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
19. To stop in a vehicle that uses air brakes, the driver should:
Explanation
To make a normal stop in a vehicle with air brakes, push the brake pedal down. The harder the pedal is pressed, the more air pressure is released.
20. In a dual air brake system:
Explanation
Most heavy-duty vehicles use dual air brake systems. A dual air brake system consists of two separate air brake systems, connected by a single set of brake controls. Each system has its own air tanks.
21. Applying the brake pedal causes air pressure to activate an electric switch and:
Explanation
In a vehicle with air brakes, the brake lights are activated when the brake pedal is pushed and air pressure moves an electric switch. With the application of air pressure, the switch will then turn on the brake lights.
22. Both systems in a dual air brake systems share:
Explanation
Both systems in a dual air brake system share a single air compressor. If the air compressor is damaged, neither system will be able to operate properly.
23. Most heavy-duty vehicles use ____ air brake systems.
Explanation
The majority of heavy-duty vehicles are equipped with dual air brake systems.
24. All air tanks must include:
Explanation
Air brake system tanks must contain drain valves. These valves are used to drain accumulated oil and water from the tanks and may be either manually or automatically operated.
25. What is a wig wag?
Explanation
