US Patent 7214134 Fixed constant velocity universal joint

A fixed constant velocity universal joint includes: an outer ring having a plurality of track grooves extending axially in its inner spherical surface; an inner ring having a plurality of track grooves extending axially in its outer spherical surface; torque transmission balls arranged in ball tracks formed by cooperation of the track grooves of the outer ring and the track grooves of the inner ring; and a cage having pockets for retaining the torque transmission balls. The center of the track grooves of the outer ring and the center of the track grooves of the inner ring are offset from the spherical center of the inner spherical surface and the spherical center of the outer spherical surface, respectively, by the same distance axially in opposite directions. An axial clearance between the pockets and the torque transmission balls is set within the range of −0.006 and −0.035 mm. A spherical portion clearance between the cage and the inner ring is set so that a clearance-to-diameter ratio falls within the range of 0.9 and 2.3.