A constant-velocity universal joint including a generally cup-shaped outer joint member and an inner joint member that define first and second groove portions. A pinch angle by which a ball is pinched in the first groove portion is open toward an opening of the outer joint member. A pinch angle by which the ball is pinched in the second groove is open toward a bottom of the outer joint member. An absolute value of the pinch angle in a larger-pinch-angle groove portion that is one of the first and second groove portions, is larger than an absolute value of the pinch angle in a smaller-pinch-angle groove portion that is the other of the first and second groove portions in a reference state. A radial clearance in the smaller-pinch-angle groove portion is larger than a radial clearance in the larger-pinch-angle groove portion when torque is not transmitted in the reference state.

A constant velocity joint includes an outer joint portion with a first longitudinal axis, a first attaching end, an aperture end and outer ball tracks on an inner circumferential surface, an inner joint portion with a second longitudinal axis, a second attaching end, an inner face facing towards the outer joint portion and inner ball tracks on its outer circumferential surface, balls for torque transmission between the outer and inner joint portions, an annular ball cage between the outer and inner joint portions with several cage windows in which the balls are guided. The inner and outer joint portions are arranged so that one outer ball track and one inner ball track are in each case arranged opposite to each other to form three different types of track pairs to receive one respective balls. The balls have different controlling behaviors due to different track geometries.

A counter track joint comprises an outer joint part, an inner joint part, first pairs of tracks widening towards the opening side of the outer joint part when the counter track joint is aligned, and second pairs of tracks widening towards the connecting side of the outer joint part when the counter track joint is aligned; a ball in each of the first and second pairs of tracks; a ball cage having circumferentially distributed cage windows each receiving one of the balls, wherein one of the outer ball track group and the inner ball track group is hardened and hard machined, and the other of the outer ball track group and the inner ball track group is soft finished and subsequently hardened. A method of manufacturing a counter track joint is provided.

A fixed type constant velocity universal joint has an operation mode in which, when a maximum operating angle is taken, in a column portion that is one of column portions on both sides of a pocket of a cage receiving a torque transmission ball at a phase angle and is located on a side corresponding to a phase angle larger than the phase angle, a projection end portion obtained by projecting an end portion of a spherical inner peripheral surface of the outer joint member on the opening side in a perpendicular direction toward the spherical outer peripheral surface of the cage and a projection end portion obtained by projecting an end portion of the spherical outer peripheral surface of the inner joint member on the back side in the perpendicular direction toward the spherical inner peripheral surface of the cage overlap in the axial direction of the cage.

A constant velocity joint assembly includes an inner annulus having a first race and an outer annulus having a second race supporting the first race for pivotal movement relative to the second race about a pivot axis. A third race is provided by the outer annulus and a fourth race is provided by an interface member. A ball spline is disposed between the third race and the fourth race for axial stroking movement of the third race relative to the fourth race, wherein the ball spline is axially offset from the pivot axis. Separate boots seal and isolate the pivotal movement and the stroking movement from one another.

A forging apparatus includes an ironing mechanism and a phase alignment mechanism. The ironing mechanism includes: a punch set, which is fitted into a cylindrical portion of a pre-processing material to be formed into the outer joint member, and is radially expandable and contractible, the cylindrical portion having grooves formed in an inner peripheral surface thereof; and a die having a hole into which the cylindrical portion is press-fitted. The phase alignment mechanism is configured to align phases of the grooves in the inner peripheral surface of the pre-processing material and phases of track groove portion forming surfaces of the punch set with each other before the pre-processing material is fitted to the punch set.

A joint-center-fixed constant velocity joint configured to be provided in a vehicle includes an outer joint member, an inner joint member, a first ball, a second ball, and a cage. While a center of the first ball is moving to a position of the maximum use angle on an opening side from a joint center, a first open angle faces the opening side. While a center of the second ball is moving to a position of the maximum use angle on a bottom side from the joint center, a second open angle is not reversed from a state where the second open angle faces the bottom side to a state where the second open angle faces the opening side.

In a constant velocity joint, a center locus of a first ball rolling on a first outer central portion is inclined such that a distance from a central axis of an outer joint member decreases toward a bottom side of the outer joint member. A center locus of a second ball rolling on a second outer central portion is formed in a linear shape and inclined such that a distance from the central axis of the outer joint member increases toward the bottom side of the outer joint member. A center locus of the second ball rolling on the second outer bottom side portion is formed in an arc shape and disposed in the outer joint member at a position radially inwardly from a tangent at a connecting position between the second outer central portion and the second outer bottom side portion.

In a constant-velocity joint, a center locus of a ball rolling on a first outer large-diameter portion has an arc shape having an arc center, and a center locus of the ball rolling on a second outer large-diameter portion has an arc shape having an arc center. Center loci of the ball rolling on an outer extension portion are positioned, throughout their lengths, in a region inducing a tangent line to an opening-side end portion of the center locus of the ball rolling on the second outer large-diameter portion, the region being positioned outward of the tangent line in a radial direction of the outer joint member. An opening-side end portion of the center locus of the ball rolling on the outer extension portion is positioned outward of the tangent line in the radial direction of the outer joint member.

Track grooves of an outer joint member include first and second track groove portions. An end portion of the ball raceway center line of each of the first track groove portions is located on the opening side with respect to a joint center and a ball raceway center line of each of the second track groove portions is connected to the end portion. A ball raceway center line of each of the track grooves of the inner joint member is formed to be mirror-image symmetrical with a ball raceway center line of a corresponding one of the paired track grooves of the outer joint member with respect to a plane that includes the joint center at an operating angle of 0 and is orthogonal to a joint axial line.