| 摘要 |
A flat surface portion is formed on a nut so as to extend to a region where an output pulley attachment portion is formed in an axial direction, and extend substantially in parallel with a tangential direction of a rotational axis of the nut. A ball circulation groove one end side opening, and a ball circulation groove opposite end side opening are formed on the nut. The ball circulation groove one end side opening is in communication with one end of a ball circulation groove and is formed so as to be opened to the flat surface portion in the region where the output pulley attachment portion is formed. The ball circulation groove opposite end side opening is in communication with an opposite end of the ball circulation groove and is formed so as to be opened to the flat surface portion. |
