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 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 is provided with at least a pair of tracks whose geometry is defined based on ball path that follows a parametric equation and the parametric function is in the form of a polynomial displacement function of a fourth order or larger.

A constant velocity joint is provided with at least a pair of tracks whose geometry is defined based on ball path that follows a parametric equation and the parametric function is in the form of a polynomial displacement function of a fourth order or larger.

A constant-velocity rotary joint includes an outer joint portion with outer ball tracks, an inner joint portion with inner ball tracks, balls guided in a track pair formed by one outer ball track and one inner ball track, and a cage with windows to accommodate and retain the balls. Each outer ball track has an outer ball track center line. Each inner ball track has an inner ball track center line. When the constant-velocity rotary joint is straight, the inner ball track center line and the outer ball track center line of the track pair intersect in an intersection point and are not mirror-symmetrical with respect to a mirror plane through the intersection point, and the inner portion of the inner ball track center line widens more, with respect to a longitudinal axis of the outer joint portion, than the outer portion of the outer ball track center line.

A constant-velocity rotary joint includes an outer joint portion with outer ball tracks, an inner joint portion with inner ball tracks, balls guided in a track pair formed by one outer ball track and one inner ball track, and a cage with windows to accommodate and retain the balls. Each outer ball track has an outer ball track center line. Each inner ball track has an inner ball track center line. When the constant-velocity rotary joint is straight, the inner ball track center line and the outer ball track center line of the track pair intersect in an intersection point and are not mirror-symmetrical with respect to a mirror plane through the intersection point, and the inner portion of the inner ball track center line widens more, with respect to a longitudinal axis of the outer joint portion, than the outer portion of the outer ball track center line.

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.

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.

A clutch tool includes a housing that is non-rotatable with respect to the first section of the work string and comprising inner grooves. The clutch tool also includes an inner mandrel that is non-rotatable with respect to the second section of the work string. The inner mandrel includes outer grooves that extend along only an axial portion of the inner mandrel. Further, the inner mandrel includes a torque transition area opening from the outer grooves and extending completely around the inner mandrel. The clutch tool also includes a torque sleeve comprising inner protrusions engageable with the outer grooves and outer protrusions engageable with the outer grooves, the outer protrusions being angled. Moreover, the clutch tool includes a biasing device to bias the inner protrusions of the torque sleeve into engagement with the outer grooves.

A clutch tool includes a housing that is non-rotatable with respect to the first section of the work string and comprising inner grooves. The clutch tool also includes an inner mandrel that is non-rotatable with respect to the second section of the work string. The inner mandrel includes outer grooves that extend along only an axial portion of the inner mandrel. Further, the inner mandrel includes a torque transition area opening from the outer grooves and extending completely around the inner mandrel. The clutch tool also includes a torque sleeve comprising inner protrusions engageable with the outer grooves and outer protrusions engageable with the outer grooves, the outer protrusions being angled. Moreover, the clutch tool includes a biasing device to bias the inner protrusions of the torque sleeve into engagement with the outer grooves.