Abstract: A tripod-shaped constant-velocity universal joint which makes downsizing feasible while reducing induced thrust force. A shaft-axis-wise width “bx” of the tripod-shaft portions of a tripod-shaped constant-velocity universal joint (i.e., a width of the tripod-shaft portions in a case where they are viewed from the torque transmission direction) is formed smaller as it goes from the root side to the leading-end side in the torque transmission region.

Abstract: In a tripod-type constant velocity joint having an inner joint member, an outer joint member, and three roller units, the radius R1, outer width W1, and inner width W2 of the outer periphery cylindrical surface of each roller unit, and the radius R3 of the center hole of each roller unit satisfy the inequalities: 0.5Rtc(1/cos 0.3??1)+(R1?R3)?<W1 and 1.5Rtc(1?cos 0.3?)+(R1?R3)?<W2, where Rtc: the radius of a circle passing through the respective centers of tripod spherical surfaces of the inner joint member, ?: the maximum joint angle between the outer joint member and the inner joint member, and ?: coefficient of friction between each tripod spherical surface and the wall surface of the center hole of the corresponding roller unit.

Abstract: A constant velocity universal unit includes an outer joint member whose inner peripheral face is formed with three guide grooves, an inner joint member including three tripod shafts each formed with a tripod spherical face, three roller units each including an outer peripheral face and an inner peripheral face coaxially formed with each other. The guide groove includes a pair of strip-shaped inner side faces formed with a pair of guide projections having a substantially half arc shape in cross section whose diameter is smaller than a height of the inner side face of the guide groove. The constant velocity universal joint further includes an annular recess formed on a substantially center portion in a height direction of the outer peripheral face of the roller unit and engaging with the pair of guide projections in a rolling manner and rotatable relative to a central axis of the guide projection.

Abstract: A constant velocity universal unit includes an outer joint member whose inner peripheral face is formed with three guide grooves, an inner joint member including three tripod shafts each formed with a tripod spherical face, three roller units each including an outer peripheral face and an inner peripheral face coaxially formed with each other. The guide groove includes a pair of strip-shaped inner side faces formed with a pair of guide projections having a substantially half arc shape in cross section whose diameter is smaller than a height of the inner side face of the guide groove. The constant velocity universal joint further includes an annular recess formed on a substantially center portion in a height direction of the outer peripheral face of the roller unit and engaging with the pair of guide projections in a rolling manner and rotatable relative to a central axis of the guide projection.

Abstract: In a tripod-type constant velocity joint having an inner joint member, an outer joint member, and three roller units, the radius R1, outer width W1, and inner width W2 of the outer periphery cylindrical surface of each roller unit, and the radius R3 of the center hole of each roller unit are determined to satisfy the following two inequalities: 0.5Rtc(1/cos0.3??1)+(R1?R3)?<W1 1.5Rtc(1?cos0.3?)+(R1?R3)?<W2 where Rtc: the radius of a circle passing through the respective centers of tripod spherical surfaces of the inner joint member, ?: the maximum joint angle between the outer joint member and the inner joint member, and ?: coefficient of friction between each tripod spherical surface and the wall surface of the center hole of the corresponding roller unit.

Abstract: A shaft assembly in which a cross-groove universal joint is mounted on each of the two end portions of a shaft. In this cross-groove universal joint, an inner race formed in the outer circumference with ball grooves inclined alternately in opposite directions with respect to the axial direction and an outer race formed in the inner circumference with ball grooves oriented to intersect the former ball grooves are concentrically fitted. Balls are arranged at the intersections between the ball grooves of the inner race and the ball grooves of the outer race, as confronting each other. The balls are retained by a cage arranged between the inner race and the outer race.