{HEAD ~ The operation pipe} is actuated and drives the piston and piston valve in {TAIL ~ the perpendicular direction} 
{ HEAD ~ The operation pipe } is actuated and drives the piston and piston valve in { TAIL ~ the perpendicular direction }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL