The document summarizes the key components and functions of automotive brake systems. It describes the main types of brakes used in vehicles like drum brakes and disc brakes. It explains how hydraulic braking systems work using a master cylinder and wheel cylinders to apply brake pressure. The document also discusses requirements for effective braking like stopping distance and factors that influence braking efficiency. It provides an overview of anti-lock braking systems and their components that help prevent wheel lockup.

1. Automotive Brake System

2. Automotive Brake System

3. Automotive Brake System

4. Introduction
 The modern automotive brake system has been refined
for over 100 years and has become extremely dependable
and efficient.
 Automotive brakes are the most important safety
devices for automobiles.
 Braking is the mechanism in the motor vehicle which is
used to slowing down and stopping the vehicle to rest in the
shortest possible distance.
 While operating the braking system the K.E of moving
vehicle is converted in to HEAT ENERGY.

5. Brakes have the following functions:
 It is used to stop the vehicle.
 It is used to control the speed where and when
required.
 It is used to control the vehicle while descending along
the slope.
 To park the vehicle and held it in stationary position
without the presence of
Driver.
Functions of Brakes

6.  It should work efficiently irrespective of road condition
and quality.
 The retardation must be uniform throughout its
application.
 The pedal effort must be within the convenient
capacity of the driver.
 It must be reliable and should not be effected by heat
water and dust.
 It should be in minimum weight.
Requirements of Automobile
Brakes:

7.  It should have long life.
 It should be easy to maintain and adjust.
 Noise and vibrations are to be minimum.
 There should be provision for secondary brake or
parking brake.
Requirements of Automobile
Brakes:

8.  For practical measure for braking efficiency that of the
minimum distance in which it can be brought in to rest after
the brake is applied. The stopping distance depends upon
◙ Grip between the tire and road surface.
◙ Tire tread condition.
◙ Tire inflation.
◙ Nature of road surface.
The stopping distance is calculated by d=kv2
Where d = stopping distance in kilometers,
k = Constant depending upon the road and tire
inflation.
v = velocity of the vehicle per hour.
Stopping distance
and Braking efficiency

9. The value of k is 1/25 for 4 wheel braking system.
1/12 for 2 wheel braking system.
The braking efficiency is calculated by the equation:
η = v2/3d
where v = velocity of the vehicle
d = stopping distance.
Stopping distance
and Braking efficiency

10. Condition of Brake Braking efficiency in %
1. Perfect 90%
2. Excellent 77%
3. Good 70%
4. Fair 60%
5. Poor 50%
6. Bad 37%
7. Very bad 30%
Below Fair is very danger.
Stopping distance
and Braking efficiency

11. The following are the classifications of Brakes:
1. By Method of Power.
a. Mechanical brakes.
b. Hydraulic brakes
c. Vacuum brakes.
d. Air brakes.
e. Electrical brakes.
f. Magnetic brakes.
g. Air assisted hydraulic brakes.
2. By Method of Application.
a. Service or foot brakes.
b. Parking or hand brakes.
Classification of Brakes:

12. 3. By Method of Operation.
a. Manual
b. Servo
c. Power operation
4. By method of Braking Contact.
a. Internal Expanding Brakes
b. External Contracting Brakes.
5. By Method of Applying Brake force.
a. Single Acting Brakes.
b. Double Acting Brakes.
Classification of Brakes:

13.  Service brakes. Operated by foot pedal. Most
automotive service brakes are hydraulic type. Some
vehicles use air or pneumatic brakes. Service brakes used
in cars are of two types:
 Drum brake.
 Disc brake
 Parking brakes. Operated by hand lever which hold
the veh stationary when applied.
By Method of application

14.  Drum Brakes (Internal Expanding or
External Contracting).
Types of Mechanical Brakes
 Disc Brakes (Single or Two caliper).

15.  The drum brake has a metal
drum that encloses the brake
assembly at each wheel - the drum
is attached to the wheel.
 Two curved brake shoes are
pushed outward by wheel cylinder
pistons which hold the drum by
friction force.
 Brake shoes are made of metal
and faced with friction material
called brake lining which is riveted
or cemented to the shoes.
Drum Brakes

16.  The lining is made of heat
resistant materials like fiber glass or
a semi-metallic material.
Drum Brakes

17. Drum Brakes
The main components of drum brakes are
 Brake drum
 Back plate
 Brake shoes
 Brake Liners.
 Retaining Springs
 Cam
 Brake Linkages

18. When the pedal is pressed the
fluid pr pushes the shoes
outwards through linkages,
there by coming in frictional
contact with the rotating drum.
As soon as the brake pedal is
released the retaining springs
help the brake shoes to
brought back and release the
brakes.
How a Drum Brakes Works

19.  It has a metal disc or rotor
instead of a drum and the braking is
achieved by lined shoes or pads that
are forced against a rotating disc.
 The pads are held in a caliper
that straddles the disc.
 The caliper has one or more
pistons which are activated by fluid
pressure from the master cylinder.
Disc brakes

20. Disc brakes

21. There are three types of disc brakes:
 Fixed-caliper disc brake.
◙ It has pistons on both sides of the disc,
sometimes one on each side and sometimes two.
◙ The caliper is rigidly attached to the steering
knuckle.
 Floating-caliper disc brake.
◙ It has one piston on the inboard side of the disc.
◙ The caliper moves or floats on rubber bushings on
one or two steel guide pins.
Types of Disc brake

