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