In addition, the present apparatus comprises surface interfaces between a slidable sleeve and {HEAD ~ a mandrel} to minimize {TAIL ~ a probability} of mandrel and sleeve separation during the plungers ascent phase and a risk of plunger stall 
to minimize
In addition , the present apparatus comprises surface interfaces between a slidable sleeve and { HEAD ~ a mandrel } to minimize { TAIL ~ a probability } of mandrel and sleeve separation during the plungers ascent phase and a risk of plunger stall
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH