Planetary transmission

An improved planetary transmission comprising

• A. a housing,
• B. orbiting means including a first circular plate having a peripheral array of similar sockets shaped as arcs of circles,
• C. a set of similar uncaptured generally cylindrical rollers rotatively seated in said sockets, said rollers having their curved surfaces projecting beyond the periphery of said plate,
• D. a first annular nonorbiting gear, said first 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 said plate, said first gear encircling said plate so that its said inner surface is in rolling contact with said rollers and said rollers are free to rotate within their sockets,
• E. a second annular nonorbiting gear, said second gear having surfaces in cooperating encircling engagement with said orbiting means,
• F. a first shaft keyed to one of said nonorbiting gears, said first shaft being rotatively secured in and projecting from said housing, and
• G. means including a second shaft rotatively secured in and projecting from said housing for eccentrically driving said orbiting means within said housing.