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 Kentucky 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
7. An emergency brake must be controlled by:
Explanation
All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. Because air pressure can eventually leak away, emergency and parking brakes should be held on by mechanical force.
8. If the safety relief valve in the air brake system releases air:
Explanation
An air brake system has a safety relief valve, which releases air from the tanks if the pressure gets too high. If the valve must operate, something in the system is wrong and should be addressed by a mechanic.
9. 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.
10. Brake fade is a result of:
Explanation
If brakes are overused, they can become too hot. This overheating causes them to fade, making them less effective at slowing the vehicle.
11. Brakes can get out of adjustment quickly, especially:
Explanation
Brakes are particularly prone to getting out of adjustment if they are hot. Be sure to routinely check the adjustment of your brakes. For a vehicle to be safely controlled, all brakes must be properly functioning and adjusted.
12. Emergency brakes:
Explanation
