ZX12T-PUMPKIT-1/YB00003288 Genuine Hitachi hydraulic pump repair kit for Hitachi ZX120 excavator.

Part No. ZX12T-PUMPKIT-1 is a dedicated overhaul kit for the HPK055 dual variable displacement axial piston pump of Hitachi ZX120 series excavators. It is compatible with ZX120-3/5, ZX130-5 and other models on the same platform, matching the Isuzu 4BG1T engine and HIOS II hydraulic system. The kit is suitable for a single pump displacement of 55cc/rev, with a main pump rated pressure of 31.4MPa and a maximum pressure resistance of 34.3MPa. The maximum combined flow rate of the dual pumps is 2×110L/min, the drive shaft spline has 14 teeth, and it is suitable for an oil temperature range of -20℃ to 80℃. Designed specifically for light to medium load conditions, it ensures stable power output.

Before maintenance, disconnect the negative battery terminal and release residual hydraulic pressure, then mark the oil pipe interfaces and coupling alignment marks. Remove the pump body fixing bolts with a torque of 150-180N·m, disassemble the variable mechanism, cylinder block, pistons and other components in sequence. After cleaning and inspection, replace parts that exceed tolerance limits. Assemble new seals coated with hydraulic oil, align the coupling marks and tighten the bolts, fill with ISO VG46 hydraulic oil. After an idle test run with no leakage, adjust the main relief valve pressure to 31.4MPa before putting it into operation.

This kit can directly replace the core worn components of the hydraulic pump without replacing the entire pump, reducing maintenance costs by more than 60%. After replacement, the pump performance is restored to 95% of the original factory standard, improving the overall machine operation efficiency by 18% and reducing the failure downtime rate by 30%. The kit components feature a dimensional accuracy of ±0.02mm and excellent wear resistance, suitable for dusty and vibrating working conditions. It extends the secondary service life of the hydraulic pump to 8000 hours, cuts fuel consumption by 7%, and significantly reduces equipment operation and maintenance costs.