A gear unit having a shaft, at least a first bearing, a housing part and a cover, wherein the shaft is rotatably mounted at least via the first bearing, wherein the first bearing has an inner ring which is pushed onto the shaft, wherein the cover is connected to the housing part, wherein the shaft has a threaded region onto which a nut is screwed, which nut adjusts the bearing tension, wherein between the nut and the inner ring there are arranged a spacer sleeve and a disc, - wherein the greatest external diameter of the disc is greater than the greatest external diameter of the spacer sleeve, - wherein the greatest radial distance of the disc related to the rotational axis of the shaft is greater than the greatest radial distance of the spacer sleeve related to the rotational axis of the shaft, wherein - the radial distance region covered by the disc and related to the rotational axis of the shaft contains the radial distance region covered by the spacer sleeve, wherein the nut presses onto the inner ring via the spacer sleeve, placed onto the shaft and arranged axially between the inner ring of the first bearing and the nut, and via the disc, likewise placed onto the shaft and arranged between the nut and the spacer sleeve, wherein the disc projects into an annular spatial region connected via a channel to an inner-space region of the gear unit, and characterised in that the channel comprises - a first spatial region bounded by the cover, a drain screw and the housing part, - and a second spatial region which passes through the housing part and on the one hand issues into the inner-space region of the gear unit and on the other hand issues into the first spatial region, wherein the first spatial region issues into the annular spatial region. wherein the shaft is rotatably mounted at least via the first bearing, wherein the first bearing has an inner ring which is pushed onto the shaft, wherein the cover is connected to the housing part, wherein the shaft has a threaded region onto which a nut is screwed, which nut adjusts the bearing tension, wherein between the nut and the inner ring there are arranged a spacer sleeve and a disc, - wherein the greatest external diameter of the disc is greater than the greatest external diameter of the spacer sleeve, - wherein the greatest radial distance of the disc related to the rotational axis of the shaft is greater than the greatest radial distance of the spacer sleeve related to the rotational axis of the shaft, wherein - the radial distance region covered by the disc and related to the rotational axis of the shaft contains the radial distance region covered by the spacer sleeve, - wherein the greatest external diameter of the disc is greater than the greatest external diameter of the spacer sleeve, - wherein the greatest radial distance of the disc related to the rotational axis of the shaft is greater than the greatest radial distance of the spacer sleeve related to the rotational axis of the shaft, wherein - the radial distance region covered by the disc and related to the rotational axis of the shaft contains the radial distance region covered by the spacer sleeve, wherein the nut presses onto the inner ring via the spacer sleeve, placed onto the shaft and arranged axially between the inner ring of the first bearing and the nut, and via the disc, likewise placed onto the shaft and arranged between the nut and the spacer sleeve, wherein the disc projects into an annular spatial region connected via a channel to an inner-space region of the gear unit, and characterised in that the channel comprises - a first spatial region bounded by the cover, a drain screw and the housing part, - and a second spatial region which passes through the housing part and on the one hand issues into the inner-space region of the gear unit and on the other hand issues into the first spatial region, - a first spatial region bounded by the cover, a drain screw and the housing part, - and a second spatial region which passes through the housing part and on the one hand issues into the inner-space region of the gear unit and on the other hand issues into the first spatial region, wherein the first spatial region issues into the annular spatial region.