Texas Cdl A Brakestion 5

Front 1

Air brakes are really made up of three different braking systems, what are they?

Back 1

service brake, parking brake, emergency brake

Front 2

What is the service brake?

Back 2

The service brake system applies and releases the
brakes when you use the brake pedal during normal
driving.

Front 3

What is the parking brake?

Back 3

The parking brake system applies and releases the
parking brakes when you use the parking brake control.

Front 4

What is the emergency brake?

Back 4

The emergency brake system uses parts of the service
and parking brake systems to stop the vehicle in
the event of a brake system failure.

Front 5

There are many parts to an air brake system. What is the air compressor?

Back 5

The air compressor pumps air into the air storage tanks
reservoirs. The air compressor is connected to the engine
through gears or a belt.

Front 6

Can the air compresssor have its own oil supply?

Back 6

It may have
its own oil supply, or be lubricated by engine oil. If the compressor
has its own oil supply, check the oil level before driving.

Front 7

There are many parts to an air brake system. What is the Air Compressor Governor?

Back 7

The governor controls when the air compressor will pump
air into the air storage tanks.

Front 8

When air tank pressure (Air Compressor Governor) rises to the “cut-out” level of what psi?

Back 8

Around 125 pounds.

Front 9

When air tank pressure (Air Compressor Governor) rises to the “cut-in” level of what psi?

Back 9

Around100 psi.

Front 10

What is Air Storage Tanks?

Back 10

Air storage tanks are used to hold compressed air. The
number and size of air tanks varies among vehicles.

Front 11

Will air storage tanks allow the breaks to stop several times.

Back 11

Tanks will hold enough air to allow the brakes to be used
several times even if the compressor stops working.

Front 12

What does the Air Tank Drains do?

Back 12

Releases water and oil that tend to collect in the bottom
of the air tank 9this should be done daily).

Front 13

What is the Alcohol Evaporator?

Back 13

Some air brake systems have an alcohol evaporator to put
alcohol into the air system. This helps to reduce the risk of
ice in air brake valves and other parts during cold weather.

Front 14

How often should the alcohol container be filled or changed?

Back 14

Check the alcohol container and fill up as necessary, every
day during cold weather.

Front 15

What is a Safety Valve?

Back 15

The safety valve protects the tank and
the rest of the system from too much pressure. The valve is
usually set to open at 150 psi.

Front 16

Is the safety relief valve installed in the first tank the air compressor
pumps air to. True or False

Back 16

True

Front 17

If the safety valve release air (set to open at 150 psi)....

Back 17

something is wrong

Front 18

Pushing the break pedal harder applies ________ air pressure.

Back 18

more

Front 19

Letting up on
the brake pedal __________the air pressure and releases the
brakes.

Back 19

reduces

Front 20

What are Foundation Brakes?

Back 20

Foundation brakes are used at each wheel. The most common
type is the s-cam drum brake

Front 21

What are the parts of the Foundation Brakes

Back 21

Brake Drums, Shoes, and Linings,S-cam Brakes, Wedge Brakes, Disc Brakes

Front 22

What is S-cam break?

Back 22

The s-cam forces the brake
shoes away from one another and presses them against the
inside of the brake drum.When you release the brake pedal,
the s-cam rotates back and a spring pulls the brake shoes
away from the drum, letting the wheels roll freely again.

Front 23

What is a Wedge Brake?

Back 23

the brake chamber push
rod pushes a wedge directly between the ends of two brake
shoes.

Front 24

What is a Disc Brake?

Back 24

In air-operated disc brakes, air pressure acts
on a brake chamber and slack adjuster, like s-cam brakes.

Front 25

What is a Supply Pressure Gauge?

Back 25

All air-braked vehicles have a pressure gauge connected to
the air tank. These
gauges tell you how much pressure is in the air tanks

Front 26

What is a Application Pressure Gauge?

Back 26

This gauge shows how much air pressure you are applying
to the brakes. This gauge is not on all vehicles.

Front 27

What is a low air pressure signal? When does it come on?

Back 27

A low air pressure warning signal is required on vehicles
with air brakes. A warning signal you can see must come on
before the air pressure in the tanks falls below 60 psi.

Front 28

When does the low pressure air warning come on on a large bus?

Back 28

On large buses it is common for the low pressure warning
devices to signal at 80-85 psi.

Front 29

Should Drivers behind you be warned when you put your
brakes on.

Back 29

The switch turns on the
brake lights when you put on the air brakes.

Front 30

What are spring breaks?

Back 30

Spring brakes are usually used to meet these
needs. When driving, powerful springs are held back by air pressure. If the air pressure is removed, the springs put on
the brakes.

