| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect pressure in a lift cylinder by providing a pressure sensor for detecting the pressure in the lift cylinder between the lift cylinder and a flow control valve for controlling its falling speed. SOLUTION: During rising and stopping, pressure between an oil control valve 3 and a lift cylinder 1 is proportional to extent of load applied to the lift cylinder 1 without receiving effect of a flow control valve 6. During falling, pressure on the oil control valve 3 side corresponding to the downstream side of the flow control valve 6 changes according to opening of the oil control valve 3, but pressure on the lift cylinder 1 side corresponding to the upstream side of the flow control valve 6 becomes stable proportionally to the load. Because pressure between the flow control valve 6 and the lift cylinder 1, a stable region proportional to the load, is detected by a pressure sensor 9, the pressure is accurately detected in spite of the actuation situation of the lift cylinder.
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