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

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

2 / 40

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

2 psi in a minute

5 psi in a minute

4 psi in a minute

3 psi in a minute

3 / 40

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

service brake system

engine brake system

none of the answers listed

lock brake system

4 / 40

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

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

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 governor stops between 75-90 psi

5 / 40

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

the engine protection valve

the tractor relay valve

the one-way check vavle

the air compressor

6 / 40

Select which vehicles are required to have a low air pressure warning signal:

all vehicles built after 2005

all vehicles built after 2010

they are optional

all operating vehicles with air brakes

7 / 40

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

it controls when the brakes will be applied

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

it controls when the warning system is activated

it controls when air is released from the storage tank

8 / 40

Why are you required to take an exam about air brakes?

it is a federal requirement

all trucks have air brakes

you would have to get a CDL with a restriction otherwise

you cannot receive a CDL at all otherwise

9 / 40

Select the true statement about emergency brakes:

they are required to be activated the loss of air pressure

all of these answers are correct

they are required to be held on by a mechanical force

they are required on all commercial vehicles

10 / 40

When should air tanks be drained?

at the end of each working day

they don't need to be drained

at every restroom break stop

every 7 days

11 / 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

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

the brake pedal flops to the cabin floor

your speed increases when pressure is removed from the brake pedal

12 / 40

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

only in ideal conditions

true

false

only in bad weather

13 / 40

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

for large vehicles only

yes

for small vehicles only

14 / 40

When should you avoid using the parking brake?

whenever you park

when the brakes are hot

while on an incline

when the air pressure is low

15 / 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?

continue on with your trip

decrease your speed and head to the closest mechanic

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

decrease your speed and test the other system

16 / 40

What does the air compressor governor control?

when the air is taken out of the hoses

when the vavle system releases pressure

when air pressure is applied to the brakes

when air is pumped into the air tanks

17 / 40

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

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

they are not allowed to have any cracks

the linings should fit loosely around the brake shoe

they should always be kept well-greased up

18 / 40

You should brake on a long steep downgrade hill as a supplement to the braking effects of the engine

yes

when the GVCW is above 20,000 lbs

when the vehicle is runaway

19 / 40

When should you not use the parking brakes?

when air pressure is low

while on a steep hill

while in hot weather

when the brakes are hot

20 / 40

The parking brakes should be used____in air brake vehicles.

only during post trip inspection

as rarely as possible

only when parked on an incline

every time the vehicle is parked

21 / 40

Commerical vehicles typically have this type of brake.

S-Cam brakes

rectangle brakes

stab brakes

drum brakes

22 / 40

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

150 psi

100 psi

75 psi

125 psi

23 / 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 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

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

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

24 / 40

What does the service brake system do?

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

they are valves that maintain air tank pressure

they are only on vehicles that have hydraulic brakes

they are part of an official vehicle inspection

25 / 40

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

run the engine at a fast idle

all of these answers are correct

monitor the air pressure gauge

decrease the tank pressure by stepping on and off the brake

26 / 40

You should___when driving down a long steep hill.

repeatedly pump the brake pedal

release the brake once the vehicle is traveling 5 mph below the safe speed

begin braking once the vehicle is 10 mph above safe speed

use the engine brakes only

27 / 40

Select what you should do before leaving the vehicle unattended:

remove the keys from the ignition

apply the parking brakes

all of these answers are correct

chock the wheels

28 / 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

brakes that are not aligned properly

when using the engine brake more than the brakes

tire retread that is mismatched

29 / 40

You should_____when the low pressure warning is activated:

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

pump the brake pedal to come to a stop immediately

wait until the air brakes kick in automatically

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

30 / 40

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

pull on the slack adjuster while the parking brakes are on

pull hard on each slack adjuster while wearing gloves

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

31 / 40

What are slack adjusters?

all of these answers are correct

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

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

32 / 40

Front wheel brakes are good under what kind of conditions?

any weather conditons

they are not ideal

ideal weather conditions

icy or wet conditions

33 / 40

Select how brakes work on long, steep downgrades:

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

they are a supplement to the braking effect of the engine

34 / 40

What is the benefit of ABS?

it decreases your stopping distance

all of these answers are correct

it provides an added layer of safety for truck drivers

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

35 / 40

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

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

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

all of these answers are correct

brake hard after accelerating

36 / 40

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

once every 14 days

at the end of each working day

once every 7 days

every 4 hours of the working shift

37 / 40

How do you test your service brakes?

apply pressure to the brake pedal when moving at highway speeds

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

38 / 40

How often should you drain your air tanks?

at the end of each trip

at the end of each shift

at the end of each week

at the beginning of each month

39 / 40

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

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

the lines are hotter

longer reaction time

none of the answers listed

40 / 40

At what pressure is the safety valve in the air compressor tank set to open?

125 psi

225 psi

100 psi

150 psi

Your score is

The average score is 84%

5/5 - (1 vote)

CDL Air Brakes Test

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