The invention relates to a gear train unit, comprising a plurality of planetary gear train stages, which are connected one after the other and which each comprise a ring gear, a sun gear, and a plurality of planet gears supported on a planet carrier, wherein the sun gear of each following planetary gear train stage is formed by the planet carrier of the preceding planetary gear train stage. The gear train unit comprises a driving element, which forms the sun gear of the first planetary gear train stage, and an output element, which forms the planet carrier of the last of the gear planetary gear train stages connected one after the other. The driving element is supported by means of first bearings arranged in the region of ends of the driving element, in such a way that the driving element can rotate about a longitudinal axis of the driving element, and at least some of the planet carriers of the planetary gear train stages are supported on the driving element in the region between the first bearings by means of bearings. The invention makes it possible to provide a gear train unit having a plurality of planetary gear train stages connected one after the other that is economical, extremely robust, and very compact and that additionally can transmit very high power.