PURPOSE: To prevent generation of a play so as to prevent generation of abrasion and abnormal noise in a connecting portion due to a play by achieving a stable tightened state at three points in a connecting structure for connecting an inner and an outer spline to each other.
CONSTITUTION: The relationship between a thickness of a spline tooth of an inner spline portion and a thickness of a spline tooth of an outer spline portion is determined as follows: The thickness of a spline tooth in an arcuate portion extending on both sides in the circumferential direction by a predetermined length is formed into a large tooth thickness 21d, a middle tooth thickness 21e and a small tooth thickness 21f. Clearances between the teeth in the engaged portion of the splines before connection of the splines exist in portions of the small and middle tooth thicknesses 21f, 21e, where the clearance in the portion of the small tooth thickness 21f is larger than that in the portion of the middle tooth thickness 21e, while are made almost zero in the portion of the large tooth thickness 21d. Furthermore, a clearance between the tooth surfaces before and after the tooth thickness of each spline of the small and middle tooth thicknesses 21f, 21e becomes approximately equal to each other.
SHINDO HIROAKI
AOYAMA NOBORU
