| 摘要 |
An extension and retraction system for a four section telescopic boom having simultaneous and equal extension and retraction of the telescopic sections, wherein a pair of hydraulic cylinders are mounted exteriorly of the boom for extending and retracting the inner mid section relative to the base section; a pair of extension chains or cables are connected between the base section and the outer mid section, and between the fly section and the inner mid section; and a pair of retraction cables are connected between the base section and the outer mid section, and between the fly section and the inner mid section. The extension and retraction chains and cables are positioned within the boom sections to thereby be protected from damage.
|
