Hydraulic door closer

Claim 1

FOR USE IN A HYDRAULIC DOOR CLOSER INCLUDING A PISTON ROD RECIPROCALLY MOUNTED IN A CASING WITH ONE END THEREOF EXTENDING WITHIN SAID CASING AND THE OTHER END THEREOF EXTENDING EXTERNALLY OF SAID CASING, THE IMPROVEMENT COMPRISING MEANS FOR SEALING AROUND A PORTION INTERMEDIATE THE ENDS OF SAID ROD COMPRISING A WASHER OF RESILIENT MATERIAL HAVING AN AXIAL OPENING THEREIN THROUGH WHICH SAID ROD PROJECTS, THE DIAMETER OF SAID OPENING BEING LESS THAN THE DIAMETER OF SAID ROD, SAID WASHER BEING SUBSTANTIALLY FLAT IN AN UNTENSIONED STATE WHEN REMOVED FROM THE CASING, A FIRST RIGID WASHER ENGAGING A SURFACE OF SAID RESILIENT WASHER AND HAVING A CENTRAL PORTION SPACED FROM SAID RESILIENT WASHER ALLOWING A CENTRAL PORTION OF SAID RESILIENT WASHER TO EXTEND AXIALLY ALONG SAID ROD IN A DIRECTION TOWARD THE INTERIOR OF SAID CASING, THE AXIALLY EXTENDING PORTION OF SAID RESILIENT WASHER BEING OF SUCH THICKNESS AND LENGTH THAT FLEXING OF SAID AXIALLY EXTENDING PORTION IS PREVENTED DURING RECIPROCATING MOVEMENT OF SAID ROD IN BOTH DIRECTIONS SO THAT SAID AXIALLY EXTENDING PORTION EXTENDS TOWARD THE INTERIOR OF SAID CASING DURING MOVEMENT OF SAID PISTON ROD IN BOTH DIRECTIONS, THE FREE END OF SAID AXIALLY EXTENDING PORTION BEING UNRESTRAINED IN A DIRECTION TOWARD THE INTERIOR OF SAID CASING, A SECOND RIGID WASHER, WHICH CLOSES A PORTION OF AN END OF SAID CASING, ON THE OTHER SIDE OF SAID RESILIENT WASHER, SAID RESILIENT WASHER HAVING A PERIPHERAL PORTION SURROUNDING AND EXTENDING AXIALLY AROUND THE RADIALLY OUTERMOST PERIPHERY OF SAID SECOND RIGID WASHER IN A DIRECTION AWAY FROM THE INTERIOR OF SAID CASING, SAID CASING HAVING A PERIPHERAL PORTION DEFORMED RADIALLY INWARDLY TO COMPRESS SAID PERIPHERAL PORTION OF SAID RESILIENT WASHER AGAINST THE RADIALLY OUTERMOST PERIPHERY OF SAID SECOND RIGID WASHER TO PROVIDE A SEAL BETWEEN SAID CASING AND THE PERIPHERAL PORTION OF SAID RESILIENT WASHER, AND MEANS FOR APPLYING AN AXIAL FORCE TO SAID FIRST RIGID WASHER AT AN AREA SURROUNDING SAID CENTRAL PORTION OF THE RESILIENT WASHER.