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

With the engine cutt off and the brakes released the air loss in a straight truck or bus should not be more than:

4 psi in a minute

5 psi in a minute

3 psi in a minute

2 psi in a minute

2 / 40

What must vehicles with air brakes have?

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

a minimum of 2 air tanks

an air pressure gauge that shows the pressure available for braking

all of these answers are correct

3 / 40

Spring brakes are usually held back by_____during normal driving.

clamps

pressure of the spring

heat

air pressure

4 / 40

Air tanks should be drained:

at the end of each shift or day

manually when the automatic devices fail

to prevent sludge from clogginng up the brake system valves

all of these answers are correct

5 / 40

How can you check slack adjusters?

by frequenctly checking the pressure gauge

by pulling hard on each slack adjuster

by using a fixed wrench

it is not possible to check manually

6 / 40

What are slack adjusters?

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

all of these answers are correct

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

7 / 40

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

it controls when air is released from the storage tank

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

it controls when the brakes will be applied

it controls when the warning system is activated

8 / 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

9 / 40

Air brake systems should not lose air faster than____when testing for air leakage rates in combination vehicles before applying the brake pedal.

2 psi a minute

6 psi a minute

3 psi a minute

5 psi a minute

10 / 40

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

all of these answers are correct

monitor the air pressure gauge

decrease the tank pressure by stepping on and off the brake

run the engine at a fast idle

11 / 40

What is the purpose of the supply pressure gauge?

all of these answers are correct

to inform you of how much air is in the tank

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

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

12 / 40

Select the true statement about emergency brakes:

they are required to be held on by a mechanical force

they are required to be activated the loss of air pressure

all of these answers are correct

they are required on all commercial vehicles

13 / 40

What should you do if the low air pressure warning comes on for only one system in a truck or bus that has a dual air brake system?

decrease your speed and head to the closest mechanic

continue on with your trip

stop and safely park your vehicle only continue once the issue has been resovled

decrease your speed and test the other system

14 / 40

What are spring brakes?

they do not function when the psi falls below 30 psi

all of these answers are correct

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

they are powerful springs that hold back air pressure when driving

15 / 40

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

for small vehicles only

yes

for large vehicles only

16 / 40

What is a supply pressure gauge used for?

it tells you how much pressure is in the air lines

it tells you how much slack is in the slack adjusters

it tells you how much pressure is in the air tanks

all of these answers are correct

17 / 40

Select whether the following statement is true or false: Front wheel brakes are good to use in all conditions.

false

only in ideal conditions

only in bad weather

true

18 / 40

What does the service brake system do?

they are only on vehicles that have hydraulic brakes

they are part of an official vehicle inspection

under normal driving it applies and releases the brakes by using the brake pedal

they are valves that maintain air tank pressure

19 / 40

When should you not use the parking brakes?

when the brakes are hot

while on a steep hill

while in hot weather

when air pressure is low

20 / 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

21 / 40

How do you know when your brakes are fading?

to control your speed on a downgrade you have to apply less pressure to the break pedal

the brake pedal flops to the cabin floor

to control your speed on a downgrade you have to push harder on the brake pedal

your speed increases when pressure is removed from the brake pedal

22 / 40

You should____to check the free play of manual slack adjusters on S-Cam brakes.

chock the wheels and release the parking brakes after parking on a level ground

after parking on a slight grade, release the parking brake, activate the service brakes and check for vehicle movements

apply the parking brake after stopping on level ground

drain off air pressure before adjusting after parking on level ground

23 / 40

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

using the service brakes excessively

all of these answers are correct

not relying on engine braking enough

the brakes are out of adjustment

24 / 40

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

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.

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 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.

25 / 40

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

50 psi

30 psi

60 psi

80 psi

26 / 40

At what "cut out" level does the governor stop pumping air?

125 psi

150 psi

100 psi

75 psi

27 / 40

What does it man when the safety valve releases air?

all of these answers are correct

there is too much air in the air compressor

pressure has passed 150 psi

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

28 / 40

Select how you would check the truck's slack adjusters.

listen for any strange noises while applying pressure to the brake pedal

all of these answers are correct

while wearing gloves, pull hard on each slack adjuster that you can reach

brake hard after accelerating

29 / 40

The compressor is connected to the engine via _____?

r-belt

stag gears

v-belt or gears

lines

30 / 40

Select what you should do before leaving the vehicle unattended:

all of these answers are correct

remove the keys from the ignition

chock the wheels

apply the parking brakes

31 / 40

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

longer reaction time

the lines are hotter

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

none of the answers listed

32 / 40

The parking brakes should be used____in air brake vehicles.

only when parked on an incline

only during post trip inspection

as rarely as possible

every time the vehicle is parked

33 / 40

Select the true statement about dual air brake systems.

there is a single set of brake controls

there is a primary system and a secondary system

all of these answers are correct

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

34 / 40

Where is compressed air stored?

in the storage tank

in the gasoline tank

in the hose lines

in the compartment for the engine

35 / 40

What does the air compressor governor control?

when air pressure is applied to the brakes

when the air is taken out of the hoses

when air is pumped into the air tanks

when the vavle system releases pressure

36 / 40

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

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

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

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

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

37 / 40

An air system that is fully charged will typically have ___ psi of pressure.

125

200

250

38 / 40

You should_____when the low pressure warning is activated:

wait until the air brakes kick in automatically

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

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

pump the brake pedal to come to a stop immediately

39 / 40

Select how brakes work on long, steep downgrades:

they are a supplement to the braking effect of the engine

it is the main braking mechanism

it's the main braking mechanism with the engine braking system available for emergency situations

it does not do anything

40 / 40

Select the true statement in regards to brake drums:

hold the brake linings and shoes

they are bolted to the wheels

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

all of these answers are correct

Your score is

The average score is 82%

5/5 - (1 vote)

CDL Air Brakes Test

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