| 摘要 |
<p>PURPOSE:To improve swiftness and accuracy by providing a load detecting means for an actuator and a detecting means for detecting switch operation amount of a hydraulic switch valve and by operating a combined valve for having pipe lines communicated according to the above detected values. CONSTITUTION:A combined valve 4 is normally located at a C position and independently connects pipe lines 15 and 16 to pipe lines 17 and 18 respectively, and when a total switch force of pilot chambers 4a and 4b exceeds a set force of a spring 38, the combined valve 4 is switched to a D position. Then, passages for connecting the pipe lines 15 to 17 and the pipe lines 16 to 18 are communicated with each other through an inner communicating passage, and operating speed of an actuator is quickened. A pipe line 28 leading to a head side oil chamber 27a of an arm cylinder 27 is connected to the pilot oil chamber 4a so as to constitute a load detecting means, and a secondary side of a remote control valve 12a is connected to the pilot oil chamber 4b so as to constitute a switch operation amount detecting means. The combined valve 4 is automatically switched based on a value obtained by the above two detecting means, and accurate operation can be carried out, when combined for high speed operation, or with independent passages for low speed operation.</p> |
