{HEAD ~ The insert} is pushed forward into {TAIL ~ the open jacket} which is pushed away from the opening blade permitting closure by gravity 
is pushed forward into
{ HEAD ~ The insert } is pushed forward into { TAIL ~ the open jacket } which is pushed away from the opening blade permitting closure by gravity
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH