Instructions

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 25

Passing Score 20

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

The warning light should activate.

The vehicle will be unable to shift out of gear.

The front lights should flash.

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.

8. Why do large vehicles use air brakes?

Other brake systems squeak too loudly.

Air braking systems are very effective.

Air brakes are complicated.

Air is free.

Air brakes are an effective and safe way of stopping large and heavy vehicles, as long as they are maintained and used properly.

9. Failing to drain air tanks could result in:

Water accumulations freezing and causing brake failure.

Squishy brakes.

Too much air collecting in the tanks.

In an air brake system, the air tanks must be periodically drained to remove accumulations of water and compressor oil. If water is not removed, it could freeze in cold weather and cause brake failure.

10. ____ make up the emergency brake system.

Only parts of the parking brake system

Only parts of the service brake system

Parts of the parking and service brake systems

In an air brake system, there are three different braking systems: a service brake system, a parking brake system, and an emergency brake system. The emergency brake system uses parts of both the parking and service brake systems.

11. Foundation brakes are used:

Only at the front wheels.

Only at the rear wheels.

Only at the driver’s side wheels.

At each wheel.

Foundation brakes are used at each wheel. The most common type is the S-cam drum brake.

12. Using an Anti-Lock Braking System (ABS):

Shortens stopping distance.

Shortens brake response time.

Provides less control.

Provides more control.

An Anti-Lock Braking System (ABS) helps prevent wheel lockup during hard braking. While it provides better control, it does not necessarily shorten a vehicle's stopping distance.

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