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 Wisconsin Commercial Driver’s 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. Before a vehicle with dual air brakes is driven, pressure of at least ____ should be built up in both braking systems.

10 psi

25 psi

50 psi

100 psi

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

2. Service brakes should:

Be tested once a month.

Only be tested by a trained mechanic.

Be tested before every trip.

Before driving, you should always verify that your service brakes are in good working order. Testing the brakes before a trip allows you to locate any problems before you need to brake while on the road.

3. Why should you regularly drain the air tanks?

Because the air gets old and needs to be replaced

Because compressed air contains some water and the water collects in the tanks

To allow for a change in pressure

Compressed air usually contains a certain amount of moisture and compressor oil, which can build up in the air storage tanks and damage the brake system. The tanks should be drained to clean out these accumulations. On a tank with a manual drain valve, draining should be performed at the end of each day of driving.

4. During an inspection, slack adjusters on S-cam brakes should not move more than:

One foot.

One centimeter.

One inch.

Check each slack adjuster after parking on level ground, setting wheel chocks, and disengaging the parking brake. Pull the slack adjusters to make sure 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.

5. 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.

6. When parking, you should not use the parking brake if:

The brakes are very hot.

The brakes are very cold.

There is snow on the ground.

If your brakes are hot after coming down a steep grade, you should not use your parking brake when parking. Let your brakes cool before applying the parking brake or risk damaging the brakes.

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