Gate valve with stripper rings for plastic melts

Claim 1

A VALVE USEFUL FOR CONTROLLING THE FLOW OF PLASTIC MELTS COMPRISING A VALVE HOUSING HAVING A BORE, A PIS TON HAVING A UNIFORM OUTER SURFACE SLIGHTLY SPACED FROM THE BORE OF THE HOUSING ALONG ITS ENTIRE LENGTH AND BEING AXIALLY MOVABLE IN SAID BORE, FLUID INLET MEANS COMMUNICATING WITH SAID BORE, FLUID OUTLET MEANS COMMUNICATING WITH SAID BORE, MEANS AT ONE END OF SID BORE IN INTIMATE SLIDING CONTACT WITH THE UNIFORM OUTER SURFACE OF SAID PISTON FOR SEALING THE BORE FROM THE EXTERIOR, MEANS AT THE OTHER END OF SAID BORE IN INTIMATE SLIDING CONTACT WITH SAID OUTER SURFACE FOR SEALING THE INLET MEANS FROM THE OUTLET MEANS WHEN SAID UNIFORM OUTER SURFACE IS IN CONTACT WITH BOTH OF SAID SEALING MEANS, AND SEALING MEANS AT SAID OTHER END BEING OUT OF CONTACT WITH SAID PISTON WHEN SAID PLASTIC MELTS ARE BEING PASSED FROM SAID INLET MEANS TO SAID OUTLET MEANS, BOTH OF SAID SEALING MEANS DEFINING THE SOLE GUIDE MEANS FOR THE MOVEMENT OF SAID PISTON, STRIPPER MEANS AT BOTH OF SAID SEALING IN DIRECT ENGAGEMENT WITH SAID SEALING MEANS AND IN SLIDIN CONTACT WITH SAID PISTON FOR REMOVING FLUID FROM SAID UNIFORM OUTER SURFACE AS SAID PISTON MOVES AXAILLY IN SAID BORE, SAID STRIPPER MEANS COMPRISING SUPPORT RINGS WITH CARBON RING INSERTS, MEANS OPERATIVELY CONNECTED TO SAID PISTON FOR MOVING SAID PISTON AXIALY IN SAID BORE AND SEPARATE MEANS ARE PROVIDED FOR EACH PAIR OF SAID SEALING MEANS AND SAID STRIPPER MEANS FOR SECURING SAID SEALING MEANS AND SAID STRIPPER MEANS IN PLACE WITHIN SAID VALVE HOUSING.