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 have one hour to correctly answer a minimum of 16 questions. The Combination test is not a replacement for the Double/Triple endorsement test.

Number of Question 20

Passing Score 16

1. The service air line is often controlled by the foot brake and is attached to the ____ valves.

Relay

Supply

Emergency

The service air line carries air and is controlled by either the foot brake or trailer hand brake. The service air line is attached to relay valves, which allow the trailer brakes to be applied quickly.

2. When coupling, after you've connected the air lines to the trailer, you should:

Supply air to the trailer.

Activate the emergency brake.

Disconnect the glad hands.

Correctly following the steps to couple and uncouple trailers is vital to safely operating a combination vehicle. After connecting the air lines to the trailer while coupling, you should supply air to the trailer.

3. 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.

4. In a sudden turn, the ____ trailer is the most likely to turn over.

Front

Last

Middle

First

When making a turn, be sure to steer gently and smoothly. Making a quick turn while pulling trailers is dangerous and can increase the risk of the last trailer rolling over.

5. Older trailers are not equipped with spring brakes. This means that if the air supply for a vehicle's air braking system leaks away:

The trailer will stop normally.

The trailer will not have brakes.

The trailer will speed up.

Older trailers do not have spring brakes. This means that if the air supply in an older trailer's air tank has leaked away, there will be no working brakes connected to the trailer and its wheels will turn freely.

6. A loss of air pressure in the emergency line will cause:

The suspension springs to extend.

The tractor protection valve to open.

The rear trailer to detach from the combination.

The emergency brakes to activate.

The emergency air line controls the emergency brakes on a combination vehicle. A loss of air pressure in the emergency line will cause the emergency trailer brakes to activate.

7. In a double or triple combination, the ____ trailer should be directly behind the cab.

Lightest

Heaviest

Smallest

When positioning trailers in a combination, the most heavily-loaded trailer should be the closest to the tractor. The lightest trailer should be positioned in the rear.

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