A gear unit having a shaft, in particular an input shaft, a fan impeller being connected to the shaft in a torsionally fixed manner, a fan hood being connected to the gear unit housing, which at least partially encloses the fan impeller, a separation plate for separating the pressure chamber of the fan from the suction chamber of the fan being connected to the fan hood, where the separation plate has an air intake opening for the fan impeller and is situated on the side of the fan impeller facing axially away from the gear unit, the fan impeller has an upper and a lower cover disk, which are axially set apart from each other, and fan blades are disposed between the cover disks, so that channels are formed, the radial clearance of the air intake opening being disposed within, especially centrally within, the radial clearance region covered by the upper cover disk, and the air intake opening is disposed axially within, especially centrally within, the axial region covered by the upper cover disk.