The pressure for moving piston 40 and mandrel 38 upwardly to open {TAIL ~ the valve} is supplied to cylinder 42 below the piston through lateral opening 60 in the sidewall of {HEAD ~ lower housing section} 12 
The pressure for moving piston 40 and mandrel 38 upwardly to open { TAIL ~ the valve } is supplied to cylinder 42 below the piston through lateral opening 60 in the sidewall of { HEAD ~ lower housing section } 12
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH