automobile braking mguniversity

Braking System

Brakes are employed to stop or slow down the speed of vehicle.
When brake applied to wheel braking force is created that force oppose the speed of wheel or rotation of force.

Braking requirement:

1)The vehicle must stop in smallest distance.
2) It must act suddenly in emergency.
3)It must have strong braking force.
4)It must neither slip nor skid the vehicle.
And less heat production.
5)It must operate on least effort.

Types of brakes:

Breaks are divided into seven types as per there uses, functionality, locations etc.
1) On the basis of purpose saved.
a) Main brake.
b) Parking brake.

2) On the basis of location.

a) Wheel mounted.
b) Transmission mounted.

3) On the basis of drivers ergonomics.

a) Foot brake.
b) Hand brake.
4) On the basis of actuating.

a) Mechanical brake.

b)Hydraulic brake.
c) Air brake.
d)Electric brake.

5) On the basis of construction.

a) Drum brake.
b)Disc brake.

6) On the basis of application of brake efforts.

a)Manual brake.
b)Power brake.
c)Power assisted.

7) On the basis of action of brake shoes.

a)Internal expanding brake.
b)External contracting brake.

Brake Drum:

Construction of Brake Drum:
The brake drum is mounted on axle hub and whole assembly is hold in wheel to brake shoes are handed on the back plate by mines of pin expander is fitted in between shoes.
 The friction material is pasted or biretta on brake shoes the expanded (cam) expander.
The brake shoe and press on drum. Due to friction action brake will get applied.
Brake drum is shown in figure.

Brake Drum

Following parts used in break drum
1) Brake drum.
2) Back plate.
3) Brake shoe.
4) Brake lining.
5) Expander.
6) Anchor.
7) Returning spring.
8) Adjuster.

Disc brake:

Construction of disc break:
1) Caliper or cylinder casing.
2) Rooter disc.
3) Piston.
4) Friction pad.
5) Pad supporting plate.
6) Bleeder plug.
Working of disc break:
Disc brake is shown in figure.

Disc brake

The disc brake are appeaser hydraulically when the vehicle is to brake the brake fluid pumped by the master cylinder it them flows and pushes the piston and pad which makes friction with  rooter disc and due to frictional action brake will get applied.

Mechanical brake:

This brake system is operated by mechanical linkage.
This brake system applied light vehicle two wheeler and some three wheeler this system required more efforts from driver and applied less force to the brake system to that system doesn’t used on four wheeler or heavy vehicle.

Hydraulic brake system :-

In this system the brake is operated with the help of oil pressure in this system master cylinder and wheel cylinder is most important part.
This system is very popular on four wheeler vehicle basically light and medium vehicle.

Working of hydraulic break system :-

The diagram of hydraulic brake system is shown in figure.

Hydraulic brake

The brake system is fitted with brake oil when driver presses the brake pedal the master cylinder creates oil pressure and sent to wheel cylinder.
Piston in wheel cylinder get expands due to oil pressure and the brake shoes also get expand and rub on brake shoes.
Also get expand and rub on brake drum so that brake will get apply.

Master cylinder:

Master cylinder it is having following part:
1) Cylinder body.
2)  Piston.
3)  Primary cup.
4)  Secondary cup.
5)  Check valve.
6)  Return spring.
7)  Push rod.
8) Dust cover.
Working of master cylinder:
The diagram of master cylinder is shown in figure.

Master cylinder

When driver depress the brake pedal the push rod pushes the piston forward and oil get compresses due to pressure the brake fluid open the hole of check valve and flows to wheel cylinder when driver release the brake pedal brake flied come back and pushes the check valve return spring and piston back ward and oil stores in reverie.

Wheel cylinder:

The diagram of wheel cylinder is shown in figure.

Wheel cylinder
As driver pressure the brake pedal and increases the pressure of oil that oil inters in the wheel cylinder it expand the piston towards outside they expand brake shoe and applies the brake.
When release the spring pushes the piston tension and flows the oil return to the master cylinder like this brake get release.

