Similarly the cam surface 31 on the lever arm circles about the rod 28 and projects in one direction on one portion 31 of the circle and {HEAD ~ projects} in the opposite direction in {TAIL ~ the opposite portion} 31 of the circle 
Similarly the cam surface 31 on the lever arm circles about the rod 28 and projects in one direction on one portion 31 of the circle and { HEAD ~ projects } in the opposite direction in { TAIL ~ the opposite portion } 31 of the circle
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH