sensing means for directly sensing and signaling the completion of {HEAD ~ the modulated increase} in {TAIL ~ fluid pressure}; and 
in
sensing means for directly sensing and signaling the completion of { HEAD ~ the modulated increase } in { TAIL ~ fluid pressure } ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH