| 摘要 |
PURPOSE:To perform backward dredging work by a method in which a rotary cutter is provided around a vertical shaft pivotally supported on the tip of a ladder, a cover is provided on the cutter, and a water suction pipe leading to the opening of the cover, a mud water pipe, and the cover are turned around the vertical shaft. CONSTITUTION:An annular support disc 18 is projected from the lower end periphery of a subladder 4, and a cover 8 is rotatably supported through a rotary roller. The cover 8 is turned alternately and reciprocally at 180 deg. by a reversibly turnable driver, e.g., oil-pressure motor, etc., fixed to the ladder 4 through the internal gear of the cover 8. the ladder 4 is held vertically to the seabed ground and dredging work is made by one-time forward movement of the dredger. Afterwards, the dredger is moved sideways, and while turning the cover 8, dredging work is made backwardly. Backward and forward dredging work can thus be made possible and the dredging performance can be greatly raised.
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