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 Kentucky 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. Braking mechanisms are located inside:

The fifth wheel.

A brake drum.

The landing gear.

Drum brakes are attached to the wheels and located on the axles of a vehicle. The braking mechanisms that cause the vehicle to stop can be found inside of a drum brake.

2. What is brake lag?

The time required for the brakes to work after the brake pedal is pressed

The distance between the brake pedal and the floor

The amount of air pressure used to stop the vehicle

Because air takes time to flow through the air lines to the brakes, air brakes cannot begin working instantly. There is often a brake lag of at least one-half of a second between the moment the brake pedal is pressed and the moment the brakes begin to work.

3. When you are about to start down a hill, you should switch into a ____ gear.

Higher

Faster

Lower

Before starting down a hill, be sure to switch into a low gear. Gravity will increase your vehicle's speed as you travel downhill.

4. 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.

5. To make a stop in a vehicle equipped with air brakes, the driver should:

Press the brake pedal down.

Lift the brake pedal up.

Pull out the air brake knob.

To make a normal stop in a vehicle that is equipped with air brakes, you should simply press the brake pedal down.

6. In a dual air brake system:

Air tanks are shared between both systems.

Each system has its own air tanks.

You must designate which system you are using.

There are two air brake systems in a dual air brake system. The systems share a set of brake controls, but each system has its own tanks, hoses, and lines.

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