a cam surface located on an exterior portion of {HEAD ~ the tieback member} in engagement with an inner side of {TAIL ~ the locking member} 
a cam surface located on an exterior portion of { HEAD ~ the tieback member } in engagement with an inner side of { TAIL ~ the locking member }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL