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