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 four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the New Hampshire CDL Driver’s Guide. 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. Once the air tanks are at an air pressure level of 125 psi, the air compressor governor will:

Explanation
An air compressor governor will stop the compressor from pumping air once the air tanks are at an air pressure level around 125 psi. This air pressure level is referred to as the "cut-out" level.

20. When leaving your vehicle unattended:

Explanation
In general, you should always use the parking brake when parking your vehicle. However, you should not apply the parking brake if your brakes are very hot or if your brakes are wet and temperatures are below freezing.

21. A dual air brake system:

Explanation
A dual air brake system has two separate air brake systems that use a single set of brake controls. One system typically operates the regular brakes on the rear axle or axles. The other system operates the regular brakes on the front axle.

22. The parking brake should be:

Explanation
The parking brake should be applied every time you park your vehicle.

23. A low air pressure warning signal:

Explanation
A vehicle with air brakes must be equipped with a low air pressure warning signal. If the warning signal goes off while a vehicle is being driven, the driver should bring the vehicle to a complete stop and have the system repaired.

24. The air pressure in a dual air brake system should build from 85 to 100 psi within:

Explanation
When inspecting a vehicle with a dual air brake system, you should wait for air pressure to build from 85 to 100 psi in both the primary and secondary systems. This should take about 45 seconds.

25. When traveling down a steep downgrade:

Explanation
On a downgrade, the braking effect of the engine should be your primary method of controlling speed. Shift down to a lower gear before starting down the hill and save the brakes for additional slowing or stopping that may be required by road or traffic conditions.
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