Brakes its functions,applications,classifications,advantages and disadvantages.

2. Made by:
Muhammad Awais
B.E(M.E) ,
Qucest Larkana,
Sindh,Pakistan
.

3. • Brake
• How brake works?
• Purpose of brakes
• Factors affecting braking
system
• Functions,Application,advanta
ges and disadvantages
.

4. What is brake?
A brake is a mechanical device which inhibits
motion. Its opposite component is a clutch. Brake
pedal slows a car to a stop. When you depress your
brake pedal, your car transmits the force from your
foot to its brakes through a fluid. Since the actual
brakes require a much greater force than you could
apply with your leg, your car must also multiply the
force of your foot.

5. How brakes work?
• Friction develops heat which
absorbs kinetic energy of the car

6. • Purpose of braking System.
• Stop the vehicle by converting the kinetic energy of
the vehicle to heat energy.
• Heat energy is created in the brakes by friction.
• Friction is created between a moving and a non-
moving surface at each wheel to generate the
heat.
• Disc and drum brakes are the most common type
of braking systems used.

7. • Factors Affecting Braking
• Number of wheels braking.
• Weight of vehicle.
• Type of friction material.
• Surface area of friction material.
• Size or discs or drums
• Tire traction.
• Road surface.
• Load transfer.
• Incline or decline
of road. (gravity)
• Engine braking.
• Pressure applied

8. Functions of Brakes:
There are two main functions of brakes :
1. To slow down or stop the vehicle in the shortest
possible time at the time of need.
2. To control the speed of vehicle at turns and also
at the time of driving down on a hill slope.

9. CLASSIFICATION OF BRAKES
On the Basis of Method of Actuation
(a) Foot brake (also called service brake)
operated by foot pedal
In the Automobile Engineering a brake
operated by applying pressure to a foot pedal
then it is called foot brake.

10. (b) Hand brake – it is also called parking brake operated by
hand
Parking brakes or emergency brakes are essentially
mechanical brakes operated by hand. These are used to
prevent the motion of vehicle when parked at a place or
when parked on slopes. In cars, these brakes are generally
attached to rear wheels. In this type, a cable connects the
hand lever to the brake. Brakes are applied by pulling the
lever and released by pushing a button (provided on lever)
and pressing the lever down.

11. On the Basis of Mode of Operation
(a) Mechanical brakes
Internal expanding shoe brakes are most commonly used in
automobiles. In an automobile, the wheel is fitted on a wheel drum. The
brake shoes come in contact with inner surface of this drum to apply
brakes.
(b) Hydraulic brakes
The brakes which are actuated by the hydraulic pressure (pressure of a
fluid) are called hydraulic brakes. Hydraulic brakes are commonly used
in the automobiles.

12. (c) Air brakes
Air brakes are applied by the pressure of compressed air. Air
pressure applies force on brakes shoes through suitable linkages
to operate brakes. An air compressor is used to compress air.
This compressor is run by engine power.
(d) Vacuum brakes
Vacuum brakes are a piston or a diaphragm operating in a
cylinder. For application of brakes one side of piston is subjected
to atmospheric pressure while the other is applied vacuum by
exhausting air from this side. A force acts on the piston due to
difference of pressure. This force is used to operate brake
through suitable linkages.

13. On the Basis of Action on Front or Rear Wheels
(a) Front-wheel brakes
Disc Brake is mostly usage in Front Wheel Brakes.
(b) Rear-wheel brakes
Drum Brake is usage in Rear Wheel Brakes.

14. Application of Brakes
When brake pedal is pressed to apply the brakes, the piston in the
master cylinder forces the brake fluid. This increases the pressure
of fluid.
This pressure is transmitted in all the pipes and upto all wheel
cylinders .This increased pressure forces out the two pistons in the
wheel cylinders.
These pistons are connected to brake shoes. So, the brake shoes
expand out against brake drums. Due to friction between brake
linings and drum, wheels slow down and brakes are applied.

15. Advantages
Equal braking action on all wheels.
Increased braking force.
Simple in construction.
Low wear rate of brake linings.
Flexibility of brake linings.
Increased mechanical advantage

16. Disadvantages
Whole braking system fails due to leakage of fluid from
brake linings.
Presence of air inside the tubing’s ruins the whole
system.

17. QUESTIONS