Differential pressure responsive device

Claim 1

A TEMPERATURE SENSITIVE DIFFERENTIAL PRESSURE INDICATING DEVICE COMPRISING A HOUSING HAVING A FIRST BORE THEREIN, A HOLLOW TUBULAR MEMBER EXTENDING INTO SAID FIRST BORE TO FORM A SECOND BORE, SAID TUBULAR MEMBER HAVING AN OPEN END AND A CLOSED END, AN ANNULAR RAMP FORMED AT SAID OPEN END OF SAID TUBULAR MEMBER, A HOLLOW PISTON MEMBER SLIDABLE IN SAID FIRST BORE FROM A FIRST POSITION TO A SECOND POSITION, SAID PISTON MEMBER BEING FORMED TO ENVELOP SAID TUBULAR MEMBER, FIRST PASSAGE MEANS FORMED IN SAID HOUSING FOR COMMUNICATING ONE SIDE OF SAID PISTON MEMBER WITH A FIRST PRESSURE SOURCE, SECOND PASSAGE MEANS FORMED IN SAID HOUSING FOR COMMUNICATING THE OTHER SIDE OF SAID PISTON MEMBER WITH A SECOND PRESSURE SOURCE, SPRING MEANS LOCATED IN SAID HOUSING AND OPERATIVELY CONNECTED TO SAID PISTON MEMBER FOR OPPOSING MOVEMENT OF SAID PISTON MEMBER FROM SAID FIRST TO SAID SECOND POSITION, FIRST MAGNETIC MEANS OPERATIVELY CONNECTED TO SAID PISTON MEMBER AND MOVABLE THEREWITH FROM SAID FIRST TO SAID SECOND POSITION, SECOND MAGNETIC MEANS LOCATED IN SAID SECOND BORE AND MOVABLE FROM A NON-SIGNALLING TO A SIGNALLING POSITION, SAID SECOND MAGNETIC MEANS BEING MAGNETICALLY REPELLED BY SAID FIRST MAGNETIC MEANS TOWARDS SAID NON-SIGNALLING POSITION WHEN SAID PISTON MEMBER IS IN SAID FIRST POSITION AND BEING MAGNETICALLY REPELLED BY SAID FIRST MAGNETIC MEANS TOWARDS SAID SIGNALLING POSITION AFTER THE PISTON MEMBER HAS MOVED A PREDETERMINED DISTANCE AWAY FROM SAID FIRST POSITION, AN INDICATOR PIN OPERATIVELY CONNECTED TO SAID SECOND MAGNETIC MEANS AND MOVABLE THEREWITH FROM SAID NON-SIGNALLING TO SAID SIGNALLING POSITION, SAID INDICATOR PIN HAVING AN ANNULAR GROOVE FORMED THEREON, A PLURALITY OF BALLS LOCATED AT THE OPEN END OF SAID TUBULAR MEMBER AND MOVABLE ALONG SAID ANNULAR RAMP INTO AND OUT OF SAID ANNULAR GROOVE, SAID BALLS BEING DIMENSIONED TO PROTRUDE FROM THE SURFACE OF SAID INDICATOR PIN WHEN LOCATED IN SAID ANNULAR GROOVE, AND A BIMETALLIC TEMPERATURE SENSITIVE CONVEX DISC ELEMENT LOCATED ADJACENT SAID BALLS AND HAVING AN OPENING AT THE CENTER THEREOF FOR PERMITTING MOVEMENT OF SAID INDICATOR PIN THERETHROUGH, MEANS FOR OPERATIVELY CONNECTING THE PERIPHERY OF SAID DISC TO SAID HOUSING, SAID DISC ELEMENT BEING CAUSED TO INVERT AND CONFINE SAID BALLS IN SAID ANNULAR GROOVE AND AGAINST SAID ANNULAR RAMP TO PREVENT MOVEMENT OF SAID INDICATOR PIN AT TEMPERATURES BELOW A PREDETERMINED VALUE.