Patent ID: 7032903

Claim:
A retractable packing segment for an apparatus that extracts work from the expansion of a gaseous working fluid, said apparatus comprising: a rotating shaft disposed in a casing, wherein a plurality of packing segments are disposed in a ring and centered on an axis defined by said shaft to provide a seal therearound, each said packing segment being retractable and comprising: an inner face for sealing against said shaft and an outer face supporting a T-shaped extension, said inner and outer faces and said extension spanning opposing common side ends, said common side ends cut parallel with radii of said axis; and at least one brush seal disposed on the inner face of said segment, said brush seal having opposing ends, at least one of said ends cut non-parallel with radii of said axis and extending past one of said common side ends, and bristles of said brush disposed at approximately the same non-parallel direction, wherein said plurality of packing segments provide a continuous 360° brush seal around said shaft.