In a truck assembly for a railway vehicle wherein the assembly has a truck frame defined by opposed side frame sections and a transom section extending transversely between the side frame sections and substantially at mid-length thereof. A pair of wheels are supported between opposed ends of the side frame sections. A truck bolster assembly is supported above the transom for supporting a cab thereon. The bolster assembly is retained in position relative to the transom by a central pivot. The improvement comprises side bearing height adjusters which are removably secured between the truck frame and the truck bolster assembly and spaced from the central pivot on a respective side thereof. The side bearing height adjusters have a bearing element with a top friction support surface to permit horizontal displacement of the bolster assembly about the central pivot.