| 摘要 |
PROBLEM TO BE SOLVED: To safely lower a lift cylinder in the same manner as in normal time even in an emergency time when a solenoid on-off valve is stuck or fails to be energized in closed condition. SOLUTION: This control device is formed so that an operation check valve 21 allowing a flow only to a cylinder is installed in a main path 12 communicating with a pump path 13a or a tank path 14a by the switching operation of a spool valve 11, an orifice 23 communicating the main path 12 with a pilot chamber 24 for the operation check valve 21 is installed in a poppet 22 of the operation check valve 21, and the pilot chamber 24 communicates with the main path 12 through the solenoid on-off valve 32. In this case, the pilot chamber 24 of the operation check valve 21 communicates with the main path 12 through a bypass path 41, and a manual stop valve 42 is installed in the bypass path 41.
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