| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic control valve excellent in stability and reliability by improving response of a holding valve and reducing a naturally lowering amount of a hydraulic cylinder. SOLUTION: The hydraulic control valve comprises a pump passage and a tank passage, a valve housing wherein a first and second cylinder passage communicating with the hydraulic cylinder are formed, a control spool which is movably provided inside the valve housing and which selectively links up both the pump passage and the tank passage to either one of the first and second cylinder passage by moving to the right and left when the pilot signal pressure is impressed while breaking connections between the pump passage and the first and second cylinder passage in the neutral positions, the holding valve which is provided between the second cylinder passage and the control spool and which holds load so that the hydraulic cylinder is not lowered naturally by breaking the second cylinder passage when the control spool stays at the neutral position, and a holding valve flow passage which connects pressure oil of the second cylinder passage to the tank passage when the control spool stays at the neutral position. COPYRIGHT: (C)2006,JPO&NCIPI
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