where did the term 5th wheel come from
Fifth-wheel coupling The term fifth wheel comes from a similar coupling used on four-wheel horse-drawn carriages and wagons. The device allowed the front axle assembly to pivot in the horizontal plane, to facilitate turning. Basically a wheel was placed on the rear frame section of the truck, which back then only had four wheels; this wheel that was placed on the frame was the "fifth wheel", hence the name. The trailer needed to be raised so that the trailer's pin would be able to drop into the central hole of the fifth wheel.
Vikings (season 5) The fifth season consists of a double order of twenty episodes, split into two parts of ten episodes; the second half will premiere in 2018.[2] The premise of the fifth season differs from the previous four after the departure of Travis Fimmel as Ragnar, and it now follows the adventures of his sons. Jonathan Rhys Meyers is introduced as a major character, after his initial appearance in the fourth season's finale.[3]