US Patent 7594453 Gear system for drive of a multi-shaft extruder

To drive an extruder which has several axially parallel shafts rotating in the same direction, with conveyor elements, arranged around a circle at equal angles with respect to each other, the shafts are attached to the driven shafts of a gear system. Each driven shaft has a pinion, and each driven pinion engages both with an externally-toothed drive wheel and with an internally-toothed hollow gear wheel. The externally-toothed drive wheel and the internally-toothed hollow gear wheel are driven with the same torque.