A coupling device includes two coaxial shafts, namely a tubular outer shaft and an inner shaft, capable of rotating about a reference axis; a wrap-around raceway formed on a first one of the coaxial shafts; an oblique raceway formed on the second coaxial shaft and a play take-up rail provided with a complementary raceway and movable relative to the second coaxial shaft parallel to a plane perpendicular to the reference axis. A row of balls is positioned to run parallel to the reference axis on the wrap-around raceway, the oblique raceway and the complementary raceway, to guide the two coaxial shafts relative to each other in translation.

A constant velocity joint includes balls each rollably supported by an associated one of outer ball grooves and an associated one of inner ball grooves facing each other such that the inclined direction of the associated outer ball groove relative to a central axis of an outer joint member is opposite to the inclined direction of the associated inner ball groove relative to a central axis of an inner joint member. The inner joint member includes escape portions to allow escape of the balls from the inner ball grooves to a first side of the central axis of the inner joint member. Each of the escape portions is provided at least between an end face at the first side of the central axis of the inner joint member and a first rolling guide lateral surface of the associated inner ball groove that forms an acute angle with the end face.

A constant velocity joint includes balls each rollably supported by an associated one of outer ball grooves and an associated one of inner ball grooves facing each other such that the inclined direction of the associated outer ball groove relative to a central axis of an outer joint member is opposite to the inclined direction of the associated inner ball groove relative to a central axis of an inner joint member. The inner joint member includes escape portions to allow escape of the balls from the inner ball grooves to a first side of the central axis of the inner joint member. Each of the escape portions is provided at least between an end face at the first side of the central axis of the inner joint member and a first rolling guide lateral surface of the associated inner ball groove that forms an acute angle with the end face.

A constant velocity universal joint includes an outer joint member and a joint internal component received in the outer joint member. A shaft is fitted into an inner joint member. The outer joint member has a cup bottom formed on a side opposite to a shaft-fitting side. The cup bottom is configured to regulate movement of the joint internal component toward the side opposite to the shaft-fitting side in a normal state in which an impact generated in an abnormal state is not applied. The cup bottom has a cut portion which is to be cut by the impact generated in the abnormal state involving movement of the joint internal component toward the side opposite to the shaft-fitting side.

A constant velocity universal joint includes an outer joint member and a joint internal component received in the outer joint member. A shaft is fitted into an inner joint member. The outer joint member has a cup bottom formed on a side opposite to a shaft-fitting side. The cup bottom is configured to regulate movement of the joint internal component toward the side opposite to the shaft-fitting side in a normal state in which an impact generated in an abnormal state is not applied. The cup bottom has a cut portion which is to be cut by the impact generated in the abnormal state involving movement of the joint internal component toward the side opposite to the shaft-fitting side.

Constant-velocity slip ball joint at least having an outer joint part with an axis of rotation and with outer ball tracks, having an inner joint part with inner ball tracks, having a plurality of torque-transmitting balls, each guided in associated outer and inner ball tracks, and having a cage, which is provided with a plurality of cage windows, which accommodate in each case one or more of the balls; wherein the inner joint part can be displaced in relation to the outer joint part by a displacement distance along the axis of rotation; wherein at least a part of the outer ball tracks and at least a part of the inner ball tracks are at a track-helix angle in relation to the axis of rotation; wherein a floor of each ball track, along the displacement path is spaced apart from the axis of rotation by a respectively constant spacing along a radial direction; wherein a maximum angle of deflection of the inner joint part in relation to the outer joint part is predetermined by an outer contact surface of the cage establishing contact with a first contact surface of the outer joint part and/or by an inner contact surface of the cage establishing contact with a second contact surface of the inner joint part; wherein the cage has a center axis and the inner contact surface is conical; wherein the inner contact surface is at an opening angle of more than 0 degrees in relation to the center axis of the cage.

A double-offset plunging type constant velocity universal joint includes inner and outer joint members each having six linear track grooves extending along an axial direction. The inner joint member has a coupling hole at a center portion thereof for coupling a shaft. Six torque transmission balls retained by a cage are incorporated between the linear track grooves of the inner and outer joint members. A ratio T.sub.CAGE/D.sub.BALL of a minimum thickness (T.sub.CAGE) of the cage to a diameter of the torque transmission ball (D.sub.BALL) is from 0.225 to 0.245, wherein a ratio D.sub.BALL/D.sub.S of a diameter (D.sub.BALL) of the torque transmission ball to a spline large diameter (D.sub.S) of the coupling hole of the inner joint member is from 0.79 to 0.85, and wherein a ball contact ratio () of the torque transmission ball is from 1.08 to 1.12.

A double-offset plunging type constant velocity universal joint includes inner and outer joint members each having six linear track grooves extending along an axial direction. The inner joint member has a coupling hole at a center portion thereof for coupling a shaft. Six torque transmission balls retained by a cage are incorporated between the linear track grooves of the inner and outer joint members. A ratio T.sub.CAGE/D.sub.BALL of a minimum thickness (T.sub.CAGE) of the cage to a diameter of the torque transmission ball (D.sub.BALL) is from 0.225 to 0.245, wherein a ratio D.sub.BALL/D.sub.S of a diameter (D.sub.BALL) of the torque transmission ball to a spline large diameter (D.sub.S) of the coupling hole of the inner joint member is from 0.79 to 0.85, and wherein a ball contact ratio () of the torque transmission ball is from 1.08 to 1.12.

A method of manufacturing an outer joint member of a constant velocity universal joint includes forming cup and shaft members of medium carbon steel, preparing, as the cup member, a cup member having cylindrical and bottom portions integrally formed by forging, and a joining end surface formed on an outer surface of the bottom portion, and preparing, as the shaft member, a shaft member having a joining end surface to be joined to the bottom portion of the cup member. The method also includes bringing the joining end surfaces of the cup and shaft members into abutment against each other, and welding the cup and shaft members from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup members.

A fixed type constant velocity universal joint (3) includes an outer joint member (31), an inner joint member (32), eight balls (33), and a cage (34). A diameter (D.sub.31c) of the outer joint member (31) at an opening end of an inner peripheral surface (31c) is set larger than an outer diameter (D.sub.34b) of the cage (34) at a center portion in a circumferential direction of pockets (34a) when the cage (34) is seen from an axial direction of the joint. A bottom surface (31f) of a mouth section (31a) of the outer joint member (31) is arranged so as to interfere with an imaginary spherical surface (Q) being an extension of the inner peripheral surface (31c) of the outer joint member (31) toward a deep-side.