When gate 15 is moved upwardly to open the valve, to bring gate passage 35 into alignment with body passages 25, 26, the cam action between {HEAD ~ pins} 44 and grooves 45 causes movement of element 41 away from the gate to deactivate the seal formed by {TAIL ~ seal element} 49 
When gate 15 is moved upwardly to open the valve , to bring gate passage 35 into alignment with body passages 25 , 26 , the cam action between { HEAD ~ pins } 44 and grooves 45 causes movement of element 41 away from the gate to deactivate the seal formed by { TAIL ~ seal element } 49
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 OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH