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 South Carolina 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

1. Brakes out of adjustment will:

Work properly.

Cause some of the brakes to overwork and malfunction.

Allow better acceleration.

Brakes out of adjustment will fade before those that are properly adjusted. Brake adjustment must be checked frequently to help prevent brake issues.

2. Air brakes are:

An effective tool for stopping large vehicles.

Prohibited on large vehicles.

Only effective in poor weather.

A tool to improve fuel efficiency.

As long as the brakes are properly maintained, using air brakes is a safe and effective method of stopping large, heavy vehicles.

3. During an applied leakage test, the maximum leakage rate for a triple combination vehicle is:

10 psi in a minute.

8 psi in a minute.

6 psi in a minute.

4 psi in a minute.

It is important to know the maximum air loss rate that is safe for your specific vehicle. A triple combination should have a leakage rate no higher than 6 psi in a minute during an applied leakage test.

4. Friction in an S-cam brake is caused when the brake shoes and linings:

Press against the outside of the brake drum.

Press against the inside of the brake drum.

Push against each other.

Friction inside a brake drum is caused when the brake shoes and linings push against the inside of the drum. The friction in the drums will slow and stop the vehicle.

5. Brakes may get out of adjustment:

If they are too hot.

In colder weather.

If they are used.

If they get wet.

Brakes can get out of adjustment quickly, especially if they are used to the point of overheating. Brake adjustment should be checked frequently.

6. How is water and compressor oil removed from the bottom of an air storage tank?

The water and oil are siphoned out of the tank.

A drain valve is opened to remove the water and oil from the tank.

The water and oil are removed automatically as the brakes are used.

A sponge is used to soak up the water and oil.

Water and compressor oil are removed from air storage tanks through a drain valve. The water and oil can damage the brakes if left to accumulate in the system. Manually operated tanks must be drained every day to remove this build-up.

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