| 摘要 |
PURPOSE:To prevent surge pressure from occurring while keeping favorable responsiveness in a logic valve, by making a spool operate at low speed when pressure in a pilot chamber of the logic valve is in a constant pressure range but making it operate at high speed when the pressure is in another pressure range. CONSTITUTION:At and interval between a solenoid valve 9 and a logic valve 2, a selector valve 13, a throttle 19 and a check valve 20 are connected thereto in parallel. Pressure in a pilot pressure chamger 5 of the logic valve is led by the selector valve via a needle valve 18 so that a rising rate of pressure in the pilot chamber of the logic valve is made to drop down to some extent at the vicinity of a cranking point of the logic valve, making a spool of the logic valve move at low speed, and pressure in the pilot chamber is made to go up quickly at a range apart from the cranking point whereby the spool of the logic valve is possible to be moved at high speed in consequence. |
