The fifth wheel is a large, flat coupling device mounted on the rear chassis of an HGV tractor unit. It connects the tractor to the trailer via a locking mechanism that secures around the trailer's kingpin.
It enables pivotal movement between the tractor and trailer, allowing safe turning and articulation. The fifth wheel also helps distribute the trailer’s weight onto the tractor's rear axles for improved stability and balance.
The term "fifth wheel" dates back to early vehicles that used a pivoting fifth wheel to aid steering. In HGVs, it's an essential component for coupling, stability, and manoeuvrability.
Proper maintenance — including lubrication and routine checks — is crucial to ensure safe operation and prevent coupling failures.
