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