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
19. During a static leakage test, what is the maximum leakage rate that is safe for a double combination vehicle?
Explanation
When performing a static leakage test on a double combination vehicle with air brakes, the leakage rate should be no more than 3 psi in one minute. If the air leaks from the air brake system at a quicker rate, the vehicle should not be driven because something likely needs to be repaired.
20. The air compressor is connected to the:
Explanation
The air compressor of an air brake system is connected to the engine through gears or a v-belt. The compressor may be air-cooled or cooled by the engine cooling system.
21. If you are braking on dry pavement while traveling at 55 mph, how much distance will brake lag add to your overall stopping distance?
Explanation
The total stopping distance for vehicles equipped with air brakes is made up of four factors: perception distance, reaction distance, brake lag distance, and braking distance. When braking at a speed of 55 mph while driving on dry pavement, the brake lag can add around 32 feet to the vehicle's total stopping distance.
22. 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.
23. Vehicles equipped with Anti-Lock Braking Systems (ABS) have ____ malfunction lamps to indicate when the ABS is not working.
Explanation
Vehicles with ABS have yellow malfunction lamps to alert drivers when the braking systems are not working. Be sure you know where the malfunction lamp on your vehicle is before beginning a trip.
24. A low air pressure warning signal:
Explanation
Any vehicle with air brakes must be equipped with a low air pressure warning signal.
25. Why do large vehicles use air brakes?
Explanation
