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 Missouri Commercial Driver’s 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. What does an air compressor do in an air brake system?
Explanation
In an air brake system, the air compressor pumps air into the air storage tanks. The air compressor is controlled by the air compressor governor.
14. When parked on a flat surface, you should:
Explanation
When parking on a level surface, you should use wheel chocks. If the vehicle is not equipped with spring brakes, this is essential to prevent the trailer from moving.
15. To ensure normal stopping power, drivers of vehicles equipped with a front brake limiting valve should:
Explanation
Some older vehicles have front brake limiting valves with "normal" and "slippery" settings. Setting a brake limiting valve to "slippery" reduces the vehicle's stopping power, so a driver should make sure the valve is in its "normal" position. Front wheel braking has proven to be effective in all driving conditions.
16. Air brakes use ____ to function.
Explanation
Air brakes function through the use of compressed air.
17. When stopping in an emergency situation, you should:
Explanation
If you need to make an emergency stop, you can use either the controlled braking method or the stab braking method. It's important to brake in a way that keeps your vehicle in a straight line but will still allow you to turn if necessary.
18. Air tank drains should:
Explanation
