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 {HEAD ~ the opposite side} of said {TAIL ~ main valve} means from said 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 { HEAD ~ the opposite side } of said { TAIL ~ main valve } means from said main valve chamber ,
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