The four corners of the frame are provided with four pulleys. Wire ropes pass round the pulleys and are tightened on the reel drum of a cranetrolley.
框架上面的四角装有四只滑轮,钢丝绳绕过滑轮向上系于起重行车的卷筒上。
2
To install the crane span before installation, camber, level of metal structure of main girder bending, trolley rail height difference, gauge deviation, diagonal bridge survey.