Abstract: In an auxiliary planet-wheel gear for a motor vehicle, a drive drum fixed in terms of rotation relative to an outer central wheel, a shift sleeve connecting an inner central wheel to a brake located outside the drive drum, and an intermediate drive shaft fixed in terms of rotation relative to a planet carrier are arranged concentrically relative to one another. With reference to the main gear axis, the radially outer drive drum and the shift sleeve are each supported by a roller bearing relative to the centrally arranged intermediate drive shaft. The roller bearing of the shift sleeve is arranged offset axially in the direction of the brake in relation to the central wheels. Finally, the planet carrier is connected to an annular bearing extension for supporting the roller bearing of the drive drum. To obtain a construction which is short in the direction of the main gear axis, the drive drum has only a single roller bearing.