control means for controlling {HEAD ~ the speed} of the electric motor to thereby control the rotating speed of {TAIL ~ the tubular member} 
control means for controlling { HEAD ~ the speed } of the electric motor to thereby control the rotating speed of { TAIL ~ the tubular member }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL