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 questions. Each question has four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Washington D.C. 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
13. When about to drive a vehicle with a dual brake system, a driver should:
Explanation
Before driving a vehicle with a dual air brake system, allow time for the compressor to build up pressure to at least 100 psi in both systems.
14. What does the air compressor governor do?
Explanation
In an air brake system, the air compressor governor controls when the air compressor pumps air into the air storage tanks.
15. Emergency brakes are:
Explanation
All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes.
16. The air pressure in a dual air brake system should build from 85 to 100 psi within:
Explanation
When inspecting a vehicle with a dual air brake system, you should wait for air pressure to build from 85 to 100 psi in both the primary and secondary systems. This should take about 45 seconds.
17. A vehicle equipped with an Anti-Lock Braking System (ABS) uses a ____ light to warn that the system is not working properly.
Explanation
Anti-Lock Braking System (ABS) malfunction lamps are usually yellow. Even if the ABS isn't working properly, a driver will still have access to the vehicle's usual braking functions.
18. In a dual air brake system:
Explanation
