rotary part 5 wherein the outer rotary part 4 is furnished with at least one outer rotary wing not illustrated here wherein the rotary wing in each case is fixedly connected to the outer rotary part 4 over a certain torque transferring axial length x and wherein the rotary wing is directed radially inwardly the inner rotary part 5 is furnished with at least one inner rotary wing 6 wherein the inner rotary wing 6 is fixedly connected to the inner rotary part 5 over the same torque transferring axial length x and wherein the inner rotary wing 6 is directed radially outwardly here the outer rotary wing and the inner rotary wing 6 are furnished in their structure such that the outer rotary wing and the inner rotary wing 6 form between themselves at least two free spaces the outer rotary wings and the inner rotary wings 6 are freely rotatable relative to each other in the region of these free spaces until the outer rotary wing and the inner rotary wing 6 come to rest on a mutual stop the kind of and therewith the force transferring axial length x of the respective attachment between the outer rotary part 4 and the outer rotary wing or respectively between the inner rotary part 5 and the inner rotary wing 6 are determined by the torque to be transferred in contrast the size of the outer rotary wing and of the inner rotary wing 6 results from the torque to be generated by the hydraulic swivel motor 3 the torque generating axial length is the basis of this size.