A force motor is operable when desired to move the slide valve to its open position to permit {TAIL ~ movement} of {HEAD ~ the member} 
A force motor is operable when desired to move the slide valve to its open position to permit { TAIL ~ movement } of { HEAD ~ the member }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD