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. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Illinois Commercial Driver’s License Study Guide. Questions come from chapters 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

1. When about to drive a vehicle with a dual brake system, a driver should:

Let the vehicle warm up to ensure the fuel reaches the engine.

Wait for air pressure to build in both the primary and secondary systems.

Begin driving just after the engine starts.

Pump the pedal about 20 times to build pressure, then begin driving.

Before driving a vehicle with a dual air brake system, allow time for the compressor to build up pressure to at least 100 psi in both systems.

2. 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.

3. If the low pressure warning light comes on while you are driving:

Braking will only occur if there is enough air in the tanks.

You can brake 14 times before the air in the system runs out.

You should continue to drive normally and check the brake system when it is convenient.

You should continue driving, but turn the emergency flashers on to warn other motorists.

If the low air pressure warning light turns on, you should stop and safely park your vehicle as soon as possible. Controlled braking will be possible only as long as enough air remains in the tanks.

4. All air tanks must include:

A drain valve.

A lock.

A trap door.

A warning sticker.

Air brake system tanks must contain drain valves. These valves are used to drain accumulated oil and water from the tanks and may be either manually or automatically operated.

5. Air tank drains:

Allow rain water to enter the tanks.

Are used to drain water and oil from the tanks.

Should never be opened.

Must remain open while driving.

In an air brake system, the air storage tanks are equipped with drains to allow water and compressor oil to be removed. The water and oil can damage the brakes if left to accumulate in the system.

6. How should you test the low pressure warning signal?

Engage and disable the parking brake.

Rapidly press and release the brake pedal.

Open the rear shut-off valves.

Uncouple and recouple all glad hands.

It is essential that your low pressure warning light functions properly. After allowing the system to charge, you can test the warning signal by rapidly applying and releasing the brake pedal. This will release air from the braking system and the warning signal should come on when pressure drops to a dangerous level.

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