Spur gear transmission having at least two toothed spur gears (1, 2) whose toothings are in meshing engagement with one another and which can each be rotated about an axis of rotation (3, 4); 1.1 having an enveloping wall which encloses the two spur gears (1, 2) in the circumferential direction and in the direction of the axes of rotation (3, 4); wherein 1.2 the enveloping wall has an inner contour which is adapted to the outside diameters of the spur gears (1, 2) in such a way that two annular gaps (6, 7) which transition into one another result between the enveloping wall and the spur gears (1, 2), wherein a respective annular gap (6, 7) is arranged concentrically to a respective axis of rotation (3, 4); 1.3 the enveloping wall is formed by a two-part housing, which is closed along a parting joint, having an upper part and a lower part, wherein the parting joint extends partially or completely within a plane in which one of the two axes of rotation (3, 4) runs or in which the two axes of rotation (3, 4) run; 1.4 the lower part has an opening which frees a portion of the circumference of at least one or both of the two spur gears (1, 2) and which is directed downwardly starting from the axes of rotation (3, 4); 1.5 a lubricating oil supply by means of which a lubricating oil flow can be channelled or injected into the toothings of the spur gears (1, 2) opens in the enveloping wall; 1.6 the upper part and/or the lower part have/has two side walls which are situated opposite to one another in the axial direction of the axes of rotation (3, 4) and which enclose between them at least part of the spur gears (1, 2) in the axial direction, characterized in that 1.7 at least the upper part of the enveloping wall or the upper part and the lower wall of the enveloping wall is/are configured as a welded construction; 1.8 at least the upper part of the enveloping wall has axial openings in the region of the annular gaps (6, 7). 1.1 having an enveloping wall which encloses the two spur gears (1, 2) in the circumferential direction and in the direction of the axes of rotation (3, 4); wherein 1.2 the enveloping wall has an inner contour which is adapted to the outside diameters of the spur gears (1, 2) in such a way that two annular gaps (6, 7) which transition into one another result between the enveloping wall and the spur gears (1, 2), wherein a respective annular gap (6, 7) is arranged concentrically to a respective axis of rotation (3, 4); 1.3 the enveloping wall is formed by a two-part housing, which is closed along a parting joint, having an upper part and a lower part, wherein the parting joint extends partially or completely within a plane in which one of the two axes of rotation (3, 4) runs or in which the two axes of rotation (3, 4) run; 1.4 the lower part has an opening which frees a portion of the circumference of at least one or both of the two spur gears (1, 2) and which is directed downwardly starting from the axes of rotation (3, 4); 1.5 a lubricating oil supply by means of which a lubricating oil flow can be channelled or injected into the toothings of the spur gears (1, 2) opens in the enveloping wall; 1.6 the upper part and/or the lower part have/has two side walls which are situated opposite to one another in the axial direction of the axes of rotation (3, 4) and which enclose between them at least part of the spur gears (1, 2) in the axial direction, characterized in that 1.7 at least the upper part of the enveloping wall or the upper part and the lower wall of the enveloping wall is/are configured as a welded construction; 1.8 at least the upper part of the enveloping wall has axial openings in the region of the annular gaps (6, 7).