Construction Equipment

MECHANICAL EQUIPMENTS IN BUILDING CONSTUCTION In the case of huge construction project 1. Proper use of the appropriate equipment contributes to the economy, quality, safety, speed and timely completion of the project. 2. Equipments are used for highway project, irrigation, buildings, power project. 3. 15%-30% of total project cost has been accounted towards equipment and machinery. It is a common fact that that we find a wide range or variety of construction machines on every construction site which makes the job easy. Depending on the application, construction machines are classified into various categories. Classification of construction Machines or Equipment 1. 2. 3. 4.

Earth moving equipment Hauling equipment Hoisting equipment Aggregate and concrete production

Operations involved in construction of any project 1. 2. 3. 4. 5. 6. 7. 8.

Excavation Digging of large quantity of earth Moving them to distances which are sometimes fairly far Placement Compacting Levelling Dozing Hauling

Excavating and Earth Movement Machine 1. 2. 3. 4. 5.

Power shovel Back hoe Drag line Clam shell Bull dozer

Power shovel    

It is used to excavate the earth and to load in trucks Capable of excavating all types of earth except hard rock Size varies from 0.375m3 to 5m3 The basic parts of a power shovel including the track system, cabin cables, rack, stick, boom foot-pin, saddle block, boom, boom point sheaves and bucket

Applications    

Suitable for close range work Capable of digging very hard materials Can remove big size boulders It is used in various types of jobs such as digging in gravel banks, clay pits, foundations, sand dump etc.

Factors affecting output of the power shovel        

Class of materials Depth of cutting Angle of swing Job condition Management condition Size of hauling units Skill of the operator Physical condition of the shovel

Back hoe    

Also know as hoe, back shovel and pull shovel It is used to excavate below the natural surface on which it rests Generally used to excavate trenches, pits for basements and also for grading works, which requires precise control of depths. The basic parts are boom, jack boom, boom foot drum, boom sheave, stick sheave, stick, buck and bucket sheave.

Application  

It is the most suitable machine for digging below the machine level, such as, trenches, footings, basement etc. It can be efficiently used to dress or trim the surface avoiding the use of manual effort for dressing the excavated surface.

Drag line     

The drag line is so named because of the prominent operation of dragging the bucket against the material to be dug. Unlike the shovel, it has a long light crane boom and the bucket is loosely attached to the boom through the cables. Because of this construction, a drag line can dig and dump over long distances than a shovel can do. Drag line are useful for digging below its track level and handling softer materials The basic parts of a drag line including the boom, hoist, cable, drag cable, hoist chain, drag chain and bucket

Application    

It is the most suitable machine for dragging softer materials and below its track level It is very useful for excavating trenches when the sides are permitted to establish their angle of repose without shoring. It has long reaches It is mostly used in the excavation for canals and depositing on the embankment without hauling units.

Clam shell    

This is so named due to the resemblance of its bucket to a clam which is like a shell fish with hinged double shell. The front end is essentially a crane boom with a specially designed bucket loosely attached at the end through cable as in the drag line. The capacity of the clamp shell bucket is usually given in cubic meters The basic parts of a clam shell bucket are the closing line, hoist line, sheaves, bracket, tag line, shell and hinges.

Application   

Used for handling loose material such as crushed stone, sand, gravel, coal etc Main feature is vertical lifting of materials from one location to another Mainly used for removing from coffer dam, sewer main holes, well foundation etc

Comparison between the different kinds of equipments S.no

Power shovel good

Back hoe

Drag line

Clam shell

good

Not good

Poor

poor

poor

small

small

Moderately good long

Moderately good long

4

Items of comparison Excavation on hard soil or rock Excavation in wet soil or mud Distance between footing and digging Loading efficiency

Very good

good

5

Footing required

Close to pit

6

Digging level

Dig below footing level

7

Cycle time

Close to work Dig at or above footing level Short

Moderately good Fairly away from pit Dig below footing level

Shortly more than

More than power

Precise but slow Fairly away from pit Dig at or above footing level More than the other

1 2 3

power shovel

shovel

equipment

Trenching machine   

Used for excavating trenches for laying pipelines, sewers, cables etc Operation is quick giving the required depth and width. Two types of trenching machine, wheeled type and ladder type

Bulldozer  

The heavy blade attached to the tractor pushes the material from one place to another The tector can be the wheeled or the crawler type

Classification of bulldozer based on the position of the blade  

Bull dozers in which the blade is perpendicular to the direction of the movement Angle dozers in which the blade is set at an angle with the direction of movement

Classification based on mounting  

Wheel mounted Crawler mounted

Classification based on control  

Cable controlled Hydraulically controlled

Applications Bull dozers are mainly used for the following operation      

For spreading earth fill For opening up pilot road through mountainous and rocky terrains Clearing constructions sites. Maintaining haul roads Clearing land from trees and stumps Back filling trenches at construction sites by dragging the earth from one place to another

Frontend loader

A front end loader is a heavy equipment machine often used in construction, primarily used in loading materials such as asphalt, demolition debris, dirt, snow etc. Into another type of machinery like dumper truck. They are of two types, wheeled and crawler mounted frontend loader.

