{HEAD ~ This series} of {TAIL ~ the actions} are repeated to provide a continual reciprocal movement of the piston 
of
{ HEAD ~ This series } of { TAIL ~ the actions } are repeated to provide a continual reciprocal movement of the piston
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH