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