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. Applicants should answer at a rate of about one question per minute. The Combination test is not a replacement for the Double/Triple endorsement test.

Number of Question 20

Passing Score 16

1. 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.

2. 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.

3. If a trailer begins to skid, it is best for the driver to:

Release the brakes.

Accelerate.

Quickly turn the steering wheel in one direction, then in the other.

If your trailer begins to skid, you should release the brakes to regain traction. The trailer will begin to straighten out once the wheels begin to grip the road again.

4. To find out if a vehicle that was built before 1998 has an Anti-Lock Braking System (ABS), you can:

Pump the air brakes to activate the ABS.

Look into the back of the fifth wheel.

Check for wheel speed sensors coming from the back of the brakes.

If you are operating a vehicle built before 1998 and are unsure if the trailer has an Anti-Lock Braking System (ABS), you can check under the trailer for wheel speed sensors coming from the back of the brakes.

5. Shut-off valves:

Prevent air from escaping air brake systems.

Prevent air from entering air brake systems.

Override vehicles that are out of control.

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.

6. When connecting a converter dolly to a second trailer, the trailer height should be ____ the center of the fifth wheel.

Level with

Slightly higher than

Slightly lower than

When connecting a converter dolly to a second or third trailer, the trailer height should correct. It should be slightly lower than the center of the fifth wheel.

7. 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.

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