Patent ID: 7635818

Claim:
For use in a pressure switch having: (a) a switch chamber; (b) an electrical switch mounted within the switch chamber and having a mechanically-actuated trigger projecting therebelow; and (c) a push rod movable in response to changes in fluid pressure acting on the pressure switch, said push rod having an upper end extending into the switch chamber; a calibration mechanism comprising: (d) a lower collar having an upper surface, said lower collar having a threaded bore extending downward from said upper surface and having a first thread pitch; (e) guide means associated with the lower collar; (f) an upper collar having an upper surface and a lower surface, said upper collar being disposable above the lower collar and engageable with the guide means so as to be movable vertically relative to the lower collar while remaining in substantial alignment therewith, said upper collar having a threaded bore aligned with the threaded bore of the lower collar and having a second thread pitch which is different from said first thread pitch of the lower collar; and (g) a calibration adjustment screw having: g.1 an upper section threaded for engagement with the threaded bore of the upper collar; and g.2 a lower section threaded for engagement with the threaded bore of the lower collar; such that rotation of the calibration adjustment screw will cause the upper collar to move either upward away from or downward toward the lower collar, depending on the direction of rotation; the calibration mechanism being mountable to a pressure switch by connecting the lower collar to the upper end of the pressure switch's push rod, with the upper collar positioned below the trigger of the electrical switch, such that the calibration adjustment screw can be rotated to raise the upper collar to depress said trigger.