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 Idaho Commercial Driver’s License Manual l. 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

13. Air tank drains should:

Only be used by mechanics.

Only be used when it is wet outside.

Be used to drain the tanks completely.

In an air brake system, air tank drains are used to remove water and compressor oil from the air tanks. When operating a drain, be sure to drain the tank completely.

14. 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.

15. If an air compressor is belt-driven, the belt should be routinely checked to ensure that it is:

Thin.

Properly tightened.

Cracked.

If your vehicle has air brakes, the air compressor drive belt should be checked before each drive. Check the tightness of the belt and verify that it is in good condition.

16. 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.

17. Brake linings should be:

Loose.

Free of oil.

Soft.

Brake linings should not be loose or soaked with oil or grease. They shouldn't be dangerously thin.

18. How much distance will an air brake-equipped vehicle need to come to a complete stop if it is traveling at 55 mph under ideal driving conditions?

300 feet

100 feet

450 feet

A vehicle's total stopping distance is made up of perception distance, reaction distance, brake lag distance, and braking distance. With all of these factors included, an air brake-equipped vehicle traveling at a speed of 55 mph under ideal driving conditions will need approximately 450 feet to come to a complete stop.

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