eering
gear is mainly composed of valve body, valve core, valve sleeve, linkage shaft,
locating spring, shifting pin, rotor, stator, and rear cap.
There are total 5 oil ports on the steering gear, namely oil inlet port P, oil r
eturn port
T, left steering oil outlet port L, right steering oil outlet port R, and feedba
ck oil port
LS, which are connected with the oil outlet port CF of priority vale, oil return
port of
hydraulic oil tank, rodless chamber of right steering cylinder, rodless chamber
of left
steering cylinder, and port Ls of priority valve respectively.
T: Oil return
P: Oil inlet
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R: Right steering
L: Left steering
T
L
P
R
LS
Location of steering gear oil ports

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Figure 7-2 Structure of fully hydraulic steering gear (a)
1 Connecting block 2
Front cap 3
Valve body 4
Spring plate 5 Shifting pin 6
Valv
e sleeve 7 Valve core
8 Linkage shaft 9
Rotor 10 Rear cap 11
Limit post 12
Spacer disc 13
Stator 14
O
ring 15 Steel ball 16
O-ring
17- X-shaped ring 18 O-ring

Left
Right
Valve body Oil return port
Oil inlet port Spacer disc
steering
steering
Linkage shaft Limit block
Valve core
Bearing Valve sleeve Check valve Rear cap
Return spring Shifting pin Stator-rotor pair
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Figure 7-2 Structure of fully hydraulic steering gear (b)

The valve body, valve core, and valve sleeve of the steering gear constitute
the follow-up swing valve of steering gear to control the oil flow direction.
The valve core is within the inner chamber of valve sleeve. It is connected
directly with steering column via connecting block and can be driven for
rotation by the steering wheel via steering column. The valve sleeve is
within the inner chamber of valve body and is driven by the rotor via
linkage shaft and shifting pin for movement within valve body.
The rotor and stator constitute the metering motor at the lower portion of
the steering gear. The stator has 7 teeth and the rotor has 6 teeth. The
stator is fixed and the rotor rotates around the center of stator in radius of
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eccentric distance. The tooth profile for metering motor is equilong arc
epicycloidal tooth, which can ensure that each point on the rotor curve can
become the engagement point. During the rotation, seven oil orifices are
connected with the oil orifices on the valve sleeve at all times so that the
valve sleeve and valve core distribute the flow to the metering motor,
namely enable the pressure to enter half of tooth chamber and drain oil
from the other half of tooth chamber, in order to convey the pressure oil to
the steering cylinder.

The metering motor composed of rotor and stator is also referred to as
cycloid gear engagement pair. During the power steering, it functions as
the metering motor to ensure that the flow into the steering cylinder is
proportional to the rotation angle of the steering wheel. During the
manual steering, it s equivalent to a manual oil pump.
The linkage shaft and shifting pin connect the rotor with valve sleeve.
During the power steering, they ensure the synchronization between
valve sleeve and rotor (for feedback function). During manual steering,
they are functioned for conveyance of torque.
The spring plate is functioned to ensure the neutral position of follow-up
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valve for centering purpose. Therefore, the spring plate is referred to as
centering spring.
The check valve is installed between oil inlet port and oil outlet port.
During the manual steering, the check valve opens so that the oil in one
chamber of the steering cylinder is sucked into the oil inlet port through
oil return port and then is compressed into the other chamber of steering
cylinder by cycloid gear engagement pair, namely it s functioned for oil
suction during the manual steering.

4. Working principle of steering gear
The schematic diagram for the working principle of BZZ6 fully hydraulic steering
gear is shown in
Figure 5-3 (a), (b), and (c). The ports A and B are connected with two chambers
of steering cylinder
respectively, the port P is connected with oil outlet port of steering pump, and
the port T is
connected with hydraulic oil tank.
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Figure 7-3 Structure of fully hydraulic steering gear (a)
1 Connecting block 2
Front cap 3
Valve body 4
Spring plate 5 Shifting pin 6
Valv
e sleeve 7 Valve core 8
Linkage shaft
9 Rotor 10
Rear cap 11
Limit post 12
Spacer disc 13
Stator 14
O-ring 15
Steel b
ll 16 O-ring 17
X-shaped ring
18 O-ring

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Figure 7-3 (b) Schematic diagram of fully hydraulic steering gear (at neutral po
sition)

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Figure 7-3 (c) Schematic diagram of fully hydraulic steering gear (at steering p
osition)

1. No rotation of steering wheel (namely neutral position)
The valve core 1 and valve sleeve 3 are at neutral positions under the action of
the
centering spring plate. The hydraulic oil from the steering pump 7 enters into t
he valve
core through the valve core and the orifice at the end of valve sleeve and then
returns
to oil tank 8 via port T. When the steering wheel is not rotated, the centering
spring is
functioning. As the oil ports A and B are blocked by the valve core 1, the oil i
n the
steering cylinder is restrained against input and output and the piston can t move
so
that the loader is traveling towards the preset direction.
2. Leftward rotation of steering wheel
The steering wheel drives the valve core 1 for counterclockwise rotation so that
the
centering spring is unilaterally compressed. As there is an up to 10º30 rotation
amount between the valve core 1 and valve sleeve 3, the valve core can rotate wi
th
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respect to the valve sleeve. In such case, the oil groove of the valve core is c
onnected
with oil inlet port P of valve sleeve so that the oil from the oil pump flows, t
hrough oil
grooves of valve sleeve 3 and valve core 1 and the valve sleeve, to the rotor 5
and
stator 4 to drive the rotation of rotor 5 with respect to the starter 4. At the
same time,
the outlet oil from the rotor and stator enters into the rodless chamber of righ
t
steering cylinder through the valve sleeve and port A so that the cylinder pisto
n rod is
extended to drive the wheels via frame for leftward steering. The oil in the rod
chamber of the cylinder flows into the valve sleeve 3 via oil port B and flows b
ack to
the hydraulic oil tank through oil return groove of valve core 1, oil return por
t of valve
sleeve, and the port T.

During the leftward steering, the rod chamber of left steering cylinder is conne
cted with the
rodless chamber of right steering cylinder so that the rod chamber is supplied w
ith oil to retract
the piston rod into the cylinder and drive the leftward steering of the frame. T
he rodless
chamber of left steering cylinder is connected with rod chamber of right steerin
g cylinder so
that the oil from the rod chamber of right steering cylinder enters into port B
via rodless
chamber of left steering cylinder and returns to the oil tank through oil return
port and oil inlet
port of valve sleeve.
When the relative rotation angle between valve core and valve sleeve is approxim
ate 1.5º, the oil
line is connected so that the rotation of rotor drives the oil from steering pum
p to the cylinder,
of which the oil supply amount is proportional to the rotation angle of the stee
ring wheel.
When the steering wheel is rotated for a certain angle and held, as the above-me
ntioned oil line
is connected, the oil from the steering pump drives the rightward rotation of ro
tor 5. When the
rotation angle of rotor 5 is same with the rotation angle of the steering wheel,
as the valve
sleeve 3 and rotor 5 are mechanically connected by linkage shaft, the rotor driv
es the leftward
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follow-up rotation of valve sleeve 3, till the stator spring drives the valve slee
ve and valve
core to neutral position and the angle rotated is same with the rotation angle o
f steering wheel.
In such case, the relative rotation angle between the valve sleeve 3 and valve c
ore 1 is
eliminated and the oil line to the rotor and steering cylinder is closed so that
the outlet oil from
the steering pump 7 enters into the valve sleeve via port P and returns to oil t
ank through oil
return groove of valve core 1, oil return port of valve sleeve 3, and oil port T
. In such case, the
loader stops the steering. When the steering wheel is rotated further, the rotor
and valve sleeve
will follow up, till the left limit position is reached. This is the hydraulic fe
edback follow-up
function.

3. Rightward steering
When rotating the steering wheel rightward, the steering wheel drives the valve
core for clockwise
rotation, of which the working principle is same with the leftward steering.
For the steering at low speed (the rotation speed of the steering wheel is less
than 10r/min), the
effective displacement of the steering gear is same with the metered displacemen
t. When the
input speed of the steering wheel is increased (the rotation speed of the steeri
ng wheel is
10~40r/min), the effective displacement is proportional to the rotation speed of
the steering
wheel. In such case, only a part of oil from the oil inlet port P enters into th
e rotor-stator pair for
metering and the remaining oil enters into the cylinder directly via ports A and
B. Therefore, the
flow amplifying function is available only at this stage. When the input speed o
f the steering wheel
exceeds 40r/min, the effective displacement of steering gear is basically consta
nt at its rated
equivalent displacement.
4. Manual steering
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In event of sudden flameout of the engine or the malfunction of steering pump, r
otate the
steering wheel with hand for static steering. While rotating the steering wheel
rightward, the valve
core rotates for a 10º30 angle to drive the rotation of valve sleeve, linkage shaft
, and rotor via
shifting pin. In such case, the rotor and stator are functioned as oil pump. The
rotation of rotor 5
sucks out the oil from the oil port T and inputs the oil into the oil inlet cham
ber of rotor pump via
check valve, valve sleeve, and valve core. The oil pumping action during the man
ual steering
compresses the hydraulic oil sucked into the steering oil so that the compressed
oil enters into the
rodless chamber of steering cylinder to extend the piston rod and steer rightwar
d the loader. The
oil in the rod chamber flows to the oil inlet chamber of rotor pump from oil por
t A through valve
sleeve, valve core, valve sleeve, and check valve and continually refills into t
he rodless chamber, in
order to maintain the steering action.

5. Combination valve block
The valve block is a combined hydraulic unit that is mainly composed of check va
lve,
two-way damping valve (overload valve), and oil refilling valve. It s connected
between the steering pump and steering gear and is assorted to the fully hydraul
ic
steering gear (Generally, it s directly installed on the valve body flange of the
steering gear and works along with steering gear to form an integral unit).
It s functioned to guarantee the normal and stable working of steering gear and
entire steering system under rated pressure on one hand and guard the steering
cylinder and connecting pipelines against damage in event of sudden overload and
protect the steering pump on the other hand.
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1) Check Valve
The check valve is composed of the valve seat 1, valve core 2, and spring 3 and
is
installed within the oil inlet port of the valve block body so that the high pre
ssure oil
from the oil pump flows into the oil inlet port of steering gear via the check v
alve. It's
functioned to prevent the backflow of oil from automatically deflecting the stee
ring
wheel and leading to steering failure.
2) Two-way damping valve
The two-way damping valve incorporates two constant pressure direct-acting safet
y
valves composed of the spring, ball valve seat, and steel ball. It s installed wit
hin the
valve port for connecting the valve body with the orifices of left and right cha
mbers of
steering cylinder and is connected with the oil return port, in order to protect
the
hydraulic steering system against impact of over-high pressure and ensure the sa
fety of
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oil lines.
3) Oil refilling valve
The oil refilling valve incorporates two check valves composed of steel ball and
is
installed within the valve port for connecting the valve body with the orifices
of left and
right chambers of steering cylinder and is connected with the two-way damping va
lve.
When the pressure within one chamber of cylinder is higher than the pressure set
ting
of damping valve, the damping valve relieves the load and the oil refilling valv
e on the
other chamber of the cylinder refills the oil to prevent the formation of cavita
tion in the
system.

