The shaft is connected to the shaft attachment by a thread. A bore with an internal thread is incorporated in the shaft attachment and the shaft has a corresponding stem which can be introduced into the threaded bore and has an external thread. An axial stop is arranged on the shaft and on the shaft attachment. The internal and external threads have torque-transmitting flanks which are flat toward the axis and which can be connected to one another frictionally by radial pressure by mutual rotation of shaft and shaft attachment with interaction between the axial stops. Owing to the small angle between the load-bearing flanks and the axis, the radial pressure decisive for the torque transmission is correspondingly greater than in conventional threaded connections. As a result, the axial prestressing force between the two parts to be connected can be correspondingly reduced.