To provide an extensible rotation transmission shaft smoothly attaining axial extension/retraction without causing looseness in a rotating direction and a radial direction, enabling the easy processing and assembling, and manufacturable at low cost.
A cylindrical elastic member 19 is installed in the gap 23 portion between a male spline part 14a and a female spline part 16a. Recessed parts 22, 22 are formed in the male spline part 14a at intervals in the circumferential direction. Second recessed parts 24, 24 are so formed in the portions of the inner peripheral surface of the elastic member 19 matching the recessed parts 22, 22 (the portions facing each other in the radial direction) as to be recessed radially outward. The hollow spaces formed by the mutually facing recessed parts 22, 22 and the second recessed parts 24, 24 are served as hollow parts 25, 25, respectively. By the elastic deformation of the elastic member 19 due to the presence of the hollow parts 25, 25, an elastic force in the direction of preventing both spline parts 14a, 16a from rattling is imparted between both the male and female spline parts 14a, 16a.
Takashi Daejeon
Masaki Muto
Kinzo Koyama