Definition
The vertical pin under a semitrailer that locks into the tractor's fifth wheel.
Practical example
Example: The driver inspects the kingpin and confirms the locking jaws are fully closed around its shank.
Why it matters
Kingpin and fifth-wheel integrity are central to safe coupling.
Kingpin in CDL training
CDL students should be able to recognize this term, explain it in plain language, and connect it to safe vehicle operation, inspection, licensing, or freight work as applicable. Review the term in context and practice using it during classroom study and hands-on training.
Frequently asked questions
What does Kingpin mean in trucking?
The vertical pin under a semitrailer that locks into the tractor's fifth wheel.
Why should a commercial driver understand Kingpin?
Kingpin and fifth-wheel integrity are central to safe coupling.
This glossary is educational. Always follow current federal and state rules, the vehicle manufacturer’s instructions, and your motor carrier’s procedures.