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 four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the New Hampshire CDL Driver’s Guide. 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. When an S-cam turns inside a brake drum, the S-cam:
Explanation
When a brake pedal is pressed and the S-cam is turned, the S-cam presses the brake shoes against the inside of the brake drum. This causes friction and will cause the vehicle to slow.
8. The application pressure gauge:
Explanation
In an air brake system, the application pressure gauge shows how much air pressure is being applied to the brakes. Not all vehicles with an air brake system have this gauge.
9. Emergency brakes:
Explanation
All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. These brakes must be held by mechanical force.
10. Air brakes use ____ to function.
Explanation
Air brakes function through the use of compressed air.
11. A ____ allows a driver to gradually apply spring brakes.
Explanation
A modulating control valve allows a driver to gradually apply spring brakes. In equipped vehicles, the valve is controlled by a lever located on the dashboard.
12. When the brake pedal is depressed, air brakes work:
Explanation
