| 摘要 |
PROBLEM TO BE SOLVED: To increase measurement accuracy by reducing the inclination and movements of an upper rim shaft during rotation. SOLUTION: The upper rim shaft 14 is inserted into an insertion hole of a drive shaft 11 which is rotatingly driven integrally with lower rim shafts 5, 8, and a hollow operation sleeve 34 is allowed to slide at an engagement position. A plurality of balls 12 held at two vertically arranged points on the peripheral wall forming the insertion hole of the drive shaft 11 are thereby engaged with an annular groove 14a formed on the outer peripheral surface of the upper rim shaft 14 to lock the upper rim shaft 14 firmly at the two vertically arranged points in the circumferential direction. The upper rim shaft 14 is thereby prevented from inclining and moving during rotation to increase measurement accuracy. COPYRIGHT: (C)2011,JPO&INPIT
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