| 摘要 |
An articulated telescopic boom assembly for a lifting device includes a first elongated boom having a central longitudinal axis and an opening in one end; a second elongated boom having a first end normally telescopically received by and extensible from the first boom opening, the first end having at least one elongated pivot guide slot therein having a central longitudinal axis with an open end remote from the first end and a closed end proximate to the first end; and a slide-through knuckle having a housing with an opening therein for receiving the second boom during extension and retraction thereof. The housing is pivotally connected to the first boom by a pair of opposing elongated pins which define a pivot axis. The central longitudinal axis of the pivot guide slot is offset from and perpendicular to the pivot axis such that when the closed end of the guide slot is registered with the pivot pins, the second boom is pivotable. The boom assembly also includes an extensible cylinder connected to the first and second booms for extending and retracting the second boom. The extensible cylinder is pivotally connected to the second boom by a pivot shaft registered with the closed end of the pivot guide slot. The boom assembly includes a hydraulic cylinder pivotally connected to the first boom and the housing for pivoting the housing and thereby the second boom with respect to the first boom. |
