PURPOSE: To make any bending moment so as not to act on a bolt by installing a through hole in an outer ring being held between a collar of an inner ring and a clamping ring, in case of a fastener for the shaft that used these inner and outer rings with tapers and a rotor.

CONSTITUTION: This fastener has taper surfaces 8 and 14 being adjoined each other, and it consists of a combination of an inner ring 5 having a collar 12 with a hole for a fastening bolt on one side and an outer ring 6 having an axial through hole 10' on the other, and a clamping ring 7 with a fastening bolt tapped hole 19 plus a clamping bolt 15. when this clamping bolt 15 is tightened, the inner ring 6 is expanded of its diameter and the inner ring 5 is contracted of its diameter the other way by each action of their taper surfaces 9 and 14, a shaft 1 and a rotor 2 are fastened together by a wedge action. In this connection, if a guideway 12a in parallel with the shaft 1 to a boss hole of the shaft 1 or the rotor 2 is installed in the collar 12 and the clamping ring 7 each in advance, it performs a centering function so that the rotor 2 and the shaft 1 are well aligned.