| 摘要 |
PROBLEM TO BE SOLVED: To avoid the occurrence of trouble in the circulation of balls resulting from an attachment structure of a top to a penetration hole, in a top-type bass screw.SOLUTION: A top 4 is a component in which a ball return path 41 for returning balls to a starting point from a terminal point of a rolling path, arranged in a penetration hole 22 which penetrates a nut 2 in a radial direction, and has a pair of arms 42 extending toward axial both ends of the nut 2. A pair of recesses 24 to which a pair of the arms 42 are fit are formed at an internal peripheral face 2b of the nut 2. The recesses 24 have retention parts which are formed so that peripheral widths become narrow toward an axial center side of the nut 2 when viewed from an axial direction in order to prevent a fall of the arms from the recesses 24, at internal peripheral faces.SELECTED DRAWING: Figure 6 |
