| 摘要 |
A hydraulic circuit (101) of an excavating and slewing working vehicle of two pump system, wherein a directional control valve for slewing (54) and a directional control valve for arm (55) are tandem-connected to the upstream side and downstream side of the delivery oil passage (32) of a second hydraulic pump (P2), respectively, a directional control valve for bucket (52) are connected to the delivery oil passage (31) of a first hydraulic pump (P1), and then a bleed switching valve (85) connected, through a check valve (68) between the directional control valve for slewing (54) and the directional control valve for arm (55) and switched to connect to or disconnect from a tank on the upstream side of the check valve (68) and the directional control valve for slewing (54) are operated interlockingly with each other. <IMAGE>
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