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 tractor protection valve?

A valve that keeps air in the brake system should a bad leak occur

A valve that prevents the trailer from being accidentally released

A valve that prevents the vehicle from going too fast

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.

2. The trailer hand valve should be used:

To test the trailer brakes.

To check the connection between the trailer and tractor.

To accelerate.

The trailer hand valve (also referred to as the "trolley valve" or "Johnson bar") works the trailer brakes and should be used only when testing them. Using the trailer hand valve while driving could result in a skid.

3. If you are backing and the trailer begins to drift off-course, the driver should:

Return the steering wheel to the 12 o’clock position.

Turn the top of the steering wheel in the direction of the drift.

Turn the top of the steering wheel in the direction opposite of the drift.

If your trailer begins to drift while you are backing, you should correct the drift immediately by turning the top of the steering wheel in the direction of the drift.

4. The tractor protection valve:

Ensures that oil adequately lubricates the engine.

Protects the tractor from exceeding a set speed.

Keeps air in the truck braking system if the trailer develops a leak.

5. When driving while pulling trailers, you should:

Make sudden turns with the steering wheel.

Avoid making sudden moves.

Push the accelerator to the floor when starting from a stop.

You should always steer gently and smoothly while pulling a trailer. Making sudden steering moves could cause the trailer to tip over.

6. Fully-loaded rigs:

Are less likely to roll over than empty rigs.

Are more likely to roll over than empty rigs.

Are just as likely to roll over as empty rigs.

Fully-loaded rigs are more vulnerable to rolling over than empty rigs because the weight of the cargo gives the vehicles higher centers of gravity.

7. The trailer hand valve:

Should always be used for parking.

Should only be used for parking on a downgrade.

Should never be used for parking.

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. Instead, use the parking brake or wheel chocks.

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