| 摘要 |
An elevating device consists of a base frame, usually mounted on running wheels, a turntable on the base frame, a vertical first post on the turntable and first and second arm means mounted on the post. The first arm means is a parallelogram linkage connecting the first post and a second post, so that the second post stays vertical as it moves up and down. The second post is skewed along its length so that the two arm means can move alongside each other into the stored position; it is therefore exceptionally compact in that position. The second arm means telescopes and a man-carrying platform is pendulously suspended at its outer end. A linkage including a telescoping shaft connects the second post and the platform to hold the platform against inadvertent movements; the linkage includes a spring connection to prevent damage thereto under accidental impacts. The movements of the first arm means relative to the first post, the second arm means relative to the second post, and the telescoping of the second arm means are under the control of respective separate hydraulic piston and cylinder motors.
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