This endorsement is required if the driver will pull two or three trailers. To receive this endorsement, applicants must pass a..

This endorsement is required if the driver will pull two or three trailers. To receive this endorsement, applicants must pass a test. The test consists of 20 multiple choice questions. To pass, the applicant must answer at least 16 questions correctly. Each question has three possible answer choices. Test questions come from the Arizona Commercial Driver License Manual. Questions come from chapters covering: Driving Safely, Air Brakes (if applicable), Combination Vehicles and Doubles and Triples. The Double/Triple endorsement can be used with the Class A CDL.

Passing grade:

Wheels with welding repairs are:

Wheels or rims that have had welding repairs are not safe for use. They should be replaced before the vehicle is taken on the road.

To control surge when stopping, you should not:

To reduce the risk of a surge in a tank vehicle, slow or stop while keeping a steady pressure on the brakes and do not release the brakes too early. Brake well in advance of a stop and increase your following distance.

While driving a triple combination, keep the shut-off valves at the rear of the middle trailer in their:

When operating a double or triple, the shut-off valves at the rear of last trailer should be closed. All other shut-off valves should be open.

When inspecting your tires, you do not want to find:

There should be at least 4/32 of an inch of tread depth in every major groove on front tires and 2/32 of an inch on other tires. Valve stems should not be cut or cracked. Tire sizes should not be mismatched.

For safety purposes, when should you turn off a retarder?

Retarders are mechanisms in some vehicles that help slow a vehicle and reduce the need for braking. However, using a retarder may cause wheels to skid when they have poor traction. Turn off retarders when traveling under wet, snowy, or icy conditions.

What is the Johnson bar?

The trailer hand valve, also called the trolley valve or Johnson bar, is used to work the trailer brakes. It should be used only to test the brakes. Using it while a vehicle is in motion could cause a skid.

Of the following, which is not a recommended way to spot potential signs of trouble?

During a trip, you should regularly make checks to ensure that your vehicle is operating properly. Check the instrument panel and gauges; look at your mirrors; and examine the tires, cargo, and lights. Use all of your senses and be alert for anything that could be an early indication of trouble.
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