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 four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the North Dakota Commercial Driver Guide. 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. What can happen if parking brakes are used in very wet weather with temperatures below freezing?

The brakes will squeak.

The brakes may freeze so the vehicle cannot move.

The brakes may suddenly release by themselves.

The brakes may become too smooth to be used.

Parking brakes should not be used in very wet weather when temperatures are below freezing. The brakes could become frozen in place, making it impossible to move the vehicle.

2. How many air storage tanks are used in an air brake system?

Two tanks

Four tanks

Six tanks

The number varies.

Air storage tanks are used to hold compressed air. The number and size of air tanks in an air brake system varies among vehicles.

3. Air tank drains:

Allow rain water to enter air tanks.

Are used to drain water and oil from air tanks.

Should never be opened.

Must remain open while driving.

In an air brake system, the air tanks are equipped with drains that allow water and compressor oil to be removed from the system. If allowed to build up, water and compressor oil can damage an air brake system.

4. In a dual air brake system, a leak in one system:

Always means there are leaks in both systems.

May not affect the other system.

Is not something to worry about.

Will also affect the other system.

A dual air brake system is made up of two separate air brake systems. If there is an air leak in one system, it may not affect the other.

5. Brake fading is caused when:

Brakes are not used often enough.

Brakes overheat.

Brakes are too cold.

Brakes are wet.

Using the brakes excessively will cause them to overheat, making them less effective. This is referred to as "fading."

6. 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.

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