4260211 Original Excavator Hydraulic Main Pump Pin for Hitachi EX100-2

Part number 4260211 is a special part number for Hitachi's original hydraulic main pump pin. This component is a key connection and positioning pin inside the Hitachi HPV091 series variable axial piston main pump, mainly used to fix or connect core moving parts such as servo pistons, inclined plates, or rotating components inside the pump. According to publicly available accessory information, it is mainly suitable for Hitachi EX series excavators equipped with HPV091 main pumps, with typical models including EX120-2, EX200-2, EX200-3, etc.

The hydraulic main pump pin is a key fastening and positioning component in the internal transmission and servo mechanism of the main pump. Its core function is to accurately fix key moving components such as servo pistons, inclined plate swing mechanisms, or cylinder bodies under high-pressure and high-speed rotation conditions, ensuring their relative position stability, transmitting mechanical force, and withstanding alternating shear stress, thereby ensuring the accuracy of the main pump inclined plate angle control and the smoothness of the entire rotating component operation. As an original component, it is usually made of high-strength alloy steel through precision turning, heat treatment, and surface hardening processes, with extremely high shear strength, wear resistance, and fatigue resistance to withstand pressure impacts of hydraulic systems up to 35MPa and thousands of revolutions per minute.

The maintenance core of this product lies in preventive inspection and standardized disassembly and assembly. The hydraulic oil and filter element must be replaced strictly according to the maintenance cycle (usually every 1000 working hours), and regular oil contamination testing must be conducted. If the pin is found to be worn, it usually means that other key components inside the pump (such as servo pistons, inclined plate bearings) may also be worn. It is recommended to check and replace the entire rotating component repair kit simultaneously. After replacement, it is necessary to conduct pressure, flow, and functional tests on the main pump to ensure that the system returns to normal.