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.. Read More

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 or four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Montana 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. A one-way check valve:

Explanation
A one-way check valve is required to be between an air compressor and the first main reservoir. This valve prevents air from escaping the system if the air compressor develops a leak.

8. You should ____ if the low pressure warning signal activates while you are driving.

Explanation
If the low pressure warning signal activates while you are driving, it is important that you safely exit the roadway as soon as possible and park your vehicle. If the air pressure gets too low, the brakes will no longer work well enough for you to stop safely.

9. Friction in an S-cam brake is caused when the brake shoes and linings:

Explanation
Friction inside a brake drum is caused when the brake shoes and linings push against the inside of the drum. The friction in the drums will slow and stop the vehicle.

10. Dollies equipped with ABS are required to have malfunction lamps located where?

Explanation
A dolly equipped with an Anti-Lock Braking System (ABS) is required to have a yellow malfunction lamp located on its left side.

11. When you press the brake pedal in a vehicle with S-cam brakes, air pressure pushes out the rod and moves the:

Explanation
When pressing the brake pedal in a vehicle with S-cam brakes, air will enter the brake chambers. The added air pressure will push out the rods and move slack adjusters, twisting the brake camshafts.

12. 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.
DMV Writen Test Logo