The priority valve is mainly composed of the valve body, valve core,
spring, safety valve assembly, and screw plug, as shown in Figure 7-4.
II. Priority valve
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Figure 7-4 Structural diagram of priority valve
1 Safety valve assembly 2
Control spring 3 Valve core 4
Valve body 5

Screw plug

II. Priority valve
There are 5 oil ports on the priority valve, namely oil inlet port P, oil outlet
ports EF and
CF, feedback oil port LS, and oil return port T, which are connected with oil ou
tlet port of
steering pump, oil inlet port of hydraulic oil radiator, oil inlet port of steer
ing gear, port
LS of steering gear, and oil return port of hydraulic tank respectively.
This valve is matched with the BZZ6 steering gear to form the load-sensing steer
ing
system. At the speed variation of the steering wheel, it can preferentially guar
antee the
flow required by the steering gear and the remaining oil flows into the working
device
hydraulic system.
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Port EF
Port P
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. When the steering wheel is stationary, the pressure oil from the steering
pump flows to port EF from port P through valve core and enters into the
working device hydraulic system or returns to oil tank directly.
Port CF

T
Port EF
Port P
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. When the steering wheel is rotating, under the joint action of the spring forc
e and LS pressure, the
valve core moves rightward to connect the port P with port CF so that the pressu
re oil enters into
the steering gear and drives the cylinder for steering of loader and the excessi
ve oil diverges into
the working device hydraulic system or oil tank through port EF.
Ls
Port CF

1) Heavy steering (analysis and judgment procedure)
Section IV Cause Judgment and Troubleshooting for
Common Malfunctions of Steering Hydraulic System
Cause Measure
Air content in system
 Failure of manual
steering check valve
 Leakage of FK
overload valve
 Internal leakage of
cylinder
Damage of steering
column
Blockage of pipeline
Bleed air from system
and check oil inlet port
of oil pump for air
leakage
 Check steel ball for
presence and
blockage
 Replace FK
combination valve
 Check cylinder for
internal leakage
Repair or replace
Clean or replace
Judge as per malfunction
symptom
Cylinder creepage, air bubbles in oil, and regular
sound
Heavy steering and no action of
steering cylinder
Check steering
column for flexible
rotation
Does system pressure
meet requirement?
Check feedback oil
pipe for blockage
Yes
Yes
Yes
No Yes
No
No
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Low system pressure
Breakage of priority
valve spring or
blockage of valve core
Shortage of oil
Blockage of pipeline
Wear or internal
leakage of steering
pump
Repair or replace
Adjustment system
pressure

Add hydraulic oil
Clean or replace
Repair or replace
Is the steering heavy
at high speed and
light at low speed?
Is hydraulic oil level
too low?
Adjust the system pressure.
Is there any pressure
change?
Is oil suction pipe
blocked?
Yes
Yes
Yes
Yes
No
No
No
No
Yes

2) No steering end or failure for steering to limit position (analysis and
judgment procedure)
No end
After the steering cylinder rotates to limit position,
when the steering wheel is rotated with high force,
the steering wheel can rotate lightly, namely there
is no feeling of end.
Malfunction
cause Troubleshooting
Appropriately
increase pressure
of overload valve
Low pressure of
overload valve
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failure for steering to limit position
The steering cylinder can t be
rotated to the limit position, with
heavy steering
Malfunction
cause Troubleshooting
Low pressure of
safety valve
Appropriately increase
pressure of safety valve

. Due to leakage towards the cylinder port when the closed
core steering gear is at neutral position, the slight offtracking
of the closed core steering gear is normal.
. Check the cylinder connecting rod for presence of
looseness.
. Internal leakage of cylinder.
. High pressure difference between two tires.
. Unilateral leakage of two-way overload valve or two-way
oil refilling valve.
3) Cause for off-tracking of machine
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. Air content in oil.

. Air content in system.
. Loose cylinder pin.
. Stagnation of priority valve or shunt
valve core.
. Internal leakage of cylinder.
. Low pump efficiency, leading to
unstable pressure. L R
4) Incorrect steering
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Fixed Engine
Pump
Reservoir
Filter
T
P
p

. Serious internal leakage of
two-way overload valve
5) No rotation or slow rotation of steering wheels, though the steering
wheel can be rotated flexibly.
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. Serious leakage of cylinder
piston.

. Loose nuts of
steering wheel.
. Worn or damaged connection between
steering column and steering gear.
L
T
R
P
6) Idle travel of steering wheel
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. Air content in oil.
. Internal leakage of
two-way overload
valve
. Internal leakage of
steering cylinder
Engine
Fixed
Pump
Reservoir
Filter
p

. Incorrect assembly relationship. At the
time of reassembly after the disassembly
for repair, it s required to align the
spline teeth of the linkage shaft shifting
pin slot with the corresponding inner
7) Vibration or autogiration of steering wheel
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spline teeth of rotor.
. When the oil pumped is connected to
the port R or L, the steering gear will
rotate on its axis like a motor.

Cause:
The check valve at oil inlet port of
steering gear is damaged.
Function of check valve:
It prevents the backflow of oil in steering
cylinder under the action of external
force when the pressure is higher than
the pressure at oil inlet port. If the check
valve is damaged, the backflow of oil will
8) Bounce of steering wheel
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lead to bounce symptom of steering
wheel.

Overview of Brake System
CONTENTS
Working Principle of Brake System
Structures and Working Principles of Brake System Units
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Use, Replacement, and Precautions of Brake Fluid
Cause Judgment and Troubleshooting for Common
Malfunctions of Brake System

Section I Overview of Brake System
I. Concept of pneumatic transmission
The transmission of energy and signal and process control that utilize
the compressed air as power source as well as working medium are
referred to as pneumatic transmission.
1. Advantages: Simple structure, low cost, easy realization of stepless
speed regulation, low resistance loss, and fast actions and response.
2. Disadvantages: Low working pressure (suitable for low power
transmission only), poor stability of pneumatic devices (as the air is a
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compressible substance), and often change of working speed along
with external load.

II. Requirements of pneumatic transmission on working medium:
1. The compressed air requires certain pressure and sufficient flow.
1) Without certain pressure, the sufficient push force of the actuators
can t be guaranteed and even the correct actions of the control
mechanisms can t be fulfilled.
2) Without sufficient flow, the action speed and procedure requirement
of the actuators can t be guaranteed.
2. The compressed air requires certain cleanliness and dryness
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1) The cleanliness refers to the oil content and dust content in the air
source.
2) The dryness refers to the water content in the compressed air (The
water content of compressed air required by the pneumatic device
shall be as low as possible).

III. Concept of braking
The braking is to generate sufficient braking moment by means of the brake
system to consume the motion energy of the machine accumulated during the
traveling and force the machine to slow down and finally stop within a certain
distance. The relatively common method in the brake system is to apply the
braking by utilizing the mechanical friction to consume the motion energy of the
traveling machine.
IV. Classification of brake system
The brake system can be classified by function of brake into service brake and
parking brake.
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1. The brake system used to slow down or stop the loader during traveling is
referred to as service brake system. As the function of the brake is controlled
by
the foot of the driver, it s also referred to as foot brake system (or foot brake
for short). In the foot brake system, the brake is installed one two ends of eac
h
drive axle, closing to the wheel reducer. When the brake is functioning, the
braking is applied directly on the wheels (brake discs). The service brake
generally utilizes the oil pressure for functioning. The booster is adopted duri
ng
the operations to realize light operations.

V. Composition of brake system
Energy supply device, control devices, transmission devices,
actuators, and accessories.
1. Energy supply device: Air compressor
2. Control devices: Oil-water separator, pneumatic brake valve, and
brake solenoid valve.
3. Transmission devices: Booster pump, and parking brake air
chamber.
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4. Actuators: Brake caliper, and parking brake.
5. Accessories: Air reservoir, and pipelines.

Section II Working Principle of Brake System
I. Service brake system
The brake system used to slow down or stop the loader during traveling is referr
ed
to as service brake system.
As the function of the brake is controlled by the foot of the driver, it s also re
ferred
to as foot brake system (or foot brake for short). In the foot brake system, the
brake
is installed one two ends of each drive axle, closing to the wheel reducer. When
the
brake is functioning, the braking is applied directly on the wheels (brake discs
). The
service brake generally utilizes the oil pressure for functioning. The booster i
s
adopted during the operations to realize light operations.
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1. Classification of service brake system
1) By brake air pressure circuit:
It can be classified into single circuit system and dual circuit system.
2) By medium in which the brake shoe is seated:
It can be classified into dry brake and wet brake.
The caliper brake belongs to dry brake.

2. Working principle of LG958L service brake system
The service brake system of LG958L is mainly composed of air compressor,
oil-water separator, air reservoir, air brake valve, shuttle valve, booster pump
,
brake caliper, and pipelines. This system is a dual circuit air-assisted hydraul
ic
caliper disc 4-wheel brake system, of which the system layout diagram is
shown in Figure 8-1 and the schematic diagram of the system is shown in
Figure 8-2.
When the brake pedal is depressed during the traveling, the compressed air
in the air reservoir enters into the chamber of air booster pump via shuttle
valve and air brake valve to push the piston of booster pump and convert to
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oil line (oil pressure is approximate 14MPa). The brake fluid pushes the piston
of caliper brake so that the friction plate is pressed tightly against the brake
disc to brake the wheels, in order to slow down or stop the machine.
When the brake pedal is released, the compressed air of the booster pump is
drained into the open air from the brake valve and the braking state is
released.

Foot brake valve
Brake caliper
Brake disc
Shuttle valve
Booster pump
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Figure 8-1 Layout diagram of LG958L service brake system
To oilwater
separator
Combinati
on valve
Air reservoir

Front axle brake pump
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Figure 8-2 Schematic diagram of LG958L service brake system
1. Air booster pump 2. Shuttle valve 3. Air brake valve 4. Air reservoir 5. Oilwater
separator combination valve 6. Air compressor 7. Brake solenoid valve
8. Parking brake air chamber
Rear axle brake pump

II. Parking brake system
The brake system used to hold the loader at original position after parking is r
eferred to
the parking brake system.
The parking brake system is used to brake the loader in event of emergency durin
g the
traveling of loader and is functioned for safety protection when the brake syste
m air
pressure is too low. However, the main function of the parking brake system is f
or hold the
loader against the movement due to tilted road or action of external force after
the loader
stops working.
As the function of the parking brake is controlled by the hand of the driver at
the time of
braking, the parking brake system is also referred to as handbrake system (or ha
ndbrake
for short). The brake of the handbrake system is generally installed on the fron
t output
shaft of the loader transmission. To apply the parking brake, when the brake kno
b is
pressed, the parking brake air chamber pulls the parking brake caliper to expand
the brake
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shoe and apply the parking brake.
1. Classification of brake system:
1) By braking mode:
Manual parking brake, electro-pneumatically controlled parking brake, and manual
pneumatically
controlled parking brake.
2) By type of brake: Caliper type and internal expanding shoe type.
The parking brake of LG958L loader adopts electro-pneumatically controlled calip
er type
parking brake system, of which the structural diagram and circuit diagram of LG9
58L
parking brake system are shown in Figure 8-3.

Brake solenoid
valve
Pressure switch
Brake knob
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Figure 8-3 Structural diagram and circuit diagram of LG958L parking brake system
1. Air pressure signal lamp switch 5. Brake solenoid valve 8. Parking brake air
chamber
14. Handbrake 17. Pressure switch 19. Pressure sensor

2. Working principle of LG958L parking brake system
1) Manual release and set of parking brake
When the pressure of compressed air in the brake system is within normal working
range, rotate the brake operating button on the right control box of the cab. Th
e
button pops up automatically to provide a electric signal (the wires 54 and 55 a
re
connected) to the brake solenoid valve so that the compressed air from air reser
voir
enters into the parking brake chamber via brake solenoid valve and then the pist
on
compresses the spring to release the caliper brake and release the parking brake
.
In event of emergency braking or parking, push down the operating button of the
brake solenoid valve to cut off the solenoid valve. In such case, the compressed
air in
the parking brake chamber is drained to the open air via brake solenoid valve so
that
the brake is pulled for braking purpose under the action of the spring force. At
the
same time, the air pressure signal is outputted to control the light-up of parki
ng brake
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indicator, in order to alert the operator that the complete machine is under bra
ked
state.
Brake operating button
Rotate to connect the wire 54 with
wire 55 so that the solenoid valve
is powered on to release the
parking brake.
Push down to disconnect the wire
54 from wire 55 so that the
solenoid valve is cut off to set the
parking brake.

2) Air pressure automatic protection and control
During the operations of the loader, if the air pressure of the air reservoir is
less than the specified safety pressure (0.4MPa) due to system leakage, the
brake pressure switch automatically cuts off the brake solenoid valve so that
the spring of the brake chamber returns to apply emergency braking, in order
to guarantee operation safety. In event of similar situation during operations,
stop the machine, check the air circuits, and resolve the malfunction before
startup again.
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The pressure switch cuts off
circuit to realize emergency
braking when the air pressure
is less than 0.4MPa.

Section III Structures and Working Principles of Brake System Units
I. Air compressor
Connecting rod
Crankshaft
Piston
Piston ring
group Exhaust pipe
Crankcase
Intake pipe
Cylinder head
Cylinder
block
Exhaust
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The air compressor is installed on the engine and is composed of intake pipe, ex
haust pipe, cylinder
head, cylinder block, crankcase, crankshaft, connecting rod, piston, piston ring
group, piston pin, intake
valve, and exhaust valve.
Intake valve
Exhaust
valve
Intake valve

Connecting rod drives downward movement of piston along cylinder Exhaust valve c
losed
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The air compressor is functioned to provide compressed air source for the brake
system to assist the braking of the
machine.
The air is filtered by the air cleaner and then enters into the intake pipe of a
ir compressor. Driven by the crankshaft
within the crankcase, the connecting rod drives the piston for downward movement
along the cylinder to open the
intake valve and close the exhaust valve to suck the air into the cylinder. Then
, the piston moves upward to close the
intake valve and open the exhaust valve to exhaust the air. The air compressor r
epeats above process to complete
the air intake and air exhaust.
Exhaust valve opened

II. Oil-water separator combination valve
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The oil-water separator combination valve is a combination valve composed of oil
water
separator and air pressure regulator. It's functioned to automatically adjust th
e
working pressure of brake system air source, guarantee the safety of loader brak
e
system, and separate the oil, water and other impurities from the compressed air
and
automatically drain through unloading device. Screw off the butterfly nut to inf
late the
tire if necessary.

