What the meanig of «5 wheel/fifth-wheel coupling»?
This is the mechanism that connects the tractor to the trailer and ensures the efficient and safe transportation of cargo. The 5th wheel consists of a horseshoe-shaped hitch that attaches to the trailer’s kingpin. The mechanism secures and rotates the trailer to the tractor and absorbs loads and forces that occur during vehicle acceleration, braking, and turning. One of the most important aspects of fifth wheel maintenance is providing proper lubrication to reduce friction and wear between moving parts.