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 Colorado 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. If the spring brakes are on, you should:
Explanation
You should not apply the brake pedal if the spring brakes are activated. The brakes could be damaged if they are subjected to the force of air pressure and the springs at the same time.
14. In a dual air brake system, a leak in one system:
Explanation
A dual air brake system is made up of two separate air brake systems. If there is an air leak in one system, it may not affect the other.
15. To inspect slack adjusters on S-cam brakes, you need to:
Explanation
Check each slack adjuster after parking on level ground, setting wheel chocks, and disengaging the parking brake. Pull the slack adjusters to make sure they do not move more than about one inch from where the push rod is attached. If they move more than one inch, they may be out of adjustment and will need to be fixed.
16. To confirm that a trailer has ABS, you can:
Explanation
If you are unsure if a trailer is equipped with an Anti-Lock Braking System (ABS), look under the vehicle for the electronic control unit and wheel speed sensor wires coming from the back of the brakes.
17. All air tanks must include:
Explanation
Air brake system tanks must contain drain valves. These valves are used to drain accumulated oil and water from the tanks and may be either manually or automatically operated.
18. The most common type of foundation brake used is the:
Explanation
