| 摘要 |
A multiple boom lifting arrangement includes a plurality of preferably four carriages, each carriage having a boom with its lower end portion pinned to the carriage. Two of the carriages are placed on a common travel path with the upper end portion of their respective booms being pinned. This provides two spaced apart pairs of carriages and booms for lifting. A horizontal beam extends between the first pair of booms and the second pair of booms being attached to the pinned connection of each pair of booms with a sling. A powered motor-driven winch is used to power a cable that is wound between sheaves on the lower end portions of a pair of booms that are connected together. During use, the winches are simultaneously or nearly simultaneously operated to elevate the first pair of the booms and the second pair of booms at about the same time so that the horizontal beam that spans in between the pinned connections of-the first and second pairs of booms is elevated. Packages can be lifted with the horizontal beam by depending one or more slings from the horizontal beam to the package to be lifted. The apparatus can use carriages that are provided with wheels that travel on rails, rubber tires, or can be sled or skid-mounted without the use of wheels or tires.
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