CDL Air Brakes Test

This is the Commercial Vehicle Driver's License Test covering Air Brakes. You will be presented with 40 questions and you must answer 34 questions correctly to pass. There is no time limit. You may not go back once you answer a question. Click the "Start Quiz" button below to begin. Good luck!

1 / 40

What does the drain valve for air tanks remove?

water and air

oil and dirt

oil and water

air and oil

2 / 40

Where is compressed air stored?

in the gasoline tank

in the compartment for the engine

in the hose lines

in the storage tank

3 / 40

Select the true statement in regards to brake drums or discs:

they should always be kept well-greased up

they should not have cracks that are longer than half the width of the friction area

the linings should fit loosely around the brake shoe

they are not allowed to have any cracks

4 / 40

What is the brake system that applies and releases the brakes when the brake pedal is used?

engine brake system

lock brake system

service brake system

none of the answers listed

5 / 40

You should_____to make an emergency stop with air brakes when using the stab braking method.

rapidly and lightly pump the brake pedal

apply a full hand valve until you stop and press firmly on the brake pedal

apply a firm pressure to the brakes, release the brake pedal once the wheels lock and then apply pressure to the brakes onces the wheels start rolling again

apply pressure to the brake pedal until the wheels lock and then stay off of the pedal for as long as the wheels are locked

6 / 40

At around____the governor allows the air compressor to start pumping again:

225 psi

175 pso

125 psi

100 psi

7 / 40

Select how you can tell if your vehicle is equipped with an anti-lock braking system:

the vehicle is manufactured after 1990

the vehicle is manufactured after 2001

the vehicle is manufactured after 1998

the vehicle is manufactured after 2005

8 / 40

Air tanks need to be drained:

to keep the tanks warm when not in use

air tanks should absolutely never be drained

to prevent water and oil from building up in the tank

to keep the tanks cold when not in use

9 / 40

What are spring brakes?

none of the answers listed

they are powerful springs that are restrained by air pressure when the air pressure is removed, the brakes are applied

they are large springs that are held closed by air pressure if the air pressure is increased the brakes are applied

they are big springs with air pressure in them if the air pressure decreases, the brakes are applied

10 / 40

The method used to make sure the spring brakes will come on automatically is to:

Apply pressure on and off the brake pedal to decrease the air tank pressure while driving at a high a speed. The parking brake knob should pop out when the air pressure meets to the manufacturer’s specification.

Apply pressure on and off the brake pedal to decrease the air tank pressure. The parking brake knob should pop out when the air pressure meets to the manufacturer’s specification.

Apply pressure on and off the brake pedal to increase the air tank pressure. The parking brake knob should pop out when the air pressure meets to the manufacturer’s specification.

Apply pressure on and off the brake pedal to decrease the air tank pressure. The parking brake knob should pop out when the air pressure drops to 120 psi.

11 / 40

What are spring brakes?

they are powerful springs that hold back air pressure when driving

they do not function when the psi falls below 30 psi

they are brakes that automatically come on for a truck or trailer when the psi drops too low

all of these answers are correct

12 / 40

Select the first action to do when the low air pressure warning comes on:

adjust the engine brake

come to a stop and safely park as soon as possible

release the supply control valve

shift into a higher gear

13 / 40

What must vehicles with air brakes have?

all of these answers are correct

a minimum of 2 air tanks

an air pressure gauge that shows how much air is used by the brake chambers for braking

an air pressure gauge that shows the pressure available for braking

14 / 40

The best way to test if the spring brakes come on automatically is to:

apply pressure on and off the brake pedal until the manufacturer's low psi specification has been met for the spring brakes to deploy

apply pressure on and off the brake pedal until the parking valve pops out on single vehicles

all of these answers are correct

apply pressure on and off the brake pedal until the parkng brake valve pops out on tractor-trailer vehicles

15 / 40

You should_____when checking the slack adjusters on S-Cam brakes.

make sure there is an inch of leeway in each direction for the slack adjuster

pull hard on each slack adjuster while wearing gloves

pull on the slack adjuster while the parking brakes are on

pull on the slack adjusters after draining the air form the system

16 / 40

Select the true statement about dual air brake systems.

