Hold-shut device for injection molding

Claim 1

A HOLD-SHUT DEVICE FOR INJECTION MOLDING APPARATUS COMPRISING A FRAME FOR THE APPARATUS, A STATIONARY MOLD SEGMENT MOUNTED ON THE FRAME, A MEMBER SLIDABLE ALONG THE FRAME, AND A TRAVERSE MOLD SEGMENT FIXEDLY MOUNTED ON THE SLIDABLE MEMBER, IN COMBINATION WITH A SHIFT BODY SLIDABLY MOUNTED ON THE FRAME AND HAVING TWO CHAMBERS OF DIFFERENT DIAMETERS SPATIALLY AND DIRECTLY UNITED MERGING INTO EACH OTHER WITHIN THE SHIFT BODY, LOCKING MEANS TO IMMOBILIZE THE SHIFT BODY AT A PREDETERMINED POSITION ALONG THE FRAME, A STATIONARY SHIFT PLISTON MOUNTED IMMOVABLY WITHIN ONE CHAMBER OF THE SHIFT BODY, A HOLD-SHUT PISTON WITHIN THE REMAINING CHAMBER OF LARGER DIAMETER THAN THAT CONTAINING THE STATIONARY SHIFT PISTON OF THE SHIFT BODY, ATTACHED TO THE SLIDABLE MEMBER AND MOVABLE THEREWITH RELATIVELY TO THE SHIFT BODY, A WITHDRAWAL FACE ON SAID HOLD-SHUT PISTON AND FORCEEXERTING RESILIENT MEANS ON THE WITHDRAWAL FACE, A SUPPLY OF HYDRAULIC FLUID, RIGID CONDUCTS TO THE FROM THE HYDRAULIC FLUID SUPPLY, DRILLED INTO AND THROUGH THE STATIONARY SHIFT PISTON AND PROVIDING FLUID SUPPLY COMMON TO THE CYLINDER CHAMBERS, LOW AND HIGH PRESSURE PUMPS CONNECTING THE RIGID CONDUITS TO THE FLUID SUPPLY, AND PRESSURE REVERSING AND DIFFERENTIAL CONTROL SLIDES ASSOCIATED WITH THE PUMPS, THE RIGID CONDUITS AND THE FLUID SUPPLY, TO CONTROL MOVEMENT OF THE HOLDSHUT PISTON WITHIN THE SHIFT BODY; WHEREBY THE SHIFT BODY AND CHAMBERS THEREIN ARE MOVABLE RELATIVE TO THE STATIONARY SHIFT PISTON AND THE HOLD-SHUT PISTON HAS A VERY SHORT, POWERFUL MOLD CLAMP-UP STROKE.