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
Passing Score

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

Explanation
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?

Explanation
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:

Explanation
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:

Explanation
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:

Explanation
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:

Explanation
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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