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