Hi, I have a Hitachi Zaxis 250LCN-3 2-piece boom (european) and when you dig, i mean bucket and arm roll-in and boom raise, last one drops. If you release de arm lever, boom raise recovers normal speed. In service mode monitor, pumps deliver normal flow rate, near 200 l/min under load. I will appreciate your comments. Thanks
HITACHI ZX-3 series (2 piecies Boom) have the flow rate control valve. The flow rate control valve is provided in boom, arm, bucket and auxiliary circuits, restricts oil flow rate in the circuit during combined operation and gives priority to other actuators. You should check it first. I attached the operational principle manual and Hydraulic Circuit Diagram for your reference. Good luck. https://www.mediafire.com/file/auqz..._Training_Text_Operational_Principle.pdf/file