US Patent 7307506 Safety switches

A switch includes a switch member and an extension and a push rod respectively extended from two ends of an underside of the switch member. A bi-metallic contact plate has a first end fixed to one of two terminals and a contact portion splits from the contact plate. A first contact point is connected to an underside of the contact portion and a second contact point is connected to the other terminal. A free end of the contact portion is connected with a free first end of a spring member and a second end of the spring member is connected to the contact plate. When overload, the contact portion and the spring member move upward to cut off the circuit while the push rod extends through a through hole defined in the spring member.