| 摘要 |
<p>An operating system for telescoping a telescopic boom for a crane, particularly a boom having three or more telescoping sections, enabling the boom to be extended and retracted automatically under load according to a predetermined sequence which optimises the load capacity of the boom and the stability of the crane. The boom may be switched rapidly between modes of operation in one of which all of the telescoping sections may extend or retract and in another of which at least one telescoping section is maintained in the fully retracted position.</p> |
