Cross groove type constant velocity joint

A cross groove type constant velocity joint, comprising:

• a cuplike outer race having a plurality of outer grooves twisting about a rotational axis of the outer race on an inner surface thereof;
• an inner race slidably disposed in the outer race and movable in a direction of the rotational axis of the outer race, the inner race including a plurality of inner grooves twisting about a rotational axis of the inner race on an outer surface thereof;
• a plurality of balls respectively disposed between the outer grooves and the inner grooves at crossing points of respective inner and outer grooves so as to roll on the outer and inner grooves;
• and
• a cage disposed between the outer race and the inner race, the cage including a plurality of windows to hold the balls,
• wherein the outer race includes a plurality of restrictions at innermost ends of the outer grooves, the restrictions being located toward a bottom of the cuplike outer race to prevent the balls from dropping out of the outer grooves when the respective balls are at innermost ends of the outer grooves,
• wherein each of the restrictions comprises a contact region at the innermost side of the outer groove and a depth region at the innermost side of the contact region, and
• wherein the ball contacts the contact region when the ball is at the innermost end of the outer groove so as to be restricted from moving further toward the innermost end of the outer groove,
• wherein the depth region is a partial spherical concavity having a larger curvature radius than the ball, and
• wherein the restrictions and the outer grooves form a contiguous surface.