Device for varying hydraulic pressure

Claim 1

A HYDRAULIC PRESSURE RATIO FOR INTERPOSITION IN A PRESSURE FLUID LINE TO FORM A PART OF THAT LINE BETWEEN A FLUID PRESSURE SOURCE AND A WORKING POINT ON THE LINE, COMPRISING A TWO-DIAMETER PISTON HAVING A SECTION OF LARGE DIAMETER AND A SECTION OF SMALL DIEMETER, A CYLINDER FOR PRESSURE RATIO CHANGE OPERATION SURROUNDING GUIDING SAID PISTON DEFINING FIRST AND SECOND AXIALLY SPACED-APART CHAMBERS IN CYLINDER, ONE OF SAID CHAMBER BEING DEFINED BY THE FACE OF THE LARGE DIAMETER SECTION OF THE PISTON AND THE OTHER BY THE OPPOSITE ANNULAR FACE OF THE PISTON DISPOSED BETWEEN ITS LARGE AND SMALL DIAMETER SECTION, ONE OF SAID CHAMBERS BEING ADAPTED TO BE CONNECTED TO SAID FLUID SOURCE AND THE OTHER SAID WORKING POINT OF THE LINE WHEN THE CYLINDER IS COUPLED IN THE FLUID LINE, MEANS DEFINING A PASSAGEWAY CONNECTING SAID FIRST AND SECOND CHAMBERS BEING DEFINED BETWEEN THE PERIPHERY OF THE LARGER DIAMETER SECTION OF THE PISTON AND THE OPPOSED CYLINDER WALL FOR PASSING FLUID DIRECTLY THROUGH THE CYLINDER, THE PERIPHERY OF SAID LARGE DIAMETER SECTION OF THE PISTON BEING FORMED WITH AN ANNULAR RECESS, A PACKING RING MADE OF RESILIENT MATERIAL SEATED IN SAID ANNULAR RECESS IN THE PERIPHERY OF SAID LARGE DIAMETER SECTION OF THE PISTON, SAID PACKING RING BEING DIMENSIONED TO BE CONSTANTLY IN CONTACT WITH THE CYLINDER WALL AND HAVING A SMALLER WIDTH AND OF A LARGER INNER DIAMETER THAN THE WIDTH AND A BOTTOM DIAMETER OF SAID ANNULAR RECESS, SAID PASSAGEWAY CONSTANTLY CONNECTING THE PORTION OF SAID RECESS LYING BETWEEN ITS INNER SURFACE AND THE INNER WALL OF SAID PACKING RING WITH SAID CHAMBER DEFINED BY SAID ANNULAR FACE OF THE PISTON, WHEREBY SAID PACKING RING ACTS AS A VALVE CONTROLLING FLUID FLOW ACROSS SAID PASSAGEWAY, A REACTION SPRING CONSTANTLY URGING THE PISTON TOWARDS THE CHAMBER DEFINED BY SAID LARGE DIAMETER FACE OF THE PISTON AND SAID PISTON MOVING AGAINST THE BIAS OF SAID REACTION SPRING ONLY AFTER THE FLUID PRESSURE IN THE CHAMBER DEFINED BY THE ANNULAR FACE OF THE PISTON HAS ATTAINED PREDETERMINED VALUE TO CAUSE THE PACKING RING TO CLOSE SAID PASSAGEWAY WHEREUPON THE PISTON IS BROUGHT INTO PRESSURE RATIO CHANGE OPERATION AND THE PACKING RING SUDDENLY REOPENS SAID PASSAGEWAY UPON THE PISTON BEGINNING ITS RETURN STROKE AFTER THE FLUID PRESSURE IN THE FLUID PRESSURE SOURCE HAS BEEN RELEASED.