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 three answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Idaho Commercial Driver’s 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

1. What color is the low air pressure warning light?

Explanation
A low air pressure warning signal is required in vehicles with air brakes. The warning light is usually red and may be accompanied by a buzzer.

2. If you are driving and the ABS light comes on, it means that the ABS:

Explanation
ABS malfunction lamps indicate that something in the Anti-Lock Braking System is not working properly.

3. A dual air brake system:

Explanation
A dual air brake system has two separate air brake systems that use a single set of brake controls. One system typically operates the regular brakes on the rear axle or axles. The other system operates the regular brakes on the front axle.

4. Some water and compressor oil is usually found in the compressed air within an air brake system. The water and compressor oil:

Explanation
If water and compressor oil are left to build up in an air brake system, the system can be damaged. Air storage tanks are equipped with drains to allow this accumulation to be removed. Manually controlled drains should be operated at the end of each day of driving.

5. Foundation brakes are used:

Explanation
Foundation brakes are used on each wheel of a CMV. The most common type of foundation brake is the s-cam drum brake.

6. Truck tractors with air brakes built on or after March 1, 1997 must have:

Explanation
Truck tractors with air brakes built on or after March 1, 1997, and other vehicles with air brakes built on or after March 1, 1998, must be equipped with anti-lock brakes.
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