| 摘要 |
<p>A supporting column-lifting device (4) has a groove for movement. A supporting column (3) is movably fit inside the groove, and the lifting device (4) vertically moves along the column (3). On both sides of an opening portion of the groove are arranges a pair or pairs of guide rollers (6). A guide roller (6) has a central projection portion (5a), an upper projection portion (5b), and a lower projection portion (5c) that extend like petals. The guide roller is urged by a spring etc. such that the central projection portion (5a) is oriented in a horizontal direction. When the central projection portion (5a) hits against a lateral member (2) while moving vertically along the column (3), the central projection portion (5a) swings upward or downward against the urging force and moves over the lateral member (2). At this time, as the central projection portion (5a) swings, the upper projection portion (5b) or the lower projection portion (5c) projects into the opening of the groove, maintaining the meshed relationship between the column (3) and the guide rollers (6) to prevent the lifting device (4) from dislocating from the column (3).</p> |
