| 摘要 |
<p>The lift device of the scissor-jack type comprises two arms (1, 2) that are midway connected by a pivot (7) and carry a platform (12). One arm (2) carries a pulley (16) between the pivot (7) and one end (4). On the other side of the pivot (7) is a slideable cam follower (17). This cam follower (17) rides on a cam surface (20) provided on the other arm (1). A cable (21) is attached to the cam follower (17), guided around the pulley (16) and back to the lower end of the cam surface carrying arm (1). The contour of the cam surface (20), and the position and diameter of the pulley (16) are chosen such that a predetermined, preferably constant, ratio between input and output is obtained. </p> |
