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 New Hampshire CDL Driver’s 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. Once the air tanks are at an air pressure level of 125 psi, the air compressor governor will:

Stop the compressor from pumping air.

Release air from the tanks.

Begin pumping air into the tanks.

An air compressor governor will stop the compressor from pumping air once the air tanks are at an air pressure level around 125 psi. This air pressure level is referred to as the "cut-out" level.

20. When leaving your vehicle unattended:

The parking brake should be used.

The parking brake only needs to be used if the vehicle is parked on a slope.

The parking brake should not be used, as it can damage the tires.

In general, you should always use the parking brake when parking your vehicle. However, you should not apply the parking brake if your brakes are very hot or if your brakes are wet and temperatures are below freezing.

21. 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.

22. The parking brake should be:

Used whenever you park the vehicle.

Used while driving.

Set when driving in bad weather.

Used to stop the vehicle in normal driving.

The parking brake should be applied every time you park your vehicle.

23. A low air pressure warning signal:

Is not required on vehicles with air brakes.

Is required on vehicles with air brakes.

Is optional on vehicles with air brakes.

A vehicle with air brakes must be equipped with a low air pressure warning signal. If the warning signal goes off while a vehicle is being driven, the driver should bring the vehicle to a complete stop and have the system repaired.

24. The air pressure in a dual air brake system should build from 85 to 100 psi within:

Two minutes.

15 seconds.

10 minutes.

45 seconds.

When inspecting a vehicle with a dual air brake system, you should wait for air pressure to build from 85 to 100 psi in both the primary and secondary systems. This should take about 45 seconds.

25. When traveling down a steep downgrade:

The air brakes should be used.

Shift into a lower gear, then use brakes to supplement the braking effect of the engine.

The vehicle should be continually downshifted in the place of using the brakes.

The vehicle should be driven on the shoulder.

On a downgrade, the braking effect of the engine should be your primary method of controlling speed. Shift down to a lower gear before starting down the hill and save the brakes for additional slowing or stopping that may be required by road or traffic conditions.

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