| 摘要 |
In a telescopic crane comprising a telescopic shaft and a variable length boom pivotally mounted on the end of the shaft, the position of the boom relative to the shaft is controlled by a jack pivotally connected at one end to the shaft and at the other end to one end of a mast, the other end of the mast being connected to the boom, and ties connect the one end of the mast to the boom outwardly of the connection of the boom to the other end of the mask.
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