Air Brakes

This endorsement is required for driving a vehicle with air brakes. To receive this endorsement, applicants must pass a written test. The test consists of 25 multiple choice.. Read More

This endorsement is required for driving a vehicle with air brakes. To receive this endorsement, applicants must pass a written test. The test consists of 25 multiple choice questions. Each question has three answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Arizona Commercial Driver License Manual. Questions come from the chapter covering: Air Brakes. The Air Brakes endorsement may be used with the Class A, B or C CDL.

Number of Question
Passing Score

19. The parking brake in a newer vehicle is applied by:

Explanation
In newer vehicles with air brakes, the parking brake is controlled by a yellow, diamond-shaped knob. The driver should pull the knob outward to apply the parking brakes and push the knob inward to release them.

20. What helps prevent wheel lockup when braking?

Explanation
The purpose of an Anti-Lock Braking System (ABS) is to prevent wheel lockup while brakes are being applied.

21. If the safety relief valve in an air brake system is releasing air:

Explanation
The safety relief valve in an air brake system releases air if necessary to prevent pressure in the system from becoming too high. If the valve starts releasing air, there is something wrong. Have a mechanic fix the problem.

22. In a dual air brake system, if one air system is very low on pressure:

Explanation
In a dual air brake system, either the front or rear brakes will not be fully operable if one of the air systems gets too low on pressure. If the air pressure in either tank gets too low while you are driving, you should exit the road and park as soon as possible.

23. What kind of force do emergency brakes use?

Explanation
Air brakes are really three different braking systems: the service brake, the parking brake, and the emergency brake. Emergency and parking brakes are applied with mechanical force.

24. When leaving a vehicle unattended, a driver should:

Explanation
Always apply the parking brake when leaving your vehicle unattended.

25. The ____ between an air compressor and reservoir tank prevents air from escaping if the air compressor has a leak.

Explanation
A one-way check valve is required to be between an air compressor and the first main reservoir. This valve prevents air from escaping the system if the air compressor develops a leak.
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