Patent ID: 8449427

Claim:
A sequential planetary stack transmission system comprising: a planetary stack assembly comprising: a rotatable hollow central shaft defining a central axis; a stack of planetary gear sets, each gear set defining an input/output gear ratio, each gear set comprising: a sun gear engageable with the central shaft for rotation with the central shaft concentrically about the central axis, and freely rotatable concentrically about the central shaft when not engaged with the central shaft, a plurality of planet gears engaged with the sun gear, and a ring gear engaged with the planet gears and rotatable concentrically about the central shaft; and the ring gears of the stack of planetary gear sets forming a ring gear barrel rotatable as a unit concentrically with respect to the central shaft; a shifting assembly disposed within the hollow central shaft and translatable along the central axis, the shifting assembly engageable sequentially with the sun gears; and a case, the planetary stack assembly and the shifting assembly disposed within the case, the case including apertures for connection of the planetary stack assembly to an input and an output.