| 摘要 |
PURPOSE:To improve the recovering efficiency of sediment. CONSTITUTION:An air suction hose 31 is connected to a suction nozzle 23, a valve 32 opened or closed based on the pressure of a suction hose 24 is provided on the air suction hose 31, the valve 32 is opened or closed in response to the pressure of the suction hose 24, and the suction air quantity of the air suction hole 31 is adjusted. The suction air quantity is kept at the optimum when accumulated sediment 26 is sucked, the accumulated sediment 26 is stationarily sucked, and the recovering efficiency is improved. |