Upper
cap
Middle
body
Safety valve
assembly
Air pressure
regulator
subassembly
Check
valve
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The oil-water separator combination valve is mainly composed of middle body, upp
er and lower caps, and
internally separated oil-water separation cavities, filter element, check valve,
and safety valve assembly, and air
pressure regulator subassembly and pneumatic-hydraulic drainage valve subassembl
y.
Lower
cap
pneumatichydraulic
drainage
valve subassembly
Filter
element

Adjustment
spring
Diaphram
Control
piston
Adjustment
Exhaust
piston
assembly
Oil
collector
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The air pressure regulator subassembly of the oil-water separator combination va
lve is composed
of the control piston, regulator valve, adjustment spring, and diaphragm.
The pneumatic-hydraulic drainage valve is mainly composed of exhaust piston asse
mbly, oil
collector, valve seat, and lower housing and spring.
valve
Valve
seat

Intake
port
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The air from the air compressor enters into the oil-water separator combination
valve via intake port and the airflow
impact the surface of housing within the combination valve so that the direction
and speed of the airflow are
changed and the oil and water, of which the densities are higher than that of ai
r, are separated and cohered under
the action of inertia force onto the lower housing wall of the oil-water separat
or combination valve. The water and
water separated will flow along the walls and accumulate in the chamber B via th
e oil collector.
Chamber B
Flow to chamber B through oil
collector

To air reservoir
The air pushes open
check valve
Chamber C
Chamber D
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After being treated by the oil-water separator, the compressed air enters into t
he chamber C
via filter element assembly, pushes open the check valve, and enters into the ai
r reservoir.
After pushing open the check valve, the air is divided into two passages, of whi
ch one enters
into the air reservoir and the other enters into chamber D via orifices on the t
hrottle plug.
Another passage flows into chamber D through orifice of throttle plug

Valve
seat
Regulator
valve
Valve
lever
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When the system pressure is less than the pressure setting (0.784MPa), the regul
ator
valve is pressed by the valve lever onto the valve seat so that the valve is und
er
closed state.
When system pressure is less than pressure setting.
Pressure setting: 0.784MPa

Pressure
regulator spring
Diaphragm
Valve lever
Regulator valve
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When the pressure of chamber D is higher than the pressure
he
compressed air overcomes the preload of pressure regulator
upward
movement of diaphragm, which drives the upward movement of
t the
valve lever is floating and the compressed air pushes open
nd valve lever.
Chamber D

setting (0.784MPa), t
spring and pushes the
control piston so tha
the regulator valve a

Lower orifice of
control piston
Chamber E
Chamber F
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While the regulator valve is moving upward, the lower orifice of the control pis
ton is
closed so that the air in the chamber E enters into the chamber F to push the
downward movement of exhaust piston and open the lower exhaust valve.
Exhaust piston
Open lower air bleeding valve

Check valve is
closed
Chamber A
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The air of chamber A from the air compressor is directly exhausted to the open a
ir to
realize the unloading of the air compressor.
In such case, the oil, water, and other impurities accumulated in the chamber B
are
exhausted along with the compressed air.
In such case, the check valve is closed to stop the air supply to the air reserv
oir.
Chamber B
In such case, check valve closes to cut off the air
supply to air reservoir.

Chamber F
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When the pressure of air reservoir is less than 0.686MPa, the control piston ass
embly is
returned under the action of the pressure regulator spring and the valve lever p
ushes the
downward movement of regulator valve to close the air passage from chamber E to
chamber F.
In addition, by means of the gap between control piston and valve lever, the pas
sage between
the chamber F and open air is connected so that the air of chamber F is rapidly
exhausted to
the open air. The exhaust piston assembly moves upward rapidly to close the lowe
r exhaust
valve and the air compressor supplies the air to the air reservoir again.
Air in chamber F is rapidly exhaust into open air and the exhaust
piston assembly moves upward rapidly

Failure of control
piston assembly
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If the pressure regulation of the oil-water separator combination valve is
failed so that the air pressures rises to 0.882MPa, the safety valve
assembly is pushed open and the compressed air enters into the open
air, in order to protect the safety of brake system.

Reservoir
body
Air pressure
sensor
Safety
valve
Tire inflation
valve
Pressure
switch
III. Air reservoir
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The air reservoir is installed on the downstream of the oil-water separator comb
ination valve and is mainly functioned
to store the compressed air and provide braking air source for the brake system,
in order to guarantee the
compressed air required for several operation cycles of the braking when the air
compressor is not working.
The air reservoir is mainly composed of the reservoir body, pressure switch, air
pressure sensor, safety valve, tire
inflation valve, and water drainage valve.
Water
drainage
valve

When the driver depresses the foot brake pedal or operates the parking brake sol
enoid
valve, the compressed air enters into the brake or working chamber via control v
alve to
realize the service braking or parking braking.
1. Safety valve
When the safety control valve of the oil-water separator combination valve is fa
iled, it
protects the brake system. The pressure setting is 0.85~0.9MPa and the safety va
lve
opens to exhaust the air when the pressure setting is exceeded.
2. Air pressure sensor
It provides the pressure value for the air pressure gauge so that the driver can
correctly
judge the braking state and the good air circuit performance depending on the re
ading
of the air pressure gauge.
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3. Water drainage valve
When the water content accumulated in the air sinks to the bottom of the reservo
ir,
loosen the water drainage valve to drain the accumulated water so that the
accumulated water within the reservoir can be drained timely to reduce the rusti
ng and
keep clean the brake pipeline.
4. Pressure switch
When the brake air pressure is less than 0.4MPa, the pressure switch cuts off th
e power
supply to the brake solenoid valve to cut off the solenoid valve and realize eme
rgency
braking.

IV. Air brake valve
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The air brake valve is used to control the compressed air amount entered into th
e booster pump
chamber at the time of braking, namely controlling the air pressure of booster p
ump, in order to
obtain different braking effects. Therefore, the driver can feel the "road feeli
ng at the time of
braking, namely the driver can feel the braking extent of machine based on the t
ravel of pedal
and the size of operating force.
The air brake valve is mainly composed of the pedal, upper and lower valve bodie
s, and the push
rod, piston, balance spring, intake valve assembly, and return spring within the
valve body.

When the driver depresses the brake
pedal 2, the push rod 1 applies certain
pressure to balance spring 4 under the
action of the pedal to push the downward
movement of piston 5, close the passage
between exhaust port C and open air, and
push open the intake valve assembly 8.
The compressed air from the air reservoir
enters into the front and rear booster
pump group or brake selector valve
through air intake port A, air intake valve
assembly 8, and air exhaust port C to
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Figure 8-4 Structure of air brake valve
1. Push rod 2. Foot brake pedal assembly
3. Dust cover 4. Balance spring assembly
5. Piston assembly 6. Piston return spring
7. Valve body 8. Intake valve assembly
9. Valve assembly 10. Exhaust valve assembly
11. Sealing plate 12. Spring seat
generate the braking effect.

Under the braked state, the stably proportional variation between the output pre
ssure
of exhaust port C and the operating force of brake pedal is achieved by the bala
nce
spring. When the operating force of the brake pedal is a fixed value, the pressu
re
applied by the push rod onto the balance spring is also a fixed value. After the
air valve
opens, the balance spring is compressed when the force applied by the lower cham
ber
pressure of the piston 5 onto the piston exceeds the spring force of the balance
spring
so that the piston moves upward, till the intake valve is closed. In such case,
the force
applied by the air pressure onto the piston is balanced with the pressure applie
d by the
brake pedal onto the balance spring so that the output pressure of the exhaust p
ort is a
fixed pressure. When the pressure applied by the brake pedal onto the balance sp
ring is
increased, the piston starts to move downward to re-open the intake valve. When
the
lower chamber pressure of the piston is increased to a certain value in such man
ner
that the force applied onto the piston is balanced again with the pressure appli
ed by
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the brake pedal to the balance spring, the intake valve is closed again and the
output
pressure of exhaust port C is maintained at a fixed value higher than the previo
us value.
In other words, the output pressure of exhaust port is proportional to the compr
ession
set of the balance spring, namely it s proportional to the travel of brake pedal.
When the brake pedal is released, the piston 5 is pushed to the highest position
under
the action of return spring 6 and the intake valve is closed under the action of
return
spring to complete the braking process. In such case, there is a fixed gap (appr
oximate
2mm) between the lower end of piston and intake valve so that the compressed air
returned from the booster pump group is exhausted into the air via this gap and
the
central orifice of intake valve.

V. Air booster pump
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The booster pump is mainly composed of the booster cylinder body, brake cylinder
body, oil pressure piston, air chamber piston, push rod, push rod seat end cap,
return
spring, oil reservoir, and seals, as shown in Figure 8-5 Structural Diagram of A
ir
Booster Pump.
The booster pump is mainly intended to pressurize the brake fluid within the bra
ke
master pump by means of the compressed from the brake valve, in order to push th
e
working of the brake caliper piston.

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1. Booster cylinder body 2. Yx-shaped seal ring 3. Piston 4. Return spring 5. En
d cap 6. Oil reservoir 7. Push
rod seat assembly 8. Oil pressure piston 9. Brake pump body 10. Air bleeding scr
ew 11. Master pump rubber
cup 12. X-shaped seal ring 13. Breather 14. Push rod
Figure 8-5 Structure of Air Booster Pump

High
pressure oil
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The working process of the booster pump is as below:
1) When the brake pedal is depressed at the braking of the loader, the compresse
d air from the
brake valve enters into the booster cylinder body via intake connector and pushe
s the
rightward movement of piston 3 by overcoming the acting force of spring 4. As th
e piston is
integrated with the push rod 15, the oil pressure piston 8 of the brake master p
ump is driven
for rightward movement by the push rod seat assembly connected with the push rod
to close
the oil within the pump body so that a high pressure (Generally, when the brakin
g pressure is
0.686MPa, the pressure at oil outlet port is approximate 12MPa) is generated for
the brake fluid
within the brake master pump. The high pressure brake fluid enters into the disc
brakes
respectively via pipelines to brake the wheels.

2) When the brake pedal is released, under the action of the return
spring 4, the piston 3 moves rightward so that the compressed air
returns the brake valve from the connector of booster cylinder
and is exhausted to the open air via brake valve. In addition, the
push rod drives the leftward movement of the push rod seat
assembly and the oil pressure piston 8 moves leftward
accordingly so that the high pressure brake fluid in the brake
returns to the brake pump body via oil pipe and the braking state
is released.
3) When the brake pedal is released rapidly, as the brake fluid within
the brake pump fails to timely return along with the oil pressure
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piston 8, a low pressure is formed within the brake pump cylinder.
Under the action of atmospheric pressure, the brake fluid in the
oil reservoir refills into the pump body via the gap between the
push rod seat assembly and the oil pressure piston. In such case,
if the brake pedal is depressed again rapidly, the braking effect
will be better.

VI. Caliper brake
The brake caliper is mainly
composed of inner caliper,
outer caliper, seal ring,
piston, rectangular seal
ring, and dust cover.
The pressurized brake fluid
is applied onto the piston
of brake caliper to drive the
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Figure 8-6 Structure of disc brake
1. Outer caliper 2. Steel ball 3. Bolt 4. Air bleeding screw 5. Piston 6. Rectan
gular seal ring 7. Hollow bolts
8. Pipe connector 9. Bolt pin 10. Bolt 11. Brake caliper cover 12. Inner caliper
13. Dust cover 14. Pin 15. Brake
caliper friction plate 16. O-ring
brake friction plate to clamp
the rotating brake disc from
both sides for braking
purpose.

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At the time of braking, the high pressure brake fluid outputted by the booster p
ump is
distributed to each branch pump cylinder via oil pipes and inner and outer calip
er oil passages
so that the symmetrically arranged pistons move inward and the brake friction pl
ates are driven
by oil to clamp the brake discs to slow down and stop the wheels connected with
brake discs, in
order to achieve the braking purpose.

