Brakes

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CALPE, Emil L.

Camber angle – angle between the wheel plane and
the
vertical
– taken to be positive when the wheel
leans
outwards from the vehicle
• Swivel pin (kingpin) inclination – angle between the
swivel pin axis and the vertical
• Swivel pin (kingpin) offset – distance between the
centre of the tire contact patch and – intersection of the
swivel pin axis and the ground plane

• Toe-in and Toe-out – difference between the front
and rear
distances separating the center plane of
a pair of wheels, – quoted at static ride height – toein is when the wheel center planes converge towards
the front of the vehicle

• A brake is a device by means of which artificial frictional
resistance is applied to a moving machine member, in
order to retard or stop the motion of a machine.

• In the process of performing this function, the brake
absorbs either kinetic energy of the moving member
or potential energy given up
• The energy absorbed by brakes is dissipated in the form
of heat.

• Category based of direction of the force
Radial Brakes
The radial brakes may be sub-divided into external
brakes and internal brakes. According to the shape of the
friction element, these brakes may be block or shoe
brakes and band brakes.

Axial Brakes
The axial brakes may be disc brakes and cone
brakes. The analysis of these brakes is similar to
clutches.

• Master Cylinder
-consist of double cylinder , piston assembly and fluid reservoir
When the brake petal is engaged, the master cylinder is the
vehicle's device that will increase the pressure to the hydraulic
fluid in the brake lines that forces the wheel cylinders (for drum
brakes) or the wheel's calipers (for disc brakes) to apply
pressure to the brake pads to the brake drum (for drum brakes)
or the disc (for disc brakes)

• Brake Caliper
• A steel housing that mounts in a fixed position on the brake rotor
that contains the piston and brake pads.

• Brake Pads
• A metal plate with a semi-metallic overlay that grips the steel rotor.

• Brake Rotor
• A steel disc mounted to the wheel hub that the pads grip to stop
the wheels from rotating.

• Brake Hoses
• flexible hoses that connect the brake lines on the chassis with the
calipers or wheel cylinders, or the junction block on a solid axle.

• Brake Drum
• a round cast iron housing attached to an axle shaft or spindle, on
which the brake shoes press to stop its rotation.

• Brake Shoe
• the brake lining in a drum brake system, when the brakes are
applied the brake shoes press against the brake drum causing the
friction to stop or slow the vehicle down

• Brake Fluid
• the hydraulic fluid used to transmit hydraulic pressure through the
brake lines in a brake system.

• Anti-lock Brake System
• a computer controlled system that allows the vehicle to be
controlled under heavy braking by releasing hydraulic pressure to
wheels that are about to lock up and skid. Sensors located at the
wheels, monitor rotating wheel speed in relation to other wheels
and send the information to a control module that in turn controls a
hydraulic modulator, which regulates hydraulic fluid pressure to
each brake assembly

• Disk Brake
• Drum Brake

• The disc brake is a lot like the brakes on
a bicycle. Bicycle brakes have a caliper, which
squeezes the brake pads against the wheel. In a
disc brake, the brake pads squeeze the rotor
instead of the wheel, and the force is
transmitted hydraulically instead of through a
cable. Friction between the pads and the disc
slows the disc down.

* Self-centering and Self-adjusting
-The caliper is able to slide from side to side so it will
move to the center each time the brakes are applied
-The rubber piston seal and any wobble in the rotor may
actually pull the pads a small distance away from the
rotor

• Emergency Brakes
-an emergency brake has to be actuated by a separate
mechanism than the primary brakes in case of a total primary
brake failure. Most cars use a cable to actuate the emergency
brake.

• Drum brakes work on the same principle as disc
brakes: Shoes press against a spinning surface
• The drum brake has two brake shoes and a piston. But
the drum brake also has an adjuster mechanism, an
emergency brake mechanism and lots of springs.

• Automatic adjuster
• For the drum brakes to function correctly, the brake shoes must
remain close to the drum without touching it. If they get too far
away from the drum (as the shoes wear down, for instance), the
piston will require more fluid to travel that distance, and your brake
pedal will sink closer to the floor when you apply the brakes.

• Automatic adjuster

• The power brake uses vacuum from the engine to
multiply the force that your foot applies to the master
cylinder.

1. should have high coefficient of friction with minimum
fading. In other words, the coefficient of friction should
remain constant over the entire surface with change in
temperature
2. should have low wear rate
3. should have high heat resistance
4. should have high heat dissipation capacity
5.should have low coefficient of thermal expansion
6. should have adequate mechanical strength
7. should not be affected by moisture and oil

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