| 摘要 |
<p>The telescopic extension system is intended for a tower crane and uses mast elements extensible by a hoisting tackle, together with a sliding inner mast. The latter is hoisted by devices carried by a dismountable cage which is lifted up to the tip of the sliding mast. The cage carrier also suitable guide elements. Between the inner mast tip and the cage base are set unsssembled outer mast elements. Then these elements are erected and secured in a specified erection cycle. The cage might need not be related directly to that of the mast elements. After finished erection the cage is dismounted.</p> |
