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 Alabama 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. An application pressure gauge shows:

How much air pressure is being applied to the brakes.

How much air pressure is available.

How much air pressure is required to stop a vehicle.

If a vehicle is equipped, an application pressure gauge shows how much air pressure is being applied to the brakes. This gauge can help a driver identify if their brakes are beginning to fade.

8. A slack adjuster should move no more than ____ from where it is attached to the push rod.

Two inches

Five inches

One inch

Before a trip, you should check each slack adjuster after parking, setting wheel chocks, and disengaging the parking brake. Pull the slack adjusters to make sure that they do not move more than about one inch from where the push rod is attached. If they move more than one inch, they may be out of adjustment and will need to be fixed.

9. The air storage tanks:

Hold only enough air for one braking cycle.

Hold enough air for the brakes to be used several times if the compressor stops working.

Do not hold air unless there is an emergency.

The air storage tanks in an air brake system store compressed air to be used for braking. They hold enough air for the brakes to still be used several times if the compressor stops working.

10. 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.

11. In a dual air brake system, air pressure should build from 85 to 100 psi within ____ 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.

12. When traveling down a steep downgrade, the best way to use your brakes is to:

Ride the brakes all the way down the hill.

Apply the brakes for a few seconds, then release the brakes for a few seconds. Continue to repeat these steps as you travel down the hill.

Apply the brakes only near the bottom of the downgrade.

Apply consistent pressure to the brake pedal all the way down the hill.

On a long or steep downgrade, brakes should only be used to supplement the braking effect of the engine. Apply the brakes just enough to feel a definite slowing down, then release them once you are about 5 mph below your target "safe" speed. Once your vehicle reaches its safe speed again, repeat this process.

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