4272674 Original Excavator Hydraulic Pump Spare Parts Piston Ring for EX100-2

Hitachi original hydraulic pump piston ring (universal part number: 4272674) is the core sealing and transmission component inside Hitachi HPV series axial piston hydraulic main pumps (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.
 

The piston ring is a key component in the plunger assembly of a hydraulic pump. Its core function is to be installed in the ring groove of the plunger, tightly adhered to the inner wall of the pump chamber (cylinder body), forming a dynamic seal to prevent internal leakage between the high-pressure oil chamber and the low-pressure oil chamber, thereby ensuring the volumetric efficiency and stable output pressure of the hydraulic pump. At the same time, it also transfers some of the heat from the plunger to the pump casing, and plays a role in supporting the plunger and reducing eccentric wear.
 

To ensure the long-term reliable operation of the piston ring 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 particles and other pollutants from entering the pump, causing abnormal wear and tear on the piston ring and pump casing. It is recommended to check the wear of the piston ring and measure whether its opening clearance, side clearance, and elasticity are within the standard range when the hydraulic pump is undergoing major repairs or when there is a decrease in output pressure, an increase in noise, or an abnormal increase in oil temperature.