{HEAD ~ a follower} secured to each of said racks and extending from said central opening to one of said peripheral openings to be received within {TAIL ~ a respective groove} of said sleeve upon rotation of said shaft, 
{ HEAD ~ a follower } secured to each of said racks and extending from said central opening to one of said peripheral openings to be received within { TAIL ~ a respective groove } of said sleeve upon rotation of said shaft ,
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH