Patent ID: 7641558

Claim:
A constant-velocity joint having a tubular outer member having a plurality of axially extending guide grooves defined in an inner circumferential surface thereof and spaced at predetermined intervals, said outer member being connected to one transmission shaft, and an inner member inserted in an open internal space of said outer member and connected to another transmission shaft, wherein said inner member comprises: a plurality of trunnions projecting into said guide grooves; a ring-shaped roller held in contact with each of said guide grooves and fitted over each of said trunnions; and a plurality of rolling elements rollingly interposed between each of said trunnions and said roller, said roller having a flange disposed on an inner circumferential surface thereof near a projecting end of each of said trunnions, said flange projecting radially inwardly and circularly extending along said inner circumferential surface, wherein an annular member is mounted on said trunnion near a proximal end thereof, said rolling elements being retained between said flange and said annular member, and wherein a ratio (r 1 /D) of a radius (r 1 ) of curvature of an outer circumferential surface of said trunnion, which extends from a cylindrical portion of the trunnion, onto which said roller is fit, to said proximal end thereof to a diameter (D) of said cylindrical portion is set to a range from 0.05 to 0.35.