there is a primary system and a secondary system

there is a single set of brake controls

one system controls the front axle and the other controls the rear axle

all of these answers are correct

17 / 40

Select the factors that can cause your brakes to fade or fail:

all of these answers are correct

not relying on engine braking enough

using the service brakes excessively

the brakes are out of adjustment

18 / 40

Select the answer that is not a part of the braking process when driving a tractor-trailer combination vehicle that has ABS:

you should brake in the same manner regardless of what you are driving

only use the braking that is necessary to safely stay in control of the vehicle

you should monitor the tractor and trailer as you decrease your speed to keep control

you should drive at a higher speed to keep the trailer in line

19 / 40

How do you check the air compressor governor "cut in" and "cut out" pressures?

all of these answers are correct

decrease the tank pressure by stepping on and off the brake

run the engine at a fast idle

monitor the air pressure gauge

20 / 40

The safety valve is usually set to open at:

75 psi

225 psi

150 psi

125 psi

21 / 40

Select the statement that is not part of the air-brake system:

emergency brake system

parking brake system

clutch brake system

service brake system

22 / 40

When should you not use the parking brakes?

while on a steep hill

when the brakes are hot

when air pressure is low

while in hot weather

23 / 40

Select the reason as to why air tanks need to be drained:

to prevent the left sided brake from locking up

to realease water and other contaminents which may cause brakes to fail in freezing weather

to provide greater control of your vehicle

tanks usually do not need to be drained

24 / 40

How do you test your service brakes?

apply pressure to the brake pedal when moving at highway speeds

after releasing the parking brake, move forward slowly and apply pressure to the brake pedal

pull over and activate the parking brake

release the air pressure and activate the parking brake

25 / 40

An example of a low pressure warning signal for air brakes is:

a wig wag mechanical arm

a buzzer

red light

all of these answers are correct

26 / 40

Select the true statement about dual air brake systems:

they are required to have two warning alarms

they require less time to build up air pressure

they have one set of controls for two air brake systems

they have a single set of air tanks and hoses

27 / 40

Water is drained from the compressed air tanks because:

the water will over cool the compressor

to keep the oil in the air compressor clean

braking power is decreased due to the low boiling point of water

the water could freeze in cold weather and cause braking failure

28 / 40

How can you check slack adjusters?

by pulling hard on each slack adjuster

by frequenctly checking the pressure gauge

it is not possible to check manually

by using a fixed wrench

29 / 40

Select what you should do before leaving the vehicle unattended:

all of these answers are correct

remove the keys from the ignition

apply the parking brakes

chock the wheels

30 / 40

What is a supply pressure gauge used for?

it tells you how much slack is in the slack adjusters

all of these answers are correct

it tells you how much pressure is in the air tanks

it tells you how much pressure is in the air lines

31 / 40

Select the factor that is known to cause brakes to fail or fade. (more than one answer may be correct, but select only one)

excessive heat from extensive use

tire retread that is mismatched

brakes that are not aligned properly

when using the engine brake more than the brakes

32 / 40

What keeps air in the tanks should the air compressor develop a leak?

the tractor relay valve

the one-way check vavle

the engine protection valve

the air compressor

33 / 40

When should air tanks be drained?

at every restroom break stop

every 7 days

at the end of each working day

they don't need to be drained

34 / 40

When does stab braking occur?

when the wheels lock up, release the brakes

when the wheels start rolling, apply the brakes

all of these answers are correct

apply pressure all the way on the brake pedal

35 / 40

You should___to reduce the air leakage rate.

release the service brake as the engine is running

monitor the air pressure gauge as you press on the brake pedal

leave the engine running while charging the air system

release the service brake after turning off the engine

36 / 40

Select the true statement in regards to brake drums:

all of these answers are correct

they are bolted to the wheels

hold the brake linings and shoes

they are located at both ends of the axles of the vehicle

37 / 40

Select the true statement in regards to the braking power of spring brakes.

braking power can only be tested by licensed mechanics

the braking prower increases when the brakes are hot

it will not be affect by the condition of the service brakes

it depends on the adjustment of the service brakes

38 / 40

How do you determine if slack adjusters need to be adjusted?

pull out the automatic slack adjustment control knob

release the parking brakes and activate the service brakes

release the parking brakes and service brakes

activiate the parking brake and service brake

39 / 40

What are slack adjusters?

they are a part of the air brake system that adjusts the brakes

they are between the S-Cam on drum brakes and the push rod

they are between the push rod on disc brakes and power screw

all of these answers are correct

40 / 40

The best way to describe a dual air brake system is:

all of these answers are correct

there is a primary and secondary system that is 2 separate air brake systems

there are 2 separate air brake systems that supply air to the trailer if there is one

there are 2 separate air brake systems that have their own hoses, lines etc

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5/5 - (1 vote)

CDL Air Brakes Test

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