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 25 multiple-choice questions, and applicants will need to correctly answer a minimum of 20 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.

Number of Question
Passing Score

13. The trailer hand valve should be used:

Explanation
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.

14. During a trip, landing gear should be:

Explanation
Landing gear, or trailer supports, should always be completely raised before a vehicle is driven. Landing gear that is not entirely raised could catch on railroad tracks or other hazards on the roadway.

15. Push in the trailer air supply control to:

Explanation
Push in the trailer air supply control to supply the trailer with air. Pull out the trailer air supply control to turn off the air supply and activate the emergency brakes.

16. After completing a pre-trip inspection, you should ensure that the:

Explanation
Before a trip, you should ensure that air reaches all air brakes on all trailers by opening up the rear emergency line and service line shut-off valves and listening for escaping air. Close both shut-off valves before beginning to drive.

17. The best way to recognize that your trailer has started to skid is by:

Explanation
The easiest way to become aware that your trailer has begun to jackknife is to observe it in your mirrors. Checking your trailer in your mirrors will also allow you to spot any skidding at the earliest possible moment.

18. What is another name for the service line?

Explanation
The service line, also called the control line or signal line, carries air to the trailer brakes and is controlled by the foot brake or trailer hand brake.
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