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 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 20

Passing Score 16

15. If you are backing and the trailer begins to drift off-course, the driver should:

Return the steering wheel to the 12 o’clock position.

Turn the top of the steering wheel in the direction of the drift.

Turn the top of the steering wheel in the direction opposite of the drift.

If your trailer begins to drift while you are backing, you should correct the drift immediately by turning the top of the steering wheel in the direction of the drift.

16. How much space should be between the upper and lower fifth wheel?

About five inches of space

A maximum of two inches of space

No space

Before a trip, be sure to inspect all couplings. There should be no space between the upper and lower fifth wheel.

17. Place the trailer air supply control in its "emergency" position to test:

The trailer emergency brakes.

A coupling device.

The anti-lock brakes.

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.

18. When coupling, you should:

Make sure to couple the proper glad hands.

Only couple one set of glad hands.

It is best to leave one glad hand loose.

When coupling air brake hoses, you should make sure the proper pairs of gland hands are connected. They are sometimes color-coded to help drivers avoid mistakes. Typically, blue is used for service lines and red is used for emergency lines.

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

Service line valve is closed.

Trailer hand brake is applied.

Emergency line valve is open.

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.

20. A trolley valve:

Should be used while driving.

Should only be used to test trailer brakes.

Should be used when parking uphill.

The trailer hand valve (also referred to as the trolley valve or Johnson bar) is a mechanism that works the trailer brakes. It should only be used to test the brakes. Using it while the vehicle is being driven could cause a skid. Never use the trailer hand valve while parking because doing so may release the air pressure from the braking system, releasing the brakes that are holding the vehicle in place.

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