| 摘要 |
<p>CONSTANT BALANCE CRANE A constant balance crane has a control tower and a plurality of gantry members mounted on the tower between its base and its upper section. Trolleys on the gantries are movably mounted, and a lift mechanism is provided on at least one trolley. On at least one other trolley a counterweight is carried. The lift and counterweight trolleys are propelled on the gantries by a hydraulic system or the like which is partially manual and partially automatically responsive to the downward moments on the gantry to adjust the counterweight trolley to a load balancing position, and to continuously adjust the counterweights relative to the load such that constant balance is maintained. In modified embodiments, the counterweight trolley travels in a horizontal plane that is vertically spaced from the plane of travel of the load trolley.</p> |
