Four-point contact ball bearing

摘要

A four-point ball bearing includes: an inner ring (1) and an outer ring (2) defining raceway grooves (12), respectively. Each of the raceway grooves is constituted by two circular arcs different in curvature (12A,12B) provided on opposite sides of a widthwise center of the raceway groove. A plurality of balls (3) are arranged between the inner and outer rings so that the balls can roll. In at least one of the raceway grooves, a center of curvature (a) of one of the circular arcs and a center of curvature (b) of the other circular arc are displaced from each other at least in a radial direction so that spin is generated in each of the balls.