DOUBLE SLEWING CRANE CONSTRUCTION

摘要

A double slewing crane comprises a vertical support or column which is adapted to be fixed in position for example on a ship between two cargo hatches. The first crane arm or cantilever arm is pivotally mounted on the support for pivotal movement about a vertical axis and a second crane arm or cantilever arm is pivotally mounted on the support for pivotal movement about a vertical axis which may for example be the same axis or an axis which is spaced angularly or radially from the first crane arm pivotal axis. Each crane arm carries a jib which is pivotally mounted at its inner end about a horizontal axis and one of the jibs may be made smaller or shorter than the other. The pivotal mounting includes a ring gear which for example may be fixed in respect to the support and each cantilever arm portion carries a drive motor with a drive pinion which engages the ring gear to effect the individual rotative motion of the associated cantilever arm. Drive motors of the two cantilever arms may be synchronized so that the arms rotate together. Each cantilever arm carries a crane tower with the jib and in the case where the cantilever arms pivot about the same vertical axis the towers may be spaced apart from each other by positioning their associated supporting arms at a respective angle from an extension of the common vertical axis. Alternately a first crane and tower may be mounted for pivotal movement about an axis directly above the supporting member and the second crane may be carried on a cantilever arm at the outer end thereof so that it pivots about a vertical axis which is at a spaced radial location from the first vertical axis which coincides with the axis of the support column.