As soon as the valve element reaches the desired extreme position in contact with a stopper, {HEAD ~ the motor} is rotated to deform the elastic coupling member and to improve the contact between the valve element and {TAIL ~ the stopper} 
As soon as the valve element reaches the desired extreme position in contact with a stopper , { HEAD ~ the motor } is rotated to deform the elastic coupling member and to improve the contact between the valve element and { TAIL ~ the stopper }
OTH OTH OTH OTH OTH OTH 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 OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL