Differential pressure transmitters

Claim 1

APPARATUS PROVIDING AN OUTPUT CORRESPONDING TO DIFFERENTIAL PRESSURE COMPRISING A PAIR OF FLEXIBLE ELEMENTS SUBJECT RESPECTIVELY TO PRESSURES THE DIFFERENCE OF WHICH IS TO PROVIDE SAID OUPUT, MEANS DEFINING A PAIR OF CHAMBERS BETWEEN SAID FLEXIBLE ELEMENTS AND INCLUDING A THIRD FLEXIBLE ELEMENT CONSTITUTING A WALL BETWEEN SAID CHAMBERS, LIQUID WITHIN SAID CHAMBERS TRANSMITTING PRESSURES EXERTED ON SAID FIRST MENTIONED FLEXIBLE ELEMENTS TO OPPOSITE SIDES OF THE THIRD FLEXIBLE ELEMENT, A LEVER HAVING TWO PORTIONS ONE OF WHICH IS WITHIN ONE OF SAID CHAMBERS AND THE OTHER OF WHICH IS EXTERNAL THERETO, MEANS CONNECTING SAID LEVER WITHIN THE LAST MENTIONED CHAMBER TO THE THIRD FLEXIBLE ELEMENT FOR MOVEMENT THEREWITH, A FLEXIBLE DIAPHRAGM ELEMENT CLOSING THE LAST MENTIONED CHAMBER AND SECURED TO SAID LEVER TO PROVIDE A PIVOTAL MOUNTING THEREFOR, THE EXTERNAL PORTION OF SAID LEVER BEING PROVIDED BY TWO PARTS, A SPRING NORMALLY HOLDING SAID TWO PARTS IN FIXED RELATIONSHIP TO EACH OTHER BUT YIELDING UPON EXCESSIVE MOVEMENTS OF THE PORTION OF SAID LEVER WITHIN ITS CHAMBER, MEANS DETECTING THE POSITION OF SAID LEVER, MEANS RESPONSIVE TO THE DETECTING MEANS TO APPLY A FORCE TO SAID LEVER TO MAINTAIN IT IN A PREDETERMINED POSITION, AND MEANS PROVIDING AN OUTPUT CORRESPONDING TO SAID FORCE.