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 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

8. The emergency air line supplies air to the:

Explanation
The emergency air line (also known as the supply line) has two functions. The first is to supply air to the trailer air tanks, and the second is to control the emergency brakes on combination vehicles.

9. When driving a vehicle equipped with an Anti-Lock Braking System (ABS), brakes should be applied:

Explanation
When driving a vehicle with ABS, you should brake in the same manner as you would in a vehicle without ABS.

10. If a trailer begins to jackknife, the driver:

Explanation
If a trailer begins to jackknife, you should release the brakes and allow the trailer wheels to regain traction with the road. Do not apply the trailer hand brake to attempt to straighten out the rig because the application of brakes is what caused the wheels to lock in the first place.

11. Rearward amplification refers to:

Explanation
The "crack-the-whip" effect is a result of rearward amplification. If not properly handled, a trailer can tip over due to rearward amplification.

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

Explanation
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.

13. When coupling:

Explanation
Incorrect coupling and uncoupling of combination vehicles can have extremely dangerous consequences.

14. When backing a trailer, you must turn the steering wheel:

Explanation
When backing a vehicle with a trailer, you must turn the steering wheel in the direction opposite of where you want to go. Once your trailer starts to turn, you should turn the steering wheel the other way to follow the trailer.
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