| 摘要 |
<p>To reduce the weight and increase the lifting capacity of a multi-section telescopic crane boom, a single hydraulic cylinder for the full extension and retraction of individual boom sections is anchored in the relatively stationary boom base section. A sled structure surrounding the single cylinder and moving therewith has guided engagement through plates fixed to the movable boom sections at or near their rear ends. Driving finger mechanisms on opposite sides of the sled are biased toward driving engagement with the plates of the movable boom sections and are retractable into chambers of the sled. A cooperative locking pin operating assembly for the movable boom sections is fixed on the forward end of the boom base section and includes power retracting devices which operate mating retracting cranks and locking pin sets individual to the movable boom sections when the retracting cranks are aligned beneath the power retracting devices. The movable boom sections are equipped near their outer and inner ends with locking receivers for said locking pins.</p> |
