| 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 a pair of 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. |
