Shaft seals including a seal element and a drive ring assembly therefor

Claim 1

A shaft seal including a sealing element and a drive ring assembly for mounting the sealing element with respect to a shaft, for rotation therewith; said drive ring assembly which is adapted to be mounted around a shaft comprising; an outer ring the bore of which is enlarged towards one end, so that a radially or substantially radially extending shoulder is provided part way along its length; a radially deformable inner ring co-axial with the outer ring and located in the enlarged bore portion thereof; and a sealing ring located in the enlarged bore portion of the outer ring between the shoulder thereof and the opposed end of the inner ring; a plurality of circumferentially spaced radial screws engaged in correspondingly threaded holes in the portion of the outer ring surrounding the inner ring, so that they may be tightened against the outer surface of the inner ring, the engaging surfaces of the screws and the inner ring being mutually inclined, so that tightening of the screws against the inner ring, when the assembly is positioned about a shaft, will force the inner ring to move axially towards the shoulder of the outer ring, thereby compressing the sealing ring positioned therebetween and causing the sealing ring to expand radially into sealing engagement with the opposed surfaces of the shaft and the outer ring, while at the same time said screws deform the inner ring into clamping engagement with the shaft.