Patent ID: 8317404

Claim:
A cage for a ball bearing assembly, comprising: a plurality of pockets, each of the pockets accommodating a ball of the ball bearing assembly, each of the plurality of pockets being defined at a plurality of locations in a circumferential direction of the ball bearing assembly, wherein each of the plurality of pockets has an inner surface so shaped as to represent a concaved surface in which a portion on an inner diametric side of a ball row pitch circle described by a circular row of the balls has its diameter reduced towards a cage inner diametric side open edge, and wherein the inner surface of each of the pockets further includes a concaved portion extending concavely from the open edge on the cage inner diametric side towards a cage outer diametric side, the concaved portion having a radius of curvature smaller than that of the concaved spherical surface forming the inner surface of each of the plurality of pockets, taken along a cage circumferential direction.