Garis besar topik

    • The mud sampling section is suspended by a special metal fitting that functions as a free-fall trigger. This metal fixture uses the principle of leverage to suspend the mud sampling section, and is called a "balance trigger" because it moves like a balance. In the balance trigger, a pilot weight is suspended from a force point far from the fulcrum, and the mud sampling section is suspended from a point of action very close to the fulcrum (Figure 4). The pilot weight is about one-tenth the weight of the mud sampling section, but because it is suspended far enough from the fulcrum, the balance is tilted toward the pilot weight.

    • Fig. 4: Balance trigger mechanism (1)

      力点　point of effort

      作用点　Point of load

      支点　fulcrum

      天秤式トリガ　Balance trigger

      パイロットウェイト　Pilot weight

      採泥部　Mud Collecting Section

    • When the balance is tilted toward the pilot weight, the mud sampling section is held suspended by the balance trigger (Figure 5-a). When the pilot weight reaches the seafloor or the force applied to the force point weakens, the balance tilts toward the mud sampling section and the sampling section is detached (Figure 5-b).

    • Fig. 5 Mechanism of the balance trigger (2)

      a) State before trigger activation b) State when trigger is activated


    • When the piston corer lands on the bottom, the impact often blows away the surface sediment. A small columnar corer, as shown in Figure 6, can be used in place of a pilot weight to collect surface sediments separately. The Frager corer (Fig. 6-a) is a mud sampler with a weight attached to the top of the mud sampler pipe, which penetrates the seafloor under its own weight to collect surface sediments several tens of cm below the surface. A check valve attached to the lower part of the collecting pipe and a lid on the upper part, which closes when collecting, hold the sediment and prevent it from falling out. The Ashlar Mud Collector (Fig. 6-b) uses the same mud collection tube unit as the Multiple Coaler and is a surface sampler that collects undisturbed, high-quality surface sediment samples by sealing the top and bottom of the collected cores with a lid.

    • Figure 6 Pilot corer

      a) Frager corer

      b) Ashlar corer (G.S. type surface corer)

      ナス型ウェイト　Eggplant type weights

      採泥管　Mud sampling pipe

      付加重錘　Additional Weights

      採泥管ユニット　Mud sampling pipe unit