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 Kansas 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 Kansas 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
Passing Score

15. A shut-off valve:

Explanation
Shut-off valves are used in air supply lines to control the passage of air from one trailer to another. The rear shut-off valve should always be closed to prevent air from leaving the braking system.

16. Air pressure in the ____ air line is controlled by either the foot brake or trailer hand brake.

Explanation
Air pressure in the service air line is controlled by either the foot brake or trailer hand brake. The service air line is also known as the control line or signal line. This line is connected to relay valves, which allow the trailer brakes to be applied more quickly than would otherwise be possible.

17. Fully-loaded rigs:

Explanation
Because the weight of cargo gives them a higher center of gravity, fully-loaded rigs are 10 times more likely to roll over in a crash than empty rigs.

18. Pull out the trailer air supply control to test:

Explanation
Be sure to test the trailer emergency brakes before beginning a trip. After ensuring that the trailer rolls freely, you can test the emergency brakes by pulling out the trailer air supply control, or placing it in the "emergency" position. Pull forward slightly with the tractor and make sure the trailer does not move.

19. To prevent a rollover, a driver should:

Explanation
Rollovers can happen when a combination vehicle is turned too quickly. To help prevent the risk of rollover, it is important to keep the vehicle's center of gravity low by loading cargo as close to the ground as possible.

20. The service air line is attached to the:

Explanation
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.
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