| 摘要 |
PURPOSE:To enhance the efficiency of dredging work by a method in which on the basis of a control signal generated according to the difference between detection signal from a depth meter provided to a drag head and a set depth signal, the drag head is driven to perform dredging work for a necessary part. CONSTITUTION:When a drag head 1 moves in the direction of arrow (m) and enters a soil and sand part 3' below a set depth 4 beyond the lower limit value L, the deviation becomes minus(-). Accordingly, after the lapse of time 2, a winch is wound up at low speeds, and the drag head 1 is lifted up and stopped at the point C. When the draft of a dredger is incrreased and the drag head 1 reaches the point D, the deviation becomes minus(-) again, and thereby the winch is wound up until the depth 4 is reached. When the draft of the dredger is reduced and the drag head 1 reaches the point E, the deviation becomes plus(+) and the position of a swell compensator 2 comes to the lower limit alarm point, and thereby the winch is wound down. |
