| 摘要 |
An aerial lift includes a bucket mounted at the outer end of an articulated boom assembly having upper and lower booms. A hydraulic cylinder is provided for extending the upper boom relative to the lower boom, and a rotary actuator is provided for varying the rotational position of the bucket relative to the upper boom. An auxiliary cylinder, actuated in response to actuation of the upper boom hydraulic cylinder, provides hydraulic fluid to the rotary actuator so as to maintain the bucket in a substantially level position as the articulated boom assembly is raised and lowered. The load train including a chain and sector-shaped sprocket automatically compensate upper boom angle for changes in the angle of the lower boom relative to horizontal so that the rotary actuator is actuated only in response to actual changes in the angular position of the upper boom relative to horizontal.
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