A gear unit having a housing part, a shaft, a first cover part and a second cover part, wherein the first cover part has a first annular region projecting towards the gear-unit interior, at the radial interior of which annular region there is received a first bearing and at the radial exterior of which annular region there is formed a seat for a sealing ring which is received at this seat and is arranged between the housing part and the first annular region, wherein the second cover part likewise has a first annular region projecting towards the gear-unit interior, at the radial interior of which annular region there is received a second bearing, wherein the output shaft of the gear unit is rotatably mounted by means of the first and the second bearing, wherein the first cover part has a second annular region projecting towards the gear-unit interior, at the radial exterior of which annular region there is likewise formed a seat for a sealing ring, wherein the second cover part has a second annular region projecting towards the gear-unit interior, at the radial exterior of which annular region there is likewise formed a seat for a second sealing ring which is received at this seat and is arranged between the housing part and the second annular region, wherein the rotational axis of the shaft defines the axial direction and the radial direction is defined related thereto, characterised in that the region covered in an axial direction by the first bearing comprises the region covered in an axial direction by the seat, formed at the first annular region, for the first sealing ring, wherein the seat, formed at the first annular region, for the first sealing ring has a cylindrical outer surface which merges into a rounded region in a smooth, in particular steady and differentiable, manner, wherein a seat, formed at the housing part, for the first sealing ring has a cylindrical outer surface which merges into a second rounded region in a smooth, in particular steady and differentiable, manner, wherein the first sealing ring is arranged in a tubular spatial region encircling in a circumferential direction, which is bounded by the two cylindrical outer surfaces and the two rounded regions, wherein the first sealing ring is pressed between the two cylindrical outer surfaces in a radial direction and is elastically spread in an axial direction, the seats, formed at the cover part and at the housing part, for the sealing rings (40, 48) are unworked. wherein the first cover part has a first annular region projecting towards the gear-unit interior, at the radial interior of which annular region there is received a first bearing and at the radial exterior of which annular region there is formed a seat for a sealing ring which is received at this seat and is arranged between the housing part and the first annular region, wherein the second cover part likewise has a first annular region projecting towards the gear-unit interior, at the radial interior of which annular region there is received a second bearing, wherein the output shaft of the gear unit is rotatably mounted by means of the first and the second bearing, wherein the first cover part has a second annular region projecting towards the gear-unit interior, at the radial exterior of which annular region there is likewise formed a seat for a sealing ring, wherein the second cover part has a second annular region projecting towards the gear-unit interior, at the radial exterior of which annular region there is likewise formed a seat for a second sealing ring which is received at this seat and is arranged between the housing part and the second annular region, wherein the rotational axis of the shaft defines the axial direction and the radial direction is defined related thereto, characterised in that the region covered in an axial direction by the first bearing comprises the region covered in an axial direction by the seat, formed at the first annular region, for the first sealing ring, wherein the seat, formed at the first annular region, for the first sealing ring has a cylindrical outer surface which merges into a rounded region in a smooth, in particular steady and differentiable, manner, wherein a seat, formed at the housing part, for the first sealing ring has a cylindrical outer surface which merges into a second rounded region in a smooth, in particular steady and differentiable, manner, wherein the first sealing ring is arranged in a tubular spatial region encircling in a circumferential direction, which is bounded by the two cylindrical outer surfaces and the two rounded regions, wherein the first sealing ring is pressed between the two cylindrical outer surfaces in a radial direction and is elastically spread in an axial direction, the seats, formed at the cover part and at the housing part, for the sealing rings (40, 48) are unworked.