{HEAD ~ angular position} determining {TAIL ~ means} connected to said engaging means for rotation therewith and for providing an indication of the angular position of said engaging means; and 
{ HEAD ~ angular position } determining { TAIL ~ means } connected to said engaging means for rotation therewith and for providing an indication of the angular position of said engaging means ; and
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH