Abstract: A rotary body fixing device capable of mounting and removing a rotary body on a shaft easily and rapidly. The device has inner and outer elastically deformable rings and a pair of oppositely tapered rings for wedging between the inner and outer rings in a clamping position. Extraction bolt holes 4F for threaded engagement with extraction bolts 7 are formed axially through one tapered ring 4. The extraction bolts 7 come into abutment at their tip ends against an end face of the other tapered ring 5 to move both tapered rings away from each other. In an axially medial part of the outer peripheral surface of the inner ring 2 and of the inner peripheral surface of the outer ring 3, annular grooves respectively form stepped portions on both sides of the annular groove.

Abstract: The invention provides an apparatus and a method for controlling the rotation frequency of an infinite variable-speed drive in which, when an error is caused in an output rotation frequency of the infinite variable-speed drive during a processing time period, a target rotation frequency is calculated in view of the error, so as to control the rotation frequency in the remaining processing time period in accordance with the calculated target rotation frequency. The target rotation frequency is calculated on the basis of the remaining processing time period and a pulse number to be counted in the remaining processing time period.