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 in regards to an application pressure gauge:

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

it prevents the brakes from failing

when accelerating it releases air

it is connected to the generator

2 / 40

The safety valve is usually set to open at:

225 psi

75 psi

125 psi

150 psi

3 / 40

Should your air compressor stop working:

there will be no affect to your brakes

the brakes will lock up on you immediately

you will lose your ability to brake immediately

there will still be air pressure left in the air tanks

4 / 40

The parking brakes should be used____in air brake vehicles.

only during post trip inspection

only when parked on an incline

every time the vehicle is parked

as rarely as possible

5 / 40

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

red light

a wig wag mechanical arm

all of these answers are correct

a buzzer

6 / 40

What does the air compressor governor control?

when the vavle system releases pressure

when the air is taken out of the hoses

when air is pumped into the air tanks

when air pressure is applied to the brakes

7 / 40

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

drain off air pressure before adjusting after parking on level ground

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

apply the parking brake after stopping on level ground

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

8 / 40

Where is compressed air stored?

in the storage tank

in the hose lines

in the compartment for the engine

in the gasoline tank

9 / 40

Alcohol evaporators in some air brake systems help to:

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

it removes fule from the air lines

cleans out oil from the air lines

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

10 / 40

A slack adjuster is:

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

a lever that connects the brake drum to the brake shoe

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

a lever that connects the brake camshaft with the brake chamber

11 / 40

What does the drain valve for air tanks remove?

air and oil

oil and water

water and air

oil and dirt

12 / 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

13 / 40

Front wheel brakes are good under what kind of conditions?

they are not ideal

ideal weather conditions

any weather conditons

icy or wet conditions

14 / 40

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

none of the answers listed

3 psi a minute

4 psi a minute

1 psi a minute

15 / 40

You should___to reduce the air leakage rate.

release the service brake as the engine is running

release the service brake after turning off the engine

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

leave the engine running while charging the air system

16 / 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 have their own hoses, lines etc

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

17 / 40

What must vehicles with air brakes have?

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

all of these answers are correct

18 / 40

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

it is a federal requirement

you cannot receive a CDL at all otherwise

all trucks have air brakes

you would have to get a CDL with a restriction otherwise

19 / 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

20 / 40

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

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

all of these answers are correct

brake hard after accelerating

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

21 / 40

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

125 psi

100 psi

175 pso

225 psi

22 / 40

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

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

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

23 / 40

Commerical vehicles typically have this type of brake.

S-Cam brakes

rectangle brakes

drum brakes

stab brakes

24 / 40

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

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.

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.

25 / 40

____is the most common type of foundation brakes used by heavy vehicles.

rectangle brakes

S-Cam drum

wedge drum

none of the answers listed

26 / 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

27 / 40

When should you not use the parking brakes?

when air pressure is low

when the brakes are hot

while in hot weather

while on a steep hill

28 / 40

Select the true statement about dual air brake systems.

there is a primary system and a secondary system

all of these answers are correct

there is a single set of brake controls

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

29 / 40

When should you avoid using the parking brake?

while on an incline

when the air pressure is low

whenever you park

when the brakes are hot

30 / 40

Air pressure should build___with a dual air system.

from 50 to 80 psi in 60 seconds

from 60 to 100 psi in 45 seconds

from 85 to 100 psi in 45 seconds

from 70 to 125 psi in 60 seconds

31 / 40

What is the benefit of ABS?

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

all of these answers are correct

it decreases your stopping distance

it provides an added layer of safety for truck drivers

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

30 psi

60 psi

50 psi

33 / 40

Spring brakes are usually held back by_____during normal driving.

pressure of the spring

air pressure

clamps

heat

34 / 40

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

bolt brakes

foot brakes

v-cam brakes

disc brakes

35 / 40

What are slack adjusters?

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

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

36 / 40

How do you know when your brakes are fading?

your speed increases when pressure is removed from the brake pedal

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

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

37 / 40

Select the true statement in regards to brake drums:

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

hold the brake linings and shoes

they are bolted to the wheels

all of these answers are correct

38 / 40

Select the part that is not a part of the drum brake:

safety valve

slack adjuster

brake drum

axle

39 / 40

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

not relying on engine braking enough

the brakes are out of adjustment

using the service brakes excessively

all of these answers are correct

40 / 40

How can you check slack adjusters?

it is not possible to check manually

by using a fixed wrench

by pulling hard on each slack adjuster

by frequenctly checking the pressure gauge

Your score is

The average score is 82%

5/5 - (1 vote)

CDL Air Brakes Test

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