Instructions

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 25

Passing Score 20

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

You should not be concerned as this is a normal process.

There is something wrong with the brakes.

The valve is operational.

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.

20. When a brake pedal is pressed and the S-cam is turned, the S-cam:

Presses the brake shoes against the inside of the brake drum.

Tightens the brake drum onto the axle.

Presses the brake lining against the wheel.

Releases air from the air tanks.

When a brake pedal is pressed and the S-cam is turned, the S-cam presses the brake shoes against the inside of the brake drum. This causes friction and will cause the vehicle to slow.

21. What does the air compressor governor do?

It stops the compressor from pumping air.

It turns on the air compressor.

It stores the compressed air.

In an air brake system, the air compressor governor controls when the air compressor pumps air into the storage tanks. It stops pumping if the pressure in the tanks becomes too high, and begins pumping if the pressure becomes too low.

22. Front brake limiting valves were intended to:

Prevent the front tires from skidding.

Prevent the front tires from overheating.

Create equal brake usage.

Remove uncertainty when applying the brakes.

Some older vehicles with air brakes have front brake limiting valves. These valves were intended to reduce the risk of front wheels skidding. However, research has shown that such devices are unnecessary, so they should be left in the "normal" position.

23. If the air pressure warning light comes on, you should:

Continue driving normally.

Activate your hazard lights and continue driving.

Call the local law enforcement agency.

Safely exit the roadway and stop.

If the air pressure warning light or buzzer comes on while you are driving, you should immediately stop and safely park the vehicle. This warning signal indicates that there is a problem in the air brake system that needs to be fixed.

24. What does ABS do?

Prevent wheel lockup

Prevent the air compressor from overheating

Prevent the front brakes from being used on ice

Prevent the brakes from being used if downshifting would be more effective

The purpose of an Anti-Lock Braking System (ABS) is to prevent wheels from locking up during hard applications of the brakes, especially on slippery surfaces.

25. When parked on a flat surface, you should:

Use wheel chocks to prevent your vehicle from moving.

Not use wheel chocks.

Use wheel chocks, but only if you have applied the parking brake.

When parking on a level surface, you should use wheel chocks. If the vehicle is not equipped with spring brakes, this is essential to prevent the trailer from moving.

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