Which item is used to connect trailer to 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 connection between a trailer and tractor is made by the kingpin. This pin sits on the front of the trailer and fits into the fifth wheel on the tractor, which locks around the pin to secure the connection and allow the trailer to pivot as the vehicle moves. The term you’re looking for is the kingpin (often written as one word). The option that describes the trailer’s pin—though it’s misspelled as “Pen” in this case—refers to the same component that engages with the fifth wheel. The fifth wheel itself is the coupling device on the tractor, not the pin on the trailer, and a drawbar is a different, older style coupling. So the kingpin is the part that connects the trailer to the tractor via the fifth wheel.