Fluid die cushion unit with air saver

Claim 1

In a self-contained die cushion comprising a first sleeve, a second sleeve telescopically and reciprocally received on said first sleeve, said sleeves having end walls and combining to define a cushion chamber for a compressible fluid between said end walls, said second sleeve being biased upwardly by the fluid in said cushion chamber during operation of said die cushion and being dropped to an inoperative position when said die cushion is to be inoperative, means for dividing said chamber into separate, isolated first and second fluid chamber portions, means for limiting the expanded volume of said first portion to an extent incapable of preventing said second sleeve from dropping to an inoperative position upon exhausting of said second portion, and means for exhausting said second portion to drop said second sleeve to the inoperative position, the improvement comprising: said dividing means comprises a flexible diaphragm secured within said first sleeve and said limiting means comprises a wall having openings therein above said diaphragm and secured to the upper portion of said first sleeve.