Reversing switch

A reversing switch comprising:

• a mounting plate assembly attachable to a wall of an explosion-proof enclosure and having a forwardly-extending hub adapted to extend through said wall and having a front thrust bearing surface on the forward end thereof;
• a shaft rotatably and axially journaled in said hub and extending forwardly and rearwardly therefrom;
• an external operator member having a base portion with an opening through which the shaft extends and within which the shaft is journaled for forward and backward reciprocable movement, said base portion having a rear thrust bearing surface engaging said front thrust bearing surface on the hub, said base portion having a pair of front, parallel, cam tracks in a plane transverse to the axis of the shaft on opposite sides of said shaft, and a forwardly projecting portion extending along the shaft from the base portion between said tracks having a pair of spaced, parallel flat cam guide surfaces extending along opposite sides of the shaft and having a plunger-receiving recess;
• an operator assembly including elongated handle means and a bifurcated cam member at one end thereof having a pair of parallel, plate-like cam elements with identical, arcuate cam lobes on the forward edges thereof, said cam elements being transversely spaced to provide an overlapping sliding fit with said pair of spaced, parallel flat cam guide surfaces on the base portion of said external operator, said cam lobes concurrently engaging said cam tracks, a pivotal connection between the shaft and said cam elements being eccentrically offset from the axis of the handle means, said handle means having a plunger engageable with said recess in the external operator to lock the handle means and shaft in a selected operated position;
• insulator base means comprising a member made of electrical insulating material and fastened to the back side of said mounting plate assembly and having a central aperture through and beyond which said shaft extends, said insulator base means having a stationary contact assembly consisting of a first set of four power conducting contacts evenly circumferentially spaced thereon, and separate control switch means;
• a movable contact assembly comprising a member made of electrical insulating material fastened to the rear end of the shaft behind said insulator base means and having a second set of four power conducting contacts evenly circumferentially spaced thereon and engageable with said first set of contacts, and adjustment screw means engageable with said control switch means to actuate the latter when said first and second sets of contacts are seated and unseated to a predetermined extent, and power bus jumpers interconnecting opposite pairs of said second set of power conducting contacts;
• spring means extending through said central aperture in the insulator base means, encircling said shaft, and acting between said mounting plate assembly and said moveable contact assembly to bias said first and second sets of contacts toward an open condition;
• and
• mechanical means acting between said insulator base means and the shaft enabling axial movement of the shaft while limiting rotation of said shaft to substantially a quarter turn thereby enabling opposite pairs of said second contacts to engage different selected pairs of said first contacts at opposite ends of said quarter turn of the shaft.