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 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

1. When using the controlled braking method in an emergency situation, you should:

Apply the brakes as hard as possible without locking the wheels.

Apply the brakes with about half of your usual force.

Apply the brakes so the wheels lock.

Apply the brakes with minimal pressure.

The controlled braking method for emergency stops involves applying the brakes as hard as you can without locking the wheels. Keep steering wheel movements small when braking in this way.

2. What can happen if parking brakes are used in very wet weather with temperatures below freezing?

The brakes will squeak.

The brakes may freeze so the vehicle cannot move.

The brakes may suddenly release by themselves.

The brakes may become too smooth to be used.

Parking brakes should not be used in very wet weather when temperatures are below freezing. The brakes could become frozen in place, making it impossible to move the vehicle.

3. The air entering air storage tanks may contain:

Water and compressor oil.

Frost.

Gravel.

Antifreeze.

The air that enters air storage tanks in an air brake system usually contains a certain amount of water and compressor oil. Because accumulations of these materials can damage the braking system, tanks are equipped with drains to allow their removal.

4. During a static leakage test, the maximum leakage rate for a double combination vehicle is:

3 psi in one minute.

6 psi in one minute.

8 psi in one minute.

4 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 air leaks from the air brake system at a quicker rate, the vehicle should not be driven because something likely needs to be repaired.

5. Failing to drain the tanks in an air brake system can result in:

Water freezing and causing brake failure.

Squishy brakes.

Too much air collecting.

Too much fuel being carried.

In an air brake system, the air storage tanks must be drained to remove accumulated water and compressor oil. Failing to do this can cause damage. For example, water that has built up in the system could freeze in cold weather and cause brake failure.

6. Air brakes are:

An effective tool for stopping large vehicles.

Prohibited on large vehicles.

Only effective in poor weather.

A tool to improve fuel efficiency.

As long as the brakes are properly maintained, using air brakes is a safe and effective method of stopping large, heavy vehicles.

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