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 South Dakota 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. Foundation brakes are used:

Only on the front wheels of a vehicle.

Only on the rear wheels of a vehicle.

On each wheel of a vehicle.

Foundation brakes are used on each wheel of a CMV. The most common type of foundation brake is the s-cam drum brake.

8. 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.

9. If using air tanks with manually operated drains, how often should you drain the tanks?

Every day

Once a week

Once a month

Once every six months

In an air brake system with manually operated drains, the tanks should be drained at the end of each day of driving.

10. An air compressor governor controls:

When the air compressor pumps air into the air storage tanks.

How fast air is pumped into the air storage tanks.

The temperature of the air pumped into the air storage tanks.

In an air brake system, the air compressor governor controls when the air compressor pumps air into the air storage tanks.

11. Vehicles with dual air brake systems:

Have air pressure in the braking system even when the vehicle is not running.

Maintain some air pressure in the braking system when the vehicle is not running.

Must be run to build air pressure to allow the brakes to operate properly.

Maintain air pressure when shut off for periods of less than four hours.

Before driving a vehicle with a dual air brake system, allow time for the air compressor to build up pressure of at least 100 psi in both the primary and secondary systems.

12. 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.

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