LOAD HOLDING VALVE DEVICE WITH DEPRESSURIZATION MECHANISM

摘要

PROBLEM TO BE SOLVED: To make it possible to facilitate a hydraulic actuator depressurizing operation and to form a load holding valve device compact as a whole.SOLUTION: A selector valve 22 of a load holding valve device 17 is configured to be switched over among not only a load holding position (a) and a load holding cancel position (b) but also a depressurizing position (c) for depressurizing a hydraulic cylinder 9. Within a housing of the load holding valve device 17, an operation mechanism 34 including a depressurizing plug 35 abutting on a spool valve element 30 of the selector valve 22 at an opposite position to a check valve 21 to switch the selector valve 22 to the depressurizing position (c) is provided. A depressurizing oil passage 31 is provided in the spool valve element 30 of the selector valve 22 for communicating a load pressure passage 24D at an actuator port 18D with a low pressure passage 24F at a tank port 19C if the selector valve 22 is switched to the depressurizing position (c).