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. A one-way check valve:

Drains the water and compressor oil from the air tanks.

Prevents air from escaping if the air compressor has a leak.

Activates the emergency brakes when there is a leak.

Holds the spring brakes in position until they are used.

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.

2. During a walk-around inspection, ensure there are no cracks on the brake drums that are more than ____ of the width of the friction area.

One half

One quarter

One third

One tenth

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.

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. The air entering air storage tanks may contain:

Water and compressor oil.

Frost.

Gravel.

Antifreeze.

The air that enters air storage tanks in an air brake system usually contains a certain amount of water and compressor oil. Because accumulations of these materials can damage the braking system, tanks are equipped with drains to allow their removal.

5. Before driving a vehicle with a dual air brake system, you must wait for the air compressor to build a minimum of ____ in both the primary and secondary systems.

25 psi

50 psi

75 psi

100 psi

Before driving a vehicle with a dual air brake system, you should wait for the air compressor to build up at least 100 psi in both the primary and secondary systems.

6. If one air system in a dual air brake system is very low on pressure:

None of the brakes will work at all.

Either the front or rear brakes will not be operating fully.

There will be no noticeable affect.

Lights on the outside of the tractor will flash.

In a dual air brake system, if one of the air systems gets very low on pressure, either the front or rear brakes will not be operating fully. You should bring your vehicle to a safe stop and have the air system repaired.

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