| 摘要 |
<p>METHOD AND APPARATUS FOR EXTENDING A BOOM ASSEMBLY The overall length of boom assembly can be increased by the use of a pair of boom extension sections. When the boom extension sections are not required, they are supported at storage locations adjacent to one side of a main boom assembly. When the overall length of the main boom assembly is to be increased, a First one of the boom extension sections is pivotally connected with the outer end portion of the main boom assembly and the second boom extension section is pivotally connected with the outer end portion of the first boom extension section. The two boom extension sections are swung outwardly together around the outer end of the main boom assembly. After the first boom extension section has been firmly connected with the outer end portion of the main boom assembly, the second boom extension section is pivoted about the outer end portion of the first boom extension section. A gantry frame is then erected to hold the two boom extension sections against movement relative to each other so that the two boom extension sections form a rigid structure which increases the overall effective length of the boom assembly. In order to guide movement of the second boom extension section from its storage position into engagement with the first boom extension section, a roller on the second boom extension section rolls along a track which is connected with the main boom assembly. As the second boom extension section is moved into engagement with the first boom extension section, the roller moves off the track to thereby release the second boom extension section for movement away from the main boom assembly.</p> |
