In {HEAD ~ the normal operation} of {TAIL ~ the pump turbine apparatus} in the turbine or pump operation mode, the fail safe valve 47 is held at the illustrated position by the force of a spring associated therewith 
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In { HEAD ~ the normal operation } of { TAIL ~ the pump turbine apparatus } in the turbine or pump operation mode , the fail safe valve 47 is held at the illustrated position by the force of a spring associated therewith
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