| 摘要 |
Several embodiments of a crane are described and require a minimum of set up and strip down time. Each embodiment includes auxiliary frame means that is slightly wider in outside dimension than the tracks for supporting the main boom and gantry at its forward end, and supporting counterweights at its rear end with rollers on both ends permitting rotation of the auxiliary frame and vertically movable components supported thereon about a vertical axis. The rollers rest upon a horizontal steel ring supported by the ground during working of the crane, and the auxiliary frame and vertically movable components operatively connected thereto are moved upwardly to provide adequate road clearance when it is desired to move the vehicle from one site to the next. In one embodiment the ring is an inexpensive thin steel ring secured to a previously constructed concrete foundation and permits the relatively narrow vehicle to be driven over a portion of the ring onto and off of each preconstructed foundation. In the other embodiments, the ring is a full depth steel ring which is a vertically movable mobile component of the crane and is elevated with the auxiliary frame for transportation with the vehicle from one site to the next site. The full depth ring may either be provided with foldable side wings to permit movement along a narrow path or may remain in its full width attitude if travel space is not a problem.
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