Variable pulses of {TAIL ~ an electric voltage} are applied to the electric motor in such a way that {HEAD ~ the rotor} of the electric motor moves at a rotational speed which can be set 
Variable pulses of { TAIL ~ an electric voltage } are applied to the electric motor in such a way that { HEAD ~ the rotor } of the electric motor moves at a rotational speed which can be set
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH