9298854 Hitachi ZX870-5G Excavator Hydraulic Pump Assembly

Part number 9298854 is a dedicated HPK300 dual variable axial piston main pump assembly (including 2 main pumps + 1 pilot gear pump) for Hitachi ZX870-5G, compatible with ZX870-5G, ZX870H-5G, ZX870LCH-5G, ZX670-5G and other models on the same platform. It matches Isuzu 6WG1X engine and HIOS IIIB hydraulic system. Single pump displacement is 300cc/rev, main pump rated pressure is 31.9MPa, maximum pressure is 34.3MPa, maximum dual-pump flow rate is 2×529L/min, pilot pump flow rate is 30L/min, rated speed is 2000rpm, drive shaft spline has 16 teeth, and total assembly weight is about 420kg. It adopts 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 (31.9MPa), 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 large-scale 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 200-220N·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 (200-220N·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 31.9MPa. This pump can increase operational efficiency by 22%, reduce hydraulic failure downtime by 38%, decrease fuel consumption by 9%, extend the service life of components such as cylinders and motors, and is suitable for high-intensity continuous operations.