It's fifth wheel, and it means not needed or not wanted, as in a fifth wheel on an automobile.

You have to have a trailer attached to do this. Lower the landing gear to the ground to take pressure off the fifth wheel. DO NOT RELEASE THE TRAILER KING PIN.

Go into the cab. To the right of the instrument panel, you'll see the switch for the fifth wheel slide. Unlock the fifth wheel. Pull backwards or forwards (whichever direction you're moving the fifth wheel). When you get it to where you want it, lock the fifth wheel. Pull forward or backwards slightly to ensure the fifth wheel is locked in place.

The Fifth Wheel - 1918 is rated/received certificates of:

USA:Approved

not sure, but probably due to spare wheel(fifth wheel) used to be kept in pickup bed, which is where fifth wheel hitch goes. ==Not quite == In the days of horse-drawn wagons, the fifth wheel was a wheel placed horizontally over the front axle of a large wagon to facilitate turning. Basically, it allowed the front axle to pivot. Today, the coupler of a tractor-trailer truck is called the fifth wheel, mostly because it's round (somewhat) and is vaguely reminiscent of the wagon's fifth wheel (which much more closely resembled the wagon's other four wheels).

The Fifth Wheel - 1918 was released on:

USA: 2 February 1918