Instructions

Combination

All applicants who are applying for a Class A CDL should be prepared to take the Combination test. This test covers information found in Section 6 of the Commercial Driver License.. Read More

All applicants who are applying for a Class A CDL should be prepared to take the Combination test. This test covers information found in Section 6 of the Commercial Driver License Manual. Section 6 provides the information needed to safely operate tractor-trailers, doubles, triples, and straight trucks with trailers. The test is made up of 20 multiple-choice questions, and applicants will need to correctly answer a minimum of 16 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.

Number of Question 20

Passing Score 16

1. What is the Johnson bar?

A hand valve that works the trailer brakes

A valve that indicates the fuel level

A valve that limits the amount of cargo

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.

2. When connecting a converter dolly to a second trailer, the trailer height should be ____ the center of the fifth wheel.

Level with

Slightly higher than

Slightly lower than

When connecting a converter dolly to a second or third trailer, the trailer height should correct. It should be slightly lower than the center of the fifth wheel.

3. The "crack-the-whip" effect can:

Turn over a trailer.

Be more effective than braking.

Make a truck move faster.

Trailers can overturn as a result of the "crack-the-whip" effect. The last trailer in a combination is the most prone to tip over due to this effect. Drivers should be aware of the rearward amplification of their specific vehicles and drive accordingly.

4. If a load is placed on one side of a trailer, the trailer:

May lean during turns.

May add extra support during turns.

May be easier to steer during turns.

Positioning the weight of a load on one side of a trailer may cause the trailer to lean to that side, increasing the risk of a rollover during turns and lane changes.

5. A combination vehicle has ____ air line(s).

One

Two

Three

Every combination vehicle has two air lines: the service line and the emergency line.

6. Rollovers happen when:

You drive too slowly.

You are stopped.

You take a turn too fast.

Rollovers are caused by operators turning too fast. To avoid rolling over, drive slowly on entrance ramps, on exit ramps, and around corners. Avoid making quick lane changes when towing trailers.

7. Which of the following will not help prevent a rig from rolling over?

Keeping the cargo as close to the ground as possible

Driving slowly around turns

Driving on the shoulder of a road

To help prevent a rig from rolling over, you should keep the weight of the cargo as close to the ground as possible when loading. You should also drive slowly around turns.

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