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. During a trip, the ____ should be open.

Rear service line shut-off valve

Rear supply line shut-off valve

Inner shut-off valves

When starting a trip, be sure that all shut-off valves are in the open position, except for the last valves on the rear trailer. It is important that air reaches the brakes on all trailers and that it is not able to escape from the back of the vehicle.

9. If a trailer begins to skid, it is best for the driver to:

Release the brakes.

Accelerate.

Quickly turn the steering wheel in one direction, then in the other.

If your trailer begins to skid, you should release the brakes to regain traction. The trailer will begin to straighten out once the wheels begin to grip the road again.

10. If you must cross traffic while driving a combination vehicle, you should:

Assume other drivers will make room for your vehicle.

Wait for a gap large enough for your vehicle to safely cross.

Rely only on your mirrors.

Combination vehicles require more space on the road than other vehicles. When entering or crossing traffic while driving a combination vehicle, it is especially important that there is a large enonugh gap in traffic to safely do so.

11. If a parked trailer does not have spring brakes, you should keep the trailer from moving by:

Having the vehicle parked against a wall or other vehicle.

Using chock blocks.

Parking on a slight incline.

If a parked trailer does not have spring brakes, wheel chocks should be used to prevent it from moving.

12. Look into the back of the fifth wheel:

While testing your air brakes.

If your vehicle begins to skid.

When inspecting a coupling.

While inspecting a coupling, you should go under the trailer and look into the back of the fifth wheel. Ensure that the fifth wheel jaws are secured around the shank of the kingpin.

13. When coupling, after you've connected the air lines to the trailer, you should:

Supply air to the trailer.

Activate the emergency brake.

Disconnect the glad hands.

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.

14. 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.

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