| 摘要 |
A ball screw comprises a screw shaft, a hollow cylindrical nut member, balls, a ball returning means and a pair of deflectors. The screw shaft has a helical ball running groove. The nut member has a helical ball running counter-groove facing on the helical ball running groove of the screw shaft, and has a pair of ball-passing holes for connecting inner and outer surfaces of the nut member with each other. The balls are arranged between the ball running groove and the ball running counter-groove. The ball returning means is arranged on the outer surface of the nut member, for connecting the ball-passing holes with each other. The deflectors are disposed so as to be respectively correspondent with the ball-passing holes, for picking up the balls from the ball running groove to transfer the thus picked up balls into the ball-passing hole. Each of the deflectors comprises a ring-shaped base member fitted in an opening end of the nut member, and a ball-picking-up member projected from the base member. The ball-picking-up member is inserted in the ball running counter-groove so as to take a prescribed position of the ball-picking-up member relative to the ball-passing hole.
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