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