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 three answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Virginia 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. What tells you how much pressure is in your vehicle's air tanks?
Explanation
A vehicle that is equipped with air brakes must also be equipped with a supply pressure gauge. This gauge tells the driver how much air pressure is in each of the vehicle's air tanks.
14. What is often found in compressed air?
Explanation
Compressed air in an air brake system usually contains a certain amount of water and compressor oil. The water and oil can damage the brakes if left to accumulate in the system. Tanks must be drained regularly to remove this build-up.
15. 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 storage tanks. It stops pumping if the pressure in the tanks becomes too high, and begins pumping if the pressure becomes too low.
16. Truck tractors with air brakes built on or after March 1, 1997 must have:
Explanation
Truck tractors with air brakes built on or after March 1, 1997, and other vehicles with air brakes built on or after March 1, 1998, must be equipped with anti-lock brakes.
17. While operating on a downgrade, you should brake until you reach a speed that is:
Explanation
While driving downhill, you should hold down the brake pedal until your vehicle reaches a speed 5 mph below your safe speed, then release the brake pedal. Repeat this process.
18. If the spring brakes are on, you should:
Explanation
