| 摘要 |
An access structure such as a petroleum products loading platform which includes a vertically moving work platform having guides restrained with a plurality of vertical support members to vertically guide the platform along the support members. A plurality of lifting elements are respectively connected to each of the support members and to the platform to vertically move the platform along each of the support members. A common actuatable power arrangement is connected to each of the lifting elements to cause the lifting elements to vertically move the platform a prescribed distance along each of the support members responsive to each actuation of the power arrangement. Each of the lifting elements may be a hoisting drum and cable arrangement which is vertically moveable responsive to rotation of the hoisting drum to reel in or pay out the cable. The actuatable power arrangement may include a mechanical drive connected to each of the lifting elements to be rotated responsive to each actuation of the power unit. Alternately, the lifting elements may be hydraulic cylinders with the actuatable power means being an electrically driven hydraulic pump system to extend or retract each hydraulic cylinder.
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