Air Brakes
This endorsement is required for driving a vehicle with air brakes. To receive this endorsement, applicants must pass a 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 Texas Commercial Motor Vehicle Drivers Handbook. Questions come from chapters covering: Air Brakes. The Air Brakes endorsement may be used with the Class A, B or C CDL.
Number of Question
Passing Score
13. If a vehicle has air brakes, the air compressor drive belt should be checked before each drive. The belt should be:
Explanation
When inspecting an air brake system with a belt-driven air compressor, it is important to check the condition and tightness of the belt.
14. How is water and compressor oil removed from the bottom of an air storage tank?
Explanation
Water and compressor oil are removed from air storage tanks through a drain valve. The water and oil can damage the brakes if left to accumulate in the system. Manually operated tanks must be drained every day to remove this build-up.
15. When inspecting your brakes, a slack adjuster should move ____ from where it is attached to the push rod.
Explanation
Check each slack adjuster after setting wheel chocks and disengaging the parking brake. Pull the slack adjusters to make sure they do not move more than about one inch from where the push rod is attached. If they move more than one inch, they may be out of adjustment and will need to be fixed.
16. 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 55 psi. This warning signal may come in the form of a light, a buzzer, or a wig wag.
17. What color are ABS malfunction lamps?
Explanation
Vehicles with Anti-Lock Braking Systems (ABS) have yellow malfunction lamps.
18. Applying the brake pedal causes air pressure to activate an electric switch and:
Explanation
