| 摘要 |
A crane of the type having a slewing upper chassis 5 carrying a jib, the lowermost component of which is shown at 10, and an erection column 12 for raising the jib from a horizontal assembly position into an upright operating position, has a hydraulic cylinder 11 connected to the component 10 and a cable 13 connecting the component 10 to the column 12. The column 12 is raised from the lowered position shown to an upright position, in which subsequently a tackle 14 swings the column 12 rearwards and raises the jib to its upright operating position, by means of the cylinder 11. A better purchase can be obtained by the cylinder 11 acting on the component 10 than by a cylinder acting directly on the column 12 which is usual, and therefore a smaller cylinder can be used.
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