of the main operating unit 2 with a higher voltage and consequently lower currents on the one hand and on the other hand not having to provide stronger insulation and unnecessarily expensive special frequency converters fu for ancillary units 16 according to one advantageous embodiment of the invention feeding of main drive system on the one hand and ancillary units on the other hand by different voltage levels will be expected a higher voltage level is provided to supply the motors with higher energy throughput and a lower voltage level will supply the motors with lower energy throughput such an embodiment is shown in fig8 wherein both voltage levels are generated by the shared generator g which may be provided with two separate stator windings each providing one voltage level as shown in fig9 displacement drives faw 1 faw 2 and faw 3 which in the embodiments according to fig7 and 8 may be combined with drive device 13 of the main operating unit 12 or may be co operated on a shared voltage level respectively may also be fed by a lower voltage level which also supplies the other ancillary units 16 in this context a shared frequency converter fu may be associated to said displacement drives faw 1 faw 2 and faw 3 while it is also possible to have one frequency converter associated to each one of the displacement drives faw 1 faw 2 and faw 3 the displacement drives faw 1 faw 2 and faw 3 may also be fed by a lower voltage level than drive device 13 of the main operating unit.