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