| 摘要 |
<p>A generally rectangular frame having a vertical support column at each corner thereof each mounted for vertical movement relative to the frame. Hydraulic cylinders adjust the height of the frame relative to the columns at one end of the frame, the cylinders being operable to maintain the frame level from side to side in spite of variations in slope of the ground on which the frame is supported. A cable suspension system slaving the two columns at the other end of the frame supports the frame from the two columns at the other end together and suspends the frame therefrom in such manner that the supports may move vertically relative to the frame to maintain ground engagement of the supports in spite of variations in ground slope while supporting the frame level from side to side. The hydraulic system and cable suspension system cooperate to enable the frame to be raised or lowered on all columns simultaneously.</p> |
