Reduction gear for a starter-generator of an internal combustion engine

The invention relates to a reduction gear for the starter-generator of an internal combustion engine, the starter-generator being drive-connected to its crankshaft via a belt drive and the reduction gear being a planetary gear train arranged in the transmission path between the crankshaft and a first belt pulley coaxial with the crankshaft. A reduction gear for a starter-generator of an internal combustion engine, wherein the starter-generator is functionally linked with the crankshaft () via a drive belt (). A planetary gear is mounted in the force-transmitting path between the crankshaft () and a first belt pulley () that is coaxial to the crankshaft. The aim is to create a reduction gear which provides the gear ratio required for the starting mode and which can be switched in such a manner that it can be operated in any mode of operation. To this end, the reduction gear () is a planetary stage that includes a housing (), an internal gear (), a sun gear (), a cage () and a planetary ring () with internal () and external (). The internal gear intermeshes with the external teeth () of the planetary ring () and is functionally linked with the crankshaft () of the internal combustion engine. The sun gear () intermeshes with the internal teeth () of the planetary ring () and is stationarily linked with the housing () via a first coupling (). The cage () is provided with eccentric bearings () for the planetary ring () and is stationarily linked with the first belt pulley (). The cage can be stationarily linked with one of the members () of the planetary stage via a second coupling ().