| 摘要 |
PROBLEM TO BE SOLVED: To perform steering operation smoothly and quickly and increase running speed when a construction machine advances straight and runs. SOLUTION: In a hydraulic circuit device of a three pump system provided with two first hydraulic pumps of hydraulic pumps 1, 2 and a second hydraulic pump 3, a running join control valve 37 is connected with the downstream side of a direction control valve 23 of a center bypass line 17 connected with a discharge line 14 of the second hydraulic pump 3, and a synchronization flow dividing valve 38 is connected with its downstream side. Output sides of the running join control valve 37 and the synchronization flow dividing valve 38 are connected with feeder lines 28L, 28R of direction control valves 20L, 20R for running to the right and left sides through join lines 40, 41. The running join control valve 37 is switched and operated by pilot pressure of operation lever devices 25L, 25R detected by shuttle valves 50L, 50R. COPYRIGHT: (C)2004,JPO
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