2038178 Original Excavator Hydraulic Pump Long Shaft for ZX120 ZX120-5A ZX130-5B

This original hydraulic pump drive shaft is specifically designed for Hitachi (HITACHI) small and medium-sized excavators. Manufactured strictly according to official part number 2038178, it perfectly fits Hitachi's main crawler excavator models such as the ZX120, ZX110, and ZX130, primarily deployed at the input end of the HPK055 main hydraulic pump. This shaft features a standard 17-tooth external spline structure, responsible for the lossless transmission of engine horsepower to the pump's internal rotor assembly. Original factory-grade geometric tolerance control ensures precise matching with the drive coupling, guaranteeing perfect mechanical coordination and highly stable operation under extreme high-pressure loads.

This hydraulic pump shaft uses high-purity, high-quality alloy structural steel as its base material, undergoing precision integral forging and digital spline milling. The spline and bearing surfaces undergo deep induction hardening and precision grinding, giving them both "external hardness and internal toughness" mechanical properties—high surface hardness, providing excellent shear and torsional resistance; and strong shaft fatigue strength, effectively mitigating alternating impacts transmitted from the engine. The product passes rigorous dynamic balancing and runout tolerance tests, exhibiting absolute physical rigidity during high-speed rotation, effectively suppressing high-frequency resonance and locking in transmission stability.

When replacing the long shaft during a major overhaul of the hydraulic pump, assembly must be performed in an absolutely dust-free environment. Before assembly, the main pump's front skeleton oil seal must be replaced; non-physical forced impacts are strictly prohibited. When installing the spline section, apply heavy-duty extreme pressure grease evenly and ensure complete axial alignment to prevent uneven wear or premature breakage due to eccentricity. During routine maintenance, closely monitor abnormal vibrations, temperature rises, and return oil purity of the hydraulic main pump. Establish a standardized hydraulic system inspection log, replace hydraulic oil and filters on schedule, and completely prevent foreign matter from turning into abrasive particles to ensure the long-term safe operation of the power transmission shaft.