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

19. Manual air tank drains should be:

Opened to drain the tanks after each day.

Left open while driving.

Sealed with glue.

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.

20. When parking, you should not use the parking brake if:

The brakes are very hot.

The brakes are very cold.

There is snow on the ground.

If your brakes are hot after coming down a steep grade, you should not use your parking brake when parking. Let your brakes cool before applying the parking brake or risk damaging the brakes.

21. Some air brake systems introduce alcohol into the system to:

Make the brakes work without squeaking.

Prevent ice from forming in the brake system.

Prevent people from breathing the air from the system.

Some air brake systems contain an alcohol evaporator. An evaporator introduces alcohol into the system to help inhibit the formation of ice in cold weather.

22. During a static leakage test, what is the maximum leakage rate that is safe for a double combination vehicle?

3 psi in one minute.

6 psi in one minute.

8 psi in one minute.

When performing a static leakage test on a double combination vehicle with air brakes, the leakage rate should be no more than 3 psi in one minute. If the air leaks from the air brake system at a quicker rate, the vehicle should not be driven because something likely needs to be repaired.

23. A slack adjuster should move no more than ____ from where it is attached to the push rod.

Two inches

Five inches

One inch

Before a trip, you should check each slack adjuster after parking, setting wheel chocks, and disengaging the parking brake. Pull the slack adjusters to make sure that they do not move more than about one inch from where the push rod is attached. If they move more than one inch, they may be out of adjustment and will need to be fixed.

24. When leaving your vehicle unattended:

The parking brake should be used.

The parking brake only needs to be used if the vehicle is parked on a slope.

The parking brake should not be used, as it can damage the tires.

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.

25. Why do large vehicles use air brakes?

Other brake systems squeak too loudly.

Air brakes are very effective systems.

Other braking systems are hard to come by.

If used and maintained properly, air brakes are a safe and effective way to stop large, heavy vehicles.

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