Pressure filter

Claim 1

A LIQUID FILTER CONSISTING OF A CASING PROVIDED WITH A FLUID INLET OPENING TO NEAR THE INNER PERIPHERY OF SAID CASING, AN AXIALLY LOCATED FLUID OUTLET LEADING FROM ONE END OF THE CASING, A HOLLOW FILTER ELEMENT AXIALLY DISPOSED IN SAID CASING HAVING ONE END THEREOF SURROUNDING SAID OUTLET, A COVER PLATE CLOSING THE OTHER END OF THE CASING, SAID PLATE HAVING AN INWARDLY PROJECTING RIB LOCATED CONCENTRIC WITH SAID FILTER ELEMENT AND OUTLET OPENING CLOSING AND SUPPORTING THE OTHER END OF SAID FILTER ELEMENT SO THAT NORMAL FLOW OF LIQUID FROM THE INLET TO THE OUTLET IS THROUGH THE WALLS OF SAID FILTER ELEMENT, A CYLINDER FORMED WITHIN SAID RIB OPENING INTO SAID LAST MENTIONED END OF SAID FILTER ELEMENT, A PISTON SLIDABLY MOUNTED WITHIN SAID CYLINDER AND NORMALLY CLOSING COMMUNICATION BETWEEN SAID CYLINDER AND THE INTERIOR OF SAID FILTER ELEMENT, PASSAGE MEANS LEADING FROM THE SPACE WITHIN THE CASING OUTSIDE OF THE FILTER ELEMENT TO SAID CYLINDER UPSTREAM OF SAID PISTON, SAID PISTON FORMED TO HAVE AN APPRECIABLE AND EXTENDED SLIDING MOVEMENT WITHIN SAID CYLINDER BEFORE SAID PISTON OPENS SAID CYLINDER TO THE SPACE WITHIN SAID FILTER ELEMENT FOR BY-PASSING OF FLUID DIRECTLY TO SAID OUTLET, GUIDE MEANS FOR SAID PISTON, A SPRING ACTING TO RESIST MOVEMENT OF SAID PISTON OUTWARDLY OF SAID CYLINDER, AND MEANS VISIBLE OUTSIDE OF SAID CASING FOR INDICATING THE POSITION OF SAID PISTON AND THE CONDITION OF THE FILTER ELEMENT, WHETHER CLEAN, IN NEED OF CLEANING, OR BY-PASSING, SAID LAST MENTIONED MEANS INCLUDING A LEGEND PLATE MOUNTED ON THE EXTERIOR OF SAID CASING, A ROTATABLE SHAFT EXTENDING THROUGH SAID CASING TRANSVERSE TO THE DIRECTION OF MOVEMENT OF SAID PISTON, AN ACTUATING ELEMENT MOVABLE RESPONSIVE TO MOVEMENT OF SAID PISTON, A CRANK ARM FIXED TO THE INNER END OF SAID SHAFT AND AT SUBSTANTIALLY RIGHT ANGLES THERETO WITH ITS END POSITIONED TO BE ENGAGED AND MOVED BY MOVEMENT OF SAID ACTUATING ELEMENT ON MOVEMENT OF SAID PISTON TO THUS ROTATE SAID SHAFT AND AN INDICATOR HAND FIXED TO THE OUTER END OF SAID SHAFT FOR MOVEMENT OVER SAID LEGEND PLATE.