| 摘要 |
<p>The primary jib (9) of the crane is supported, at its upper end (10), by first and second jib control lines (17 and 19) extending to the upper end (10) of the primary jib (9) from first and second parts (6 and 7) of a cross-member (5) extending laterally of a supporting mast (3). The first jib control line (16) also extends from the upper end (10) of the primary jib (9) to a base (1). The second jib control line (18) has no such extension. Adequate support is provided because the second part (7) is spaced further than the first part (6) from an intermediate reference point (8) cross-member (5) disposed above the pivotally supported lower end (11) of the primary jib (9). The first part (6) of the cross-member (5) and said reference point (8) are disposed on the same side of the mast (3) and so the primary jib (9) can be swung around the mast (3). </p> |
