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 answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Virginia 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

7. Before driving a vehicle with air brakes, you should ensure that the ____ come on automatically when air pressure falls below 45 psi.

Spring brakes

Parking brakes

Air brakes

Before driving a vehicle with air brakes, you should ensure that the spring brakes come on automatically when air tank pressure falls to a level between 20 and 45 psi. You can do this by chocking the wheels and releasing air from the braking system by stepping on and off the brake pedal. Once the pressure levels drop to an unsafe level, the parking brake valve should pop out and spring brakes should come on.

8. If the low air pressure warning signal comes on in a vehicle with air brakes, the driver should:

Test the brakes while driving, but continue driving if nothing seems wrong.

Immediately stop driving.

Drive with the hazard lights activated.

If the low air pressure warning signal comes on while you are operating a vehicle with air brakes, you should stop and safely park the vehicle as soon as possible. It is essential that you are able to stop safely while you still have some braking power remaining.

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

Slack adjuster

One-way check valve

Tractor protection valve

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.

10. Some water and compressor oil is usually found in the compressed air within an air brake system. The water and compressor oil:

Are necessary for the proper function of the system.

Should take up about 10 percent of the tank.

Should be removed regularly.

If water and compressor oil are left to build up in an air brake system, the system can be damaged. Air storage tanks are equipped with drains to allow this accumulation to be removed. Manually controlled drains should be operated at the end of each day of driving.

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

Moving a lever to the right.

Pushing a yellow, diamond-shaped knob.

Pulling a yellow, diamond-shaped knob.

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.

12. Air tank drains should:

Not be used by the driver.

Only be used when it is wet outside.

Be used to drain the tanks completely.

Compressed air in an air brake system usually contains a certain amount of water and compressor oil. The water and oil can damage the brakes if left to accumulate in the system. Manually operated air tank drains must be opened daily to remove this build-up.

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