Ball bearing

Abstract

A ball bearing prevents vibration of a cage while preventing deformation of the cage in strain wave gearing. A ball bearing includes an inner ring deformable, an outer ring deformable and installed outside the inner ring, a plurality of rolling elements having a spherical shape and provided between the inner ring and the outer ring, and a cage provided with a plurality of pockets respectively accommodating the plurality of rolling elements and separated by gaps in a circumferential direction. Each of the plurality of pockets includes a pocket surface spread about a pocket axial line extending in a radial direction, and a flange part protruding from the pocket surface toward the pocket axial line. The pocket surface is configured to accommodate the rolling element with a gap interposed between the pocket surface and the rolling element, and the flange part is configured to come into contact with the rolling element positioned at at least a position of a minor radius of the inner ring from an inner side in the radial direction.