Abstract: A threaded bush assembly for receiving and coupling a shaft to a rotatable hub includes a tubular sleeve member which is located within the rotatable hub and a tubular bush member adapted to be received in either end of the sleeve member. The bush member has a central bore in which the shaft is received and is axially moveable relative to the sleeve member by means of screw threaded members. The inner circumferential surface of the sleeve member and the outer circumferential surface of the bush member each have a helical thread formed thereon. The cross-section of both threads is defined by a pair of mutually opposed tapered surfaces. The two threads are screw threadedly engageable with one another, yet define a gap therebetween which enables relative axial movement of the two threads with respect to one another such that upon axial movement of the bush member relative to the sleeve member, one tapered surface of one thread wedges against the facing tapered surface of the other thread.

Abstract: The present specification discloses a tapered, longitudinally-split contractible taper bush for securing pulleys, sprockets, coupling flanges or other machine elements onto cylindrical shafts and utilizing a plurality of screws or bolts parallel with the hub axis for effecting wedging of the bush between the hub of the element and the shaft onto which it is mounted. Known bushes of this type suffer an out of balance moment due to the arrangemnt of locking holes, part threaded holes provided for de-wedging and bush removal, and the size of the longitudinally extending slit which is necessary to promote flexibility in the bush for bush removal.The present invention overcomes the out of balance problem by providing profiling in the region of the longitudinal slit so that the disposition of metal is then such as to compensate for the mass imbalance in both the bush and a co-operating mating hub, a rotationally balanced system being thus provided.