Differential fluid pressure indicator

Claim 1

A FLUID PRESSURE DIFFERENTIAL INDICATOR COMPRISING A CASING FORMING TWO AXIALLY ALIGNED CYLINDERS SEPARATED BY A WALL, A RECIPROCATIVE PISTON IN ONE OF SAID CYLINDERS, MEANS FOR CONDUCTING FLUID OF SAID ONE CYLINDER ON OPPOSITE SIDES OF SAID PISTON, THE LATTER INCLUDING A MAGNET ON ITS SIDE FACING SAID WALL, A RECIPROCATIVE SIGNAL ELEMENT IN THE OTHER CYLINDER AND INCLUDING A MAGNET ON ITS SIDE FACING SAID WALL, SAID MAGNETS PRESENTING SIMILAR POLES TOWARD EACH OTHER, AND MEANS FOR BIASING SAID PISTON TOWARDS ONE OF ITS RECIPROCATIVE LIMITS, THE MOTION OF SAID PISTON BEING TRANSMITTED TO SAID SIGNAL ELEMENT BY MAGNET REPULSION BETWEEN SAID MAGNETS, SAID HIGHER PRESSURE FLUID CONDUCTING MEANS HAVING A PORT IN THE END OF SAID PISTON''S CYLINDER REMOTE FROM SAID WALL, SAID PISTON FORMING A VALVE HEAD NORMALLY CLOSING SAID PORT AND PRESENTING TO SAID HIGHER PRESSURE FLUID A PISTON AREA SMALLER THAN THAT OF THE ENTIRE PISTON END, SAID PISTON AREA SMALLER MEANS FOR BIASING IT TOWARDS SAID PORT AND SAID PISTON OPENING SAID PORT WHEN SAID HIGHER FLUID PRESSURE OVERCOMES THE BIAS OF THE PISTON''S BIASING MEANS AND THEREBY EXPOSES ITS ENTIRE PISTON AREA TO THE FLUID PRESSURE.