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

8. Friction inside a brake drum is caused when the brake shoes and linings:

Push against each other.

Separate from the axle.

Push against the inside of the drum.

Create excess heat.

Friction inside a brake drum is caused when the brake shoes and linings push against the inside of the drum. The friction in the drums will slow and stop the vehicle.

9. When you press the brake pedal in a vehicle with S-cam brakes, air pressure pushes out the rod and moves the:

Slack adjuster.

Axle.

Brake drum.

Alcohol evaporator.

When pressing the brake pedal in a vehicle with S-cam brakes, air will enter the brake chambers. The added air pressure will push out the rods and move slack adjusters, twisting the brake camshafts.

10. The ____ between an air compressor and reservoir tank prevents air from escaping if the air compressor has a leak.

Slack adjuster

One-way check valve

Tractor protection valve

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.

11. Some air brake systems use alcohol:

To reduce the risk of ice forming in air brake valves.

To make the compressor run more efficiently.

To lubricate parts of the braking system.

To reduce the risk of rust forming on air brake valves.

Some air brake systems contain an alcohol evaporator. This device introduces alcohol into the braking system to inhibit the formation of ice.

12. Applying the brake pedal causes air pressure to activate an electric switch and:

Turn off the brake lights.

Turn on the low pressure warning light.

Turn on the brake lights.

Turn off the low pressure warning light.

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.

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