Front 31

When doe the tractor and straight truck spring brakes will come fully on

Back 31

When air pressure drops to a range of 20 to 45 psi (typically
20 to 30 psi).

Front 32

When the low air pressure warning light and
buzzer first come on the driver should?

Back 32

bring the vehicle to a safe stop right
away, while you can still control the brakes

Front 33

The braking power of spring brakes depends on the brakes
being in adjustment. True or False

Back 33

True. If the brakes are not adjusted properly,
neither the regular brakes nor the emergency/parking
brakes will work right.

Front 34

What is the Parking Brake Control?

Back 34

Put on the parking
brakes using a diamond-shaped, yellow, push-pull control knob.

Front 35

Never push the brake pedal down when the spring
brakes are on. true or false

Back 35

True. If you do, the brakes could be damaged by
the combined forces of the springs and the air pressure.
Many brake systems are designed so this will not happen.

Front 36

What is a Modulating Control Valve.

Back 36

A control
handle on the dash board that may be used to apply the spring
brakes gradually. This is called a modulating valve. It is
spring loaded so you

Front 37

Dual Parking Control Valves.

Back 37

Some vehicles, such as
buses, have a separate air tank which can be used to
release the spring brakes.

Front 38

What is a DUAL AIR BRAKE.

Back 38

A dual air brake system has two separate air
brake systems which use a single set of brake controls.
Each system has its own air tanks, hoses, lines, etc.

Front 39

Before driving a vehicle with a dual air system, allow time for
the air compressor to build up a minimum of 100 psi pressure
in both the primary and secondary systems. True or False

Back 39

True

Front 40

The warning
light and buzzer should shut off when air pressure in both
systems rises to a value set by the manufacturer.

Back 40

This value must be greater than 60 psi.

Front 41

The warning light and buzzer should come on before the air
pressure drops below 60 psi in either system.

Back 41

If this happens
while driving, you should stop right away and safely park the
vehicle.

Front 42

INSPECTING AIR BRAKE SYSTEMS During Step 2 Engine Compartment Checks

Back 42

During Step 2 Engine Compartment Checks
Check Air Compressor Drive Belt (if compressor is belt
driven). If the air compressor is belt-driven, check the condition
and tightness of the belt. The belt should be in good
condition.

Front 43

During Step 7 Final Air Brake Check Test Air Leakage Rate fro single vehicle.

Back 43

turn off the engine, release the service
brake, and time the air pressure drop.two psi in one minute for single vehicles typically 125 psi

Front 44

During Step 7 Final Air Brake Check Test Air Leakage Rate fro combination vehicle.

Back 44

turn off the engine, release the service
brake, and time the air pressure drop. less than three psi in one minute for combination vehicles. typically 125 psi

Front 45

When testing the air brake after timing the psi loss rate apply apply 90 psi or more with the brake pedal. After the initial
pressure drop, if the air pressure falls more than three
psi in one minute for single vehicles more than four psi for
combination vehicles, the air loss rate is too much. True or False

Back 45

True. Check
for air leaks and fix before driving the vehicle. Otherwise,
you could lose your brakes while driving.

Front 46

Test Low Pressure Warning Signal.

Back 46

Shut the engine off
when you have enough air pressure so that the low pressure
warning signal is not on. Turn the electrical power on and
step on and off the brake pedal to reduce air tank pressure.The low air pressure warning signal must come on before
the pressure drops to less than 60

Front 47

Check That the Spring Brakes Come on Automatically

Back 47

Chock the wheels, release the parking brakes when you
have enough air pressure to do it, and shut the engine off.
Step on and off the brake pedal to reduce the air tank pressure.
The “parking brake” knob should pop out when the air
pressure falls to the manufacturer’s specification (usually in
a range between 20-40 psi). This causes the spring brakes
to come on.

Front 48

Check Rate of Air Pressure Buildup.

Back 48

When the engine is
at operating rpm, the pressure should build from 85 to 100
psi within 45 seconds in dual air systems.

Front 49

Check Air Compressor Governor Cut-in and Cut-out
Pressures

Back 49

Pumping by the air compressor should start at
about 100 psi and stop at about 125 psi

Front 50

Test Parking Brake

Back 50

Stop the vehicle, put the parking brake
on, and gently pull against it in a low gear to test that the
parking brake will hold.

Front 51

Test Service Brakes.

Back 51

Wait for normal air pressure, release
the parking brake, move the vehicle forward slowly (about
five mph), and apply the brakes firmly using the brake pedal.

Front 52

total stopping distance for vehicles with air
brake systems is made up of four different factors.

Back 52

Perception Distance
+ Reaction Distance
+ Brake Lag Distance
+ Effective Braking Distance
= Total Stopping Distance

Front 53

The air brake lag distance at 55 mph on dry pavement adds--------------fett

Back 53

32