| 摘要 |
PURPOSE:To raise the efficiency of even other operations by a method in which discharge oil from each pump is independently supplied to left- and right-handed traveling circuits, and during composite operations like arm operation, etc., excess oil for traveling is supplied even to arm operation, etc. CONSTITUTION:When control valves 4 and 13 for traveling direction are switched to advancing, discharge oils from pumps 1 and 10 are supplied through control valves 4 and 13 to a traveling motor for advancing operation. During the advancing period, pilot pressure directed by one pilot circuit 4a or 4b of the control valve 4 is selected for higher pressure by a shuttle valve 23 and supplied to the pilot circuit 24. Both bypass circuits 9 and 21 are connected with each other by switching a confluence switch valve 22. When a direction valve 8 for arm is switched for example, excess oil for traveling from the pumps 1 and 10 is supplied to the arm cylinder and the inflow of the oil to traveling circuits 12 and 3 is interrupted by check valves 5 and 14. The straight forward traveling property can thus be enhanced.
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