Shaft seal assembly with inflatable annular member

A shaft seal assembly for sealing a propeller shaft of sea-going vessels, the shaft emerging from a housing attached to the aft end of the stern tube, the assembly comprising:

• a bush mounted on the propeller shaft;
• an annular radial-contact seal as an outboard water seal consisting of a plurality of circumferential segments which have circumferentially overlapping ends, said contact seal being disposed coaxially with the propeller shaft within an annular chamber of said housing and being nonrotatably and axially supported within said housing, said contact seal being surrounded by at least one peripheral inflatable member inserted in said annular chamber, said inflatable member being connected by conduit means to a supply system of a variably pressurized medium for inflating said inflatable member, whereby in use the segments are radially constrained and forced against the bush by an actually present pressure of the pressurized medium in said inflatable member, the assembly further including a void annular leakage space near said annular chamber and positioned in an inboard direction of it, said leakage space being connected to a drain pipe, the assembly including a further annular chamber adjacent to and separated from said annular leakage space by an inboard facing lip seal bearing on the bush, said further annular space communicating with a lubricant supply system.