| 摘要 |
<p>PURPOSE:To eliminate the limitation to flow rates of pressure oil by controlling a part of plural hydraulic pumps for switching valve groups with switching valves for small flow rate-actuated attachments by means of a pilot circuit having a selection valve operating with the switching valves for the attachment. CONSTITUTION:The first switching valve group 26 having a vacancy-directed switching valve 30 for breaker is connected to one confluence circuit of plural hydraulic pumps 22-25 to be operated by the first and second engines 20 and 21. The second switching valve 32 is connected to the other confluence circuit. A pilot circuit send discharge amount-controlling signals to the pumps 22-25 is divided into a pilot circuit H to control signals only to one hydraulic pump 24 of the hydraulic pumps 22 and 24 of the first switching valve group 26 with the valve 30 and a pilot circuit I to send control signals to other hydraulic pumps 22, 23 and 25. A selection circuit 52 to be operated with the valve 30 is provided to the circuit H.</p> |
