| 摘要 |
A compact hoisting device is constructed with a primary hoist link pivoted at one end on a shaft secured to a base and pivotally connected to a final hoist link by means of a journal in the other end. A load support is pivotably mounted at the free end of the final hoist link on a shaft driven by attitude control transmission means into a constant spatial attitude regardless of the angular movement of the primary and final hoist links. Motion transmission means engage said journal to ensure that the angular rotation of the final hoist link mirrors the rotational motion of the primary hoist link, itself governed by a hydraulic jack or other drive means. The motion transmission means and the attitude control means may employ planetary gear trains, sprocket-and-chain drives, or parallel-rod drives, as suited to a particular application. One or more intermediate links may be interposed between the primary and final hoist links, with the several links in the hoist train sequentially pivoted to one another. |
