Abstract: In a lateral cross section passing through a center of a trunnion in the form of a retaining member that constitutes part of a constant velocity joint, and an orthogonal site where a virtual tangent line at a contact region is perpendicular to a longitudinal direction of a guide groove, a curved surface having a first arcuate portion and a second arcuate portion is formed. The second arcuate portion is contiguous with the first arcuate portion, and has a smaller radius of curvature than the first arcuate portion. Further, the first arcuate portion and the second arcuate portion are arranged in this order from a side in proximity to an annular member of the trunnion.

Abstract: A constant velocity joint includes spherical rollers. At least parts of first inner bottom wall portions provided on an inner bottom wall surface of a cylindrical portion of the constant velocity joint are located in closer proximity to the side of an opening of the cylindrical portion than second inner bottom wall portions. When the spherical rollers are disposed at an innermost location inside the cylindrical portion and the axial directions of the spherical rollers are perpendicular to the axial direction of the cylindrical portion, at least parts of the first inner bottom wall portions abut against inner side outer circumferential surface portions of the spherical rollers, and the second inner bottom wall portions are separated away from outer side outer circumferential surface portions of the spherical rollers.

Abstract: In a lateral cross section passing through a center of a trunnion in the form of a retaining member that constitutes part of a constant velocity joint, and an orthogonal site where a virtual tangent line at a contact region is perpendicular to a longitudinal direction of a guide groove, a curved surface having a first arcuate portion and a second arcuate portion is formed. The second arcuate portion is contiguous with the first arcuate portion, and has a smaller radius of curvature than the first arcuate portion. Further, the first arcuate portion and the second arcuate portion are arranged in this order from a side in proximity to an annular member of the trunnion.

Abstract: A constant velocity joint includes spherical rollers. At least parts of first inner bottom wall portions provided on an inner bottom wall surface of a cylindrical portion of the constant velocity joint are located in closer proximity to the side of an opening of the cylindrical portion than second inner bottom wall portions. When the spherical rollers are disposed at an innermost location inside the cylindrical portion and the axial directions of the spherical rollers are perpendicular to the axial direction of the cylindrical portion, at least parts of the first inner bottom wall portions abut against inner side outer circumferential surface portions of the spherical rollers, and the second inner bottom wall portions are separated away from outer side outer circumferential surface portions of the spherical rollers.