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 North Dakota Commercial Driver Guide. 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. Air tank drains:
Explanation
In an air brake system, the air storage tanks must be drained to remove accumulated water and compressor oil. Failing to do so can cause damage. Manually operated drains should be used at the end of each day of driving.
20. The air storage tanks:
Explanation
In an air brake system, the air storage tanks hold enough air for brakes to be used several times if the compressor stops working.
21. The air compressor governor controls:
Explanation
In an air brake system, the air compressor governor controls when the air compressor pumps air into the air storage tanks.
22. Brake fade is a result of:
Explanation
If brakes are used too much, they will overheat and become less effective. This is referred to as brake fade.
23. Most heavy-duty vehicles use:
Explanation
Most heavy-duty vehicles use dual air brake systems. A dual system has two separate air brake systems with a single set of controls.
24. To inspect slack adjusters on S-cam brakes, you need to:
Explanation
Check each slack adjuster after parking on level ground, 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.
25. The brake pedal is part of which braking system?
Explanation
