Abstract: A rolling bearing, comprising an inner race, an outer race and rolling members which roll therebetween, at least one of the inner and outer races being subjected to carburizing and heating treatment, is characterized in that:the one race comprises a carbon steel containing 0.1 to 0.7 wt. % of carbon, with the residual austenite content on the track surface layer being 20 to 45 vol. % and the rolling members comprise a carbon steel containing 0.7 to 1.1 wt. % of carbon having carbonitriding and heating treatment applied on the surface layer, with the residual austenite content in such surface layer being 20 to 45 vol. % and the carbonitride in such surface being 3 to 15 vol. %.In another form of the bearing, the rolling members may comprise a carbon steel containing 0.1 to 0.7 wt. % of carbon, with the surface layers thereof being subjected to carburizing and heating treatment and having a residual austenite content of 20 to 45 vol. %.

Abstract: In a bearing including an inner race and an outer race disposed concentrically, a plurality of rolling members interposed between the two races, and two ring members of synthetic resin axially spaced on the outer peripheral surface of the outer race and wherein a rotating member is inserted in the inner race and the outer race is fitted and held in a non-rotating member through the ring members, two circumferential grooves are provided at an interval in the outer peripheral surface of the outer race. Each of the circumferential grooves comprises a first portion located toward a respective axial end of the outer race and whose bottom surface comprises an arcuate surface of a single radius, and a second portion located more toward the opposite axial end than the first portion and being narrower and shallower than the first portion.