| 摘要 |
PROBLEM TO BE SOLVED: To compose a spool valve for switching a control oil pressure to an open drain circuit to be compact and light weight at a low cost. SOLUTION: This spool valve 1 comprises a spool 39 slidably disposed in a spool housing 11. An oil groove 41 on a ring is formed in an outer circumference of the spool 30. This oil groove 41 is opened at a spool end part through a through oil way 42 perpendicular to the spool 30 and through oil ways 43 and 44 axially penetrating the spool 30, and it is communicated with a drain line 43 at the open end part. As a signal pressure is applied to a signal line 21 of the spool valve 1, the spool 30 slides to move to the left to communicate a control line 22 with the oil grove 41. At this time, the control oil pressure of the control line 22 goes through the oil way 42 to be jetted from the through oil way 43, thereby additive thrust is applied to the spool 30.
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