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 three or four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Alabama 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 25

Passing Score 20

19. If an air compressor is belt-driven, the belt should be routinely checked to ensure that it is:

Thin.

Properly tightened.

Cracked.

If your vehicle has air brakes, the air compressor drive belt should be checked before each drive. Check the tightness of the belt and verify that it is in good condition.

20. If the low pressure warning signal activates while you are driving, you should:

Continue driving normally.

Exit the road and park as soon as safely possible.

Stop where you are and park.

Put on your hazard lights and continue driving.

If the low pressure warning signal activates while you are driving, it is important that you safely exit the roadway as soon as possible and park your vehicle. If the air pressure gets too low, the brakes will no longer work well enough for you to stop safely.

21. ABS brakes:

Help you avoid wheel lockup.

Lock up your vehicle's wheels.

Prevent your vehicle from accelerating when going uphill.

The purpose of an Anti-Lock Braking System (ABS) is to prevent a vehicle's wheels from locking up when the driver brakes hard on a slippery surface.

22. When operating a vehicle with a dual air brake system, the driver should:

Let the vehicle warm up before driving to ensure that the fuel reaches the engine.

Let the air compressor build up a minimum of 100 psi pressure in the primary and secondary systems before driving.

Begin driving just after the vehicle starts.

Before driving a vehicle with a dual air brake system, allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems. Watch the air pressure gauges to monitor the pressure levels.

23. In a dual air brake system:

Air tanks are shared between both systems.

Each system has its own air tanks.

You must designate which system you are using.

There are two air brake systems in a dual air brake system. The systems share a set of brake controls, but each system has its own tanks, hoses, and lines.

24. An emergency brake must be controlled by:

Mechanical force.

Air pressure.

Gravity.

All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. Because air pressure can eventually leak away, emergency and parking brakes should be held on by mechanical force.

25. If the spring brakes are on, you should:

Not use the brake pedal.

Press the accelerator.

Move the steering wheel.

Do not use the brake pedal when the spring brakes are on. This could damage the brakes by subjecting them to the combined forces of springs and air pressure.

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