VII. Brake solenoid valve
P. To air reservoir
A. To brake air chamber
T. To open air
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The brake solenoid valve is used in the parking brake system, of which the intak
e port is connected
with the compressed air from the air reservoir, the outlet port is connected wit
h the parking brake
chamber, and the exhaust port is connected with the open air.
1. When the control button is released, the solenoid valve is powered on so that
the solenoid
valve core is actuated to open the air passage to the parking brake chamber and
the air
pressure overcomes the spring force of the brake chamber spring to release the p
arking brake.
2. When the control button is pushed down or the brake pressure is less than 0.4
MPa, the brake
solenoid valve is cut off so that the valve core closes the air passage to the b
rake chamber. At
the same time, it opens the passage of brake chamber to the open air to engage t
he brake.

VIII. Parking brake chamber
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Figure 8-7 Structural diagram of parking brake chamber
1. Hinge pin 2. Split pin 3. Washer 4. Connecting plate 5. Connector 6. Nut 7. W
asher 8. Bolt 9. Cap
10. Baseplate 11. Spring 12. Push rod 13. Housing 14. Piston 15. Nut 16. Washer
17. Seal ring
18. Piston rubber ring 19. Bolt 20. Washer 21. Guide ring

The engagement and disengagement of the emergency brake and parking brake are
fulfilled by the brake chamber. When the air pressure overcomes the spring force
of
the brake chamber spring, the parking brake is released. When the air source is
cut
off or brake air pressure is less than the specified value, the air chamber spri
ng
returns to engage the brake.
The brake air chamber is fixed on the frame and the brake push rod is connected
with the cam handle of the brake. The structure of the parking brake chamber is
shown in Figure 4-6.
When the air pressure drops to 0.4MPa, the brake solenoid valve automatically cl
oses
the valve port to prevent the input of compressed air into right chamber of brak
e air
chamber. The spring force of the spring 11 drives the piston 14 to the right end
of
brake air chamber and the push rod port moves rightward to drive the cam lever o
f
brake and engage the brake.
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Precautions:
The compression force of the brake spring within the parking brake air chamber i
s
really high and shall not be disassembled. In event of malfunction, replace the
assembly, in order to prevent safety accidents.
When it s necessary to tow the machine in event of causes such as machine
malfunction, make sure to release the air chamber push rod and brake handle befo
re
towing, in order to prevent the damage of machine.

I. Classification of brake fluid
The brake fluid is mainly classified into glycol brake fluid, mineral oil brake
fluid, and synthetic brake fluid. At present, the glycol and mineral oil brake
fluids are seldom applied and the main brake fluid in use is the synthetic
brake fluid.
1. Synthetic brake fluid
It s a brake fluid fabricated on the basis of the synthetic fluid with addition
of multiple additives.
Section IV Use, Replacement, and Precautions of Brake Fluid
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2. Identification method
By taking the HZY3 brake fluid for instance, the letters H, Z, and Y represent
the first Chinese phonetic alphabets for synthetic, brake, and fluid
respectively and the number 3 represents the marking for differentiating the
different standards within this series, without any specific meaning.
The service brake system of our products adopts HZY3 (DOT3) synthetic
brake fluid.

II. Use of brake fluid
1. It s prohibited to mix the brake fluids of different brands for service,
in order to prevent the loss of braking effect due to delamination of
brake fluid.
2. The container for the brake fluid must be special container, in order to
prevent the mixture of other oil from causing failure of brake fluid due
to reaction.
3. The container for brake fluid must be clean and securely covered to
prevent the ingress of mechanical impurities and water content.
Any dust or impurity on the surface of the brake fluid detected during the
use shall be removed and the stirring is absolutely prohibited. Use clean
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special tools while adding the brake fluid.
III. Replacement of brake fluid
1. When the brake fluid contains mineral oil, such as gasoline and diesel.
2. When the occasional light and heavy brake operations occur during
normal traveling of the vehicle.
3. When the brake fluid in the system becomes less due to certain cause
or when the machine fitted with level alarm alarms.
4. When the muddy brake fluid or the multiple impurities and sediments
are detected during the checking of brake fluid.

IV. Precautions for replacement of brake fluid
1. Make sure to use our designated brake fluid.
2. At the replacement of brake fluid, fully drain the used fluid from the
brake system and carefully check new brake fluid.
3. At the replacement of brake fluid, minimize the contact time between
the brake fluid and the open air, in order to prevent the performance
deterioration of brake fluid due to moisture adsorption.
4. Before the replacement of brake fluid, it s better to thoroughly clean
the brake system with ethanol.
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V. Air bleeding of brake system
The ingress of air into the brake pipeline will impair the braking effect and,
under worse condition, lead to failure of brake. Bleed the air from the system
after the replacement of parts, cleaning of system, and replacement of brake
fluid.

The air bleeding method is as below:
1. Top up the brake fluid to the booster pump reservoir.
2. Loosen the air bleeding screw of the booster pump, till the fluid
flows out continually, and then tighten the air bleeding screw.
3. Start the engine. After the air pressure reaches the specified value
(0.68MPa), depress he brake valve pedal for several times to fully fill
the brake pipeline and brake calipers with brake fluid. While the
brake pedal is depressed, loosen the brake caliper bleeding screw
to bleed the air and then rapidly tighten the bleeding screw. Repeat
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above operation, till the brake fluid flows out without any air
bubble from the brake caliper, and then stop the bleeding and
tighten the bleeding screw.
4. During the air bleeding, continually add brake fluid into the brake
fluid reservoir to prevent the ingress of air.
5. After the air bleeding, add brake fluid till the level is above 2/3 of
the reservoir, and then tighten the reservoir cap.

Case 1
Malfunction Symptom:
What is the cause for braking drag?
Definition of braking drag: After the brake is released, the brake
caliper still has the incomplete disengagement malfunction so that
the brake caliper still transmits partial braking torque under the nonbraked
state.
Section V Cause Judgment and Troubleshooting
for Common Malfunctions of Brake System
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braked Judgment thinking:
. Air content in brake system.
. Check the front and rear axles for locking.
. Malfunction of brake caliper.
. Malfunction of brake valve.
. Malfunction of booster pump.

Case 2
Malfunction Symptom:
What is the cause for brake fluid leakage of booster pump?
Judgment thinking:
. Firstly observe the leakage portion of the brake fluid and determine
the internal leakage or external leakage.
. Damage or internal leakage of push rod guide seal if the brake fluid
leaks from the booster cylinder breather or its joint.
. Damage or external leakage of seal ring if the brake fluid leaks from
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the joint between pump body and end cap.
. Damage or external leakage of seal ring if the brake fluid leaks from
the joint between reservoir and end cap.
. The brake fluid returns from high pressure chamber to low pressure
chamber due to fluid permeation at reservoir port or damage of
brake pump oil seal.
. The damaged sealing seat of push rod seat will cause external fluid
permeation of the reservoir.

Case 3
Malfunction Symptom:
What is the cause for braking squeal of the brake, which is
generally accompanied with brake heating?
Judgment thinking:
. Firstly observe which brake caliper portion has the squeal.
. Loose connecting bolts between brake caliper and drive
axle and collision or wear between friction pair.
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. Inclusion of hard object between brake lining and brake
disc.
. Material problem of brake plate and brake disc.

Case 4
Malfunction Symptom:
What is the cause for braking off-tracking of the loader?
Judgment thinking:
. The direct cause for off-tracking is the unequal braking torque
between left and right wheels.
. The brake caliper of the wheel on one side is blocked against
disengagement during the travelling, This is commonly caused by
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the damaged rectangular seal ring of the brake caliper, which is
functioned for return purpose.
. When the brake pedal is depressed, the brake caliper on one side
is braked and, due to internal leakage, blockage of oil line, or
rusting of brake caliper piston, the brake fluid can t enter into
the brake caliper on the other side to cause unequal braking
torque and off-tracking.

Case 5
Malfunction Symptom:
What is the cause for sudden unavailable braking during traveling of the loader?
How to take emergency measures?
Judgment thinking:
If the unavailable braking occurs suddenly when the air pressure within the air
reservoir or the oil amount in the reservoir of brake master pump are within
specified ranges, check for the following causes:
. The lip of air chamber rubber ring of the booster pump is reversed or damaged
suddenly so that the compressed air permeates into the low pressure chamber
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through seals.
. The lip of rubber cup of brake master pump is reversed or damaged suddenly so
that the brake fluid of high pressure chamber permeates into the low pressure
chamber.
. The piston assembly of the air brake valve is suddenly blocked so that the int
ake
valve core can't be moved downward effectively to open the intake port.
. Under emergency conditions, in event of sudden unavailable braking ,
immediately lower level the bucket onto the ground and apply pressure
downward or brake by shifting to reverse gear.

Case 6
Malfunction Symptom:
What is the cause for rise failure of brake pressure?
Judgment thinking:
. Pipeline malfunction.
. Oil-water separator malfunction.
. Brake valve malfunction.
. Air compressor malfunction.
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Brief of A/C System
CONTENTS
Maintenance of A/C System
Common Malfunctions and Troubleshooting of
A/C System
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I. Composition of A/C system
The A/C system is composed of compressor, evaporator assembly, condenser assembl
y,
fluid reservoir, throttling units, and refrigeration hoses. The compressor is dr
iven by the
engine via belt. The A/C system is powered by the power supply of the machine an
d
the temperature and fan speed are controlled by the panel switches.
Compressor
Fluid reservoir
Condenser assembly
Section I Brief of A/C System
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Evaporator assembly
Refrigeration hoses

II. Technical specification of A/C system
Refrigerating
output 4600W Air output 800 m3/h
Voltage 24V Total power
consumption =310W
Compressor SE5H14 Refrigerant R134a
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Filling amount of
refrigerant 1000-1300g Heating output 5000W

1. Refrigeration principle
III. Working principle of A/C system
Cool air
Low pressure and low
temperature mist
refrigerant
Low pressure and low temperature gas
Thermal sensing cylinder
Evaporator
Low pressure and low
temperature fluid
Fan motor
Expansion valve
Fluid refrigerant
Cool air
Composition and working principle of A/C system
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Air within body
compartment
Compressor
Hot air
Front cool air
Condenser
Low pressure side
service valve High pressure side service valve
High pressure and high
temperature gas
Engine cooling fan
Fluid reservoir
Moderate temperature
and high pressure fluid
Fluid reservoir tube
Desiccant (bagged)
Filter screen

C Throttling and expansion process
After being dried and filtered by the
reservoir drier, the fluid refrigerant is
conveyed to the expansion valve and is
converted to low temperature and low
pressure fluid through the throttling and
expansion by the expansion valve. This
process features the sharp reduction of
pressure and temperature.
D Evaporation process
Through the temperature and pressure
reduction by expansion valve, the fluid
refrigerant enters into the evaporator. The
fluid refrigerant is vaporized to absorb heat
and is converted to low temperature and
low pressure gas and conveyed into
compressor. The air heat within the machine
is absorbed by the evaporator via fan to
cool down the inside of the machine and
achieve the refrigeration purpose.
Air within body
compartment
Hot air
Cool air
Low pressure and
low temperature
mist refrigerant
Low pressure side
service valve
High pressure side
service valve
Low pressure
and low
temperature
gas
Thermal
sensing
cylinder
Evaporator
High pressure and
high temperature gas
Engine cooling fan
Low pressure and low
temperature fluid
Fan motor
Expansion valve
Fluid refrigerant
Moderate
and
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A Compression process
The refrigerant at low temperature and pressure is
sucked by the compressor and is compressed to gas
refrigerant under high temperature and high pressure
for input into condenser. This process consumes the
mechanical power.
B Condensation process
The gas refrigerant at high temperature and
pressure is conveyed into the condenser for

forced heat radiation and is gradually converted
to high temperature and high pressure fluid
refrigerant.
Compressor
Front cool air
Condenser
Fluid reservoir
temperature
high pressure fluid
Fluid reservoir tube
Desiccant (bagged)
Filter screen

The heating process utilizes the engine coolant.
A. Pressure control
The system pressure is controlled by high and low pressure switch, with the
pressure range at 0.169MPa~3.14MPa. The system will turn off the
compressor when the medium is short or unavailable. The compressor is
turned off in event of abnormally high system pressure to protect the
system.
B. Power fuse
2. Heating principle
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This system is fitted with three-way fuse to prevent short-circuit and
overload.
C. Fusible plug (high temperature) control
When the system pressure exceeds 2.9MPa or the system medium
temperature reaches 102~110ºC, the fusible plug is fused so that the
medium in the system is exhausted to the open air to guard the entire
system against damage.

