Pump having a bushing removal mechanism

Claim 1

A pump comprising in combination: a pump casing; a backplate cooperating with said pump casing to define a pump chamber, said backplate having an access opening extending therethrough and communicating with said pump chamber and providing an abutment surface facing away from said pump chamber; a pump shaft having an inner end and an outer end, said inner end extending through said access opening and supporting an impeller within said pump chamber for pumping fluid therethrough; bushing means for supporting said inner end of said pump shaft for rotation relative to said backplate, said backplate removably supporting said bushing means within said access opening by sliding surface engagement between an inner surface of said access opening and an outer surface of said bushing means, wherein an assembled position of said bushing means within said access opening is defined by engagement of said bushing means with said abutment surface, said backplate having means for constraining said bushing means against rotational movement relative thereto while said bushing means is in said assembled position; a gland having a through aperture to permit passage of said outer end of said pump shaft therethrough; means for removably fixing said gland to said backplate for releasably retaining said bushing means in said assembled position, while permitting rotational movements of said gland relative to said backplate; and connecting said operable to response to said rotational movements of said gland while said bushing means is in said asembled position for removably connecting said gland to said bushing means for extracting the latter from said assembled position within said access opening upon disassembling movement of said gland in a direction away from said backplate and towards said outer end of said pump shaft wherein said inner surface of said access opening is of stepped diameter configuration having axially spaced relatively small and larger diameter support wall portions disposed axially adjacent to and remote from said pump chamber, respectively; and said bushing means includes a sleeve bushing internally sized for engagement with said pump shaft and a bushing holder for supporting said sleeve bushing within said access opening, said bushing holder engages with said abutment surface to define said assembled position and said outer surface of said bushing holder having axially spaced relatively small and relatively large diameter wall portions arranged for slidably engagement with said relatively small and large diameter support wall portions to provide a relatively small clearance fit support for said bushing holder when said bushing means is in said assembled position, while providing a relatively loose fit for said bushing holder relative to said backplate during a substantial portion of travel of said bushing means axially of said pump shaft towards and away from said assembled position.