Momentary electrical switch with mechanical interlock

Abstract

A momentary electrical switch includes fixed contacts fixed relative to a switch housing and slidable contacts located within the housing. A contact operating mechanism includes a manual control knob, slide element and a support attached to the slide for supporting the slidable contacts, the contact operating mechanism being movable axially in a first direction against a compression spring when the knob is pulled. An interlock element extends beyond the periphery of the slide to engage the casing to prevent movement of the contact operating mechanism when the knob is pulled. A spring biased interlock release stem is moved axially in an opposing second direction by pressing on a pushbutton to disengage the interlock element from the casing. The movable switch contacts are moved in the first direction relative to the fixed contacts only by concurrently pressing in one direction on the pushbutton while pulling on the knob in the opposite direction. When the knob is released the compression spring returns the contact operating mechanism and the movable contacts to their neutral position. When the pushbutton is released the interlock element is again extended beyond the periphery of the slide. The switch has three positions and two sets of fixed contacts. In the neutral position one slidable contact bridges a first set of fixed contacts. When the knob is pulled in the first direction while releasing the interlock element, the slidable contacts bridge both sets of fixed contacts. In the second direction, neither set of fixed contacts is bridged.