Schematic diagram of A/C units
Evaporator fan
3-speed switch
Resistor
Relay
Fuse
Pressure switch
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Note: Framed line indicates main unit harness.
Thermostat
Temperature
Compressor Condenser fan sensing unit
Indicator lamp

Working indicator lamp
IV. Operation Method of A/C System
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Fan speed and power switch Temperature control switch

A. Refrigeration
. Start the engine.
. Turn on the fan speed and power switch and rotate the fan speed to
maximum speed.
. Turn on the temperature control switch to maximum position (the
working indicator lamp lights up).
. The A/C system starts the refrigeration. After the temperature is
appropriate, rotate the temperature control switch backward, till the
indicator lamp goes out.
. Adjust the fan speed switch (There are three speeds. When the
temperature is appropriate, adjust the fan speed to medium or low
speed.
. Adjust the direction of air outlets.
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B. Heating
. Start the engine.
. Open the water line valve.
. Turn on the power switch.
. Adjust the fan speed
switch.
Caution:
Close the heating water valve
during refrigeration in
summer.
Close the refrigeration
temperature control switch
during heating in winter.

The service life of loader s A/C system depends on the normal maintenance by the
user to a great extent.
I. Daily maintenance of A/C system
a) Check and clean the A/C condenser. Ensure that the radiator fins are clean wi
thout
any blockage material. Use cool water or compressed air, instead of hot water or
hot steam, for the cleaning.
b) Check the refrigerant amount in the refrigeration system, namely observe the
sightglass of the fluid reservoir. Normally, there is free of air bubble in the
sightglass
and there is a small amount of air bubble at the speed change of the engine.
c) Check the tension of the compressor drive belt.
Section II Maintenance of A/C System
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d) Check the hoses for normal appearance and secure connecters.
e) Check the power wires of refrigeration system for secure connections and pres
ence
of open-circuit and short-circuit.
Caution:
Periodically check and maintain the pipelines and other devices, no matter the A
/C
system is used or not.
If the A/C system is not used for several months, run the A/C system for approxi
mate
10min once a month to help the normal running of the system.
In winter, make sure to add antifreeze to the heater system to prevent the froze
n
cracking of the core.

II. Maintenance and schedule of A/C system
Maintenance and schedule of A/C system
No. Item Description
Maintenance schedule
Weekly Monthly Quarterly Yearly
1 Evaporator
Check motor for abnormal running noise . .
Check for non-obstructed air inlet and outlet .
Check for non-obstructed water drainage .
2 Compressor
Check fastening bolts for looseness .
Check for appropriate belt tension .
Check clutch for normal engagement .
Add refrigerant oil .
3 Condenser Check cleanliness of core and clean periodically
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.
4 Refrigerant Observe sightglass of fluid reservoir. Normally there is no
air bubble, otherwise the leakage is present. .
5 Pipeline
Check connectors for looseness and leakage (there is
generally oil trace for oil leakage) .
Check pipeline for damage. .
6 3-speed switch Check for clear control position and check for clear
change of airflow. .
7 Electric
connectors Check for looseness, falloff, and exposure .
8 Thermostat Check for normal working and check the indicator lamp
for normal light-up. .
9 system Check all parts for normal running, without any noise. .

I. Repair notices
1. The operator shall pass the training of automotive A/C basic knowledge
and safety knowledge.
2. The working environment shall be clean and moisture proof to prevent
the ingress of dirt and water content into the circuits. Avoid the working
under rainy weathers.
3. The A/C parts for repair or replacement shall use the parts of same
models manufactured by same manufacturer and mixed use is absolutely
prohibited. Check by self to ensure that the replacement parts meet all
Section III Common Malfunctions and Troubleshooting of A/C
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technical requirements, without any scratch or damage, and shall be good
sealed with dry and clean insides.
4. Guard against the dust and water during the entire repair process to
prevent the ingress of dirt and water into the system.
5. While connecting the connectors, check the seal ring for intactness. Apply
an appropriate amount of refrigerant oil (model: SUNISO 5GS for fluoro
rubber and SUNISO PAG for non-fluoro rubber) to the O-rings to prevent
the damage of O-rings. After the application of refrigerant oil, insert the
guide part to the dead end and then tighten the nuts to specified torque.

6. While tightening or loosening the nuts, use two wrenches. Clamp the
connector with one wrench and tighten the nut with another wrench and finally
tighten to specified torque with torque wrench. During the operations, tighten
to specified torque. While assembling the pipe connectors, tighten to specified
tightening torques, as listed in the table below:
Thread size Tightening torque
5/8-18UNF, M16×1.5 16~20N.m
3/4-16UNF, M22×1.5 20~25N.m
7/8-14UNF, M24×1.5 30~35N.m
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7. The arrangement of pipelines and harnesses shall keep away from the heat
source and rotating parts, in order to prevent wear and burst. The pipelines
shall not be too tight. Both ends of the hoses shall be fixed by hoops, with the
middle part fixed with pipe clamps. The harnesses shall be bundled by cable
ties.
8. While installing the hoses, pay attention to the minimum bending radius, in
order to prevent the sharp bends from causing bent pipeline and ensure the
appropriate orientation and non-obstructed pipelines.
9. During the repair, pay attention to protect the electric connectors to preven
t
collision. The electric circuits shall be correctly, reliably, and securely conn
ected.

II. Poor refrigeration effect
Phenomenon Cause Measure
1. Loose belt Adjust
2. Insufficient refrigerant due to leakage Find out leaks and add refrigerant
3. Over-high high pressure line and over-high low
pressure line.
a. Dirt and blockage of condenser radiator fins Clean
b. Stop of condenser fan Repair or replace
c. Excessive filling of refrigerant Drain as appropriate
d. Air content in system and reading vibration of
pressure gauge Find out leaks and drain or add
e. High opening extent of expansion valve Adjust or replace
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Normal evaporator fan 4. Over-high high pressure line and under-low low
pressure line
a. Dirt and blockage of expansion valve Clean or replace
b. Dirt and blockage of fluid reservoir Replace
c. Blockage of high pressure pipeline Repair or replace
5. Under-low high pressure line and under-low low
pressure line
a. Insufficient refrigerant due to leakage Find out leaks and add refrigerant
b. Small opening extent of expansion valve Adjust or replace
c. Blockage of low pressure pipeline Repair or replace
d. Blockage of evaporator Repair or replace

II. Poor refrigeration effect
Phenomenon Cause Measure
Normal evaporator fan
6. Under-low high pressure line and
over-high low pressure line
a. Malfunction of compressor Repair or replace
Insufficient evaporator airflow
1. Blockage of air inlet Remove blockage
material
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2. Blockage of air outlet Remove blockage
material
3. Frosting of evaporator Repair
Abnormal turn-on or turn-off of
refrigeration system
1. Air in system Vacuumize
2. Mis-adjustment of thermostat Adjust
3. Actuation failure of compressor
relay Repair and replace

Actuation failure of compressor
relay . Repair or replace
Insufficient or excessive refrigerant .
Check for leakage and add or drain.
Loose belt .
Adjust
Air in system .
Mis-adjustment
of thermostat .
Adjust
Dirt blockage of
condenser radiator fins
. Clean
Stop of condenser fan .
Repair or replace
II. Poor refrigeration effect
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Vacuumize Blockage of air
inlet . Clean
Blockage of air
outlet . Clean
Frosting of
evaporator .
Repair
Excessive or insufficient opening extent
or dirt blockage of expansion valve .
Adjust and clean
Blockage of high pressure
pipeline . Repair or replace
Blockage of low pressure
pipeline . Repair or
replace
Dirt blockage of
reservoir .
Replace

III. No refrigeration
Phenomenon Cause Measure
Normal functioning of evaporator fan and
working failure of compressor
1. Skid of compressor clutch Repair or replace
2. Falloff of wires Check and reconnect
3. Breakage of belt Replace
4. Activation of pressure switch
a. Excessive leakage of refrigerant Find out leaks and add
refrigerant
b. Excessive filling of refrigerant Replace damaged parts
c. Damage of switch Replace damaged parts
5. Damage of thermostat.
Normal functioning of evaporator fan and
1. Excessive leakage of refrigerant Find out leaks and add
refrigerant
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working of compressor 2. Excessive filling of refrigerant Drain as appropriate
3. Damage of compressor Repair or replace
No rotation of evaporator fan and working
failure of compressor
1. Malfunction of input power supply
a. Poor contact of grounding wire Check and repair
b. Burnout of fuse Check and replace
c. Damage of power switch Check and replace
No rotation of evaporator fan and working
of compressor
1. Damage of fan Replace
2. Burnout of fuse Replace
3. Damage of fan speed switch Replace
4. Damage of speed regulation resistor Replace

Excessive leakage of
refrigerant . Find out leaks
and add refrigerant
Damage of compressor clutch
. Repair or replace
Damage of compressor .
Repair or replace
Falloff of wires .
Check and connect
Breakage of belt
. Replace
Damage of pressure switch
. Replace damaged parts
Damage of
evaporator fan .
Replace
III. No refrigeration
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Damage of
thermostat .
Replace
Burnout of fuse .
Check and replace
Poor contact of grounding
wire . Check and repair
Damage of power
switch . Check and
replace
Damage of fan
speed switch .
Replace
Damage of speed
regulation resistor
. Replace
Circuit

IV. High noise
Phenomenon Cause Measure
1. Loose belt Adjust or replace
2. Loose compressor
bracket Adjust
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Abnormal system
sound
3. Loose evaporator fan
impellor Adjust
4 Clutch skid Repair or replace
5. Internal wear of
compressor Repair or replace

IV. High noise
Loose belt .Adjust
or replace
Loose evaporator fan
impellor .Adjust
Internal wear of
compressor .Replace
Clutch skid .Repair
or replace
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or replace
Loose compressor
bracket .Adjust

3 4
1.... 2....
3....(LO)
4....(HI)
A
B C
V. Filling of Refrigerant
1. Low pressure gauge
2. High pressure gauge
3. Low pressure valve (LO)
4. High pressure valve (HI)
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1. Vacuumization
Close the high pressure valve (HI) and low pressure valve (LO) of the pipeline p
ressure
tester, remove the plastic cap from the filling joint valve of the compressor, a
nd
connect the port B of pipeline pressure tester to joint valve on low pressure side
and port C to joint valve on high pressure side. Connect the port A of central
filling hose to vacuum pump. Open the low pressure valve and high pressure valve
of
pipeline pressure tester and the valve on vacuum pump and run the vacuum pump fo
r
approximate 15min, till the reading of the low pressure gauge is -0.1MPa.

At completion of vacuumization, close the high pressure valve (HI) and low
pressure valve (LO) of pipeline pressure tester, wait for 5min, and ensure that
the reading of the low pressure gauge is free of change, which indicates that
the system is free of leakage (or it indicates the presence of leakage and the
leak test and repair shall be conducted). Open the manual valve and
continue the vacuumization for approximate 15min. Caution: Under humid
weathers, appropriately prolong the vacuumization time as per the humidity
condition of the weather, in order to ensure the vacuum requirement.
2. Leak test
Close the manual high pressure and low pressure valves, the reading of
pressure gauge shall stable, which indicates that the system is free of
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leakage. If the reading of pressure gauge is unstable, it indicates the
presence of leakage and the leak test and repair shall be conducted. If the
reading is stable, turn on the manual valve and continue the vacuumization
for 15~20min.
Caution:
The vacuumization time must be as per the requirement, in order to
ensure that the water content in the system is sufficiently bled.
Repeat the vacuumization under humid weathers.

3. Filling of refrigerant (R134a)
Install the plug cock to the refrigerant container. Connect the central
filling hose of pipeline pressure tester to the plug cock of refrigerant
container, rotate the plug cock handle clockwise, till the shaft needle
punctures the refrigerant container, and then rotate the valve cock handle
counterclockwise to withdraw the shaft needle. Press the air bleeding core
at the low pressure valve side of the pipeline pressure tester to bleed the
air from the central hose by means of the refrigerant pressure.
While filling the refrigerant to the A/C pipeline for the first time, fill the
refrigerant from the high pressure side when the engine is stopped. To
ensure the filling of refrigerant in specified amount, then continue to fill
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the refrigerant from the low pressure side while the engine is running (the
compressor is running).
Filling from high pressure side: When the engine is stopped, open the
high pressure valve of the pipeline pressure tester so that the refrigerant
enters into the system from high pressure side. In such case, the reading
of the pressure gauge at low pressure side rises slowly, till the specified
amount is fully filled or the pressure fails to rise further.

