| 摘要 |
A boom lifting system for a crane of the type having an upright mast and a boom hinged to the mast. The system has a brace extending between the mast and the boom. The brace is pivotally connected to both the mast and the boom and has a hinge dividing it into a short section, connected to the boom, and a long section, connected to the mast. A hydraulic cylinder is pivotally connected to both the boom and the short brace section. Actuation of the cylinder straightens or bends the brace to respectively lift or lower the boom relative to the mast. |
