Pressure switch having head portions held by groove means

Claim 1

A PRESSURE SWITCH ADAPTED TO CHANGE ITS SWITCHING CONDITION IN RESPONSE TO A PREDETERMINED FLUID PRESSURE, COMPRISING: A SWITCH COMPRISING A CONTACT MOVABLE TO CHANGE THE SWITCHING CONDITION OF THE SWITCH; AND AN ACTUATOR CONNECTED TO THE SWITCH COMPRISING A BODY TUBE HAVING AN AXIS AND A FIRST END AND A SECOND END, A FIRST AND A SECOND HEAD IN THE RESPECTIVE ENDS OF THE BODY TUBE, A FIRST AND A SECOND AXIAL BORE PASSING THROUGH THE RESPECTIVE FIRST AND SECOND HEADS, THE FIRST BORE BEING ADJACENT TO THE SWITCH, AND THE SECOND HEAD BEING ADAPTED TO CONNECT THE SECOND BORE TO A SOURCE OF PRESSURE TO WHICH THE ACTUATOR IS RESPONSIVE, A FIRST AND A SECOND PISTON, SAID SECOND PISTON SLIDABLY FITTED IN THE SECOND BORE, THE SECOND PISTON MAKING A FLUID SEALING FIT IN THE SECOND BORE, ONE END OF THE SECOND PISTON BEING EXPOSED TO SAID FLUID PRESSURE AT THE SECOND END, FORCE SPRING MEANS INTERPOSED BETWEEN THE BODY AND THE SECOND PISTON IN OPPOSITION TO SAID FLUID PRESSURE; MEANS FOR ADJUSTING THE INITIAL LOADING OF THE FORCE SPRING MEANS COMPRISING A TUBULAR SCREW THREADED INTO SAID FIRST BORE, SAID FIRST PISTON SLIDABLY FITTED IN SAID TUBULAR SCREW, THE FORCE SPRING MEANS BEING BACKED UP BY THE TUBULAR SCREW, A PROTRUSION ON SAID SECOND PISTON, A PAIR OF AXIALLY SPACED APART SURFACES ON SAID ACTUATOR ADAPTED TO BE ENGAGED BY THE PROTRUSION TO LIMIT THE AXIAL MOVEMENT OF THE SECOND PISTON, A PAIR OF AXIALLY SPACED APART INTERNAL UNDERCUT GROOVES IN THE BODY TUBE, A SHOULDER ON EACH HEAD, AND A SEGMENT IN EACH OF SAID GROOVES WHICH SEGMENT PROJECTS INTO THE BODY TUBE TO RADIALLY OVERLAP THE RESPECTIVE SHOULDER AND THEREBY PREVENT EXPULSION OF THE HEADS FROM THE TUBE.