Slide 1

Brake System Fundamentals

Chapter 71


Slide 2

Basic Brake System
Brake lines • Metal tubing and rubber hose that transmit
Emergency brake •
Brake pedal assembly •
Master cylinder •
Brake booster •
Wheel brake assembly •

pressure to the wheel brake assemblies.
Mechanical system for applying rear brake
assemblies
Foot lever for operating the master cylinder and
power booster.
Hydraulic-piston pump that develops pressure
for the brake system.
Vacuum or power steering operated device that
assists brake pedal application.
Devices that use system pressure to produce
friction for slowing or stopping wheel rotation.


Slide 3

Drum and Disc Brakes

• Caliper - assembly that holds the
cylinder, piston, and brake pads.


Slide 4

Drum and Disc Brakes

• Caliper cylinder - machined hole in the caliper;
the piston fits into this cylinder.


Slide 5

Drum and Disc Brakes

• Brake pads - friction members pushed against
the rotor by the action of the master cylinder,
caliper cylinder, and piston.


Slide 6

Drum and Disc Brakes

• Rotor - metal disc that uses friction from the
brake pads to stop or slow wheel rotation.


Slide 7

Drum and Disc Brakes

• Wheel cylinder - houses hydraulic pistons that are forced
outward by fluid pressure and is found on drum brakes.


Slide 8

Drum and Disc Brakes

• Brake shoes - friction units that are pushed against the
rotating brake drum by the action of the wheel cylinder
assembly.


Slide 9

Drum and Disc Brakes

• Brake Drum - rubs against the brake shoes to
stop or slow wheel rotation.


Slide 10

Braking Ratio

• Typically the front brakes handle 60-70% of the braking power, while
the rear brakes handle 30-40% of the braking. Front wheel drive
vehicles have even a higher braking ratio at the front wheels.


Slide 11

Brake System Hydraulics

Pascal’s Law
• Liquids in a confined area will not compress, however, air in
a confined area will compress.
• When pressure is applied to a closed system, pressure is
exerted equally in all directions.
• A hydraulic system can be used to increase or decrease
force or motion.


Slide 12

Brake System Components

• Brake Pedal Assembly - Foot lever for operating
the master cylinder and power booster.


Slide 13

Brake System Components

•
•
•
•
•

Master Cylinder –
It is a foot operated pump that pumps brake fluid.
Helps equalize the pressure required for braking.
Keeps the system full of brake fluid.
It maintains a slight pressure to keep contaminants (air &
water) from entering the hydraulic system.


Slide 14

Brake System Components


Slide 15

Brake System Components

Vacuum Booster

Hydraulic Booster

• Brake Boosters
• Vacuum brake boosters use engine vacuum to help stop the vehicle.
• Hydro-boost systems use pressure created by the power steering pump
to help stop the vehicle.
• All brake boost systems are designed to help stop the vehicle.


Slide 16

Brake Fluid

Brake Fluid
DOT 3 Standard Brake Fluid

DOT 4 Hi-Temp Brake Fluid
DOT 5 Silicone Brake Fluid
Keep brake fluid in tightly sealed containers.
Should be flushed every 2 years regardless of mileage!


Slide 17

Brake System Components
Disc Brake Components
•

1 Caliper assembly
2 Bracket mounting bolt
3 Bleed screw
4 Dust cap
5 Anti-rattle spring
6 Guide bolt
7 Brake pad wear warning light wire
8 Cable clamp
9 Brake disc
10 Allen bolt
11 Shield
12 Bolt
13 Washer
14 Plug
15 Plug
16 Caliper bracket
17 Cable clamp
18 Piston seal, piston, dust boot and circlip
19 Guide bush repair kit
20 Brake pads


Slide 18

Brake System Components

Drum Brake Components


Slide 19

Please refer to textbook chapter 71
for balance of worksheet