Abstract: A fifth wheel assembly for coupling tractor and trailer units includes an improved trunnion bracket, comprising a pair of forged bearing caps having an inverted, U-shaped configuration, with bearing sleeves fixedly mounted therein. In sliding fifth wheel embodiments of the present invention, the bearing caps are mounted on rectangular channels fabricated from two L-shaped channel members with a flat plate attached to the upper edges of the L-shaped channels. An improved plunger is provided for adjustably connecting the trunnioned fifth wheel assembly with a base plate on which slotted racks have been mounted, and comprises a forged, two-prong construction with internal guides which minimizes structural disruption in the channels to provide greater strength. Adjustable stops are mounted on the exterior ends of the plungers, and abut the exterior sides of the racks to accurately maintain the plungers in a locked position.

Abstract: A fifth wheel hitch includes a kingpin locking mechanism having a pair of pivoting locking jaws which form a socket in which the kingpin is retained. An adjustment device varies the angular position of the closed jaws to vary the side-to-side dimension of the socket, and thereby compensate for side wear in the hitch. A stationary, semicircular bearing is fixedly mounted in the hitch to form a portion of the forward half of the socket, such that pivotal adjustment of the closed jaws also varies the fore-to-aft dimension of the socket, and thereby compensate for end wear in the hitch.