22. Types of Disc brake

23.  Sliding-caliper disc brake. Similar to the floating-
caliper disc brake, except that the caliper moves slightly on
machined surfaces on the steering knuckle adapter or anchor
plate.
Types of Disc brake

24.  The discs are made of gray cast Iron.
 It consists of rotating disc and two friction pads which
are actuated by the four hydraulic wheel pistons contain in
two halves of an assembly is called a caliper.
 The caliper assembly is secured to the steering knuckle
in a front wheel brakes.
 The road wheel is fashioned to the outer surface of the
disc.
 The friction pads rides freely on each side of the discs.
 They are in position being the hydraulic systems.
Construction Disc brakes

25. When the brakes is applied
hydraulic pressure is supply
to the fluid inlet tube, due to
which the wheel cylinder
piston force the friction pads
against the rotating disc. In
the released piston, the
spring hold the piston pads so
that they maintain contact
with disc surface.
Disc brakes

26. Hydraulic brakes make used of hydraulic pr to force
brake shoes out words against the brake drum based
on PASCAL’S LAW.
The main components of the service braking systems is
a. Master Cylinder.
b. Wheel Cylinder.
Hydraulic brakes

27. When the driver release the brake pedal,
the piston in the master cylinder returns
back to its original position due to the
return spring pressure. Thus the pistons
in the wheel cylinder come back in its
original inward position. Thus the brakes
are released.
When the brake pedal is pressed the
piston is forced in to the master cylinder,
the hydraulic pr is applied equally to all
wheel cylinders. The pistons in the
wheel cylinders pushed outwards
against the brake drum.
Hydraulic brakes

28. Master Cylinder
The Master Cylinder is the heart
of the hydraulic brake system. It
consists of two main chambers.
The fluid reservoir which contains
the fluid to supply to the brake
system, and the compression
chamber in which the piston
operates. The reservoir supplies
fluid to the brake system through
two ports.

29. The larger port is called the filler
or intake part and is connected to
the hollow portion of the piston
between the primary and
secondary cups which act as
piston seals. The smaller port is
called the relief, bypass or
compensating port which
connects the reservoir directly
with the cylinder and lines when
the piston is in the released
position.
Master Cylinder

30. When the pedal is pushed
down, the piston pushed toward
the closed end of the MC and
sends the fluid from the front pr
chamber to the front wheel
brakes. Fluid from the rear
chamber is sent to the rear
wheel brakes. All four brakes
then operate to slow or stop the
veh.
Master Cylinder
 If there are two pistons in the master cylinder - known as
the dual braking system. Dual braking system adds to the
vehicle safety.

31. Wheel Cylinder
 It consists of two pistons which
can move in opposite directions by the
fluid pr and a spring in between. It is
rigidly mounted on the brake shield or
backing plate.
 Wheel cylinders are larger than
the master cylinders and again, the
front-wheel cylinders are larger than
the rear-wheel cylinders.

32.  When the brakes are
applied the brake fluid enters
the cylinder from a brake line
connection inlet between the
two pistons. It causes to force
out the two pistons in opposite
directions. This motion is
transmitted to the brake shoe.
Directly or through links force
them against the brake drum,
thus applying the brake.
Wheel Cylinder

33. Parking brakes
 Parking brakes are mechanically operated brakes
generally applied to the rear wheels to hold the vehicle
stationary when it is parked. The two types of parking brakes
are:
◙ Integral
◙ Independent

34.  If both disc and drum brakes are used in a car, the front
one is generally the disc brake.
 Disc brake provides more braking force than the drum
brake
 During hard braking, more vehicle weight transfers to
the front wheels
 A proportioning valve is used in the brake line with front-
disc and rear-drum brakes
 If same braking force is applied to both front wheels and
rear wheels, the rear wheels become locked and try to skid.
Imp Point to be Note

35.  When the wheel skids, kinetic friction results and when
the wheel still rotates the friction is static.
 Static friction is generally more than the kinetic friction,
i.e. static friction gives better braking force.
Anti-lock braking system (ABS)
 An ABS is designed to modulate braking pr to attain the
peak coefficient of kinetic friction between the tire and the
road, and thereby prevents wheel lockup & skidding.
 An ABS, under hard braking conditions, is designed to
reduce stopping distances under most conditions, while
maintaining vehicle stability and steer ability.

36.  Basically, there are sensors at each of the four wheels. These
sensors watch the rotation of the wheels. When any one of the wheels
stops rotating due to too much brake application, the sensors tell the
computer, which then releases some of the brake line pr that you have
applied - allowing the wheel to turn again.
 Then, just as fast as it released the pr, the computer allows the pr to
be applied again - which stops the rotation of the wheel again. Then it
releases it again. And so on.
 With most ABS, this releasing and re-application - or pulsing - of the
brake pr happens 20 or more times per second.
 ABS prevents you from ever locking up the brakes and skidding - no
matter how hard you apply the brakes.
Anti-lock braking system (ABS)

37.  Wheel Speed Sensors (up to 4)
 Electronic Control Unit (ECU)
 A Brake Master Cylinder, with accompanying Hydraulic
Modulator Unit and Solenoid Valves
 Vehicle’s Physical Brakes
Typical ABS Components