The swinging end slides on a surface of the interlocking member as {HEAD ~ the swinging} of {TAIL ~ the interlocking member} 
The swinging end slides on a surface of the interlocking member as { HEAD ~ the swinging } of { TAIL ~ the interlocking member }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL