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 two, three or four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Nebraska 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. Which of the following is not part of a vehicle’s air brake system?

Air gauges

Low pressure warning device

Air filter

Components of an air brake system include an air compressor, an air compressor governor, air storage tanks, air tank drains, an alcohol evaporator, a safety valve, a brake pedal, foundation brakes, supply pressure gauges, an application pressure gauge, a low air pressure warning signal, a stop light switch, a front brake limiting valve (on some older vehicles), spring brakes, and parking brake controls.

8. What should happen if the air pressure in the air brake system tanks falls below 60 psi?

A warning light should come on.

Lights should flash on the outside of the vehicle.

A message should appear on the control panel.

The vehicle should stop.

On vehicles with air brakes, a low air pressure warning signal will come on if the pressure in the air tanks falls below 60 psi. On large buses, the signal may activate at 80 to 85 psi.

9. 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.

10. 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.

11. Brakes can get out of adjustment:

If they are hot.

During the winter.

If they are used at all.

If brakes on one side are used more often than brakes on the other side.

Brakes are particularly prone to getting out out adjustment if they are hot. Use proper braking techniques to avoid letting your brakes overheat.

12. In a dual air brake system, if one air system is very low on pressure:

None of the brakes will work at all.

Either the front or rear brakes will not be fully operable.

There is usually no noticeable effect.

In a dual air brake system, either the front or rear brakes will not be fully operable if one of the air systems gets too low on pressure. If the air pressure in either tank gets too low while you are driving, you should exit the road and park as soon as possible.

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