| 摘要 |
PROBLEM TO BE SOLVED: To prevent interference between the pressure oil for a traveling motor and the pressure oil for a work actuator, particularly when the traveling and the operation of the work actuator are carried out at the same time. SOLUTION: There is installed traveling bypass cut valves 37R, 37L respectively on center bypass passages 28, 29 in between direction selector valves 22R, 22L for traveling and corresponding direction selector valves 24, 23 for work in the downstream side. The traveling bypass cut valves 37R, 37L are switched from neutral position A to position B, when the operation of a traveling motor 2R or 2L and the operation of at least one of work actuators 4, 7-9 are carried out at the same time, during which a traveling straight advancing valve 38 is switched from neutral position D to E, with relatively small operation amount of the operation lever for traveling.
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