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.. Read More

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 two, three or four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Nebraska 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

7. If air pressure drops to a level between ____, a visual low pressure warning signal should have already activated.

Explanation
A visual low pressure warning signal should activate before air pressure drops to a level between 55 and 75 psi. This signal could be a light, a buzzer, or a wig wag.

8. If your tractor is equipped with ABS but your trailer is not, the ABS:

Explanation
In a tractor-trailer combination, if the tractor is equipped with an Anti-Lock Braking System (ABS) but the trailer is not, the ABS will still improve the driver's steering control. The driver should keep an eye on the trailer and let up on the brakes if the trailer begins to swing out.

9. What should happen before the air pressure in an air brake system tank falls below 55 psi?

Explanation
The low air pressure warning signal must activate before the air supply pressure drops below 55 psi in the air tank. If the warning signal does not turn on when being tested during an inspection, the vehicle is not safe to drive.

10. An air compressor governor will stop the compressor from pumping air once the air tanks have an air pressure level of:

Explanation
An air compressor governor will stop the compressor from pumping air once the air tanks are at an air pressure level of 125 psi. This air pressure level is referred to as the "cut-out" level.

11. What can happen if parking brakes are used in very wet weather with temperatures below freezing?

Explanation
Parking brakes should not be used in very wet weather when temperatures are below freezing. The brakes could become frozen in place, making it impossible to move the vehicle.

12. To make a stop in a vehicle equipped with air brakes, the driver should:

Explanation
To make a normal stop in a vehicle that is equipped with air brakes, you should simply press the brake pedal down.
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