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

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

May lean, and could result in a rollover.

May add extra support during turns.

Have improved braking.

Have improved steering.

If the weight of a load is placed primarily one side of a trailer, the trailer may lean, increasing the risk of a rollover.

9. When lightly loaded, combination vehicles:

Should not be driven.

Have reduced braking capabilities.

Will not rollover.

Should be loaded with most of the weight in the rear of the trailer.

When a combination vehicle is lightly loaded, it may have poor traction. It is very easy for wheels to lock up on lightly-loaded vehicles when they are being stopped.

10. A tractor protection valve is:

A device that keeps air in the tractor or truck brake system, should the trailer break away or develop a bad leak.

A device that prevents theft.

A device that controls fuel levels.

A device that allows the battery to recharge efficiently.

On combination vehicles with air brakes, the tractor protection valve keeps air in the tractor or truck brake system, should the trailer develop a bad leak or break away from the tractor.

11. Failure to keep the fifth wheel plate properly greased could:

Cause the trailer to disconnect.

Cause steering problems.

Cause braking problems.

Affect the lights.

Failure to keep the fifth wheel plate properly lubricated can create friction between the tractor and trailer, causing steering problems.

12. When a combination vehicle goes around a corner:

The turn should be made as tightly as possible.

The front and rear wheels move in different paths.

The rear wheels should run over the curb.

It is acceptable for street signs to be knocked over if they are too close to the road.

When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels. This is called off-tracking. This effect is especially pronounced on vehicles with trailers.

13. What does the trailer air supply control look like?

It is a square blue knob.

It is a triangular yellow knob.

It is an eight-sided red knob.

It is a circular orange knob.

On newer vehicles, the trailer air supply control is an eight-sided red knob. It's used to control the tractor protection valve.

14. What is a bobtail?

A tractor without a semi-trailer

A tractor with two semi-trailers

A tractor that goes faster than the speed limit

A tractor that goes slower than the speed limit

Tractors without semi-trailers are referred to as bobtail tractors. Operating a bobtail tractor requires drivers to exercise caution.

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