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

Select the true statement about emergency brakes:

all of these answers are correct

they are required on all commercial vehicles

they are required to be held on by a mechanical force

they are required to be activated the loss of air pressure

2 / 40

Alcohol evaporators in some air brake systems help to:

decreases the risk of water in the air brake valves in cold weather

it removes fule from the air lines

decrease the chances of ice in the air brake valves in cold weather

cleans out oil from the air lines

3 / 40

Select the true statement in regards to an application pressure gauge:

it is connected to the generator

it shows how much air pressure you are applying to the brakes

it prevents the brakes from failing

when accelerating it releases air

4 / 40

The best way to test the low air pressure warning signal is to:

apply pressure on and off the brake pedal until the air pressure drops below 20 psi

manually release the air out of your brakes to see if the signal activates

apply pressure on and off the brakes while the engine is running

apply pressure on and off the brake pedal with the engine off to drop the air pressure to below 60 psi

5 / 40

How can you check slack adjusters?

by frequenctly checking the pressure gauge

it is not possible to check manually

by using a fixed wrench

by pulling hard on each slack adjuster

6 / 40

You should be in the proper gear before going down a hill because:

brakes may fail or fade from excessive heat due to relying on them too much and not using the engine brake effect

it helps control your speed better

it builds up the air pressure in the air tanks

water may build up in the air tanks if you do not rely on the engine brake

7 / 40

How often should air tanks be drained?

every 6 hours

every 4-5 days

once a day

every 7 days

8 / 40

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

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

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

pull on the slack adjuster while the parking brakes are on

pull hard on each slack adjuster while wearing gloves

9 / 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 service brakes

release the parking brakes and activate the service brakes

activiate the parking brake and service brake

10 / 40

Select the inappropriate way to test for the low pressure warning signal.

have the electrical power on

turn off the engine

ask for a pedestrian to listen for the signal

decreased the air pressure by stepping on and off the brake pedal

11 / 40

When does stab braking occur?

when the wheels lock up, release the brakes

all of these answers are correct

when the wheels start rolling, apply the brakes

apply pressure all the way on the brake pedal

12 / 40

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

all of these answers are correct

a buzzer

red light

a wig wag mechanical arm

13 / 40

Is it mandatory that all vehicles with air brakes have low air pressure warning signals?

for large vehicles only

for small vehicles only

yes

14 / 40

Select the true statement about what the Air Compressor Governor controls:

it controls when the brakes will be applied

it controls when air is released from the storage tank

it controls when the warning system is activated

it controls when the air compressor pumps air into the storage tanks

15 / 40

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

using the service brakes excessively

not relying on engine braking enough

all of these answers are correct

the brakes are out of adjustment

16 / 40

When should you drain air tanks that do not have an automatic tank drain?

once every 7 days

at the end of each working day

once every 14 days

every 4 hours of the working shift

17 / 40

How do you test your service brakes?

pull over and activate the parking brake

release the air pressure and activate the parking brake

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

apply pressure to the brake pedal when moving at highway speeds

18 / 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)

when using the engine brake more than the brakes

brakes that are not aligned properly

tire retread that is mismatched

excessive heat from extensive use

19 / 40

The safety valve is usually set to open at:

225 psi

150 psi

75 psi

125 psi

20 / 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

21 / 40

When should you not use the parking brakes?

when the brakes are hot

while on a steep hill

when air pressure is low

while in hot weather

22 / 40

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

the vehicle is manufactured after 2001

the vehicle is manufactured after 1998

the vehicle is manufactured after 1990

the vehicle is manufactured after 2005

23 / 40

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

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

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

rapidly and lightly pump the brake pedal

24 / 40

Water is drained from the compressed air tanks because:

the water could freeze in cold weather and cause braking failure

to keep the oil in the air compressor clean

the water will over cool the compressor

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

25 / 40

What does it man when the safety valve releases air?

pressure has passed 150 psi

all of these answers are correct

there is too much air in the air compressor

you need it to have it checked out by a mechanic because something is wrong

26 / 40

Select the statement that tells you how you can check the low pressure warning signal.

The low pressure warning signal is only testable by the factory.

Turn the electrical power on and apply pressure on and off the brake pedal to increase air tank pressure. The low air pressure warning signal must come on before the pressure increases to more than 60 psi in the air tank.

Turn the electrical power on and apply pressure on and off the brake pedal to decrease the air tank pressure. The low air pressure warning signal must come on before the pressure drops to less than 60 psi in the air tank.

Turn the electrical power off and apply pressure on and off the brake pedal to decrease air tank pressure. The low air pressure warning signal must come on before the pressure drops to less than 30 psi in the air tank.

27 / 40

Why do air brakes take longer to stop than hydraulic brakes?

the lines are hotter

it takes more time for the air to flow throught the lines

longer reaction time

none of the answers listed

28 / 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

29 / 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 parking valve pops out on single vehicles

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 parkng brake valve pops out on tractor-trailer vehicles

all of these answers are correct

30 / 40

What is the purpose of the supply pressure gauge?

to inform you if there is too little air in the tank

to inform you of how much air is in the tank

all of these answers are correct

to inform you about how hot the air in the tank is

31 / 40

You should_____when the low pressure warning is activated:

come to a safe stop while you still have control of the brakes

pump the brake pedal to come to a stop immediately

maintain highway speed and keep an eye on your air pressure gauge

wait until the air brakes kick in automatically

32 / 40

Should the air pressure in the service air tanks fall below____the driver must be alerted via warning mechanism in the truck cab.

80 psi

60 psi

50 psi

30 psi

33 / 40

When does your vehicle's single brake system need an adjustment?

when the governor stops between 75-90 psi

if the compressor cuts out at between 70 and 90 psi

if the pressure builds from 50 to 75 psi in less than 3 minutes

when the pressure builds from 85 to 100 psi in less than 1 minute

34 / 40

What is the benefit of ABS?

it provides an added layer of safety for truck drivers

it decreases your stopping distance

it prevents the wheels from locking up during heavy braking or slippery conditions

all of these answers are correct

35 / 40

When should air tanks be drained?

at every restroom break stop

at the end of each working day

they don't need to be drained

every 7 days

36 / 40

Spring brakes are usually held back by_____during normal driving.

heat

clamps

pressure of the spring

air pressure

37 / 40

Front wheel brakes are good under what kind of conditions?

ideal weather conditions

they are not ideal

icy or wet conditions

any weather conditons

38 / 40

Commerical vehicles typically have this type of brake.

stab brakes

rectangle brakes

S-Cam brakes

drum brakes

39 / 40

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

engine brake system

none of the answers listed

lock brake system

service brake system

40 / 40

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

service brake system

clutch brake system

parking brake system

emergency brake system

Your score is

The average score is 82%

5/5 - (1 vote)

CDL Air Brakes Test

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