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 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. While operating on a downgrade, you should brake until you reach a speed that is:

5 mph below your safe speed.

10 mph below your safe speed.

15 mph below your safe speed.

While driving downhill, you should hold down the brake pedal until your vehicle reaches a speed 5 mph below your safe speed, then release the brake pedal. Repeat this process.

2. A low air pressure warning signal should activate:

When tank pressure falls below 120 psi.

When tank pressure falls below 60 psi.

When tank pressure falls below 10 psi.

When tank pressure falls below 5 psi.

In an air brake system, a low air pressure warning signal must come on if air pressure in the tanks falls below 60 psi. This warning signal may come in the form of a light, a buzzer, or a wig wag.

3. 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.

4. Pressing and releasing a brake pedal unnecessarily can:

Release air faster than it can be replaced.

Add more air to the braking system.

Make the brake pedal more sensitive.

Create a loud noise.

In an air brake system, pressing and releasing the brake pedal unnecessarily can release air from the braking system faster than the compressor can replace it.

5. What can happen if the air pressure gets too low in an air brake system?

The brakes may squeak.

The brakes may not work.

The brakes may be sluggish.

The brakes will be very sensitive.

Pressing and releasing the brake pedal unnecessarily can let air out faster than the compressor can replace it, reducing the available air pressure. If the air pressure in an air brake system gets too low, the brakes will no longer work.

6. If the low air pressure warning signal comes on in a vehicle with air brakes, the driver should:

Test the brakes while driving, but continue driving if nothing seems wrong.

Immediately stop driving.

Drive with the hazard lights activated.

If the low air pressure warning signal comes on while you are operating a vehicle with air brakes, you should stop and safely park the vehicle as soon as possible. It is essential that you are able to stop safely while you still have some braking power remaining.

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