| 摘要 |
PURPOSE:To have a rapid valve opening, if an overloading arises at the input port, by opening the valve hole of a pilot valve against the force of pilot spring and by blocking the communication hole of main valve. CONSTITUTION:When an overloading arises at a protector 5 to bring about high pressure in the cylinder chamber 7, the pilot valve element 39 goes apart from the valve seat 32 against the force of spring 43 with the aid of an oil line 17 and a pressure oil chamber 31 to permit the oil in the pilot oil chamber 26b to flow out through the gap between the valve element 39 and valve seat 32, and this oil then returns to the tank 10 pass holes 26a, 26b, a port 18 and an oil line 19. Accordingly, the pressure in the pilot oil chamber 26b sinks rapidly. This sinking of pressure will cause blockade of a communication hole 38 through pressure contact of the blocking valve seat 46 with the main valve element 34, and the pressure in the oil chamber 26b sinks still more rapidly. Therefore the main valve element 34 receives an extremely large relative pressure to be opend rapidly. |
