Switch for automatically providing a safety function when its contacts

Abstract

A switch for providing a safety function when its main contacts are fused or stuck together in the 'ON' position, comprising a housing containing a pair of main contacts, one being designated an ON contact, and the other main contact being carried by a movable switch arm in the housing. This switch arm has a first end which carries the movable main contact and a second end, and spring means mechanically coupled to the movable switch arm normally bias the movable main contact toward open position away from engagement with the ON contact. Switch operating means including movable actuator means overcome the biasing force of the spring means for moving the movable main contact to closed position into engagement with the ON main contact. There are auxiliary safety contact means positioned proximate to the second end of the movable switch arm for completing a safety circuit and for deenergizing a main circuit in response to abnormal movement of the second end of the movable switch arm under influence of the biasing force of the spring means when the actuator means is moved to OFF position, but the movable main contact remains fused or stuck to the ON main contact. In a further embodiment, safety contact means become triggered and moved from a first to a second position for providing a safety function when the actuator means are moved to OFF position but the main contacts remain fused or stuck together in their ON relationship.