Gear unit

A gear unit comprising:

• a gear unit housing with at least one drive-side shaft, at least one output-side shaft, and at least one gear ratio stage having intermeshing toothed wheels;
• a toothing space in the gear unit housing configured to receive the intermeshing toothed wheels and configured to be operated in one or more of:
• a partial vacuum, under atmospheric pressure, or at atmospheric pressure;
• a bearing space in the gear unit housing which is separated from the toothing space and in which shaft bearings are arranged and configured to be operated permanently in atmospheric operation under atmospheric pressure;
• lubricating oil configured to lubricate the toothing and the shaft bearings and to be collected in the toothing space
• and the bearing space;
• an oil collecting receptacle external to the gear unit, configured to collect the bearing lubricating oil guided from the bearing space;
• a delivery pump configured to convey the toothing lubricating oil from the toothing space into the oil collecting receptacle during partial vacuum operation;
• a check valve configured to convey the toothing lubricating oil from the toothing space into the oil collecting receptacle external to the gear unit during atmospheric operation;
• a first oil line that leads from the toothing space in direction of the oil collecting receptacle external to the gear unit, wherein the check valve is arranged in the first oil line;
• a second oil line that leads from the toothing space in direction of the oil collecting receptacle external to the gear unit, wherein the delivery pump is arranged in the second oil line;
• and
• a third oil line that leads from the bearing space in direction of the oil collecting receptacle external to the gear unit.