Abstract: A process and device for cleaning lubricating oil in a gearbox with pressurized oil lubrication of bearings and gears is described wherein a lubricating oil pump delivers lubricating oil from a container, preferably the oil pan of the gearbox. In a shaft of the gearbox, preferably the input shaft, the lubricant channel is expanded into a rotation chamber. Flow velocity is thereby greatly reduced and the rotation of the outer surface of this chamber is imparted to the lubricating oil. As a result of this, the dirt particles are centrifuged onto the outer surface, where they form a firmly adhering film. The cleaned lubricating oil is drawn off in the center of the rotation chamber and conveyed in known manner via a bore provided in the main shaft to oil consumer parts, e.g. the bearings.