Patent ID: 7219775

Claim:
Apparatus comprising: a base member; a shaft carried on bearings attached to the base member in a mounting plane of the base member such that the shaft rotates about a longitudinal axis of the shaft spaced from the base member; and an assembly for use in preventing reverse rotation of the shaft carried on a base member, the assembly comprising: a stop member mounted on the base member adjacent the shaft, the stop member having an abutment surface at a position spaced outwardly from the shaft; a mounting member mounted on the shaft; at least one wing member mounted on the mounting member; said at least one wing member being mounted on the mounting member for pivotal movement relative to the shaft about a pivot axis of the wing member generally at right angles to the axis of the shaft and parallel to a tangent to the axis of the shaft at its respective position on the shaft; said at least one wing member being pivotal from a retracted position, in which it is free from the stop member to allow the shaft to rotate without engagement of the wing member with the stop member, to an extended position in which it engages the abutment surface of the stop member to prevent reverse rotation; said at least one wing member being shaped and arranged such that, with the shaft stationary, gravity acting upon the said at least one wing member moves the said at least one wing member into the extended position for engaging the stop member; and said at least one wing member being shaped and arranged such that rotation of the shaft beyond a predetermined angular velocity causes centrifugal force to move the said at least one wing member to the retracted position; wherein the mounting member comprises a collar which surrounds the shaft and is clamped around the shaft; and wherein said at least one wing member has a generally v-shaped abutment edge defining two leg portions and an apex adjacent the shaft and is pivotal about its axis adjacent the apex of the v-shaped abutment edge such that the retracted and extended positions are defined by engagement of respective ones of the leg portions on the outer surface of the shaft.