| 摘要 |
PURPOSE:To enhance the efficiency of operations by a method in which the following cylinder of the telescopic arm of a working machine is connected with an oil-pressure switch valve, and a following pump, an electromagnetic valve, and a low-pressure relief valve are combined to make up an oil-pressure circuit. CONSTITUTION:Under a condition that a telescopic arm 7 is extended, a working machine 1 is advanced for scraping-off, and the tip roller 13 of a tool 12 is contacted with the upside of a side wall 17. A boom cylinder 5 is contracted and the tool 12 is lowered along the side wall 17. Whereupon, a piston rod 31 connected to a front arm 10 is pushed into a following cylinder 11 and contracted. Oil in an oil chamber 32 on the head side of the cylinder 11 is sent through oil paths 50 and 51, c-position of an electromagnetic valve 32, and an oil path 52 to an oil chamber 33 on the rod side, and excess pressure oil from a following pump 44 is returned through a low-pressure relief valve 36 and an oil path 53 to an oil tank 46. When the cylinder 5 is extended upwards, the tool 12 rises along the side wall 17.
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