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 answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Alaska 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

19. When the spring brakes are on, you should never:

Turn on the lights.

Turn off the vehicle.

Push down the brake pedal.

Never push down the brake pedal while the spring brakes are activated. The combined force of springs and air pressure could damage the brakes.

20. Air storage tanks:

Are not allowed on a vehicle.

Hold compressed air for the brakes.

Should be drained of excess air after every trip.

In an air brake system, the air storage tanks hold compressed air to be used by the brakes. The number and size of air tanks varies among vehicles.

21. If you are braking on dry pavement while traveling at 55 mph, how much distance will brake lag add to your overall stopping distance?

32 feet

45 feet

20 feet

The total stopping distance for vehicles equipped with air brakes is made up of four factors: perception distance, reaction distance, brake lag distance, and braking distance. When braking at a speed of 55 mph while driving on dry pavement, the brake lag can add around 32 feet to the vehicle's total stopping distance.

22. What kind of force do emergency brakes use?

Air pressure

Mechanical

Heavy

Air brakes are really three different braking systems: the service brake, the parking brake, and the emergency brake. Emergency and parking brakes are applied with mechanical force.

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. What color light indicates a vehicle's ABS is not working?

Green

Blue

Yellow

On vehicles with Anti-Lock Braking Systems (ABS), yellow malfunction lamps alert the driver to ABS malfunction.

25. When operating a vehicle with a dual air brake system, the driver should:

Let the vehicle warm up before driving to ensure that the fuel reaches the engine.

Let the air compressor build up a minimum of 100 psi pressure in the primary and secondary systems before driving.

Begin driving just after the vehicle starts.

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

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