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 30 multiple-choice questions, and applicants will need to correctly answer a minimum of 24 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.

Number of Question 30

Passing Score 25

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. When a vehicle goes around a corner, the rear wheels:

Follow the same path as the front wheels.

Follow a different path than the front wheels.

Should not be a concern to the driver.

When any vehicle goes around a corner, the rear wheels follow a different path than the front wheels. This is called off-tracking. The degree of off-tracking will be greater on long vehicles than on short vehicles.

11. 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.

12. Compared to other commercial motor vehicles, combination vehicles need more space on the road because they are longer and they:

Need more space to turn and stop.

Drive more slowly.

Are twice the width.

Swerve more often.

Combination vehicles need more space on the road than other commercial vehicles because they are longer and need more space to turn and stop. It is especially important to properly manage space when you are operating a combination vehicle.

13. 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.

14. The service air line is often controlled by the foot brake and is attached to the ____ valves.

Relay

Supply

Emergency

The service air line carries air and is controlled by either the foot brake or trailer hand brake. The service air line is attached to relay valves, which allow the trailer brakes to be applied quickly.

15. When should the trailer hand valve be used?

Only when the trailer is carrying a load

Only to test the trailer’s brakes

Only in inclement weather when the trailer may skid

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.

16. If unsure if a trailer has an Anti-Lock Braking System (ABS), you can:

Look under the trailer for wheel speed sensors coming from the back of the brakes.

Remove a tire and look for the ABS sensor on the axle.

Assume it does have ABS.

If you do not know whether or not a trailer is equipped with ABS, look under the vehicle for the electronic control unit and wheel speed sensor wires coming from the back of the brakes.

Grade This Section