| 摘要 |
An apparatus for maintaining a uniform grade of the surface being excavated or leveled by a waterborne dredge. The apparatus includes a shore mounted laser that projects a horizontal beam which is utilized to establish a reference plane, a dredge mounted photo receiver responsive to the beam from said shore mounted laser, a hydraulic system for repositioning the dredge cutter in response to changes of position of the dredge relative to the reference plane established by the laser beam. The hydraulic system includes a specifically designed pulley arrangement which raises and lowers the dredge ladder to maintain the cutter at a constant elevation.
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