| 摘要 |
PURPOSE:To permit drain materials to be driven at an optimum interval by enabling the interval between mandrels to be changed. CONSTITUTION:According to the kinds of draining materials and the conditions of the ground, draining materials are allowed to be driven at an optimum interval by permitting the interval between the mandrels to be exactly and easily altered for a draining material driver having a plurality of mandrels. Draining materials D, e.g., paper drain and chemical drain, can be driven concurrently at intervals by means of many mandrels 5.
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