Kingpin and Locking Jaws - ONLINE CDL SCHOOL

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Kingpin and Locking Jaws

Build confidence with 10 original questions about Kingpin and Locking Jaws. Review your answers and explanations after finishing.

Supplemental study practice. This is not a government licensing exam or ELDT certification, and does not replace hands-on training. Follow your state’s current handbook.

1 / 10

After connecting the air lines to the trailer during coupling, what should you do before moving the vehicle?

Release the parking brakes on the tractor

Check the brake system for crossed air lines by applying and releasing the trailer brakes

Lower the landing gear completely

Immediately drive forward to test the connection

2 / 10

You are about to couple your tractor to a trailer. What should you check about the fifth wheel before backing under the trailer?

Ensure the jaws are open and the wheel is tilted down toward the end of the tractor

Verify the electrical cord is connected

Check that the landing gear is fully raised

Make sure the trailer brakes are released

3 / 10

You are preparing to uncouple a loaded trailer. After lowering the landing gear until it touches the ground, what should you do next?

Disconnect the air lines and electrical cable

Raise the landing gear completely off the ground

Release the trailer brakes

Turn the crank a few extra turns in low gear to lift some weight off the tractor

4 / 10

You have just backed your tractor slowly under the trailer and stopped when the kingpin is locked into the fifth wheel. What should you do next to confirm the connection is secure?

Drive forward to the next inspection area

Raise the trailer landing gear slightly and gently pull forward with the trailer brakes locked

Lower the landing gear completely before checking the connection

Immediately connect the electrical cord and air lines

5 / 10

During a walkaround inspection, you notice a visible gap between the upper and lower fifth wheel after coupling. What should you do?

Do not drive the vehicle and get the coupling fixed

Tighten the landing gear crank

Add more grease to the fifth wheel

Continue driving as long as the locking lever is in place

6 / 10

When inspecting the coupling system, where should the fifth wheel jaws be locked?

On top of the kingpin

Around the shank of the kingpin

Around the head of the kingpin

Under the trailer frame

7 / 10

After raising the landing gear and securing the crank handle, what clearance should you check before driving away?

Check that the kingpin is fully greased

Verify that the trailer brakes are released

Make sure the electrical cord is unplugged

Ensure there is enough clearance between the rear of the tractor frame and the landing gear

8 / 10

While uncoupling, why should you pull the tractor partially clear of the trailer but leave the frame under the trailer before fully pulling away?

To allow the air lines to disconnect automatically

To make it easier to reconnect the next time

To check the kingpin for damage

To prevent the trailer from falling if the landing gear collapses or sinks

9 / 10

You are about to drive away after coupling a trailer. What should you do with the landing gear crank handle?

Remove it from the vehicle

Leave it hanging for easy access

Tie it to the air lines

Secure it safely in its bracket

10 / 10

During a walkaround inspection, what should you check about the fifth wheel’s release arm and safety latch?

That the release arm is in the open position

That the safety latch is disconnected

That the release arm is properly seated and the safety latch or lock is engaged

That the release arm is greased

Your score is

The average score is 0%

About the Kingpin and Locking Jaws practice quiz

This practice quiz focuses on Kingpin and Locking Jaws, listed under CDL Practice — Combination Vehicles. Use it to check what you understand, spot topics to revisit, and connect the material to safe, informed decisions on the road.

Before you begin

Keep your current CDL manual or course notes nearby. Read each prompt carefully and think through why an answer fits, especially when a question describes a vehicle, road, or workplace situation. Licensing rules and procedures can vary, so confirm requirements with current official materials for your state.

After you finish

Review any explanations shown with your results. Note unfamiliar terms or missed concepts, then revisit your manual or course notes before trying again. Use your score to guide study; understanding why an answer is correct matters more than the number alone.

Study note: These quizzes are independent study practice. They are not state licensing exams, official government materials, or ELDT certification, and they do not replace required training.

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