Condition responsive switch

A thermal or pressure responsive switch has a contact arm movable between switch positions opening and closing switch contacts, has a spring biasing the arm to one of the switch positions, and has a dished disc element movable with snap action between original and dished configurations during changes in pressure or temperature conditions. The dished disc element cooperates with the spring in moving the contact arm between switch positions on the occurrence of selected switch actuating or reset pressure or temperature conditions, and the switch components are arranged to permit overtravel of the disc during snap acting movement for closing switch contacts without substantially altering the pressure or temperature response characteristics of the switch.