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. 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.

9. After connecting the air lines to the trailer while coupling, you should:

Supply air to the trailer.

Chock the wheels.

Inspect the fifth wheel.

Connect the electrical cord.

Correctly following the steps to couple and uncouple trailers is vital to safely operating a combination vehicle. After connecting the air lines to the trailer while coupling, you should supply air to the trailer.

10. The easiest way to recognize that your trailer has begun to skid is to:

Ask another driver.

Use your mirrors to determine if the trailer has left the lane.

Release the brake pedal and then push it down again.

Watch the jackknife warning light on the control panel.

The easiest way to spot a trailer skid is to use your mirrors. Any time you brake hard, check your mirrors to ensure that your trailer is still in its proper position.

11. If a trailer's spring brakes do not release when you push the tractor air supply control, you should:

Check the air line connections.

Release the pintle hook.

Replace the spring brakes.

Drive normally without checking anything.

It is important that all of your vehicle's equipment is in proper working condition before you begin a trip. If a trailer's spring brakes do not release when you push in the tractor air supply control, you should make sure the air line connections are properly attached and sealed.

12. The best way to recognize that your trailer has begun to skid is by:

Seeing other drivers' faces.

Seeing it in your mirrors.

Feeling it.

Listening to the radio.

The earliest and best way to recognize the beginnings of a trailer skid is by seeing the trailer veer off-course in your mirrors.

13. Trailers with low underneath clearance may be difficult to drive:

On interstate highways.

Over railroad crossings.

On dirt roads.

At the posted speed limit.

Railroad-highway crossings may be difficult to cross when pulling a trailer with a low underneath clearance. In particular, both low-slung units and single-axle tractors pulling long trailers are especially challenging to drive over raised crossings.

14. What is another name for the service line?

Control line

Exchange line

Surplus line

Parallel line

The service line, also called the control line or signal line, carries air to the trailer brakes and is controlled by the foot brake or trailer hand brake.

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