Patent ID: 7172361

Claim:
An extendable shaft comprising: a first and a second shaft section aligned on a same axis; and a clamping member for clamping the first shaft section as surrounding the first shaft section, the clamping member having a substantially circular shape, and having a pair of end portions in a circumferential direction, and being elastically diametrically expandable, the second shaft section including: an outer periphery, and external splines formed on the outer periphery, the first shaft section including: a fit hole in which the second shaft section is inserted; internal splines formed on an inner periphery of the fit hole and engaged with the external splines; an open end via which the fit hole is opened; at least one slit extended from the open end for a predetermined length along an axial direction of the first shaft section; a diametrically contractible portion which is elastically contractible and formed in a region ranging from the open end to a place away from the open end by the predetermined length along the axial direction of the first shaft section; and the diametrically contractible portion comprising at least a first portion and a second portion along a length thereof, the first portion having a wall thickness that is less than a wall thickness of the second portion, the clamping member elastically clamping at least a part of the diametrically contractible portion of the first shaft section due to its elastic resilient force.