| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve operational capability of horizontal tow, by operating a selector valve by being operatively associated with the tilting and falling down starting operation of an oil pressure remote control valve, and momentarily communicating an oil chamber having confined inner pressure and an oil tank with each other through an position having the throttle of the selector valve. SOLUTION: In the case that an operating lever 18 is operated on an arm drawing-in side, pressure Pi generated when the leading-out of low pressure pilot secondary pressure is started is firstly led out from the pilot valve 19R of an oil pressure remote control valve 17 at a point of time in an extremely small range where the tilting and falling down of the operating lever 18 is started, and actuated to the pilot port 26 of a control valve 13 and the pilot port 29 of a selector valve 28. In an extremely small range where the stroke of the valve 13 is started, the channel of the valve 13 leading to a lock valve 4 may not be opened, however the built-in spring 35 of the selector valve 28 has lower pressure than pressure Pi so that the selector lever 28 is passed from an oil pass shut off position 30 through an oil pass position 31 with a throttle and changed over to an oil pass position 33 with a shut off port, and an oil chamber 23 is momentarily communicated with an oil tank 16. Therefore, confined inner pressure in the oil chamber 23 is gone, and the falling plumb phenomenon of an arm can be prevented.</p> |
