The retainer is able to secure {HEAD ~ the terminal member} to prevent {TAIL ~ removal} when the retainer is in the fully secured position 
to prevent
The retainer is able to secure { HEAD ~ the terminal member } to prevent { TAIL ~ removal } when the retainer is in the fully secured position
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH