Zero-lash Oldham coupling

An Oldham-style coupling assembly wherein a driving shaft is rotatably coupled to a driven shaft using a reduced-lash flexible coupling assembly. The coupling assembly includes an intermediate coupling plate stationed between the driven and driving shafts. A driven lug associated with the driven shaft has tapered contact faces and engages a driving slot in the center of the coupling plate. Likewise, a pair of diametrically opposed half-lugs associated with the driving shaft engage in respective half slots through a similar tapered interface. Springs backing each of the half lugs establish a continuous axial compression force within the coupling plate to urge seating of the tapered interfaces but without frustrating transverse sliding in the respective slots, thereby taking up lash from the system. The lugs are oriented perpendicular relative to each other, so as to simulate a traditional Oldham-style coupling. The coupling assembly is useful to rotatably unite a fuel pump and a vacuum pump in a vehicular engine.