What term is used to refer to the comparison of
front-wheel to rear-wheel braking effort?
Typically, what percentage of the braking does
the rear brake handle?
What component of a hydraulic brake system
coverts the force of an operators foot into
In a vehicle using a dual master cylinder, what
type of system operates the brake assemblies on
What component in a hydraulic brake system is
used where a single brake line feeds two wheel
What type of self-adjusting system uses braided
Disc brakes use servo actions. (T/F)
What are the three types of brake shoes?
What component of a disc brake system is a
Why is a metering valve used?
Describe a combination valve.
What component of an ABS system uses a wheel
speed sensor signal to operate the hydraulic
What component of an ABS system is mounted on
each spindle or hub?
A hydroboostpower brake system uses pressure
from the power steering pump. (T/F)
What are the three brake pedal application
At what thickness should disc brake pads be
What action should be taken before installing a
new master cylinder on a vehicle?
What device is used to measure brake drum
The amount of side-to-side movement of a brake
disc is known by what term?
How much metal is to be removed when
resurfacing a brake disc?
When pressure bleeding a brake system, what is
the charging pressure of the bleeder ball?
AIR BRAKE SYSTEM
Learning Objective: Describe the operation, terms,
and component functions of an air brake system.
Describe the procedures for servicing an air brake
Unlike liquids, gases are compressed easily. If a
gas, such as air, is contained and a force applied to it, it
is compressed and has less volume. Placing a weight
on a piston that fits in the container can exert such a
force. The air that originally filled the entire container
is pressed into only a portion of the container due to the
force of the weight upon it. The pressure of the
compressed air, resulting from the force exerted upon
it by the weight, will be distributed equally in all
directions just as it is in a liquid.
An air brake system performs the following basic
An air pump or compressor driven by the engine
is used to compress air and force it into a
reservoir where it is forced under pressure and
made available for operating the brakes.
Air under pressure in the reservoir is released to
the brake lines by an air valve operated by the
This released air goes to brake chambers
(located at each wheel) that contains a flexible
diaphragm. Against this diaphragm is a plate that
is connected directly to the mechanism on the
wheel brakes by linkage.
The force of the compressed air admitted to the
brake chamber causes the diaphragm to move
the plate and operate the brake shoes through the
Considerable force is available for braking
because the operating pressure may be as high as 110
psi. All brakes on a vehicle, and on a trailer when one is
used, are operated together by means of special
regulating valves. A diagram of a typical air brake
system is shown in figure 7-39.
COMPRESSOR, GOVERNOR, AND
The COMPRESSOR is driven from the engine
crankshaft or one of the auxiliary shafts. The three
common methods of driving the compressor from the
engine are gear, belt, and chain. The compressor may
be lubricated from the engine crankcase or
self-lubricating. Cooling may be either by air or liquid