there is shown a rear view being opposite to the loading opening view of a laundry drum 11 of a domestic washing machine or a domestic spin dryer which is mounted rotatably here in a rear wall of a tub 12 sketched in cubic form the tub 12 is suspended in an oscillable but elastically damped manner in a machine housing 13 in the simplified illustrations of the drawing a motor which is coupled directly or by a gear mechanism to the laundry drum 11 for the rotational movement of the laundry drum 11 about its axis of rotation 14 that is inclined for example with respect to the horizontal has been omitted however fig1 does illustrate a transmission 15 for the rotationally rigid coupling of a permanent magnet type rotor of a rotational sensor 18 in the form of a tachogenerator 18 to the laundry drum 11 which is driven by the electric motor an axis of rotation 20 of the rotor of the rotational sensor 18 is oriented substantially parallel to the axis of rotation 14 of the laundry drum 11 which for its part shall be defined in the three dimensional cartesian coordinate system as indicated in fig1 as the x axis this is the main axis of inertia of the rotating system of the loaded laundry drum 11 in the event.