CDL Air Brakes Knowledge Test 2025

CDL Air Brakes Knowledge Test 2025: Try our free  Commercial Driver’s License (CDL)  Endorsements Air Brakes Permit Test. There are 30 sample questions and answers for better CDL written exam preparation.

Air brakes use compressed air to make the brakes work. You can apply all the braking force you need to each of the wheels of a heavy vehicle, even units pulling two or three trailers. Air brakes are a safe way of stopping large vehicles if the brakes are well-maintained and used properly. However, you must know more about air brakes than you need to know about the simpler brake systems used on light vehicles.

CDL Air Brakes Knowledge Test 2025

CDL Air Brakes Knowledge Test 2025

Test Name CDL Practice Test 2025
Language English
License Endorsements Permit
Total Questions 30 MCQs
Test For Commercial Driver License
Test Preparation  Air Brake Endorsements
Country USA
Answers Yes
0%
0 votes, 0 avg
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CDL Air Brakes Knowledge Test

CDL Air Brakes Knowledge Test

1 / 30

What protects the tank and the rest of the air system from too much pressure?

2 / 30

Foundation brakes are used

3 / 30

ou are driving a vehicle at 55 mph on dry pavement under good traction and brake conditions. What is the approximate total stopping distance needed to bring your vehicle to a complete stop?

4 / 30

During walkaround inspections of your vehicle, which parts of the air brake system should be checked?

5 / 30

You have a fully-charged air system (125 psi). After turning off the engine and releasing the service brake, what are the maximum leakage rates per minute for both single and combination vehicles?

6 / 30

The main purpose of the alcohol evaporator is to

7 / 30

When should you NOT use the parking brakes?

8 / 30

Before driving a vehicle with a dual air system, allow time for the air compressor to build up to 100 psi pressure in which of the following?

9 / 30

Which of the following pumps air into the air storage tanks?

10 / 30

Why, on long downhill grades, do experts recommend using a low gear and light steady pressure instead of on-again, off-again braking?

11 / 30

Spring brakes do which of the following?

12 / 30

A safety relief valve is installed in the first tank the air compressor pumps air to. The valve is usually set to open at what psi level?

13 / 30

If your truck or bus has dual parking control valves, you can use pressure from a separate tank to:

14 / 30

Most newer heavy-duty vehicles use dual air brake systems for safety. A dual air brake system has

15 / 30

Pressing and releasing the brake pedal quickly and repeatedly

16 / 30

Which of the following statements is true?

17 / 30

How often should you drain your air tanks?

18 / 30

The low-air-pressure warning light must come on before the air pressure in the tanks falls below what psi level?

19 / 30

Total stopping distance for air brakes is longer than that for hydraulic brakes due to ________ distance

20 / 30

Which of the following tells you how much pressure there is in the air tanks?

21 / 30

In checking that the spring brakes come on automatically, you should not

22 / 30

During the walkaround inspection, if a slack adjuster moves slightly more than an inch where the push rod attaches to it, then

23 / 30

Air brakes use

24 / 30

Which of the following is a proper technique in using controlled braking?

25 / 30

The most common foundation brake is the

26 / 30

When braking on downgrades,

27 / 30

The braking power of spring brakes depends on

28 / 30

The brake system that applies and releases the brakes when the driver uses the brake pedal is the _____________ brake system.

29 / 30

Air brake systems are three braking systems combined. They are

30 / 30

What should you do if the low-air-pressure warning comes on?

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The average score is 82%