| 摘要 |
<p>Brackets 9, 9 for supporting respective opposite ends of a guide rod 4 are provided with respective cam faces 95, 95 approximately symmetric about an approximate longitudinal midportion C of the guide rod 4, and at least one of the brackets 9 is provided with an adjusting member for moving the guide rod 4 longitudinally thereof. The cam faces 9 guide the guide rod 4 toward a direction in which the guide rod 4 pivotally moves about the approximate longitudinal midportion C, as the guide rod 4 is moved longitudinally thereof by the adjusting member. <IMAGE></p> |