Pneumatic or air brake system :-

In this brake system air pressure is used to apply brake.
Parts or components used in air brake system :-
1) Air compressor.
2) Reservoir air tank.
3) Water and oil separator.
4)  Brake valve.
5)  Air pressure gauge.
6)  Safety valve.
7)  Brake chamber.
8)  Pipes.
Working of air brake system :-
The diagram of pneumatic or air brake system is shown in figure.

Pneumatic or Air Brake System
Mostly it is used heavy vehicle the compressor run by engine sucked air from atmosphere and the piston of compressor compress the air and supplied to air tank.
 In between compressor and tank water separator is used which remove the water partial from air the air tank stores the air with pressure up to 8kg/cm2.the safety valve is used in the tank to manifold constant air pressure.
 The pipe is connected from tank to brake valve and from brake valve to brake pedal the brake valve get open and pressure air flows from tank to brake chamber as soon as the air pressure inter in brake chamber the diaphragm get deflect which pushes the push rod for tarring the cam as the cam get turned it expand the brake shoe and brake will get applied.
When driver release the brake pedal the brake valve gets closed and air pressure cannot supplied to the brake chamber so that brake will get not applied.

Brake lining:

The brake lining are high friction material beings used rub again the rotating brake drums and to stop them will the brake are applied for on efficient braking and longer lifer they are expect to have high standard of quality they are required to full fill various requirement such as given below:-
1) No water swells.
2) Low heat swells.
3) Low wear rate.
4) The high coefficient of normal and hot friction.
5) High strange and physically properties.

Brake lining material:

The brake lining are made of asbestos, rubber, metallic particles, resin, minerals, and coefficient of friction modifies among these the asbestos is most important there for brake.
Lining are commonly known as asbestos brake linings.
1) Chrysalides asbestos fibers are comparatively cheap posses the hot coefficient of friction around 0.33 to 0.40 in the temperature range of 200 to 300’.
2) The metallic partial of aluminum brass and zinc are used for high heat dissipation and better antiwar characteristics.
3) The asbestos can resist temperature up to 350’ without folding.

Types of brake linings:

On the basis of manufacturing the brake lining are group in to following types.
1) Rigid molded.
2) Flexible molded.
3) With metallic partial.
4) The wealth out metallic partial.
1)  Non asbestos brake lining.
i)  Flexible.
ii)  Roll lining.

Rigid molded asbestos brake lining :-

Rigid molded asbestos brake lining has a random asbestos filigrees friction material with metallic inclusion in the form of steel wool brass chips.
 The coefficient of friction is well maintained even at higher temperature it is suitable for used under dry operating condition only it offer exceptional resistance to wear wealth out any penalty in the form of drum damage it finds application in light the medium and heavy commercial drum brake such a lining are two types:-
With Metallic Partial
Without Metallic Partial

Flexible molded roll brake lining :-

The flexible molded non metallic roll brake lining are of a dark gray in color having a random asbestos they have a random asbestos they have a high level of friction with a good anti squall properties and excellent temperature and wear resistance they are produce in roll and liner form and are suitable used under a dry operating condition only its material is manufactured with a good finish on both the surface suit may be bounded on inter surface.

Wire meshed roll lining:

The molded rubberized and flexible wire meshed backed and with medium coefficient of partition these brake lining are suitable car and light commercial vehicle running in cities and also for agricultural tractors.

Woven brake lining:

These are solid non magically using women the configuration of abbots fabric this lining do not feed up to 250 to 300 wire inclusion is also done for better heat transfer the turnery since copper or this alloys are preferred there coefficient of friction morally lies in the vicinity of 0.4.

The wear properties of brake lining:

The wear resistance is a very important properties aliening should have the backing efficient will be have only of the timing are capable of sustaining a large number of braking stroke at a elevated temperature a test report conducted on lining at a 400 if show that the lining are stable or a long period of time and there is no reduction in brake effective even a after 100 cycle of inter brake operation a good brake lining should work well over about 800 km.