An electromagnetic clutch (4) which serves for connecting a steam engine (2) to a combustion engine (3), wherein a first shaft (8) which can be driven by the steam engine (2) and a second shaft (9) which can be driven by the internal combustion engine (3) are provided, wherein an intermediate gear (23) which is connected to the first shaft (8) and a clutch bell (26) which is at least indirectly connected to the second shaft (9) are provided, wherein a freewheel (27) is provided between the intermediate gear (23) and the clutch bell (26).