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 Commercial Driver 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
19. What must be on an air tank in an air-braked vehicle?
Explanation
All air tanks on air-braked vehicles must have one-way check valves located between the air compressor and the first reservoir. This prevents air from flowing out in the event of a leak.
20. The ____ are activated by an electric switch that is triggered by the brake pedal.
Explanation
In a vehicle with air brakes, the brake lights are activated when the brake pedal is pushed and air pressure moves an electric switch. With the application of air pressure, the switch will then turn on the brake lights.
21. What is a wig wag?
Explanation
A wig wag is a type of low air pressure warning device in an air brake system. It drops a mechanical arm into the driver's view when the air pressure in the tanks falls below 60 psi.
22. The parking brake should be:
Explanation
The parking brake in a vehicle with air brakes should be used every time the vehicle is parked.
23. 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.
24. The ____ between an air compressor and reservoir tank prevents air from escaping if the air compressor has a leak.
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.
25. If an air compressor is belt-driven, the belt should be routinely checked to ensure that it is:
Explanation