When the refrigerant can t be filled
further from the high pressure side,
namely the specified amount of
refrigerant is not achieved, close the
high pressure valve (HI) of pipeline
pressure test and the plug cock of the
refrigerant container, start the engine,
open all doors, turn on the A/C switch,
rotate the fan speed switch to
MAX and temperature control
knob to COOL , and adjust the
compressor speed to 1,800~2,000rpm.
Open the low pressure valve (LO) of
the pipeline pressure test to fill the
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Refrigerant filling tool
1. Rapid coupler
2. Vacuum pump
3. Filling hose
4. Refrigerant repair container
refrigerant into the system, till the
reading of the pressure gauge at the
high pressure side of pipeline pressure
tester is 1.5~1.7MPa. After the filling,
close the low pressure valve of pipeline
pressure tester and the valve of
refrigerant container and stop the
engine.

A Drain refrigerant
B Start drainage
Brief for filling procedure of refrigerant
D Check after 5-10min
C Stop drainage (-710mmHg)
E Bleed air (-750 ~ -760mmHg)
J Check and correct
pipeline
Pressure drop
Normal
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G Check air-tightness
F Add refrigerant (appr. 200g)
I Operation checking
H Fill refrigerant
Abnormal
Normal
Specified amount

Carefully check the A/C pipelines for presence of leakage by leak tester.
Check the filling amount of refrigerant: Start the engine, open all doors, rotat
e the
A/C switch to position ON , and rotate the fan speed switch to MAX and
temperature control knob to COOL . Maintain the compressor speed at
approximate 1,800rpm. Based on the flow of refrigerant, visually observe the fil
ling
amount of refrigerant via sightglass. Disassemble the pipes of pressure tester.
Pay
attention to disassemble the pipes rapidly to prevent the excessive outflow of
refrigerant and wear gloves during disassembly to prevent cold injuries.
Refrigerant
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.......
.......
amount State of refrigerant via sightglass
Excessive The reading of low pressure gauge is above 0.2MPa,
with presence of occasional air bubble or no air bubble.
Appropriate
amount
The reading of low pressure gauge is 0.15~0.2MPa, with
presence of a small amount of air bubble.
Insufficient The reading of low pressure gauge is below 0.1MPa,
with presence of continual air bubble. sightglass Excessive or Appropriate
no refrigerant
Insufficient

V. Safety precautions
1. Operator shall wear the protective goggles and gloves to guard against the co
ld injuries
by sprayed fluid refrigerant.
2. Use the refrigerant model specified by the manufacturer and never use mixed r
efrigerant.
The filling amount of refrigerant shall be filled as per the specified requireme
nts of the
A/C operation manual of specific manufacturer, without any insufficient or exces
sive
filling.
3. Make sure to keep away from open fire during operations, in order to prevent
the
occurrence of accidents.
4. It s absolutely prohibited to fill the refrigerant under rainy weathers.
5. While filling with large cylinder, it s prohibited to overturn or tilt the cyli
nder, in order to
prevent the residues within the cylinder from flowing into the A/C system and ca
using
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blockage.
6. It s prohibited to fill the fluid refrigerant from the low pressure side while
the
compressor is running, or it will lead to liquid impact and damage the compresso
r and
under worse cases cause personal injuries. While the compressor is running, only
fill the
gas refrigerant from the low pressure side.
7. While filling the refrigerant under extremely low environment temperature, fo
llowing the
continual outflow of refrigerant from the cylinder, the pressure and temperature
within
the cylinder will drop, which will lead to over-long filling time. If the heatin
g with hot
water is adopted to improve the efficiency, the temperature of hot water shall n
ot exceed
49ºC.

8. While filling gas refrigerant from the low pressure side when the engine is r
unning, pay
attention to keep the high pressure valve under closed state.
9. To fill the refrigerant under low temperature condition (the environment temp
erature is
less than 18ºC), firstly turn on the heating system and close the cab doors. Start
the filling
of refrigerant after the temperature within cab is above 18ºC.
10. As the readings of the high pressure and low pressure gauges during filling
are subject to
the influence of the environment temperature, to ensure the normal system pressu
re
during the working of A/C, please refer to the Table 1 for the readings of the h
igh pressure
and low pressure gauges under different environment temperatures.
Environment
temperature (outside
Reading of
high pressure Reading of low
Table 1 Approximate range for readings of pressure
gauges
Unit name and symbol Conversion relation
Table 2 Conversion among different pressure
units for high pressure and low pressure gauges
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temperature)
gauge
pressure gauge
ºC MPa MPa
20 1.2±0.2 0.15±0.02
25 1.4±0.2 0.18±0.02
30 1.6±0.2 0.20±0.02
35 1.8±0.2 0.22±0.02
40 2.0±0.2 0.25±0.02
Condition: While filling the R134a refrigerant, the compressor speed
is 2,000rpm, the fan speed is at MAX , and the humidity is
moderate.
Psi - British pressure unit
(pound/in2) 1 Kg/cm2=14.22 psi
inHg - British vacuum
pressure unit (in.mmHg) 1 inHg=25.4 mmHg
Bar - Metric pressure unit
(bar, dyne/cm2) 1 Kg/cm2=0.98 bar
Pa - Metric pressure unit
(Pascal, N/m2) 1 Kg/cm2=0.98×105 Pa

Structure, Characteristics, and Circuit Diagram Analysis of Electric System
CONTENTS
Power Supply and Starter System
Instrumentation and monitoring system
Automatic leveling of bucket
Lighting
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Backup warning system
Wiper and washer
Electric horn
Spare socket

Section I Composition, Structural Characteristics, and Circuit
Diagram Analysis of Electric System of Loader
The electric system is an important
part of the loader and is mainly
functioned for start and control of
diesel engine and fulfillment of the
operations including lighting,
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signal indicators, and instrument
monitoring. The quality of electric
system directly influences the
working reliability and the traveling
and operation safety of the loader.

The electric system of loader is mainly composed of the following 5 parts:
1. Power part: Including the battery and alternator assembly.
2. Start part: Mainly including starter, starter relay, and electric lock, which
are functioned to start the diesel engine.
3. Lighting and signaling part: Mainly including all kinds of lighting and
signal lamps and horns and buzzers, which are functioned to ensure the
safety of human and machine and the successful implementation of
operations under all kinds of operation conditions.
I. Main Composition of LG958L Electric System
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4. Instrument monitoring part: Including pressure gauges, pressure
sensors, temperature gauges, temperature sensors, and low pressure
alarms.
5. Control part: Engine control unit and transmission control unit (detailed
in the engine system and transmission system).
6. Accessory part: Including the electric wiper, heater, and A/C system.

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1. Low voltage:
The rated voltage for electric system of the LG958L loader is 24V powered by two
12 batteries in series connection.
2. DC
The diesel engine is started by the starter motor. The starter motor is a DC ser
ies
excitation motor that must be powered by battery. Therefore, the DC current must
be used to charge the battery, which determines that the electric system of the
loader is a DC system.
3. Single-wire system
II. Characteristics of Electric System of LG958L Loader
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All electric devices are in series connection, namely only one wire is connected
from the positive post of power supply to the switch and the electric devices an
d
the metal bodies such as the loader frame, diesel engine block, transmission, an
d
torque converter are functioned as the public grounding wire . When the
single-wire system is adopted, the wire that connected to the metal body is
referred to as grounding wire . The connection between the negative post of
battery and metal body (such as frame) is referred to as negative grounding
and the connection between positive post and metal body is referred to as
positive grounding .

Expressing method of loader circuit diagram: The circuit diagram is a integral
body in which the power supply, starter system, lighting, instruments, and
accessories are connected by switches, wires, and fuses as per the
corresponding working characteristics and mutual internal relationship.
1) Expressing method for circuit diagram of loader
The expressing methods include circuit diagram, schematic diagram,
harness diagram, and distribution diagram of electric units.
2) Circuit analysis
Abiding principles of circuits:
III. Circuit Diagram and Malfunction Analysis Method of
Construction Machinery
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1. Single-wire system
2. All electric devices are in parallel connection and are controlled by
corresponding switches.
3. Low voltage. All electric devices adopt 24V design (the output voltage
of alternator is 28V).
4. Negative grounding of battery.

Every complete circuit is composed of power supply, fuse, switch, control device
,
electric device, and wires. The flow direction of the current must start from th
e
positive post of power supply, reach the electric device through fuse, switch,
control device, and wires, and then return to negative post of power supply
through wire (or grounding wire) to form the circuit. Therefore, there are three
thoughts for reading the electric circuits:
Thought 1: Along the flow direction of the circuit current, start from the posit
ive
post of the power supply, check the electric device, switch, and control device,
and return to negative post of power supply.
Thought 2: Against the flow direction of circuit diagram, start from negative po
st
of power supply (earthing) and return to positive post of power supply through
IV. Circuit Principles to be Borne in Mind
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electric device, switch, and control device.
Thought 3: Start from electric device, check the control switch, wires, and cont
rol
unit, and finally reach the positive post of power supply and grounding wire (or
negative post of power supply).
During the actual application, choose different thoughts depending on specific
circuit. However, please pay attention to this point that, following the extensi
ve
application of the electric control technology, most of the electric device circ
uits
incorporate the main circuit and control circuit. Therefore, both circuits shall
be
taken into consideration while reading the diagram.

Circuit diagram of LG958 electric syste

Section II Power Supply and Starter System
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Power circuits of engine and transmission
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The overall machine adopts 2 batteries in
series connection. The battery is one
invertible DC power supply and is parallel
connected with alternator to power the
electric devices. A single battery can supply
200A~600A start current to the starter motor
within a short period (5~10s). The battery is
also equivalent to a large capacitor, which
can absorb the over-voltage that may occur
any time in the circuit, in order to protect the
electric devices against puncture.
I. Battery (6-QW-120B)
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Caution: The battery must be securely and reliably installed, in order to
prevent damage due to bumps during traveling of the machine. Please turn
off the power switch when the machine is to be parked for a long time.
Warning: Please keep open fire away from the battery. Before the welding
operations, please disconnect all connecting wires of the battery, in order to
prevent explosion.

........ID .rId2 ......
1. Installation location of battery
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1 Green 2
Black 3
Light yellow 4 Battery cap 5
window 6 Optic charge indicator 7
Green small ball
2. Structure and color change of charge indicator
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Figure 10-1 Structure and color of charge indicator
Color of charge
indicator Electric quantity
The electric quantity is above 65% and the
battery is normal
The electric quantity is less than 65% and the
charging is required.
The battery is over-charged and shall be
replaced with new one.

Observation

The electric quantity of the battery can be understood via the color change of
charge indicator (also referred to as charge indication densimeter). Green
Normal, black
to be charged, light-up (or white) depleted.
When the machine can t be started, firstly please check the electric quantity of
the battery and check the battery cables for reliable connections.
Caution: While frequently checking the battery cable connections and
connecting points for reliable connections, please firstly disconnect the
negative post of power supply.
2. Structure and color change of charge indicator
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At the time of assembly, firstly assemble the positive post of battery and then
assemble the negative post. At the time of disassembly, firstly disassemble the
negative post and then disassemble the positive post. This is intended to
prevent the short-circuit from damaging the battery posts and wrenches.
Check method for terminal voltage of battery: Check with DC 200V measuring
range of multimeter. Connect the red probe to the output cable end of the
positive post of battery and connect the black probe to the negative post of the
battery. The reading of the multimeter is the terminal voltage of the battery
(generally at 24V~26V).

Power switch (K01K18-A, also referred to as
negative switch):
The power switch controls the connection and
disconnection between battery negative post
and frame (grounding). Turn on the power
switch to connect the negative post of battery
with frame. Turn on the electric lock to power
on the electric loads of overall machine. Turn off
the power switch to cut off the negative post of
battery from frame so that no loop is formed in
the circuits of the overall machine. Even when
the electric lock is turned on, the overall
machine can t be powered on nor started. The
II. Power switch
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installation location of the power switch is
shown in Figure 10-2.
Operations of power switch: . is turn-off
position and | is turn-on position.
Warning: When the loader is parked for a long time, please ensure to
turn off the power switch, in order to prevent electric leakage and
other accidents. Before connecting the battery cables, re-tightening
the battery cables, or disconnecting the connecting wires of battery,
please make sure to turn off this switch for the purpose of safety.
Figure 10-2 Power switch

3.1 Working principle of alternator
The schematic diagram of alternator is
shown in Figure 10-3. The alternator is
composed of rotor, stator, drive pulley,
fan, front and rear end caps, and electric
brush. The excitation winding is generally
wound on the rotor and the stator adopts
Y-shaped connection mode. The rectifier
is generally a 6-tube bridge full wave
rectifier.
1. When a DC voltage is applied on two
III. Alternator
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ends of excitation winding, the current
will generate a magnetic field. Driven
by the engine, the magnetic field
rotates along with the rotor and the
three-phase symmetric winding of the
stator will, under the application of
rotating magnetic field, generate
three-phase sine electromotive force
with same frequency and same
amplitude in spacing of 120º.

