CDL Air Brakes Test | Free Practice Questions & Answers

Air Brakes Test #1
(english)

Air Brakes Test #1 (en)

1 / 32

What pressure (PSI) in the service air tank triggers the low air pressure warning?

2 / 32

When is it safe to leave your truck unattended without applying parking brakes and chocking the wheels?

If you are parked on a flat surface.

If you are only away for a few minutes.

Never.

3 / 32

Using your brakes too much can also cause:

Brake to fade or fail.

Tire pressure to decrease.

Brake fluid to evaporate.

4 / 32

What holds the air in the tanks if there is a leak in the air compressor?

The dual circuit brake system

The one-way check valve.

The pressure release valve

5 / 32

When the spring brakes are activated, when is it okay to press the brake pedal?

Only at a full stop.

Only when making sharp turns.

Never.

6 / 32

The safety valve automatically open at ____.

75 psi

150 psi

200 psi

7 / 32

You should NOT apply the parking brake, ____.

If it's raining lightly outside.

If the brakes are very hot (e.g . Just after coming down a steep grade).

If the parking area is completely flat and secure.

8 / 32

Your truck is equipped with a dual air brake system and minimum-size air tanks. How long should it take for the air pressure to go up from 85 to 100 psi?

9 / 32

Parking or emergency brakes must be kept in position by something that does not leak, like:

Spring pressure.

Magnetic force

Electric current

10 / 32

Why is it important to remove water from the compressed air tanks?

Water makes the air tank rust faster.

Water increases air tank pressure too quickly.

Water can freeze in cold weather and cause brake failure.

11 / 32

What does the term "Wig Wag" mean?

A light that flashes when the engine is overheating

A mechanical arm that signals low air pressure

A lever that controls the speed of the engine.

12 / 32

When the air pressure falls below ___ psi, the straight truck spring brakes will come fully on.

100

13 / 32

When going down a steep hill and reaching your safe speed of 40 mph, you would use the brake until your speed goes down to _____ mph.

14 / 32

What is the purpose of a brake light switch?

It activates the turn signals when you apply the brakes

It turns on the brake lights when you put on the air brakes.

It adjusts the brightness of your headlights.

15 / 32

How can you tell if your brakes are fading?

Less pressure is needed on the brake pedal for each stop.

You have to push harder on a brake pedal to control your speed on a downgrade.

The vehicle stops more quickly than usual.

16 / 32

Excessive heat caused by overusing your brakes can also cause ___.

Engine oil to overheat.

Tire pressure to decrease.

Brake to fade or fail.

17 / 32

What happens if your vehicle's brake drums overheat?

They expand.

They crack and leak fluid.

They glow bright red

18 / 32

At what psi does the air compressor stop pumping air?

125

135

140

19 / 32

If you pull hard on a slack adjuster and it moves more than __ , it needs to be adjusted.

5/8 inch

1 inch

3 inches

20 / 32

Air brakes have a longer total stopping distance than hydraulic brakes due to ____ distance.

Acceleration distance

Brake lag

Cooling time

21 / 32

What statement about spring brake braking power is correct?

It depends on the service brakes being in adjustment.

It decreases as the vehicle's speed increases.

It is most effective when the vehicle is fully loaded.

22 / 32

Which of the following types of foundation brakes are most commonly found on heavy vehicles?

Air pad

S-cam drum.

Hydraulic disc

23 / 32

lf the air pressure doesn't go up to the needed level fast enough, then:

The headlights could become dimmer.

You might need to adjust the mirrors more frequently.

Air pressure may drop to a low point while driving, requiring an emergency stop.

24 / 32

When you use the service brakes too much, they can get too hot and this can cause __.

Expansion of the brake drums.

Decreased fuel efficiency

Reduced tire pressure

25 / 32

What does the air compressor governor control?

The amount of fuel the engine uses

The temperature of the engine.

When air is pumped into the air tanks.

26 / 32

A low air pressure warning signal must appear when the air pressure in the tank falls below __ psi.

100

27 / 32

The safety valve lowers pressure when it reaches ___ psi.

100

150

28 / 32

How do you normally engage the parking brakes?

Shift into neutral gear.

Push the gas pedal down.

Apply brakes by pulling the parking brake control knob out.

29 / 32

If your vehicle doesn't have automatic tank drains, you should drain the oil and water from the bottom of the air tanks __.

Every month.

Before starting the engine each morning.

At the end of each day of driving.

30 / 32

What brake system applies and releases the brakes when the driver steps on the brake pedal?

Automatic

Service

Manual

31 / 32

lf your truck has an alcohol evaporator, what should you do with it when the weather gets cold?

Drain and remove the evaporator.

Check and fill the alcohol level.

Adjust the coolant system for alcohol.

32 / 32

Why do we use an alcohol evaporator?

Toclean the air filters more efficiently.

To increase fuel efficiency by adding alcohol to the engine.

Reduce the risk of icing in air brake valves in cold weather.

Your score is

The average score is 78%

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Air Brakes Test #2 (english)

Air Brakes Test #3 (english)

Air Brakes Test #4 (english)

What is the CDL Air Brakes Test?

The CDL Air Brakes test is a written exam that covers the principles of air brake operation, inspection, and maintenance. The test is designed to ensure that drivers understand how air brakes work and how to operate them safely. This test is required for any driver who wants to operate a commercial vehicle equipped with air brakes. This page provides resources and information to help you prepare and pass the exam.

Who Needs to Take the CDL Air Brakes Test?

Anyone who wants to drive a commercial vehicle with air brakes is required to take and pass this test. This includes drivers who want to operate:

Tractor-trailers
Buses
Trucks with a GVWR of 26,001 pounds or more

Why are Practice Tests Important?

Practicing for the CDL Air Brakes test is crucial for success. Here’s why:

Familiarization: Practice tests help you become familiar with the format of the real exam, the types of questions you’ll encounter, and the time constraints.
Knowledge Assessment: They allow you to assess your current knowledge and identify areas where you need to focus your studies.
Confidence Building: Taking practice tests and seeing your progress can boost your confidence and reduce test anxiety.
Improved Performance: Studies have shown that students who use practice tests perform significantly better on exams.