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 Maryland 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

19. The ____ tells a driver how much pressure is in the air tanks.

Application pressure gauge

Air compressor governor

Supply pressure gauge

Drum brake

A vehicle that is equipped with air brakes must also be equipped with a supply pressure gauge. This gauge tells the driver how much air pressure is in each of the vehicle's air tanks.

20. What helps prevent wheel lockup when braking?

An Anti-Lock Braking System (ABS)

Air brakes

An alternator

The purpose of an Anti-Lock Braking System (ABS) is to prevent wheel lockup while brakes are being applied.

21. Alcohol evaporators are:

Illegal.

Used to add alcohol to braking systems to prevent items from freezing.

Only allowed on vehicles carrying hazardous materials.

Some air brake systems include an alcohol evaporator. The evaporator introduces alcohol into the braking system to prevent the formation of ice, which can cause damage.

22. A dual air brake system:

Has a single air brake system, but uses two sets of controls.

Has one air brake system for each side of the truck.

Has two brakes for each wheel.

Has two separate air brake systems, but uses a single set of controls.

A dual air brake system has two separate air brake systems that use a single set of brake controls. One system typically operates the regular brakes on the rear axle or axles. The other system operates the regular brakes on the front axle.

23. A driver can rely on front wheel braking to work:

On dry roadways only.

Under all conditions.

Under all conditions, except for snow.

Front wheel braking is effective under all road conditions. It is unlikely that you will experience a front wheel skid, even on ice.

24. If your tractor is equipped with ABS but your trailer is not, the ABS:

Will not be effective.

Will still improve your steering control.

Will make jackknifing easier.

Will allow others to see when you brake.

In a tractor-trailer combination, if the tractor is equipped with an Anti-Lock Braking System (ABS) but the trailer is not, the ABS will still improve the driver's steering control. The driver should keep an eye on the trailer and let up on the brakes if the trailer begins to swing out.

25. 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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