Plunger assembly for hand-operated grease gun

Claim 1

IN A HAND-OPERATED GREASE GUN OF THE KIND HAVING A CYLINDRICAL GREASE CONTAINER WITH A ROD EXTENDING AXIALLY THEREIN, SAID GREASE GUN BEING ADAPTED FOR USE WITH BOTH CARTRIDGE-PACKAGED GREASES AND BULK-FILLED GREASES, THE PLUNGER ASSEMBLY INCLUDING: (A) A CYLINDRICAL SLEEVE HAVING A FORWARD END AND A REARWARD END AND PROVIDING A BORE THERETHROUGH FOR SLIDABLY RECEIVING SAID ROD; (B) A GUIDE CUP RIGIDLY MOUNTED ON THE FORWARD END PORTION OF SAID SLEEVE, SAID CUP HAVING A TRANSVERSE WALL PROVIDING A CENTRAL OPENING THEREIN RECEIVING SAID FORWARD END PORTION AND A CYLINDRICAL WALL CONCENTRIC WITH SAID SLEEVE EXTENDING REARWARDLY FROM THE OUTER PERIPHERY OF SAID TRANSVERSE WALL, THE OUTSIDE OF SAID CYLINDRICAL WALL BEING SPACED INWARDLY FROM THE INSIDE OF SAID GREASE CONTAINER FOR INSERTION WITHIN A GREASE CARTRIDGE; (C) SEALING MEANS CARRIED BY SAID SLEEVE PROVIDING A SLIDING GREASE-TIGHT SEAL WITH SAID ROD; AND (D) ANNULAR SEALING MEANS MOUNTED ADJACENT THE REARWARD END OF SAID GUIDE CUP CYLINDRICAL WALL, SAID SEALING MEANS HAVING A GREATER NORMAL OUTSAID DIAMETER THAN THE OUTSIDE DIAMETER OF SAID GUIDE CUP CYLINDRICAL WALL FOR SELECTIVELY PROVIDING A SLIDING GREASE-TIGHT SEAL AROUND THE OUTSIDE OF SAID PLUNGER ASSEMBLY WITH EITHER THE INSIDE OF SAID GREASE CONTAINER OR THE INSIDE OF A GREASE CARTRIDGE.