An apparatus 4, wherein said pocket inner surface of said retainer is formed into a shape which substantially coincides with {HEAD ~ the shape} of {TAIL ~ the ball} in contact with said pocket inner surface at the major axis position of said cam 
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An apparatus 4 , wherein said pocket inner surface of said retainer is formed into a shape which substantially coincides with { HEAD ~ the shape } of { TAIL ~ the ball } in contact with said pocket inner surface at the major axis position of said cam
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 HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH