| 摘要 |
A crane for ships and having a boom pivotally mounted for vertical movement on a base, telescopic hydraulic jack means connected to the boom to support the outer end thereof in a desired position, a pulley carried by the boom near the outer end thereof and means for shifting the pulley towards and away from the base, a cable threaded over the pulley and winch means for reeling in and paying out this cable, and a control system including accumulator means connected to the jack means for maintaining the boom outer end substantially in the position thereof regardless of ship motion under wave action when the cable is supporting a load in the water.
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