Fifth-wheel coupling - Wikipedia

File:ISO 7000 - Ref-No 3714.svg - Wikimedia Commons

Could someone define 'fifth wheel' regarding trailer trucks

fifth wheel - Wiktionary, the free dictionary

Fifth Wheel Coupling Market Will Hit Big Revenues In Future

FIFTH WHEEL COUPLING

Kingpin (automotive part) - Wikiwand

Semi-trailer, Tractor & Construction Plant Wiki

Semi Coupling Technologies

File:Volvo Truck FH-Semi-trailer truck-Fifth-wheel coupling-11ASD

The 5th Wheel and its origins - Singing Wheels: The History of the

Semi-trailer truck, Tractor & Construction Plant Wiki

What is the origin of the term 'fifth wheel'? Why is it used to

List of recreational vehicles - Wikipedia