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 Kansas 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

7. When the brake pedal is pushed down, air brakes work:

Immediately.

After a short delay.

After about a minute.

Only if it is warm outside.

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.

8. In cold weather, an alcohol evaporator should be checked and filled:

Once a week.

Every day.

Every hour.

Once a month.

An alcohol evaporator can help prevent ice from building up in an air brake system. In cold weather, the evaporator should be checked and refilled every day.

9. How is the parking brake released?

By tapping on the brake pedal three times

By pushing in the brake control knob

By engaging the accelerator

By tapping the accelerator twice

In newer vehicles with air brakes, the parking brakes are controlled by a diamond-shaped yellow knob. Pull the knob out to activate the parking brakes and push it in to release them.

10. To ensure normal stopping power, drivers of vehicles equipped with a front brake limiting valve should:

Set the control to normal.

Set the control to the off position.

Set the control to neutral.

Keep the control at the halfway mark.

Some pre-1975 vehicles have a front brake limiting valve, which has "normal" and "slippery" settings. The idea behind these valves was to limit the air pressure available to the front brakes when driving on slippery surfaces, and thereby reduce the danger of a front-wheel skid. Studies have found that this is not actually a concern, so if your vehicle has a front brake limiting valve, leave it in the "normal" position.

11. Brakes may get out of adjustment:

If they are too hot.

In colder weather.

If they are used.

If they get wet.

Brakes can get out of adjustment quickly, especially if they are used to the point of overheating. Brake adjustment should be checked frequently.

12. 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.

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