| 摘要 |
A self-lifting crane adapted to raise or lower itself to different levels of any building or horizontal structural members of the building said crane including a frame having four lower outriggers and four upper outriggers which can be retracted and extended by hydraulic cylinders to selectively support the crane on horizontal structural members of a building and four lift outriggers which can be retracted and extended by hydraulic cylinders to selectively support the crane on horizontal structural members of a building; said lift outriggers being mounted in a support structure which can be moved up or down by hydraulic jacks to raise or lower the crane through the use of four positive displacement pumps; said crane including in its hydraulic system trim valving to supply to any one or more of said hydraulic jacks additional fluid to maintain the level of the crane. |
