A device (13) for transferring rotational power from a first shaft (14) to a second shaft (15), comprising an endless toothed belt (16) and a housing (17), wherein the belt (16) is arranged inside said housing (17) and is connectable to the first and second shafts (14, 15) for transferring rotational power from the first shaft (14) to the second shaft (15). The housing (17) comprises a first cavity (18) and a second cavity (19), wherein the second cavity (19) is separated from the first cavity (18) by means of a wall (20). The belt (16) is arranged in the first cavity (18) and the first cavity (18) is provided with a first liquid for contacting the belt (16). The second cavity (19) is provided with a second liquid, the second liquid being a cooling liquid. The housing (17) comprises an inlet (23) to the second cavity (19) and an outlet (24) from the second cavity (19) for the second liquid, and the second cavity (19) is connected to a source of the second liquid through the inlet (23), so that the second liquid can be circulated through the second cavity (19). Disclosed is also a machine including such a device and uses of such a device for industrial machines.