Abstract: A thermally actuated switch which embodies an active unit which includes a heat responsive element which is part of an enclosure enclosing electrical resistance elements for heating. Heat is applied internally to the enclosure and cooling is by way of dissipation of heat externally from the enclosure. The thermally responsive element is in the form of a flat plate which expands lengthwise. The plate engages the shorter arm of a pivoted bell crank lever, which along with the leaf spring engages the actuating member to be actuated.

Abstract: An actuator system for use in an electrical relay or the like. An actuator member is carried by a frame and is movable between a first and a second position, being biased toward its first position by a spring and having an actuating wire coupled between it and the frame. This wire is stretched from its original length to a second length by the spring when the actuator member is in its first position. The wire is of a selected metal alloy which, upon being heated, shortens its length and thus causes the tension in the wire to increase an amount sufficient to overcome the bias of the spring and to move the actuator member towards its second position.