| 摘要 |
PURPOSE:To keep the temperature of oil in pipes appropriate, by connecting through a confluence pipe a return pipe extending from changeover valve groups to a tank, to pipes which connect the ports of pilot valves and changeover valves to each other, near the pilot ports, to provide a simple circuit. CONSTITUTION:When pilot valves 21-23 are operated, changeover valves 7-12 are shifted to drive actuators 13-18. A confluence pipe 27 to a pipe 25 for return from the group changeover valve groups 3, 4 to a tank is connected through a stop valve 29 to pilot pipes 24 which connect the pilot valves 21-23 to the changeover valves 7-12, near the pilot ports. When the stop valve 29 is opened, some of pressurized oil from hydraulic pumps 1, 2 is diverted through relief valves 5, 6 to heighten the temperature of the oil in the pipe 25 and is then returned to the tank through the confluence pipe 27, the pilot pipes 24 and the pilot valves 21-23 to heighten the temperature of the oil in the pipes 24. |
