Abstract: In a constant-velocity joint, an inner member thereof includes holders that serve to retain respective roller assemblies. When each of the holders is hypothetically divided into three equal parts made up of a proximal end portion, an intermediate portion, and a distal end portion from a side of an annular member, an inner wall surface of an inner roller of the roller assembly contacts only a side wall surface of the proximal end portion. The inner roller preferably has an inside diameter, which is minimum at a contact point that contacts the side wall surface of the proximal end portion. More specifically, the inside diameter of the inner roller gradually expands in diameter from the contact point to a side that faces toward the annular member, and further, gradually expands in diameter from the contact point to a side that faces toward the distal end portion.

Abstract: A constant-velocity joint includes an inner member. The inner member has holders that hold respective roller assemblies. Each of the holders has contact regions, which are held in abutment against an inner circumferential wall surface of an inner roller of a corresponding one of the roller assemblies, and non-contact regions, which are spaced from the inner circumferential wall surface of the inner roller. The contact regions are formed by first through fourth lobes, and the non-contact regions are formed by first through fourth recesses, for example. Hypothetical tangential lines L1 and L3, which are tangential to the first lobe and the third lobe, extend parallel to the longitudinal directions of respective guide grooves. Hypothetical tangential lines L2 and L4, which are tangential to the second lobe and the fourth lobe, extend perpendicularly to the longitudinal directions of the guide grooves.

Abstract: In a constant-velocity joint, an inner member thereof includes holders that serve to retain respective roller assemblies. When each of the holders is hypothetically divided into three equal parts made up of a proximal end portion, an intermediate portion, and a distal end portion from a side of an annular member, an inner wall surface of an inner roller of the roller assembly contacts only a side wall surface of the proximal end portion. The inner roller preferably has an inside diameter, which is minimum at a contact point that contacts the side wall surface of the proximal end portion. More specifically, the inside diameter of the inner roller gradually expands in diameter from the contact point to a side that faces toward the annular member, and further, gradually expands in diameter from the contact point to a side that faces toward the distal end portion.

Abstract: A constant-velocity joint includes an inner member. The inner member has holders that hold respective roller assemblies. Each of the holders has contact regions, which are held in abutment against an inner circumferential wall surface of an inner roller of a corresponding one of the roller assemblies, and non-contact regions, which are spaced from the inner circumferential wall surface of the inner roller. The contact regions are formed by first through fourth lobes, and the non-contact regions are formed by first through fourth recesses, for example. Hypothetical tangential lines L1 and L3, which are tangential to the first lobe and the third lobe, extend parallel to the longitudinal directions of respective guide grooves. Hypothetical tangential lines L2 and L4, which are tangential to the second lobe and the fourth lobe, extend perpendicularly to the longitudinal directions of the guide grooves.