Abstract: A ball bearing retainer includes two annular members that face each other in an axial direction. The two annular members have opposed surfaces each including hemispherical pockets that are formed at a plurality of positions in a circumferential direction and configured to receive balls. The opposed surfaces are snap-fitted to each other so as to couple the two annular members to each other with coupling portions provided at both circumferential end portions of each of the hemispherical pockets Inner peripheral surfaces of the hemispherical pockets of the two annular members and the opposed surfaces of the two annular members have recessed grooves that are opened by extending from radially inner surfaces of the two annular members and reaching radially outer surfaces of the two annular members.

Abstract: Provided is a ball bearing retainer, comprising two annular members (10) that face each other in an axial direction, the two annular members (10) having opposed surfaces (11) each comprising hemispherical pockets (12) that are formed at a plurality of positions in a circumferential direction and configured to receive balls, the opposed surfaces (11) being snap-fitted to each other so as to couple the two annular members (10) to each other with coupling portions (18) provided at both circumferential end portions of each of the hemispherical pockets (12). Inner peripheral surfaces of the hemispherical pockets (12) of the two annular members (10) and the opposed surfaces (11) of the two annular members (10) comprise recessed grooves (19, 20) that are opened by extending from radially inner surfaces of the two annular members (10) and reaching radially outer surfaces of the two annular members (10).

Abstract: A rolling bearing is disclosed of which the lifespan is increased by reducing brittle flaking and impression-induced flaking on the raceways of inner and outer races and the rolling elements. Steel containing 1.80-1.89% by weight of chrome (brittle flaking-resistant steel) is subjected to carbonitriding and then to hardening and tempering. The chrome reduces generation of white layers which are aggregates of carbon, thus reducing brittle flaking on e.g. the raceways (1a, 4a) due to the white layers. A residual austenite region (5) that forms when the steel is hardened and tempered increases toughness of the steel surface, thus reducing impression-induced flaking due to foreign matter such as wear dust. By reducing both brittle flaking and impression-induced flaking, it is possible to extend the lifespan of the bearing, and reduce maintenance cost such as the cost for changing lubricating oil.

Abstract: The object is to improve heat dissipation ability of a rolling bearing while preventing creeping of a resin pulley. With two axially spaced apart circumferential grooves 13 formed in the radially outer surface of the outer race 12, the resin pulley 14 is integrally fixed to the outer race 12 by injection molding such that the end surfaces of the outer race 12 and both end portions of the radially outer surface of the outer race 12 are exposed. Since resin forming a boss portion 15 of the resin pulley 14 is engaged in the circumferential grooves 13, radially extending side walls of the circumferential grooves 13 contact radial surfaces of the resin pulley 14. This prevents creeping of the resin pulley 14. Since the exposed end surfaces and radially outer surface of the outer race 12 act as heat dissipation surfaces, it is possible to improve the ability to dissipate heat from the bearing.

Abstract: A pulley fixing structure includes a pulley with a ball bearing, and a bracket having a shaft portion on which the inner race of the bearing is pressed with an interference fit. The thermal expansion of the radially outer portion of the shaft portion of the bracket is larger than that of the radially inner portion of the inner race of the bearing. The interference thus decreases at a low temperature. Reduction of the radial clearance of the bearing 1 by pressing is thus compensated, and cold weather noise can be prevented while reducing the number of required parts and making the assembly process simple.

Abstract: An auto-tensioner for engine accessories is proposed which can smoothly follow shrinkage and expansion of a belt and which can minimize the amplitude of vibration of the belt. A seal member 13 is mounted to a cylinder 11 at its top open end. A rod 16 slidably extends through the seal member 13. A return spring 21 biases the rod 16 outwardly. A plunger 24 is slidably received in a sleeve 12 having a bottom and received in the cylinder 11, and is connected to the bottom of the rod 16. The plunger 24 has a passage 27 through which a lower pressure chamber 25 and an upper reservoir chamber 26 communicate with each other. A check valve 28 is provided at the passage 27. A return chamber 29 is defined under the sleeve 12 so as to communicate with the reservoir chamber 26. In the bottom of the sleeve 12, a valve hole 31 is formed through which the return chamber 29 communicates with the pressure chamber 25. A relief valve 32 is provided at the valve hole 31.