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 Virginia 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 25

Passing Score 20

1. The air compressor is connected to the:

Transmission.

Engine.

Radiator.

The air compressor of an air brake system is connected to the engine through gears or a v-belt. The compressor may be air-cooled or cooled by the engine cooling system.

2. Air tank drains should:

Only be used by mechanics.

Only be used when it is wet outside.

Be used to drain the tanks completely.

In an air brake system, air tank drains are used to remove water and compressor oil from the air tanks. When operating a drain, be sure to drain the tank completely.

3. Air storage tanks:

Are not allowed on a vehicle.

Hold compressed air for the brakes.

Should be drained of excess air after every trip.

In an air brake system, the air storage tanks hold compressed air to be used by the brakes. The number and size of air tanks varies among vehicles.

4. The air storage tanks:

Hold only enough air for one braking cycle.

Hold enough air for the brakes to be used several times if the compressor stops working.

Do not hold air unless there is an emergency.

The air storage tanks in an air brake system store compressed air to be used for braking. They hold enough air for the brakes to still be used several times if the compressor stops working.

5. When an S-cam turns inside a brake drum, the S-cam:

Presses the brake shoes against the inside of the brake drum.

Presses the brake shoes against the brake linings.

Presses the brake linings against the wheel axles.

When a brake pedal is pressed and the S-cam is turned, the S-cam presses the brake shoes against the inside of the brake drum. This causes friction and will cause the vehicle to slow.

6. Do not operate a vehicle if any brake drums have cracks that are larger than ____ of the width of the friction area.

One half

One third

One fifth

Before beginning a trip, it is important to check the brake drums during your walk-around inspection. It is unsafe to drive if any brake drum has a crack more than one half of the width of the friction area.

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