2. The unidirectional conduction performance of silicone diode is
utilized for rectification. At any moment, only the positive diode
connected with the winding of the phase with highest potential is on.
In same way, the negative diode connected with the winding of the
phase with lowest potential is on. Through the sequential turn-on of
six diodes repeatedly, one relatively stable pulsed DC voltage is
obtained at two sides of the load.
3. The terminal voltage of alternator is proportional to the speed of the
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alternator. Due to high speed variation range of the engine, the
terminal voltage of alternator will also vary within a high range and
the output of terminal voltage can't meet the operation requirements
of the loader s electric devices for constant voltage. Therefore, the
voltage regulator must be set.

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Figure 10-3 Schematic diagram of alternator
4. The voltage regulator utilizes the on/off of switching tube to change the siz
e of
excitation current so as to change the intensity of magnetic field to stabilize
the
voltage of the alternator.
5. The filter capacitor is mainly functioned to filter away the peak pulse and h
igh
frequency interference issued by the alternator.

The alternator is generally an assorted part of
diesel engine and has three lead terminals, as
shown in the Figure 10-4, which are
respectively:
B+: Alternator power output terminal
D+: Charging indicator signal
W+: Phase output terminal, which can be
functioned as timer signal as well as
speedometer signal.
The alternator is in parallel connection with
battery set to power the electric devices of
whole loader. The electric devices are
3.2 Wiring method of alternator
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powered by the battery before the start of the
loader and are powered by the alternator
after the start of loader. At the same time, the
alternator also charges the battery set.
Figure 10-4 Alternator
Warning: It s strictly prohibited for the alternator to independently power the
electric devices without the battery.
Warning: It s prohibited to check the power generation of alternator by instantly
short-circuiting the positive and negative posts of alternator for generation of
spark, in order to prevent burning the diode and impairing the regulator.

1. Check with DC 200V measuring range of multimeter. Turn on the electric
lock, measure the terminal voltage of alternator (connect red probe to
terminal D+ of alternator and connect black probe to grounding), and
record the reading of multimeter (This reading is actually the terminal
voltage of battery and is generally less than 26V). Start the machine,
measure the terminal voltage of alternator again, and record the
reading of multimeter (If the alternator is generating power normally,
this reading shall be approximate 28V).
3.3 Judgment method for normal power generation
of alternator and treatment
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2. Treatment
If the alternator fails to generate power or the voltage generated is too
low, firstly check the drive belt of alternator for looseness. Turn off the
electric lock and use wrench to check the wiring terminals of alternator for
correct, tightened, and reliable connections. In addition, check the
alternator for reliable grounding.

IV. Starter system
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IV. Composition of starter system
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I. Structure of starter motor
The starter motor is an assorted
unit of diesel engine. It is mainly
composed of electromagnetic
switch, DC motor, shifting fork,
and drive gear. The starter motor
converts the electric energy of
the battery to mechanical energy
through DC motor and drives the
engine flywheel through drive
gear to realize the start of
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Warning: After the engine is started, immediately release the starter switch, or
it
will lead to damage of drive gears, burnout of DC motor, damage of flameout
electromagnet, and serious impairment of service life of the battery.
Caution: Please frequently check the wirings of contacts and terminals for
reliable connections. Before the checking, make sure to disconnect the negative
post of power supply, or it will probably generate short-circuit spark and damag
e
the wrench and wiring posts.
Figure 10-5 Exterior view of starter motor
engine.

2. Internal structure of starter motor
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Figure 10-6 Internal structure and principle description of starter motor

When the power switch is turned on, the 24V terminal voltage of the battery is a
pplied
onto the starter motor via the contact of starter relay. At the moment when the
electric lock is rotated to position START , two coils of the electromagnetic switc
h
of the starter motor are powered and actuated. The electromagnetic resultant for
ce
generated by above two coils drives the movement of movable contact disc so that
two contacts of the electromagnetic switch are engaged and the current is inputt
ed to
the DC motor coil from the battery for form the circuit via the housing of start
er
motor. In such case, the DC motor starts the rotation. At the same time, the iro
n core
moves to drive the shifting fork to engage the drive gear with the engine flywhe
el
gear ring. The DC motor drives the rotation of the flywheel and the engine start
is
initiated.
3. Working principle of starter motor
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During the start process (within more than 10s when the electric lock is rotated
to
position START ), the 1# wire is constantly live (24V) and the contacts 1# and 2# a
re
constantly engaged. As the contact voltage is 24V, the voltage is equal between
two
terminals of the pull-in coil and no current is flowing. In such case, the iron
core is
maintained at start status under the action of the electromagnetic force of the
holding
coil. When the driver release the electric lock key after the successful start o
f the
engine, the electric lock automatically returns to position ON and the 1# wire is
powered off immediately. Within a really short period, the flow direction of the
current
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is contact 1# - contact 2# - pull-in coil
terminal S holding coil, and grounding
. It can
be seen that the current flow direction is opposite between the holding coil and
pull-in
coil. As the magnetic fields generated are in opposite directions, the electroma
gnetic
forces applied onto the iron core are cancelled out with each other and the iron
core
returns to initial position under the action of spring force. In such case, the
contacts 1#
and 2# are disengaged, no current flows through the pull-in coil and holding coi
l, and
the driver gear resets to initial position. The starter motor stops working.

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1) Malfunction symptom: The starter motor runs automatically after the
negative switch is turned on.
Cause analysis: This symptom is generally caused by the ablated contacts of
starter relay, electric lock, or electromagnetic switch.
Treatment: Re-grind the contacts and movable contact disc or replace
electromagnetic switch or starter motor.
4. Judgment for common malfunctions of starter motor:
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2) Malfunction symptom: No reaction of starter motor at the time of start.
Treatment: While rotating the electric lock to position START , check the
wire voltage at the electromagnetic switch of pneumatic motor. If no
voltage is detected, check the electric lock, starter relay, and battery (For
instance, check the battery set connecting circuit, negative switch, and
grounding wire for reliable connections), or it can be determined as the
malfunction of starter motor that leads to start failure.

Starter switch
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Battery relay
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Back

Transmission control unit (ECU)
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Engine control unit (ECU)
Back

Electric pump
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Back

Section III Instrumentation and monitoring system
1. Circuit diagram of instrumentation system
The instrumentation system includes the instrument panel assembly, sensor, and a
larm
pressure switch, of which the schematic diagram is shown in Figure 3-1.
Transmission oil
pressure gauge Instrument panel
Low pressure
alarm
Engine water
temperature
gauge
Torque
converter oil
temperature
gauge
Vehicle speed
gauge
Braking air
pressure gauge
Working
Fuel gauge hourmeter
High beam
indicator
Left turn
lamp
Low engine oil
pressure
warning lamp
Emergency
turn lamp
Strainer
warning lamp
Preheating
indicator
Handbrake
indicator
Charging
indicator
Low air
pressure
warning lamp
Power
cutoff lamp
Power case
working lamp Right turn lamp
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Figure 10-7: Schematic diagram of instrumentation and alarm system
Emergency turn
alarm Flasher
Engine water
temperature sensor
Braking pressure
sensor Parking brake indicator
switch
Engine oil
pressure switch
Torque converter oil Fuel level sensor
temperature sensor

Strainer
warning switch

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2. Sensors
2.1 Temperature Sensor
LG958L is fitted with two temperature sensors to monitor the torque converter oi
l
temperature and engine water temperature. The temperature sensor is equivalent t
o
a thermistor, of which the resistance is reduced along with the increasing of
temperature. (226Ohm at 26ºC ambient temperature and 26.4Ohm at 115ºC)
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Figure 10-10 Torque converter oil
temperature sensor
Figure 10-9 Exterior view of
temperature sensor

2.2 Braking air pressure sensor
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The swing of the instrument pointer is achieved by the change of current arising
from the slide of resistor pointer within the sensor, which is caused by the
deformation of beryllium bronze diaphragm due to change of pressure, as shown in
Figure 10-11.
2.3 Fuel level sensor
The fuel level sensor is actually a discrete slide resistor, of which the resist
ance is
reduced along with the increasing of fuel level. It s installed on the fuel tank.
Figure 10-11 Internal structure of braking air pressure sensor

2.5 Alarm pressure switch
The overall machine is fitted with two pressure switches, namely low braking
pressure alarm switch and low engine oil pressure alarm switch.
The specific installation positions are shown in Figure 10-13 and Figure 10-14
respectively.
The alarm indicator will alarm when the braking air pressure is less than
0.45MPa or the engine oil pressure is less than 0.08MPa.
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Figure 10-13 Low braking pressure
alarm switch
Figure 10-14 Engine oil pressure alarm
switch

3.1 Abnormal indication of temperature gauge
Disassemble the sensing wire from the temperature sensor (the torque converter
oil temperature gauge and the water temperature gauge correspond to wire 15#
and wire 14# respectively). If the instrument indicates full measuring range whe
n
the sensing wire is grounded and indicates minimum reading when the sensing
wire is hung in the air, it indicates that the instrument and circuit are normal
and
the sensor is damaged. Replace the sensor. Otherwise, check the circuit. If the
circuit is normal, the instrument is malfunctioned.
3. Examples for troubleshooting of common malfunctions of
instrumentation and monitoring system
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3.2 Abnormal fuel level indication
Disassemble the sensing wire (wire 19#) from the fuel level sensor. If the
instrument indicates full measuring range when the sensing wire is grounded and
indicates minimum reading when the sensing wire is hung in the air, it indicates
that the instrument and circuit are normal and the sensor is damaged. Replace th
e
sensor. Otherwise, check the circuit. If the circuit is normal, the instrument i
s
malfunctioned.

1. Schematic diagram
The schematic diagram is shown in Figure 10-15.
Section IV Automatic Resetting System of Bucket
Proximity switch (boom)
Brown Load Blue
Brown
Floating
solenoid valve
Bucket solenoid
valve
Boom solenoid
valve
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Figure 10-15: Schematic diagram for circuit of automatic resetting system
Proximity switch (bucket)
Normally closed (N.C.)
Black
Blue
Blue
Brown
Black
Black

1.1 Bucket leveling limiter:
This device is composed of proximity switch
installed on the bucket cylinder bracket (as shown
in Figure 10-16) and solenoid valve on the pilot
valve. There is a red indicator on the proximity
switch, which indicates the status of the proximity
switch. When the retraction rod is misplaced from
the proximity switch, the proximity switch is turned
off, the red indicator goes off, and there is no
output signal in the black output wire. If the driver
pulls the bucket operating lever to the most
rearward position when there is no unloading angle
for the bucket, the magnetic circuit is turned on so
that the electromagnetic field force generated by
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the solenoid coil will hold the bucket operating
lever (in such case, the driver may release the
operating lever and the bucket operating lever will
not return to neutral position) and the bucket will
keep retracting, till the proximity switch approaches
the retraction rod. In such case, the proximity
switch is turned on, the red indicator lights up, the
solenoid coil is turned off, and the magnetic force
disappears so that the bucket operating lever
automatically returns to neutral position under the
action of spring force and the bucket stops at
leveling position.
Figure 10-16 Bucket retraction
rod and proximity switch

1.2 Boom floating device
This device does not incorporate the proximity switch and only
incorporates a boom floating coil that is located on the pilot valve. After
the electric lock is turned on, the coil is powered on constantly. When the
driver pushes the operating lever to most forward position, the magnetic
circuit is turned on so that the electromagnetic field force generated by the
solenoid coil will hold the boom operating lever (in such case, the driver
may release the operating lever and the boom operating lever will not
return to neutral position) and the pilot valve connects the oil lines of
rodless and rod chambers of boom cylinder with the oil pipes by
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controlling the distributor valve. In such case, the pressure is zero for both
rodless and rod chambers and the pressure difference is also zero. If the
driver pushes the boom operating lever to floating position during the
loading operations, the bucket will fluctuate along with the ups and downs
of the ground. If the driver pushes the boom operating lever to floating
position to operate the lowering of boom, the boom will lower at fastest
speed under the action of dead weight, in order to improve the working
efficiency.

1.3 Troubleshooting of system malfunctions
. Check 10A fuse for burnout.
. Check all connectors for good connections.
. Check gap between metal body and proximity switch (generally no
more than 8~10mm).
. Check proximity switch for damage: Turn on the electric lock. The red
indicator shall light up when the metal body approaches (When
measured with multimeter, the black output wire shall be connected to
ground).
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. Check the pilot coil: The resistance is approximate 100~200Ohm for
three pilot coils.

