Mechanical Brakes

1. AUTOMOTIVE BRAKING SYSTE
1

2. How it Works
Friction
develops heat which
absorbs kinetic energy of the
car
2

3. 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 nonmoving surface at each wheel to generate the heat.
 Disc and drum brakes are the most common type of
braking systems used.
3

4. Factors Effecting 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
4

5. Types of Braking Systems
 Service
brakes. It’s
the primary braking
system using a the
pedal connected to a
hydraulic system
causing it to operate.
 Parking brakes. It’s
mechanically applied
by a lever or pedal.
5

6. 

BASIC PARTS




Pedal assembly
Hydraulic system
Power booster
Disc brake
assembly
Drum brake
assembly
6

7. DISC BRAKES
 Disc
brakes use a
rotating disc with
two stationary
friction pads that are
pressed against to
rotor by the caliper
to create friction and
heat.
 Disc brakes are
more effective at
dissipating heat.
7

8. Rotor
Pads
Caliper
Piston
Brake
Line
Bleeder
screw
Through
Bolts
Disc Brake Rotor
8

9. Rotors
9

10. Performance Rotors
10

11.  Boot
Caliper
 Piston
 Seal
 Caliper
Housing
 Bleed Screw
 O-Ring
 Bushing
 Bolts
11

12. Caliper*
12

13. Disc Brake Pads
 Asbestos
 Metallic
 Semi-Metallic
 Organic
13

14. Wheel Assembly
14

15. Disc Brake Assembly
15

16. Drum Brakes
16

17. Drum Brakes
17

18. Drum Brake Action
Adjust by driving in reverse and braking
18

19. DRUM BRAKES
 Wheel
Cylinder
 Piston
 Upper
 Anchor
Pin
 .Backing
Plate
 Parking Brake
Lever
Return
Spring
 Primary
Brake
Shoe
 .Secondary
Brake
Shoe
 Adjuster
 .Lower
Spring
Return
19

20. Two Types of Drum Brakes
20

21. Two Types of Drum Brakes
21

22. HYDRAULIC SYSTEM









Brake pedal assembly
Power booster
Master cylinder
Proportioning valve
Metering valve
Warning light valve
Lines
Calipers
Wheel cylinders
22

23.  Hydraulic
system
Brake Light
fails
 Parking brake is on
23

24. Master Cylinder
The master cylinder displaces brake fluid under
pressure to brake system.
 When brake pedal is depressed, push rod moves the
primary piston forward in the cylinder.
 Hydraulic pressure created and the force of the
primary piston spring moves the secondary piston
forward.
 forward movement of the pistons causes primary
cups to cover bypass holes, hydraulic pressure
builds up and is transmitted to the wheel cylinders.

24

25. MASTER CYLINDER
 pedal
retracts, the pistons allow fluid from
the reservoir to fill the chamber
 Special sensors within the master cylinder
used to monitor level of fluid in reservoir,
and alerts driver if pressure imbalance
develops.
 standard dual master cylinder gives front
and rear brakes separate hydraulic systems.
25

26. Master Cylinder
 If
a brake fluid leak occurs in one system,
the other system will still operate, making it
possible to. . .
 STOP THE CAR
26

27. Master Cylinder
Reservoirs
Master
Cylinder
To
Front
Brakes
To Rear
Brakes
Vacuum Line
Power
Booster
Brake Pedal
27

28. Reservoirs
28

29. Reservoir Problems
29

30. Power Brake Booster
Gain power from vacuum in intake manifold
30

31. Booster
Operation
31

32. Brake Lines

Brake lines are stee
tubing with copper
and lead coatings to
prevent rust and
corrosion. As the
brake pedal is
depressed, it moves
pistons within the
master cylinder and
forcing hydraulic
brake fluid
32

33. Brake Lines




Throughout the brake
system and into the wheel
(or brake) cylinders.
The pressure placed
upon this fluid causes the
cylinder pistons to
move, forcing the brake
shoes or friction pads and
brake drums or
rotors to slow the
vehicle.
33

34. Brake Parts
34

35. Hydraulic Valves
35

36. Hydraulic Action in the Caliper
 Squeeze
Rotor
 Push out on Drum
36

37. Basics of Hydraulics
37

38. Hydraulic Action in the Wheel
Cylinder
38

39. Braking Videos
http://www.raybestos.com/main.htm?techcenter.htm
39

40. PARKING BRAKE
 Parking
brake pedal or
lever
 Cables
 Adjuster
 Drum brake linkage
 Disc brake lever
40

41. BRAKE INSPECTION
 Remove
all four wheels of the vehicle.
 On drum brakes remove the drums and
wash brake dust with proper cleaner.
 Check brake pads and brakes shoes for
wear.
 Check drums and rotors for wear and
damage.
41

42. Brake Fluid
 Litmus
test
 Color
 Non
compressible
 Resists boiling
 High &low
temperature stability
 Non-corrosive to
rubber parts
 Hydroscopic
– Absorbs water
42

43. Brake Fluid
 DOT
3
 DOT4
 DOT5
– Silicone
43

44. Brake Service
 Visual
Inspection
 Measure
 Resurface
 Repair
 Recondition
 Bleed
 Test
44

45. Problems
45

46. ABS
 Modulator
 VSS/
 Vehicle
speed
sensors
 Electronic
Brake
Control Unit
46

47. ABS
 Wheel
locks upreduces power to that
wheel
 Pulsates brakes if
sliding
 Pulsates brakes on hard
braking
 Stops vehicle under
control
 NOT faster
47