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

1. What is a tractor protection valve?

A valve to keep air in the brake system should there be a bad leak

A valve that prevents the truck from being stolen

A valve that prevents the driver from going too fast

A valve that prevents the trailer from accidentally being released

In a combination vehicle with air brakes, the tractor protection valve keeps air in the tractor or truck brake system in the event of the trailer breaking away or developing a leak.

2. Trailers built before ____ are not required to have spring brakes.

1985

1975

1999

Trailers built before 1975 are not required to have spring brakes. When parking a trailer without spring brakes, be sure to use wheel chocks to prevent the trailer from rolling.

3. When backing up your tractor while coupling it to a trailer, the trailer brakes should be:

Deactivated.

Locked.

Unlocked.

Correctly following the steps to couple and uncouple trailers is vital to safely operating a combination vehicle. Before backing your tractor under the trailer while coupling, make sure your trailer brakes are locked.

4. The trailer hand valve should:

Be used for parking.

Be used only to test the trailer brakes.

Be used together with the brake pedal.

Be used on slippery surfaces.

The trailer hand valve works the trailer brakes but should only be used when testing them. Using it while driving could create 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.

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

Look for a red light on the front right corner of the converter dolly.

Pump the air brakes to activate the ABS.

Assume the vehicle has ABS.

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.

6. The trailer hand valve should be used:

To test the trailer brakes.

To check the connection between the trailer and tractor.

To accelerate.

The trailer hand valve (also referred to as the "trolley valve" or "Johnson bar") works the trailer brakes and should be used only when testing them. Using the trailer hand valve while driving could result in a skid.

7. When coupling:

You can assume all vehicles are the same.

Be sure that you are coupling correctly.

Cracks in the mounting are acceptable.

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

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