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 or four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the South Dakota 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
13. 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.
14. Brakes out of adjustment will:
Explanation
Brakes out of adjustment will fade before those that are properly adjusted. Brake adjustment must be checked frequently to help prevent brake issues.
15. A low air pressure warning signal:
Explanation
A vehicle with air brakes must be equipped with a low air pressure warning signal. If the warning signal goes off while a vehicle is being driven, the driver should bring the vehicle to a complete stop and have the system repaired.
16. A driver can rely on front wheel braking to work:
Explanation
Front wheel braking is effective under all road conditions. It is unlikely that you will experience a front wheel skid, even on ice.
17. Brake fading is caused when:
Explanation
Using the brakes excessively will cause them to overheat, making them less effective. This is referred to as "fading."
18. You should ____ if the low pressure warning signal activates while you are driving.
Explanation
