Differential pressure responsive device

Claim 1

A DIFFERENTIAL PRESSURE INDICATING DEVICE COMPRISING A HOUSING HAVING A FIRST BORE FORMED THEREIN, A FITTING FOR CLOSING ONE END OF SAID FIRST BORE, SAID FITTING HAVING A HOLLOW TUBULAR MEMBER EXTENDING INTO SAID FIRST BORE, SAID TUBULAR MEMBER HAVING A SECOND BORE FORMED THEREIN, PARTITION MEANS LOCATED IN SAID TUBULAR MEMBER FOR PREVENTING COMMUNICATION BETWEEN SAID FIRST AND SECOND BORES AND FOR FORMING A CAVITY WITHIN AND AT ONE END OF SAID TUBULAR MEMBER, A PISTON MEMBER SLIDABLE IN SAID FIRST BORE FROM A FIRST POSITION TO A SECOND POSITION, STOP MEANS FORMED ON SAID HOUSING FOR PREVENTING MOVEMENT OF SAID PISTON MEMBER PAST SAID SECOND POSITION, FIRST PASSAGE MEANS LOCATED IN SAID HOUSING FOR COMMUNICATING ONE SIDE OF SAID PISTON MEMBER WITH A FIRST PRESSURE SOURCE, SECOND PASSAGE MEANS LOCATED IN SAID HOUSING FOR COMMUNICATING THE OTHER SIDE OF SAID PISTON MEMBER WITH A SECOND PRESSURE SOURCE, FIRST SPRING MEANS LOCATED IN SAID FIRST BORE AND CONFINED BETWEEN SAID HOUSING AND SAID PISTON MEMBER FOR OPPOSING MOVEMENT OF SAID PISTON MEMBER FROM SAID FIRST TO SAID SECOND POSITION, A SLEEVE-LIKE RETAINER MEMBER SURROUNDING SAID TUBULAR MEMBER AND MOVABLE FROM A FIRST SITE TO A SECOND SITE, SAID RETAINER MEMBER HAVING INNER AND OUTER SURFACES AND A SHOULDER FORMED ON THE INNER SURFACE THEREOF, PASSAGE MEANS FOR COMMUNICATING SAID CAVITY WITH SAID FIRST BORE, A PLURALITY OF BALLS LOCATED IN SAID PASSAGE MEANS, SAID BALLS BEING PARTIALLY LOCATED WITHIN SAID CAVITY AND PARTIALLY PROTRUDING FROM SAID TUBULAR MEMBER FOR ABUTTING SAID SHOULDER AND PREVENTING MOVEMENT OF SAID RETAINER MEMBER TO SAID SECOND SITE, A CONTROL MEMBER LOCATED IN SAID FIRST BORE, A TRIGGER PIN OPERATIVELY CONNECTED TO SAID CONTROL MEMBER AND EXTENDING INTO SAID CAVITY FOR CONTACTING AND MAINTAINING SAID BALLS IN A PROTRUDING POSITION FOR ABUTMENT WITH SAID SHOULDER, FIRST MAGNETIC MEANS OPERATIVELY CONNECTED TO SAID RETAINER MEMBER AND MOVABLE THEREWITH FROM SAID FIRST TO SAID SECOND SITE, SECOND MAGNETIC MEANS LOCATED IN SAID SECOND BORE AND MOVABLE FROM A NONSIGNALLING TO A SIGNALLING POSITION, SAID SECOND MAGNETIC MEANS BEING MAGNETICALLY RETAINED IN SAID NON-SIGNALLING POSITION BY MAGNETIC ATTRACTION TO SAID FIRST MAGNETIC MEANS WHILE SAID RETAINER MEMBER REMAINS AT SAID FIRST SITE AND BEING MAGNETICALLY MOVED TO SAID SIGNALLING POSITION BY MAGNETIC ATTRACTION TO SAID FIRST MAGNETIC MEANS WHEN SAID RETAINER MEMBER IS MOVED TO SAID SECOND SITE, SECOND SPRING MEANS LOCATED IN SAID HOUSING BETWEEN SAID RETAINER MEMBER AND SAID CONTROL MEMBER FOR URGING SAID RETAINER MEMBER TOWARDS SAID SECOND SITE AND FOR URGING SAID CONTROL MEMBER TOWARDS SAID PISTON MEMBER, SAID SECOND SPRING MEANS UPON MOVEMENT OF SAID PISTON MEMBER TOWARDS SAID SECOND POSITION BEING ARRANGED TO INITIALLY CAUSE MOVEMENT OF SAID CONTROL MEMBER AND THE TRIGGER PIN CONNECTED THERETO TOWARDS THE SECOND POSITION OF SAID PISTON MEMBER UNTIL SAID BALLS ARE FREE TO MOVE INTO SAID CAVITY AND TO SUBSEQUENTLY CAUSE MOVEMENT OF SAID RETAINER MEMBER TO SAID SECOND SITE AFTER SAID BALLS HAVE MOVED INTO SAID CAVITY, AND AN INDICATOR PIN OPERATIVELY CONNECTED TO SAID SECOND MAGNETIC MEANS AND MOVABLE THEREWITH FROM SAID NON-SIGNALLING TO SAID SIGNALLING POSITION.