A power transmission shaft includes: a bearing including a cylindrical portion, an internal spline portion, and an internal spline side annular groove including a bottom surface, and a first side wall and a second side wall, the first side wall which includes a first inclination surface inclined with respect to the rotation axis of the shaft portion, and on which the circlip is abutted in a state where a radius of the circlip is decreased within the internal spline side annular groove, and the second side wall on which the circlip is abutted in the state where the radius of the circlip is decreased within the internal spline side annular groove.

A power transmission shaft includes: a bearing including a cylindrical portion, an internal spline portion, and an internal spline side annular groove including a bottom surface, and a first side wall and a second side wall, the first side wall which includes a first inclination surface inclined with respect to the rotation axis of the shaft portion, and on which the circlip is abutted in a state where a radius of the circlip is decreased within the internal spline side annular groove, and the second side wall on which the circlip is abutted in the state where the radius of the circlip is decreased within the internal spline side annular groove.

A joint assembly for use in a motor vehicle. The joint assembly includes a first joint member that is drivingly connected to a second joint member via one or more third joint members. At least a portion of the first joint member is drivingly connected to at least a portion of a first shaft and at least a portion of the second joint member is drivingly connected to at least a portion of a second shaft. One or more first joint member tool grooves circumferentially extends along the outer surface of the first joint member. The joint assembly further includes a nut that drivingly connects at least a portion of a third shaft to at least a portion of the second shaft. The nut includes one or more nut tool grooves circumferentially extending along the outer surface of the nut.

A joint assembly for use in a motor vehicle. The joint assembly includes a first joint member that is drivingly connected to a second joint member via one or more third joint members. At least a portion of the first joint member is drivingly connected to at least a portion of a first shaft and at least a portion of the second joint member is drivingly connected to at least a portion of a second shaft. One or more first joint member tool grooves circumferentially extends along the outer surface of the first joint member. The joint assembly further includes a nut that drivingly connects at least a portion of a third shaft to at least a portion of the second shaft. The nut includes one or more nut tool grooves circumferentially extending along the outer surface of the nut.

A constant velocity universal joint includes a body which encloses the constant velocity joint components and provides a smooth outer surface. A semi-rigid plastic boot has a spherical surface sized to generally match the outer surface of the body. The material of the boot is sufficiently elastic to allow the boot to fit over the body, yet sufficiently resilient to snap the open end closed after the boot is placed over the body to provide a substantial seal preventing entry of debris under the seal. A retaining ring is positioned on the boot near the truncated end, the ring establishing the location of an elastic seal that contacts the outer surface of the body.

A constant velocity universal joint includes a body which encloses the constant velocity joint components and provides a smooth outer surface. A semi-rigid plastic boot has a spherical surface sized to generally match the outer surface of the body. The material of the boot is sufficiently elastic to allow the boot to fit over the body, yet sufficiently resilient to snap the open end closed after the boot is placed over the body to provide a substantial seal preventing entry of debris under the seal. A retaining ring is positioned on the boot near the truncated end, the ring establishing the location of an elastic seal that contacts the outer surface of the body.

A constant velocity universal joint includes an inner ring and an outer ring. A cage is disposed between an outer spherical surface of the inner ring and an inner spherical surface of the outer ring, and has windows in which respective balls are received. The cage has ball contact surface areas with which the balls come into contact, and includes soft portions that are lower in hardness than the ball contact surface areas. The soft portions are formed by local heat treatment at portions of the windows that are kept out of contact with the balls or surface portions around the windows.

A constant velocity universal joint includes an inner ring and an outer ring. A cage is disposed between an outer spherical surface of the inner ring and an inner spherical surface of the outer ring, and has windows in which respective balls are received. The cage has ball contact surface areas with which the balls come into contact, and includes soft portions that are lower in hardness than the ball contact surface areas. The soft portions are formed by local heat treatment at portions of the windows that are kept out of contact with the balls or surface portions around the windows.

An axle assembly for a driving wheel of a vehicle allows a wheel-side joint and a shaft to be rotated separately from a boot while driving so as to prevent generation of friction noise of the boot. The axle assembly includes the shaft rotated by receiving driving force from a powertrain; an axle housing disposed to pass through a center of a steering knuckle connected to a steering apparatus; a wheel bearing mounted between the steering knuckle and the axle housing; a joint bearing mounted on an outer part of the shaft; and a boot unit configured to have a first end coupled to an outer race of the joint bearing and a second end coupled to an outer race of the wheel bearing so as to form a space filled with a lubricant outside the shaft.

A ball-type constant velocity joint may include: an outer race part installed on a shaft and having a plurality of first grooves formed axially in the inner surface thereof; a first inner race part including: a first inner race rotatably installed in the outer race part, having a plurality of second grooves formed on the outer surface thereof, and having a plurality of third grooves formed axially on the inner surface thereof; and a plurality of first balls installed between the first grooves and the second grooves; and a second inner race part including: a second inner race rotatably installed in the first inner race, and having a plurality of fourth grooves formed on the outer surface thereof and facing the third grooves; and a plurality of second balls installed between the third grooves and the fourth grooves.