This document describes various brake system components and types. It discusses parking brakes, service brakes, hydraulic brakes, drum brakes, disc brakes, and anti-lock brake systems (ABS). Key components include the master cylinder, calipers, rotors, pads, shoes, and various valves and pumps. Hydraulic principles allow force multiplication from the brake pedal. Drum brakes use expanding shoes to brake while disc brakes use calipers and pads to squeeze a rotor. ABS monitors wheel speeds to prevent locking during heavy braking.

2. Types
Parking Brake
Service Brake
Hydraulic
Disc Brakes
Drum Brakes
Dual System
Antilock Brake System (ABS)

3. Parking Brake
 Not an “Emergency” Brake
 Used specifically to keep a parked
vehicle from moving
 Usually on rear wheels only
 Mechanically operated
 Static Friction: at rest friction- More
friction
 Kinetic Friction: in motion friction-
less friction

4. Typical Parking Brake

5. Service Brakes
 Primary Braking System
 Should be stronger than the
engine
 Hydraulic Operated
 Can be Vacuum, Hydro or Motor
assisted
 Disc System
 Drum System
 Dual System

6. Typical System

7. Hydraulic Principles
 Fluids cannot be compressed
 Fluids can transmit Movement
 Acts “Like a steel rod” in a closed
container
 Master cylinder transmits fluid to
wheel cylinder or caliper piston bore.
 Fluids can transmit and increase
force
Force
Area
Pressure

8. Hydraulics
Simplified Hydraulic Brake System
Drum Brake
Master Cylinder
Disk Brake
Simplified Hydraulic Brake System
Drum Brake
Master Cylinder
Disk Brake

9. Hydraulic pressure is
distributed equally in all
directions

10. Same line pressure toSame line pressure to
all wheelsall wheels

11. The Hydraulic pressure is theThe Hydraulic pressure is the
same, but the applied force cansame, but the applied force can
be changed by thebe changed by the piston sizepiston size

12. System Basics
Hydraulic
actuation allows
multiplication of
pedal force.
In this system, a
10lb force on the
pedal produces
360 lbs of force
at the friction
surface.

13. Brake Fluid
Properties of Brake Fluid
Does not thicken or thin with
changing heat
Must not boil
Must be compatible with brake parts
material
Must lubricate internal parts
Must not evaporate easily

14. Brake Fluid types
 DOT 3 and 4-
 Polyglycol based
 Most common
 Compatible with
one another
 Inexpensive
 Destroys paint
 Ruined by moister
DOT= Department of Transportation
High #= High stands, quality and boiling point
• DOT 5-
• Silicone Based
• Used only for heavy
duty applications
• Not Compatible with
4&3
• Very Expensive
• Does not damage
paint

15. Fluid Contaminates
 Moister- Lowers boiling point
 water boils @ 212*F DOT 3 boils @ 401*F
 Petroleum Based Product-
 soften rubber parts causing swelling
 Dirt & Debris-
 causes corrosion and clogs
 Air and Vapors-
 Compressible prevents pressure from
reaching brakes

16. Master Cylinder
 Provides a reservoir for brake fluid and
contains the driving pistons in the
hydraulic circuit
 2 Types
Front - Rear split
-One piston for front brakes and one for rear
-If a leak occurs you could lose front brakes
Diagonally split
-One piston drives one front wheel and one rear wheel
-Diagonal layout allows you to maintain directional
control if a leak occurs

17. Power Booster in closed
position

18. Drum Brakes
 Expanding shoes
create force on the
inner surface of the
drum
 Used on the rear of
some trucks and
SUV’s
 Self-energizing
design requires less
activation force
 Require periodic
adjustment

19. Drum Brake System

20. Vented Rotors
Vented Rotors have Fins in the spaces
between their machined surfaces.
These spaces allow air to pass through,
which helps carry heat away.

21. Nonvented Rotor
Non Vented Rotors are used on smaller
vehicles, and have no cooling fins

22. Disc Brake Caliper
Assembly

23. Caliper Types
There are 2 types of Calipers
Fixed
 Calipers are disc brakes that use a caliper that
is FIXED in position and does not slide. They
have pistons on both sides of the disc. There
may be 2 or 4 pistons per caliper
Floating
 Much more common
 Single Piston
 Easier to work with
 On “inboard” side of caliper

24. Fixed Caliper
•Motorcycles and
some trucks and cars
use this type
•Similar to bicycle
brakes

25. Sliding Caliper
 Applies pressure
to two pads on
opposite sides of
rotor
 Caliper
 Sliding
 Fixed
 Friction Material
exposed to air

26. Fixed Caliper
 Applies two
pistons to
opposite sides of
rotor
 Caliper stays
stationary
 Disc Brakes
require higher
hydraulic pressure

27. Diagnosis
Several different types of
Complaints
Noise
Pulsation
Pedal travel
More later…

28. Brake Noise
Wear
Indicator

29. Brake Pulsation
Usually a
warped Rotor
Rotor needs
trued on a
brake lathe

30. Pedal Travel
NO BRAKES!!!!
•Excessive pedal travel
•Pedal feels soft and squishy
•Requires excessive effort to
stop vehicle or my cause
brakes to not function at
all

31. Anti-Lock Brakes
 A locked (sliding) wheel offers less
braking force than a decelerating
rolling wheel
 The locked wheel also produces little
lateral force, preventing steering
control
 Anti-Lock systems (ABS) monitor
wheel lock-up and modulate brake
pressure to provide controlled
braking under most circumstances

32. Anti-Lock Brakes
 System can have 2, 3 or 4 channels
 Trucks typically use 3 channel with
only one sensor for the rear axle
 Most modern cars use 4 channel
system
 Wheel speed sensors monitor each
wheel speed
 ABS controller and high-pressure
pump increase or reduce pressure to
wheels in order to maintain consistent
wheel speeds

33. Other Braking Systems
Air Brakes
Exhaust Brakes
Electric or Trailer Brake