| 摘要 |
An elevator has a horizontal chassis, a telescopingly extensible and retractable mast having upper and lower ends, a guide extending along the mast between its ends, and a platform adapted to support a worker and displaceable in the guide along the mast between its ends. The lower end of the mast is pivoted on the chassis for movement of the mast relative to the chassis between an erect position with the upper end above the lower end and a recumbent position with the mast lying on the chassis and the mast ends generally level with each other. This axis is sufficiently above the chassis that in the recumbent position the platform can lie between the chassis and the mast. The chassis has opposite ends, one of which carries the mast and pivot. The center of mass of the mass is horizontally between the pivot axis and the other chassis end so that a drive connected between the chassis and the mast first pivots the mast about the axis from the recumbent to the erect position and then vertically extends the mast and raises the platform. This drive is normally a motor mounted on the chassis and having a drum and a cable connected between the drum and the mast. |
