ZX850-3 ZX650-3 EX1200-6 Excavator Main Pump 4635645 K3V280 For Hitachi Spare Parts

ZX850-3 ZX650-3 EX1200-6 excavator main pump 4635645 K3V280 for Hitachi spare parts

We could supply the hydraulic pump and also the inner spare parts as below model:

Open-Circuit Pump vs. Closed-Circuit System Application in Excavators:
This description focuses on the core system principle difference and how pump selection dictates function suitability. Principle: An open-circuit pump draws fluid from a reservoir, pressurizes it, sends it through control valves to actuators (cylinders, motors), and the return fluid from the actuators flows back to the reservoir. Fluid constantly cycles through the tank. Axial piston (variable disp.), gear, and vane pumps are typically used here. A closed-circuit pump (as described previously) circulates fluid primarily in a sealed loop between the pump and a motor, with only a small charge pump drawing from/replenishing to the reservoir. Structural Implications: Open-circuit pumps have dedicated inlet (suction) ports connected to the reservoir and outlet (pressure) ports feeding the valve manifold. They require a larger reservoir for cooling and de-aeration. Closed-circuit pumps have two main working ports (A & B) directly connected to the motor and an integral charge circuit connected to the reservoir. Excavator Application & Pump Selection: Open-circuit systems dominate the implement hydraulics (boom, arm, bucket, blade, swing typically) because multiple actuators share a common pump and reservoir, controlled by valves. The flexibility, ability to easily handle multiple functions simultaneously via valves, and suitability for linear cylinders make variable displacement axial piston pumps (often pressure-compensated or load-sensing) the ideal choice here. Closed-circuit systems excel in driving rotary travel motors (and sometimes swing) due to their efficiency in bi-directional power transmission, inherent braking, and controllability.