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. To control surge when stopping, you should not:

Keep a steady pressure on the brakes.

Brake well in advance of a stop.

Release the brakes too quickly.

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.

9. 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.

10. 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.

11. 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.

12. A tractor protection valve:

Keeps air in a brake system if there is a bad leak.

Prevents a truck from being stolen.

Prevents a trailer from being accidentally released.

A tractor protection valve keeps air in a tractor or truck air brake system should the trailer break away or develop a bad leak. The valve will close automatically if the pressure drops to an unsafe level.

13. 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.

14. A trolley valve:

Should be used while driving.

Should only be used to test trailer brakes.

Should be used when parking uphill.

The trailer hand valve (also referred to as the trolley valve or Johnson bar) is a mechanism that works the trailer brakes. It should only be used to test the brakes. Using it while the vehicle is being driven could cause a skid. Never use the trailer hand valve while parking because doing so may release the air pressure from the braking system, releasing the brakes that are holding the vehicle in place.

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