| 摘要 |
<p>An improved boom structure is provided which is attachable to a vehicle and includes a boom support member for pivotally supporting a telescopic boom. The telescopic boom includes a generally square outer boom and a generally circular inner boom housed within the outer boom but prevented from rotational movement therein. A first winch is connected to the boom support member with a first cable windingly connected to the first winch. Movement of the first cable from about the first winch controls the pivoting of the telescopic boom through an arc of 180 degrees from a generally horizontal position. A second winch is connected to the boom support member with a second cable windingly connected to the second winch. Movement of the second cable from about the second winch controls the extension and retraction of the inner boom relative to the outer boom. A third winch is also connected to the boom support member with a third cable windingly connected to the third winch. Movement of the third cable from about the third winch controls the extension and retraction of the third cable from the outer end of the telescopic boom.</p> |
