closure means covering said main valve means and secured to said main body and cooperating with them to provide an outer chamber to which said inlet pressure conduit leads, so as to exert pressure on the opposite side of said {HEAD ~ main valve} means from said {TAIL ~ main valve chamber}, 
closure means covering said main valve means and secured to said main body and cooperating with them to provide an outer chamber to which said inlet pressure conduit leads , so as to exert pressure on the opposite side of said { HEAD ~ main valve } means from said { TAIL ~ main valve chamber } ,
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH