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. While inspecting a coupling, you should go under the trailer and:

Detach the jaws from around the kingpin.

Make sure the locking lever is in the "emergency" position.

Remove the safety latch.

Look into the back of the fifth wheel.

While inspecting a coupling, you should go under the trailer and look into the back of the fifth wheel. Ensure that the fifth wheel jaws are secured around the shank of the kingpin.

2. When testing ____, you should apply your vehicle's brakes with the hand control while moving the vehicle forward slowly.

The Anti-Lock Braking System

The emergency braking system

The trailer service brakes

To test the trailer service brakes, you should first ensure that the braking system has a normal air pressure level, then release the parking brake. You should then move the vehicle forward slowly and apply the brakes with the hand control. If the trailer service brakes are working properly, you will feel the brakes activate.

3. A trailer that is too high:

May not couple correctly.

Will couple securely.

Is not an issue.

Before coupling together a tractor and a trailer, you should make sure the trailer is at the proper height. If the trailer is too low, the trailer nose may be damaged. If the trailer is too high, it may not be able to couple correctly.

4. What is another name for the service line?

The signal line

The cable line

The surplus line

The power line

The trailer service air line is also referred to as the control line or signal line.

5. When driving while pulling trailers, you should:

Make sudden turns with the steering wheel.

Avoid making sudden moves.

Push the accelerator to the floor when starting from a stop.

You should always steer gently and smoothly while pulling a trailer. Making sudden steering moves could cause the trailer to tip over.

6. The trailer hand valve should be used:

To accelerate in rural areas.

Only to test the trailer brakes.

Together with the brake pedal.

On slippery surfaces.

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. Using it while a vehicle is in motion could cause a skid.

7. 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.

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