Method for assembling and calibrating a condition-responsive electric switch mechanism

A method for assembling a condition-responsive switch mechanism comprising the steps of:

• assembling in a housing a bellows, said bellows changing in at least one dimension in response to fluid pressure conditions inside the bellows, actuator link means connecting the movement of the bellows to a switch actuator, means for adjusting the movement of the switch actuator in response to fluid pressure in the bellows, and a bistable spring switch element extending generally between first and second blade terminals and operable upon actuation by the switch actuator to snap between an open position in which the blade terminals are disconnected and a closed position in which the blade terminals are connected;
• calibrating the switch mechanism by filling and evacuating the bellows with air, monitoring the pressure at which the spring switch element snaps between said open and closed positions, and manipulating said switch actuator adjustment means until the actuator operates the spring switch element to snap between the open and closed positions when the bellows is filled to a predetermined pressure;
• following said calibrating step, sealingly connecting a capillary tube to the bellows;
• filling the capillary tube and bellows with an operating fluid;
• and
• sealing the capillary tube thereby to capture the operating fluid within the capillary tube and bellows.