| 摘要 |
<p>A first group (G1) is supplied with hydraulic power from a first hydraulic pump (7). In the first group (G1), an arm control valve (12) is disposed at the most downstream position. A throttle (20) is provided at the entrance of the arm control valve. Thus, a circuit is configured to give priority to boom raising or bucket excavation. During a combined operation, according to the operation amount of boom pulling or bucket excavation, a controller (35) decreases the upper limit of the discharge amount of the first hydraulic pump (7) determined by the operation amount of arm pulling and increases the recycling rate of oil to the expansion side of an arm cylinder (4).</p> |