Section V Lighting System
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1. Circuit of front combination lamp
1.1 Schematic diagram for circuit of front combination lamp
Right combination lamp
Right rear lamp Left rear lamp
Warning lamp switch
Combination switch
(headlamp
low beam)
(headlamp
high beam)
Left combination lamp
Green BrownYellow Red Black Grey Blue OrangeWhite
Terminal
Position
Off
Left
turn
Right
turn
Backlight
Headlamp
High
beam
Low
beam
Overtaking
lamp
Green
Brown
Yellow
Red
Black
Grey
Blue
Orange
White
Terminal
Position
Off
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Figure 10-18: Schematic diagram for circuit of front combination
lamp, turn lamp, and warning lamp
Left combination lamp
Reserved

1.2 Principle description
When the electric lock is turned on, the 10A headlamp fuse within
the 20-circuit fuse case is turned on (24V) to turn on the
combination switch via wire 44# and turn on the contact of high
beam/low beam relay of front combination lamp via wire 35#. When
the combination switch is not turned on, the wire 49# and wire 50#
are not turned on and both left and right headlamps are not
working. When the combination switch is at high beam or low beam
position, the wire 49# or 50# is turned on (24V) and the coil of high
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beam/low beam relay of front combination lamp is turned on and
actuated so that high beam or low beam of front combination lamp
is turned on (24V) and left and right headlamps work at
corresponding position.

1.3 Troubleshooting of common malfunctions of system
Lighting failure of headlamp
1.3.1 Check the bulbs for blackening. If yes, it can be determined
that the bulbs are damaged. Replace the bulbs.
1.3.2 Unplug the connector, shift the dimmer switch to high beam
position and low beam position respectively, and measure the
voltage between wire 49# and wire 50# at the connector with
DC voltage measuring range of multimeter. If the voltage is
24V, check the connector for reliable connection. If the
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connection is loose, re-connect. If the connection is secure,
the internal wire of headlamp is loose or the bulb is damaged.
If the voltage is 0V, check as below.
1.3.3 Check the 10A headlamp fuse for burnout.
1.3.4 Check the connectors for reliable connections and check the
harnesses for wear.
1.3.5 Check the functions of dimmer switch positions as per the
Accessories
Combination Switches.

2. Circuits of working lamp, rear lighting lamp, and
interior lamp
Rocker switch of rear lighting lamp (high beam and low beam)
Rear lighting lamp Rear lighting lamp
OFF
Terminal
Position
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Figure 10-19: Schematic diagram of rear lighting lamp

Rocker switch of headlamp
Headlamp Headlamp
Rocker switch of rear illuminator
OFF OFF
Terminal
Position
Terminal
Position
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Figure 10-20 Schematic diagram for headlamps and rear illuminators
2.1 Four lamps on the top front and rear of the cab are defined as headlamp and
rear illuminator,
two lamps on the rear hood are defined as rear lighting lamp. The switch of inte
rior lamp is
attached. Refer to Accessories
Rocker Switches for details of switches of rear l
ighting lamps
and working lamps.
2.2 Schematic diagram: As shown in Figure 10-19 and Figure 10-20.
2.3 The basic principle and the troubleshooting of system malfunction are basic
same with the
headlamp circuit and are omitted herein.

3. Circuit of turn lamps:
3.1 Schematic diagram: As shown in Figure 10-18.
3.2 Introduction of main units:
3.2.1 The actual combination switch and installation position are shown in Figur
e 54 and Figure 5-5 respectively. The turn lamp switch is realized by partial
function of the combination lamp and the wire colors of three pins used are
grey, yellow, and white, of which the grey wire is connected to turn flasher
power supply (wire 33#), the yellow wire is connected to left turn signal wire
(wire 6#), and the white wire is connected to right turn signal wire (wire 7#).
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Figure 10-21 Combination switch Figure 10-22 Installation position of combinatio
n switch

3.2.2 Flasher relay (SG252): Three pins of the flasher are defined as below:
B power terminal, connected to wire 21#; L
Flasher signal output
terminal, connected to wire 33#; E Grounding, connected to wire
0#. During normal working, the flasher relay will issue slight
rattle sound at a frequency of approximate 50 cycles/min.
Otherwise, it can be determined that the flasher relay is damaged.
3.2.3 Warning lamp switch: The parking lamp switch controls four turn
lamps and two turn indicators on the instrument panel. When this
switch is turned on, four turn lamps and two turn indicators flash at
the same time to alert the vehicles crossing by.
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. The basic principle and the troubleshooting of system malfunction
are basic same with the headlamp circuit and are omitted herein.

4. Circuit of clearance lamp:
4.1 Schematic diagram: As shown in Figure 10-23.
Right rear lamp
Right combination lamp
Left rear lamp
Rocker switch of
backlight
Terminal
Position
OFF
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Figure 10-23: Schematic diagram for circuit of clearance lamp
Left combination lamp

Figure 10-24: Combination headlamp
Left Figure 10-25: Left rear tail lamp
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4.2 The installation positions of the clearance lamps are shown in Figure
10-24 and Figure 10-25.
4.3 The basic principle and the troubleshooting of system malfunction are
basic same with the headlamp circuit and are omitted herein.

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5. Brake lamp circuit:
5.1 Schematic diagram: As shown in Figure 10-26.
To ECU case
Intermediate relay
(start interlock) Intermediate relay
(power cutoff)
Intermediate relay
(backup)
To terminal G2 of starter
switch
Parking brake indicator switch
To backup lamp
To starter relay signal
terminal
To instrument panel ECU case indicator
Brake switch (left)
To brake lamp
Brake switch (right)
Figure 10-26: Schematic diagram for circuit of brake lamp
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5.2 Principle description:
When the brake pedal is depressed, the braking air pressure at the brake lamp sw
itch engages the
contact of brake lamp switch so that the current flows to brake lamp through 10A
fuse, wire 57# at
brake lamp fuse, brake lamp switch, and wire 8# to light up the brake lamp.
5.3 Brake lamp switch: The switch adopts normally open contact, which acts and e
ngages at
approximate 1.3bar.
Troubleshooting
How to judge the damage of brake lamp switch: Firstly determine
whether the
braking pressure is normal (turn on the electric lock. If the low service brakin
g pressure alarm lamp
on the instrument panel is off, it indicates that the braking pressure is normal
. Otherwise, start the
engine, till the low service braking pressure alarm lamp is off). If normal, unp
lug the wire at the brake
lamp switch and measure two pins of the switch with 200Ohm measuring range of mu
ltimeter. If the
measurement differs from the table below, it indicates that the pressure switch
is damaged and shall
be replaced.
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Brake pedal is not
depressed OFF
Brake pedal is
depressed ON
Figure 10-27: Installation position of brake lamp switch

Section VI Backup Warning System
Right rear lamp Left rear lamp Backup buzzer
Backup switch
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1. Principle description:
When the electric lock is turned on, the 10A backup warning fuse is turned on (2
4V).
When shifted to reverse gear, the backup switch is turned on, the wire 9# is tur
ned on,
and the backup warning buzzer sounds. At the same time, the backup lamps on the
left
and right rear lamps light up.
Figure 10-28 Schematic diagram for backup warning system

2. Analysis of Common Malfunctions
The backup warning buzzer fails to sound when the electric lock is turned on and
the reverse gear is engaged.
1.
Check the 10A backup warning buzzer fuse for burnout.
2.
Check the connectors and wires for secure and reliable connections. Generally,
the loose connector or worn harness will lead to middle open-circuit of wire 9#.
3.
Check the backup switch for damage. If normal, two wires of the backup switch
are connected when the reverse gear is engaged.
44.
If no problem is detected in above checking items, check the voltage of wire 9#
If no problem is detected in above checking items, check the voltage of wire 9#
at the backup warning buzzer. If the voltage is normal (24V), it indicates that
the
backup warning buzzer is damaged and shall be replaced. If no voltage is
detected, generally the connector is loose or the harness is worn.
Analysis of common malfunctions: After the electric lock is turned on, the backu
p
warning buzzer sounds constantly no matter which gear is engaged. This problem
is generally caused by the bonded contact of backup switch. In few cases, it s
caused by the short-circuit between wire 9# and certain power wire.
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Section VII Wiper and Washer System
1. Principle description
1.1 Principle of washer: When the electric lock is turned on, the 10A wiper fuse
is powered
on (24V) to turn on the washer switch (it s an automatic resetting rocker switch.
Please
refer to the Accessories Rocker Switch for details) so that the washer motor (in
stalled
on the water reservoir) is powered on via wire 37# to pump the water from water
reservoir to the nozzles (installed beneath the front windscreen of the cab) and
spray
onto the windscreen.
Rocker switch of washer reservoir (with resetting
function)
Rocker switch of front wiper
OFF OFF
Terminal
Position
Terminal
Position
531 RELIABILITY IN ACTION
Figure 10-29 Schematic diagram of wiper and washer system
Spray motor Front wiper

1.2 Principle of wiper:
The wiper motor is a permanent magnet motor that adopts the positive control
mode.
As shown in the figure, the wiper motor has 4 output wires, of which the red is
the power wire (the public wire for high speed armature and low speed
armature), the black wire is the resetting wire, the blue wire is another brush
wire
for high speed armature, and the white wire is another brush wire for low speed
armature. When the electric lock is turned on, the wire 37# is powered on (24V).
If the wiper switch (refer to Accessories
Rocker Switch for details) is at posit
ion
I, the pin 37# and pin 24# are connected and the motor runs under low speed
mode.
RELIABILITY 532 IN ACTION
If the wiper switch is at position II, the pin 37# and pin 26# are connected and
the motor runs under high speed mode.
If the wiper switch is turned off (namely rotate from position I to position
OFF ), the pin 24# and pin 25# are connected. At the wiper is not stopped at
the initial position at the moment when the switch is turned off, the current fl
ows
through wire 25# - wiper switch pin 24# - low speed armature
grounding
(Note: There is an internal automatic stop device to ensure that the wiper alway
s
stops at initial position. When the wiper is at initial position, the resetting
wire is
connected to the ground).

2. Troubleshooting of common malfunctions
2.1 Working failure of wiper motor
1. Check 10A wiper fuse for burnout.
2. Check wiper switch for damage.
3. Check connectors for looseness and harnesses
4. Check wiper motor armature for short-circuit
RELIABILITY 533 IN ACTION
circuit.
2.2 No water spray from nozzles
1. Observe the motor for running and pumping of
2. Check water line for interruption (The water
disconnected or over-tightly bundled).
3. Check the nozzles for blockage.

for wear.
or opencircuit.

water.
pipe is

Section VIII Electric horn system
Horn assembly
Horn button
RELIABILITY 534 IN ACTION
1. Principle description:
When the electric lock is turned on, the 10A electric horn fuse is turned on
(24V). When the electric horn switch is pressed, the current flows through
10A electric horn fuse
electric horn
electric horn switch
grounding and
the electric horn sounds continually (as shown in Figure 8-2).
Figure 10-30: Schematic diagram for circuit of
electric horn
Figure 10-31: Installation
location of electric horn

2. Troubleshooting of common malfunctions
The electric horn fails to sound when the electric lock is turned on and the
electric horn switch is pressed:
2.1 Check 10A electric horn fuse for burnout.
2.2 Check electric horn switch (the button switch in the center of steering
gear) for normal functioning. Normally, the wire 12# is grounded
when the electric horn button switch is pressed.
2.3. Check connectors for looseness and harnesses for wear.
2.4 Check the electric horn for damage (For two wiring posts of the
RELIABILITY 535 IN ACTION
electric horn, connect one post to 24V power supply and connect
another to ground. If the electric horn fails to sound, it can be
determined as the damage of electric horn).

Section IX Spare Socket System
Spare socket
RELIABILITY 536 IN ACTION
1. Principle description
When the electric lock is turned on, the 10A spare socket fuse is turned on (24V
) to turn on
the spare socket through wire 77# and wire 0#. When the external power supply is
required,
after the external wire and plug are correctly connected, insert into the socket
to obtain the
power. Please be noted that the consuming power shall not exceed 150W. The spare
socket
provides a standard DC 24V power socket for connection of external loads such as
electric
kettle and interphone. The installation position is shown in Figure 10-33.
Figure 10-32: Schematic diagram for
circuit of spare socket
Figure 10-33: Installation
position of spare socket

2. Troubleshooting of common malfunctions
Working failure of spare socket:
2.1 Check the 10A spare socket fuse for burnout.
2.2. Check connectors for looseness and harnesses for wear.
2.3 Check the spare socket for damage.
RELIABILITY 537 IN ACTION

THE END

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