| 摘要 |
PROBLEM TO BE SOLVED: To prevent sludge from being splashed upward caused by the reciprocating motion of a scraper. SOLUTION: This scraper device comprises a scraper provided on the underside of a settling reservoir to scrape built-up sludge from the underside to a sludge-pit provided at one side of the underside by the reciprocating motion of the scraper at a pre-determined uniform rate. A scraper controlling means is provided, which controls the following respective rates of movement in this order with deliberation a transition rate before reaching a pre-determined uniform rate for the scraper to scrape the sludge, a transition rate before said rate reaches 0, a transition rate before reaching the pre-determined uniform rate for the scraper to return and a transition rate before said rate reaches 0. COPYRIGHT: (C)2003,JPO
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