| 摘要 |
PURPOSE: To enable the same flow or different flows to be discharged from plural variable pumps easily in a simple constitution. CONSTITUTION: An electromagnetic proportional valve 22 is connected to pump control cylinders 3, 4 of variable pumps 1, 2, respectively, and a control pump is connected to the electromagnetic proportional valve 22 to apply oil pressure P. An electromagnetic switching valve 23 is disposed on the downstream side of the pump control cylinders 3, 4, an electromagnetic proportional valve 24 is connected to the valve, and further the valve is connected to the control pump. If the electromagnetic proportional valve 24 is not operated, but the electromagnetic proportional valve 22 is operated, oil pressure P1 is applied to the pump control cylinders 3, 4 which are equal in property, so that the discharge rates of the variable pumps 1, 2 are equal. When the electromagnetic proportional valve 24 is operated and oil pressure is applied to the pump control cylinders 3, 4 by thee electromagnetic switching valve 23, the oil pressure is applied in the opposite direction to the oil pressure P1 , so that a difference is made between the discharge rates of the variable pump 1 and the variable pump 2. |
