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 State of Delaware 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

15. If you cannot reverse your trailer in a straight path, you should:

Swerve back and forth while backing.

Back toward the driver's side.

Back toward the passenger's side.

If you need to back your trailer but cannot back up in a straight path, you should back on a curved path toward the driver's side of the vehicle. This will allow you the best possible visibility while backing.

16. Before a drive, ensure that air flows to all trailers by:

Opening the rear shut-off valves and listening for escaping air.

Closing the rear shut-off valves and listening for escaping air.

Disconnecting air supply lines and listening for escaping air.

Rolling each trailer down a hill and testing the brakes.

Before a trip, ensure that air in the air brake system reaches all trailers. Do this by waiting for air pressure to build, then sending air to both the emergency and service lines and opening the shut-off valves on the rear of the last trailer. If air escapes from the shut-off valves in the rear of the combination, the air is being supplied to the entire vehicle.

17. A trailer that is too high:

May not couple correctly.

Will couple securely.

Is not an issue.

Before coupling together a tractor and a trailer, you should make sure the trailer is at the proper height. If the trailer is too low, the trailer nose may be damaged. If the trailer is too high, it may not be able to couple correctly.

18. If you press the tractor air supply control and your trailer's spring brakes do not release, you should:

Inspect the air line connections.

Activate the Anti-Lock Braking System.

Turn the engine off and on again.

It is important that all of a vehicle's equipment is in proper working condition before beginning 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.

19. Older trailers are not equipped with spring brakes. This means that if the air supply for a vehicle's air braking system leaks away:

The trailer will stop normally.

The trailer will not have brakes.

The trailer will speed up.

Older trailers do not have spring brakes. This means that if the air supply in an older trailer's air tank has leaked away, there will be no working brakes connected to the trailer and its wheels will turn freely.

20. To test the trailer service brakes, you should:

Move the vehicle forward slowly and apply the brakes with the brake pedal.

Reverse the vehicle slowly and apply the brakes with the hand control.

Reverse the vehicle slowly and apply the brakes with the brake pedal.

Move the vehicle forward slowly and apply the brakes with the hand control.

To test the trailer service brakes, you should first ensure that the braking system has a normal air pressure level, then release the parking brake. You should then move the vehicle forward slowly and apply the brakes with the hand control. If the trailer service brakes are working properly, you will feel the brakes activate.

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