When a fluid pressure in {TAIL ~ the extension chamber} exceeds {HEAD ~ a certain level}, the pressure relief assembly allows fluid to flow through the relief passageway 
When a fluid pressure in { TAIL ~ the extension chamber } exceeds { HEAD ~ a certain level } , the pressure relief assembly allows fluid to flow through the relief passageway
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH