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 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
Passing Score
17. In a double or triple combination, the ____ trailer should be directly behind the cab.
Explanation
When positioning trailers in a combination, the most heavily-loaded trailer should be the closest to the tractor. The lightest trailer should be positioned in the rear.
18. When a combination vehicle goes around a corner:
Explanation
When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels. This is called off-tracking. This effect is especially pronounced on vehicles with trailers.
19. Look into the back of the fifth wheel:
Explanation
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.
20. When coupling:
Explanation
Incorrect coupling and uncoupling of combination vehicles can have extremely dangerous consequences.
21. During a trip, which shut-off valves should be open?
Explanation
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 the air is not able to escape from the back of the vehicle.
22. Keeping cargo centered on a rig can:
Explanation
A rollover is more likely if cargo is unevenly loaded in a rig. To help prevent a dangerous rollover, it is important to keep a load as centered on the rig as possible.
23. What does the trailer air supply control look like?
Explanation
