| 摘要 |
A movable gantry crane for erecting a wide span structure comprising several bridge-like sub-structures arranged side by side in spaced relationship, which crane comprises: a horizontal girder long enough to span the structure and supported at each side of the structure by movable support columns; a platform suspended from the girder from hangers so as to lie beneath a sub-structure to be erected and enable work to be carried on without interference with the area spanned by the structure; there being at least one set of hangers in front of this sub-structure, and at least one other set of hangers behind it and which can be displaced to permit the crane and the platform to be moved forward when the sub-structure has attained a stable condition; and a lifting device movable along the girder between the sets of hangers. |
