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 or four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Alabama 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. Some air brake systems introduce alcohol into the system to:
Explanation
Some air brake systems contain an alcohol evaporator. An evaporator introduces alcohol into the system to help inhibit the formation of ice in cold weather.
14. What is removed when an air tank is drained?
Explanation
In an air brake system, air tanks have drains to remove accumulations of water and compressor oil. Allowing water and oil to accumulate in the system could cause damage to the brakes.
15. A low air pressure warning signal should activate:
Explanation
In an air brake system, a low air pressure warning signal must come on if air pressure in the tanks falls below 60 psi. This warning signal may come in the form of a light, a buzzer, or a wig wag.
16. What color are ABS malfunction lamps?
Explanation
Vehicles with Anti-Lock Braking Systems (ABS) have yellow malfunction lamps.
17. Where is the safety relief valve usually located?
Explanation
An air brake system's safety relief valve is located in the tank that is first to receive air from the compressor.
18. The most common type of foundation brake used is the:
Explanation
