| 摘要 |
A ball screw includes a nut, a screw shaft, an end deflector attached to the nut, plural balls, and a pair of ball lifting portions. A spiral groove is formed at an outer peripheral surface in the screw shaft. The plural balls roll along the spiral groove. The pair of ball lifting portions is provided at the end deflector so as to interpose a width center of the spiral groove. The pair of ball lifting portions supports the balls by a first part of one of the pair of ball lifting portions and a second part of other of the pair of ball lifting portions being apart from each other in a width direction of the spiral groove so as to interpose the width center of the spiral groove between the first and second parts to thereby lift the balls from the spiral groove. |
