| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve to be apt to be contaminated property of a spool of pilot pressure operation mounted on a valve for a high and low pressure switching, and prevent erroneous operation of the valve. SOLUTION: A high and low pressure switching valve 49 is arranged to switch a high pressure line and a low pressure line arranged in an oil hydraulic circuit 27, a pipe passage formed as an outside piping for supplying pressure oil to the P port of a three-position switching valve 97 for operating a spool for switching high and low pressure is arranged in the other oil pressure circuit, and the filter 103 of small mesh is arranged on the way of the pipe passage 99. It is, thus, possible to improve to be apt to contaminated of the spool for switching the high and low pressure switching valve 49, and it is possible to prevent erroneous operation of the high and low pressure switching valve 49.</p> |
