Abstract: A improved planetary drive employs a pair of radially inner and outer nonorbiting members between which is radially disposed an annular orbiting member. The inner nonorbiting member and the inner surface of the inner wall of the orbiting member are formed with opposing surface in meshing engagement to form one stage of a planetary drive, while the opposing surfaces of the outer nonorbiting member and the orbiting member are formed with teeth in meshing engagement to form a second stage of a planetary drive. All of the orbiting and nonorbiting members and their teeth lie in the same plane or planes disposed radially outward from the means for orbiting the orbiting member so that when that member is orbited, the forces exerted on the orbiting means are in said plane or planes. Various combinations of rollers and lobed surfaces to formed the gear stages are also described.

Abstract: An improved planetary transmission employs orbiting means including a first circular plate having a peripheral array of similar sockets shaped as arcs of circles. A set of similar uncaptured generally cylindrical rollers is rotatively seated in said sockets, said rollers having their curved surfaces projecting beyond the periphery of said plate. A first annular nonorbiting gear having an inner surface formed with a hypo-cycloidal curvature with a number of lobes exceeding by at least one the number of sockets in the plate, encircles the plate so that its inner surface is in rolling contact with rollers and they are free to rotate within their sockets. A second annular nonorbiting gear has surfaces in cooperating encircling engagement with said orbiting means. A first rotary shaft is keyed to one of said nonorbiting gears, and a second rotary shaft is provided to eccentrically drive said orbiting means.