| 摘要 |
An articulated telescopic boom assembly (12) for a lifting device (10) includes a first elongated boom (20) having a central longitudinal axis and an opening in one end; a second elongated boom (22) having a first end (86, 88) normally telescopically received by and extensible from the first boom (20) opening, the first end (86, 88) having at least one elongated pivot guide sl ot 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 (38) having a housing (40) with an opening therein for receiving the second boom (22) during extension and retraction thereof. The housing (40) i s pivotally connected to the first boom (20) by a pair of opposing elongated pins (82, 84) which define a pivot axis (42). The central longitudinal axis of the pivot guide slot (90) is offset from and perpendicular to the pivot axis (42) such that when the closed end of the guide slot (90) is registered with the pivot pins (82, 84), the second boom (22) is pivotable. |
