| 摘要 |
PROBLEM TO BE SOLVED: To perform smooth work early even in low-temperature environment, in a hydraulic work vehicle that uses an electric lever as an operation lever of a pilot valve, and is used in a cold district.SOLUTION: A pilot valve supplying pilot pressure oil from a pilot oil pressure pump 16 to the pressure reception chamber of a control valve 31 by changeover of the pilot oil pressure, includes proportional solenoid valves 38-41. The gas between a pump side pipe line 28 connected to the pump ports of the proportional solenoid valves 38-41 and a tank side pipe line 29 connected to a tank port is connected by a bypass oil passage 50. A throttle 51 is provided in the bypass oil passage 50, and a small amount of pilot pressure oil is circulated in the pipe lines 28, 29. |
