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. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Michigan 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. During an inspection, slack adjusters on S-cam brakes should not move more than:
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.
14. What do air brakes use to make the brakes work?
Explanation
Many large CMVs are equipped with air brakes. An air braking system uses compressed air to operate.
15. The air storage tanks:
Explanation
The air storage tanks in an air brake system store compressed air to be used for braking. They hold enough air for the brakes to still be used several times if the compressor stops working.
16. Brakes out of adjustment will:
Explanation
Brakes out of adjustment will fade before those that are properly adjusted. Brake adjustment must be checked frequently to help prevent brake issues.
17. What do the two systems of a dual air brake system share?
Explanation
Both systems in a dual air brake systems share a single air compressor. If the air compressor is damaged, neither system will be able to operate properly.
18. What is often found in compressed air?
Explanation
