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 Georgia Commercial Driver’s Manual. Questions come from 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. During an applied leakage test, the maximum leakage rate for a single vehicle with air brakes is:
Explanation
It is important to know the maximum air loss rate that is safe for your specific vehicle. A single vehicle with air brakes should have a leakage rate no higher than 3 psi in a minute during an applied leakage test.
20. On trucks and buses, where are ABS malfunction lamps located?
Explanation
Tractors, trucks, and buses with Anti-Lock Braking Systems (ABS) have yellow malfunction lamps located on their instrument panels. Trailers have yellow ABS malfunction lamps on their left side, either on the front or rear corner.
21. If the brake pads rub against the brake drums and create too much heat:
Explanation
Brakes heat up with use. If they are overused and become too hot, expansion and chemical changes will make them less effective and eventually cause them to stop working altogether. This is known as "brake fade."
22. To stop in a vehicle that uses air brakes, the driver should:
Explanation
To make a normal stop in a vehicle with air brakes, push the brake pedal down. The harder the pedal is pressed, the more air pressure is released.
23. The emergency brake system uses:
Explanation
In an air brake system, there are three different braking systems: a service brake system, a parking brake system, and an emergency brake system. The emergency brake system uses parts of both the parking and service brake systems.
24. When only the tractor is equipped with an Anti-Lock Braking System (ABS):
Explanation
If a tractor is equipped with an Anti-Lock Braking System (ABS) but the trailer is not, the risk of jackknifing will be reduced and the driver should still be able to maintain steering control. If only the trailer is equipped with ABS, it is less likely that the trailer will swing out to one side.
25. If the low pressure warning light comes on while you are driving:
Explanation
