Seals for rotating shafts, especially for stern tube seals for ships

Claim 1

A seal for a rotating shaft for the stern tube seal of a ship comprising a housing, a rotatable shaft within said housing, at least one radial sealing ring bearing in sealing manner against the shaft or a shaft bush, a support within said housing, at least one spare sealing ring mounted on said support, guides for said support movable within said housing, said support being movable by axial displacement of the support from a reserve position into a working position on the shaft, the support together with at least one spare sealing ring being movable in said guides on parts of the housing of the seal, the support of the spare sealing ring comprising on one side an annular shoulder which is supported on its outer surface for sliding movement in a supporting part of the housing, the support of the spare sealing ring being provided on its opposite side with guiding means being shiftable in a stationary part of the housing of the seal, the support on one side being provided with a chamber for receiving a pressure medium, especially a hydraulic medium, for moving the support and the spare sealing ring into a working position on the shaft, the said quiding means on one side of the support bearing one spare ring being formed by a number of sliding rods distributed around its circumference which are guided so as to slide in recesses in a stationary part of the housing of the seal.