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 Wisconsin Commercial Driver’s 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

7. In a dual air brake system:

Explanation
A dual air brake system is made up of two separate air brake systems. The systems share a single set of brake controls, but each has its own air tanks, hoses, and lines.

8. Foundation brakes are used:

Explanation
Foundation brakes are used at each wheel. The most common type is the S-cam drum brake.

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

Explanation
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.

10. Air tank drains:

Explanation
In an air brake system, the air storage tanks are equipped with drains to allow water and compressor oil to be removed. The water and oil can damage the brakes if left to accumulate in the system.

11. During an applied leakage test, what is the maximum leakage rate that is safe for a single vehicle with air brakes?

Explanation
It is important to know the maximum air loss rate that is safe for your specific vehicle. A single vehicle with air brakes should have a leakage rate no higher than 3 psi in a minute during an applied leakage test.

12. In a dual air brake system:

Explanation
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.
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