The sensing means includes a directing means for directing pressurized fluid to the second reaction chamber upon {HEAD ~ completion} of the dual modulated increases in {TAIL ~ fluid pressure} 
The sensing means includes a directing means for directing pressurized fluid to the second reaction chamber upon { HEAD ~ completion } of the dual modulated increases in { TAIL ~ fluid pressure }
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 TAIL TAIL TAIL TAIL TAIL TAIL