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 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
19. Air brakes are:
Explanation
As long as the brakes are properly maintained, using air brakes is a safe and effective method of stopping large, heavy vehicles.
20. Vehicles with dual air brake systems:
Explanation
Before driving a vehicle with a dual air brake system, allow time for the air compressor to build up pressure of at least 100 psi in both the primary and secondary systems.
21. If using air tanks with manually operated drains, how often should you drain the tanks?
Explanation
To prevent the build up of oil and water in a vehicle's air tanks, manually operated air tank drains should be used at the end of each day of driving.
22. The parking brake should be:
Explanation
The parking brake should be applied every time you park your vehicle.
23. When traveling down a steep downgrade:
Explanation
On a downgrade, the braking effect of the engine should be your primary method of controlling speed. Shift down to a lower gear before starting down the hill and save the brakes for additional slowing or stopping that may be required by road or traffic conditions.
24. Air tank drains:
Explanation
In an air brake system, the air storage tanks must be drained to remove accumulated water and compressor oil. Failing to do so can cause damage. Manually operated drains should be used at the end of each day of driving.
25. Emergency brakes:
Explanation
