| 摘要 |
PURPOSE:To maintain a cross rail horizontal by arranging a pair of position detectors on both ends of the cross rail then driving a correction driver on the basis of each detected signal. CONSTITUTION:An elevating motor 34 is driven by a position command signal F to elevate a cross rail 5. Here the absolute position of the cross rail is detected by an absolute position detector D and the signal is fed back to an elevation controller E. When elevating a cross rail, a pair of pinions 8R, 8L will rotate and the phase signals from the detectors 12R, 12L are fed to a decision device 15 and when the phase difference exceeds over predetermined level the left and right correction drive motors 16R, 16L are driven to perform the correction. Consequently the horizontal correction of the cross rail can be performed well. |
