Pressure operated electrical differential switching devices

Claim 1

AN ELECTRICAL DIFFERENTIAL SWITCHING DEVICE COMPRISING A PRESSURE ELEMENT ADAPTED TO BE MOVED BY PRESSURE TO WHICH IT IS EXPOSED DURING USE, A PIVOTALLY MOUNTED ACTUATOR LEVER, MEANS CONNECTING THE PRESSURE ELEMENT TO THE LEVER TO CAUSE SAID ELEMENT TO MOVE THE LEVER IN ONE DIRECTION AROUND ITS PIVOTAL MOUNTING WHEN THE PRESSURE ELEMENT IS MOVED BY PRESSURE, PRESSURE MEANS BEARING AGAINST THE LEVER AND OPPOSING THE MOVEMENT OF THE PRESSURE ELEMENT, A PIVOTALLY MOUNTED FOLLOWER ELEMENT BESIDE THE LEVER MOVABLE BOTH THEREWITH AND RELATIVE THERETO, LIMITING MEANS BETWEEN THE LEVER AND FOLLOWER ELEMENT PERMITTING RELATIVE MOVEMENT BETWEEN THE LEVER AND THE FOLLOWER ELEMENT BETWEEN PREDETERMINED LIMITS, A PLUNGEROPERATED SWITCH FOR CONTROLLING AN ELECTRIC CIRCUIT, SAID SWITCH REQUIRING A CERTAIN OPERATING FORCE AND HAVING A SMALLER RETURN FORCE, SAID SWITCH BEING POSITIONED TO HAVE ITS PLUNGER MOVED BY THE FOLLOWER ELEMENT UPON PREDETERMINED MOVEMENT OF SAID LEVER BEYOND ONE OF SAID LIMITS BY THE PRESSURE ELEMENT TO OPERATE THE SWITCH, MEANS FOR ADJUSTING SAID LIMITING MEANS TO ADJUST SAID ONE OF SAID LIMITS WITHOUT MOVING THE FOLLOWER ELEMENT RELATIVE TO THE ACTUATOR LEVER, AND A COIL SPRING CONNECTED TO THE FOLLOWER ELEMENT SPACED AWAY FROM THE PIVOTAL MOUNTING THEREOF AND NORMALLY DRAWING SAID FOLLOWER ELEMENT INTO ENGAGEMENT WITH THE SWITCH PLUNGER WITH A FORCE LESS THAN THE SWITCH OPERATING FORCE AND GREATER THAN THE SWITCH RETURN FORCE, WHEREBY SAID COIL SPRING IS EFFECTIVE TO MAINTAIN THE PLUNGER IN THE SWITCH-OPERATED POSITION UNTIL THE LEVER REACHES ONE OF SAID PREDETERMINED LIMITS TO MOVE THE FOLLOWER ELEMENT THEREWITH AGAINST THE ACTION OF SAID COIL SPRING.