What is true about the connection between a truck tractor and a semi-trailer?

• A. It is connected by a kingpin and a fifth wheel
• B. It is connected by a bumper hitch
• C. It uses a pintle hitch
• D. It is connected by a ball and socket

Answer: (A)

The connection between a truck tractor and a semi-trailer uses a fifth wheel and a kingpin. The front of the trailer has a kingpin that fits into the fifth wheel on the tractor. The fifth wheel is a locking, rotating plate on the tractor that grabs the kingpin, allowing the trailer to pivot for steering while still being securely attached. When coupling, the kingpin slides into the fifth wheel and the locking jaws engage, keeping the trailer attached until you release the lock to uncouple.

Other hitch types, like bumper hitches, pintle hitches, or ball-and-socket connections, are used for different trailer setups and do not provide the standard semi-trailer coupling used in tractor-trailer combinations.