What component is used to connect the trailer to the tractor and locks into the fifth wheel, located on the front of the trailer?

What component is used to connect the trailer to the tractor and locks into the fifth wheel, located on the front of the trailer?

• A. Trailer King Pen
• B. Tractor Fifth Wheel
• C. King Pin
• D. Drawbar

Answer: (A)

The component that connects the trailer to the tractor and locks into the fifth wheel is the kingpin. A kingpin is a sturdy steel pin mounted on the front of the trailer that fits into the fifth wheel on the tractor. When the tractor backs up and the kingpin seats into the fifth wheel, the locking mechanism on the fifth wheel clamps around the pin, securing the linkage while still allowing the trailer to pivot as you steer. This setup is specific to semitrailers—the drawbar and older coupling systems are different, and the device on the tractor side is the fifth wheel, not the component on the trailer. The correct term used in manuals is kingpin.

The component that connects the trailer to the tractor and locks into the fifth wheel is the kingpin. A kingpin is a sturdy steel pin mounted on the front of the trailer that fits into the fifth wheel on the tractor. When the tractor backs up and the kingpin seats into the fifth wheel, the locking mechanism on the fifth wheel clamps around the pin, securing the linkage while still allowing the trailer to pivot as you steer. This setup is specific to semitrailers—the drawbar and older coupling systems are different, and the device on the tractor side is the fifth wheel, not the component on the trailer. The correct term used in manuals is kingpin.