a railway car truck assembly includes spaced side frames supported by truck journal bearings . a bolster extends transversely between the side frames . a spring assembly is supported on the spaced side frames and engages the lower surface of the boltster . the bolster includes a center bearing and a pair of side bearings mounted on either side of the center bearing . the side bearings receive the weight of the car body . each of the side bearings includes an upper surface made of a first low friction material . the car body includes a depending center portion engaging the center bearing and spaced side portions having a lower surface made of a second low friction material engaging the side bearings . one of the first and second low friction materials is selected from nylon polyesters , polycarbonates , polyacetals and polysulfones . the other of the first and second low friction materials is selected from polytetrafluoroethylene . the coefficient of friction between the upper and lower surfaces is sufficiently low that the truck easily rotates with respect to the car body . the second low fricion material may optionally include a polymeric polyolefin component such as polyethylene , having a low exchange time , and the minor amount of a chemically inert fluorinated hydrocarbon polymeric material such as polytetrafluoroethylene .