| 摘要 |
A telescopic boom broadly comprises an elongated hollow outer boom, an elongated inner boom telescopically received within the outer boom, and a guidance structure for guiding the inner boom for telescopic movement is provided. The guidance structure includes a plurality of guide rails attached to the interior corners of the outer boom, a first roller assembly attached to one end of the inner boom, a second roller assembly attached to one end of the outer boom, and a mid roller assembly positioned proximal to the second roller assembly. The first roller assembly includes a plurality of wheels mounted on axles for engaging the guide rails. The second roller assembly includes roller bars positioned on opposed sides of one end of the outer boom for guiding the inner boom during telescopic movement. The mid roller assembly includes a third roller bar that engages guide rails positioned on the inner boom.
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