Comparison between crawler and wheeled tractors

Crawler type

Wheeled type

Slow speed More compact and powerful and can handle heavier jobs Costly Cost of operation and maintenance is high Stick control for steering Moves on rough roads only Used forshort distances Requires skilful operation, maintenance and repairs

Greater speed Can handle only lighter jobs Cheaper Cost of operation and maintenance is less Wheel steering control Moves on rough as well as good roads Used for longer distances Lesser skills required for operations maintenance and repairs

Hauling equipment   

The machine used for the transportation of materials is known as hauling equipment or simple haulers. Haulers may operate on the road way or railways It involves transportation of building materials carriage and disposal of excavated earth haulage of heavy construction equipment

They are classified on the basis of method of dumping the load  

Dump truck Dumpers

Dump trucks These are used for earth moving purpose. The selection of the type of dump truck for a specific job depends on the soil condition. a) Side or rear dump trucks; These are heavy duty trucks with strongly built body which is hinge on the truck chassis at the rear end and one side

respectively and can be fitted to the rear in the case of the rear dump and to the hinged side in the case of the side dump the action of a hydraulic jacks. The trucks are suitable for use in hauling wet clay, sand, gravel, quarry rock etc b) Bottom dump trucks; these are similar to semi trailers in which their front is supported on the rear of the hauling tractor and the rear is resting on its own wheels. The body of the truck remains in the same position and the discharge of the materials takes place through its bottom after opening of two longitudinal gates. The gates are hinged on the side of the body. These trucks are suitable for the use in hauling free flowing materials such as sand gravel, dry earth, hard clay etc.

Dumpers      

High speed pneumatic wheeled trucks Short chassis Strong body Loading, hauling and dumping is done very fast as compared to other equipments Suitable for short hauls on rough road Specially where a shuttle movement is required.

Aggregate and Concrete Production Concrete mixer A concrete mixer also knows as cement mixer is a device that homogeneously combines cement, aggregate such as sand or gravel and water to form concrete. Atypical concrete mixer uses a revolving drum to mix the components. For smaller volume works portable concrete mixers are used so that the concrete can be made at the construction site, giving the workers ample time to use the concrete before it hardens. Special concrete transport trucks (in transit mixers) are made to transport and mix concrete up to the construction site. They can be charged with dry materials and water with the mixing occurring during the transport. With this process the materials has already been mixing. The concrete mixer transport truck maintains the material liquid state through agitation or turning of the drum until delivery.

Hoisting equipment  

Hoisting is the lifting of a weight from one location and moving to another location which is a reasonable distance Buig projects like construction of dams, industrial buildings etc require hoisting equipment

 

Hoisting equipment includes jack, winches, chain hoists and cranes Crane is the only single machine, which as a single piece is capable of providing three dimensional movement of weight

Cranes are generally classified into Stationary or derrick crane mobile crane overhead and gantry cranes traveller crane tower crane

Derrick Cranes    

Derrick crane consist of a mast, a boom and bull wheel on which the boom rotate, about a vertical axis and guys or supporting members They are either electrically operated, diesel operated or diesel-electrically operated The boom can revolve through 3600 This crane is used for heavy loading up to 200tons

Mobile cranes   

These cranes are mounted on mobile units which is either crawler type or wheeled type Truck cranes have high mobility while the crawler mounted cranes move slowly Crawler mounted cranes are capable of moving on rough terrain

Overhead or gantry cranes        

There have large service area Freedom from floor obstruction Its mobility is in three ways Widely used in erection foundry, steel plant, storage yards and different types of industrial works. These type of crane consist of two main parts; the bridge and the crab The bridge consists of two main girdles fixed at their end to end and there are capable of moving on gantry rails. The crab consist of the hoisting gear mounted on the frame The frame its self is mounted on another set of wheels and capable of travelling across the main girders.

Traveller Cranes 



Travelling or bridge cranes have their crabs moving on the girders which are supported on legs instead of on overhead gantry track as used in overhead cranes The legs are capable of moving on tracks laid on the floor.

Tower cranes     

Tower cranes are actually derrick cranes mounted on steel towers Tower cranes are usually used for industrial and residential high rise buildings These are also commonly used for the assembly of industrial plants with steel structures. The main part of the tower crane are under carriage, slewing platform, towers with operators cabin and jibs. The tower has a truss structure welded from steel bars and channels