Epicyclic gearing or planetary gearing is a gear system consisting of one or more outer, or planet, gears or pinions, revolving about a central sun gear or sun wheel. The sun gear is usually mounted on the axle and the gear pinions engage the planet cage which is typically part of the hub shell of the wheel.
First used by John Boyd Dunlap in 1888. This tire uses a bladder or tube filled with air encased by an outer rubber casing like a modern bicycle tire. Introduced commercially in 1892.