| 摘要 |
<p>The device is assembled of a base (1) with four vertical bars (8) and two long upper bars with a horizontal upper segment (10) and a sloping front (9). The stretcher (3), resting on a carriage (2) with two pairs of rollers (6) located at each side, can be moved along two round bars (7) in the center of the base (1) in order to be used. The outer surfaces of the rollers (6) are of a concave shape, enveloping the bars (7) partly and supporting the carriage (2) vertically as well as horizontally when they are moved along the round bars (7).</p> |
