the first pump 10 and hence the torque at higher pressures fig2 shows a speed controlled electric drive with the multi flow pump and the optional suction jet pump 90 it is advantageous that only the first pump 17 for producing the high system pressure has to be driven by the first electric motor 27 by means of the first electric motor 21 and the second speed controlled motor 22 the hydraulic energy source in fig3 allows two completely independent branches for supplying the actuator system and the cooling system 100 according to fig4 coupling between the branches can be provided by means of the selector valve 50 fig5 shows a hydraulic energy source with a speed controlled first electric motor which is associated with the pumps 13 and 14 the second pump 14 which is of larger design can be connected up by means of the disengageable coupling fig6 shows a hydraulic energy source having a first electric motor which has a variable speed and a variable direction of rotation with for the smaller first pump 191 which is designed to produce a the high system pressure and the low cooling pressure and for a for the second larger pump 192 which is designed to produce the lower cooling pressure the one way clutches 150 and 151 are built in.