9257348 Hitachi ZX330-3 Excavator Hydraulic Pump Assembly

Part number 9257348 is a dedicated HPV145 dual variable axial piston main pump assembly (including 2 main pumps + 1 pilot gear pump) for Hitachi ZX330-3, compatible with ZX330-3, ZX350K-3, ZX350H-3 and other models on the same platform. It matches Isuzu 6HK1 engine and HIOS III hydraulic system. The main pump has a rated pressure of 31.4MPa, a maximum pressure of 34.3MPa, a single pump displacement of 145cc/rev, a maximum dual-pump flow rate of 2×288L/min, a pilot pump flow rate of 30.2L/min, a rated speed of 2000rpm, a drive shaft spline with 14 teeth, and a total assembly weight of about 380kg. It adopts a high-pressure combined seal + dust-proof structure, suitable for oil temperature -20℃ to 80℃, ensuring stable hydraulic supply for heavy-duty excavation and compound operations.

Its core function is to convert engine power into high-pressure hydraulic oil to drive swing, travel, boom/stick/bucket cylinder movements. The dual pumps feature independent variable control, with built-in main safety valve (31.4MPa), overload relief valve and servo proportional valve for intelligent flow matching and system protection. The plungers/cylinder blocks are made of wear-resistant alloy, equipped with NSK bearings (rated service life ≥12000 hours). The gear pump provides 3.9MPa pilot pressure, suitable for heavy-duty working conditions such as mining and infrastructure construction, with an average service life of ≥10000 hours and a response time ≤0.3s, reducing energy consumption and hydraulic shock, and improving operational smoothness.

Before replacement, disconnect the negative pole of the battery and release the hydraulic system pressure. When disassembling, mark the oil pipe interfaces (to avoid misconnection), remove the coupling and fixing bolts with a torque of 180-200N·m, and clean the mounting surface (free of oil stains/iron filings). When installing, replace with new seals (apply hydraulic oil), tighten the bolts symmetrically (180-200N·m), add ISO VG46 anti-wear hydraulic oil after connecting the oil pipes, perform a test run after venting (no leakage/abnormal noise), and set the main safety valve pressure to 31.4MPa. This pump can increase operational efficiency by 20%, reduce hydraulic failure downtime by 35%, decrease fuel consumption by 8%, extend the service life of components such as cylinders and motors, and is suitable for high-intensity continuous operations.