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

When should air tanks be drained?

every 7 days

at the end of each working day

at every restroom break stop

they don't need to be drained

2 / 40

A slack adjuster is:

a lever that connects the brake camshaft with the brake chamber

a lever that connects the brake drum to the brake shoe

a lever that connects the return spring and the brake chamber push rod

a lever that connects the brake chamber push rod with the foundation brake camshaft

3 / 40

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

emergency brake system

clutch brake system

service brake system

parking brake system

4 / 40

How do you test your service brakes?

pull over and activate the parking brake

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

release the air pressure and activate the parking brake

apply pressure to the brake pedal when moving at highway speeds

5 / 40

What must vehicles with air brakes have?

an air pressure gauge that shows the pressure available for braking

a minimum of 2 air tanks

all of these answers are correct

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

6 / 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

decrease your speed and test the other system

continue on with your trip

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

7 / 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

8 / 40

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

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

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

9 / 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

10 / 40

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

brake hard after accelerating

all of these answers are correct

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

11 / 40

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

once every 7 days

every 4 hours of the working shift

at the end of each working day

once every 14 days

12 / 40

What does the air compressor governor control?

when air is pumped into the air tanks

when the vavle system releases pressure

when the air is taken out of the hoses

when air pressure is applied to the brakes

13 / 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 on the slack adjusters after draining the air form the system

pull on the slack adjuster while the parking brakes are on

pull hard on each slack adjuster while wearing gloves

14 / 40

What are spring brakes?

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

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

15 / 40

Select what you should do before leaving the vehicle unattended:

apply the parking brakes

remove the keys from the ignition

all of these answers are correct

chock the wheels

16 / 40

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

all trucks have air brakes

you would have to get a CDL with a restriction otherwise

you cannot receive a CDL at all otherwise

it is a federal requirement

17 / 40

Select when you should use the parking brake:

when you are leaving your vehicle for more than an hour

each time you leave your vehicle for any amount of time

when in residential areas

with rare exception, every time you leave your vehicle

18 / 40

Select how brakes work on long, steep downgrades:

it does not do anything

it is the main braking mechanism

they are a supplement to the braking effect of the engine

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

19 / 40

What are slack adjusters?

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

all of these answers are correct

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

20 / 40

Select the true statement about dual air brake systems.

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

there is a primary system and a secondary system

there is a single set of brake controls

all of these answers are correct

21 / 40

The 3 parts of the air brake system are: service brakes, parking brakes, and ____.

foot brakes

bolt brakes

disc brakes

v-cam brakes

22 / 40

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

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

if the compressor cuts out at between 70 and 90 psi

when the governor stops between 75-90 psi

23 / 40

Select the true statement about slack adjusters:

they should only be adjusted by a mechanic that is certified in slack adjusters

they should move a minimum of 2 inches from the push rod attachment

they do not ever need to be adjsuted

they can be adjusted automatically or manually

24 / 40

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

the brakes are out of adjustment

not relying on engine braking enough

all of these answers are correct

using the service brakes excessively

25 / 40

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

to provide greater control of your vehicle

to prevent the left sided brake from locking up

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

tanks usually do not need to be drained

26 / 40

Air pressure loss in a vehicle with a fully charged air system should be less than_______after the initial drop and brake applied.

1 psi a minute

3 psi a minute

none of the answers listed

4 psi a minute

27 / 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

28 / 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

29 / 40

Should your air compressor stop working:

there will still be air pressure left in the air tanks

there will be no affect to your brakes

you will lose your ability to brake immediately

the brakes will lock up on you immediately

30 / 40

How can you check slack adjusters?

it is not possible to check manually

by frequenctly checking the pressure gauge

by pulling hard on each slack adjuster

by using a fixed wrench

31 / 40

What is the purpose of the supply pressure gauge?

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

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

32 / 40

Select the true statement in regards to brake drums:

all of these answers are correct

hold the brake linings and shoes

they are bolted to the wheels

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

33 / 40

The safety valve is usually set to open at:

225 psi

150 psi

125 psi

75 psi

34 / 40

The compressor is connected to the engine via _____?

v-belt or gears

stag gears

r-belt

lines

35 / 40

Is this statement true or false: you do not need to use the parking brake if are leaving your vehicle for a short amount of time.

false

true

only when the vehicle has over 60,000 miles on it

only when the vehicle has over 25,000 miles on it

36 / 40

What is the benefit of ABS?

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

it decreases your stopping distance

37 / 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

38 / 40

After the initial drop, the maximum leakage rates per minute is:

4 psi for a combination vehicle and 3 psi for a single vehicle

10 psi for combination vehicle and 5 psi for single vehicle

3 psi for combination vehicle and 1 psi for single vehicle

6 psi for a combination vehicle and 5 psi for single vehicle

39 / 40

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

yes

when the vehicle is runaway

when the GVCW is above 20,000 lbs

40 / 40

Spring brakes are usually held back by_____during normal driving.

clamps

pressure of the spring

air pressure

heat

Your score is

The average score is 82%

5/5 - (1 vote)

CDL Air Brakes Test

CDL Category Practice Tests