4280841 Original Excavator Main Hydraulic Pump Bearing for ZX120-5A

The bearing of the Hitachi original excavator main hydraulic pump (universal part number: 4280841) is the core rotating support component inside the Hitachi HPV series axial piston hydraulic main pump (such as HPV091DW, HPV0118, etc.). This original spare part is mainly suitable for multiple Hitachi ZAXIS series excavators, including but not limited to medium-sized to large models such as ZX200-3, ZX250-3, ZX330-3, ZX360-3, etc. It may also be used for other Hitachi excavator models that use the same series of main pumps.
 

This bearing is a key supporting component of the hydraulic main pump drive shaft or rotor assembly. Its core function is to withstand the radial and axial loads generated by the high-speed rotation of the pump shaft, ensuring smooth and precise operation of the transmission components, while minimizing frictional resistance and ensuring efficient output of the hydraulic pump. As an original component, it is usually made of high carbon chromium bearing steel (such as GCr15), which undergoes precision grinding and special heat treatment, and has extremely high hardness, wear resistance, fatigue strength, and dimensional stability.

To ensure the long-term reliable operation of the bearing and hydraulic pump, strict preventive maintenance must be carried out. Keeping the hydraulic oil highly clean is of utmost importance, and it is necessary to regularly replace the hydraulic oil and filter element (recommended every 500 hours of operation) to prevent metal debris and other pollutants from entering the bearing raceway and causing abnormal wear and pitting. It is recommended to check the bearing clearance, rotational flexibility, and whether there is overheating, discoloration, peeling, or damage to the retaining frame every 1000 hours of operation or during pump overhaul.