Constant-velocity-ratio universal joints

A fixed (i.e. non-plunging) constant-velocity-ratio universal joint, comprising:

• an outer joint member (10) of hollow configuration having a rotational axis (16), a plurality of at least partially arcuate tracks (17) circumferentially spaced about said axis (16) in the interior of the outer joint member and having centre lines extending in meridian planes relative to said axis,
• lands (18) defined between said tracks and which are integral with the outer joint member and have radially-inwardly directed surfaces;
• an inner joint member (11) disposed within the outer joint member and having a rotational axis,
• a plurality of at least partly arcuate tracks (19) on the exterior of the inner joint member, having centre lines extending in meridian planes with respect to the rotational axis of the inner joint member and which face the tracks (17) in the outer joint member in opposed pairs,
• lands (23) defined between the tracks on the inner joint member, the lands on the inner joint member having radially-outwardly directed, surfaces;
• a plurality of balls (13) disposed one in each pair of facing tracks (17, 19) in the outer and inner joint members for torque transmission between the members;
• a cage (12) of annular configuration disposed between the inner and outer joint members (11, 10) and having openings (20) in which respective balls (13) are received and constrained so that their centres lie in a common plane (P);
• the cage having external and internal surfaces (22, 21) which engage the land surfaces on the outer and inner joint members respectively;
• first contacting portions (27, 30, 343, 40) of the external surface (21) of the cage and the facing surfaces of the lands (18) of the outer joint member adjacent one end (A) of the outer joint member which are in contact when the joint is transmitting torque and resist the axial forces on the cage due to the joint geometry,
• at least one of the configurations of the tracks (17, 19) in the outer and inner joint members, and the the internal and external surfaces (21, 22) of the cage, being such that when the joint is articulated said common plane (P) is caused substantially to bisect the angle between the rotational axes of the joint members;
• characterised in that there is a relief portion (25;
• 32, 33;
• 36;
• 42) in each of said land surfaces of the outer joint member located, when the joint is in its unarticulated position, either between the first contacting surface portion (27, 30, 34, 40) of the land surface and said common plane (P) or about said common plane, each relief portion comprising a surface portion (32, 33;
• 37, 38, 39;
• 43-47) of the outer joint member which, during articulation and use of the joint to transmit torque, does not contact the facing external surface of the cage and which:
• is separated from the adjacent first contacting surface portion (27) by an abrupt change in the gradient of said surface in longitudinal section which may form a step (26);
• or is defined by a surface or surfaces (32, 33) the or each of which has a different radius of curvature from the surface of the adjacent first contacting surface portion (30) and which may be tangential to the surface of said first contacting surface portion;
• or
• in longitudinal section (43, 44) is straight;
• or
• is defined by a surface which in longitudinal section meets the surface of the adjacent first contacting surface in a point of inflexion (34, 37),
• each relief portion extending across the whole circumferential width of the land (18) between the tracks (17) that border the land;
• and
• in that there are second contacting portions (127, 31, 35, 41) of the facing surfaces of the lands (18) of the outer joint member and of the external cage surface (21) to control the axial float of the cage and which are separated from the first contacting portions by the relief portions (25, 32, 33), 36;
• 42).