coupling units and landing gears
coupling units normally include fifth wheel and pintle hooker,both used to connect the truck and tractor to trailers or semi-trailer.
When we say connection, we actully refer the so called "quick connection and release " mechainism. This kind of device normally require quickly connect or disconnect (maybe couple seconds?) while at the same time,totally seal the connecting and conected units.
Fifthe wheel is the most popualr coupling unit for all automotive machine to tow or connect another machines,units, for instance, trailer or semi trailer.
Fifth wheel system ususally include two parts. one part is the towing unit, should install the fifth wheel, and another part is the so called kingpin,which is a alloy pre-heated bar to drop into the fifth wheel when the towing unit and towed units connected together.
