Grease supply cartridge for dispensing

Claim 1

In an air-pressure-actuated grease dispenser pressure chamber having an aperture in the bottom thereof for dispensing grease contained therein, an air pressure supply therefor, and an annular cushion support disposed in the bottom thereof above said aperture for passage of said grease being dispensed, an improved supply cartridge on the order of nine and one-half inch diameter for the grease to be dispensed comprising a relatively rigid cylindrical laminated paperboard body loaded with grease for insertion within said chamber and further characterized by (a) An end closure member fixed at one end of said body and substantially transverse thereto, significantly annularly inwardly ribbed for reinforcement adjacent thereto, and having a port in said member and a removable cap therefor for providing an exit for dispensed grease through said support when placed over and in contact with said cushion support; and (b) a free piston in said body at the other end thereof covering the grease therein for forcing the grease therefrom upon application of air pressure within said chamber and thereby on said piston, said piston being formed of a thinwalled flexible plastic material that is impervious to grease and having an annular peripheral portion transverse to said body, a drop center of said piston surrounded by said annular portion and provided for receiving on said drop center a significant portion of said pressure on said piston, a generally annular upstanding wall connecting said annular portion and said drop center, and an upstanding peripheral flange on said annular portion that is gently flared outwardly with the upper flange edge having an outside diameter slightly larger than the inside diameter of said body to provide airtight contact with the inside wall of said cylindrical body prior to said pressure application and to maintain said airtight contact during said dispensing by said pressure exerted against said flange and together with said pressure received on said drop center substantially below the location of said airtight contact during said dispensing acting to continue said dispensing until said piston reaches the bottom of said cartridge at an interfitted relation with said end closure thereby preventing by-passing said grease on said cylindrical wall and preventing allowing air to leak past said piston into said grease, said flange, annular portion, wall, and drop center being proportioned to form a generally W-shaped radial cross-section of said piston adjacent its periphery for reinforcing said piston and nesting and interfitting with the reinforcing ribbing of said closure member for essentially completely expelling said grease from said chamber.