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