4179179 Excavator Pins PIN for Hitachi ZX200

Part number 4179179 is the fixing screw for the distribution plate of Hitachi's original hydraulic pump. According to publicly available accessory information, it is mainly suitable for hydraulic excavators such as Hitachi ZX330-3 and ZX240-3 models. This screw is used to firmly fix the valve plate of the hydraulic pump to the pump body and is a key fastener for the hydraulic main pump. The original part number is 4179179, which should be used as the reference for procurement. Due to significant differences in the internal structure of hydraulic pumps of different brands and models, there is usually no universal substitute part number for this screw. Original parts or certified high-strength screws of equivalent specifications must be used to ensure sealing and reliability.
 

This screw is a key pressure bearing fastener in hydraulic axial piston pumps that can withstand high-frequency pulsating pressure and vibration. Its core function is to press the distribution plate tightly onto the end face of the pump body with a specified pre tightening force, ensuring high-precision planar sealing between the two and preventing high-pressure oil from leaking between the distribution plate window and the cylinder body distribution surface. It is usually made of high-strength alloy steel (such as SCM435), which has undergone quenching and tempering heat treatment and surface rust prevention treatment, and has extremely high tensile strength and shear resistance. The machining accuracy of the threaded part is high to ensure uniform pre tightening force distribution.

The maintenance core of this screw lies in standardized installation torque, regular inspection, and preventive replacement. During each maintenance or overhaul of the hydraulic system, all valve plate screws should be checked for signs of looseness (such as misplaced paint markings). If the hydraulic pump produces abnormal noise, pressure fluctuations, or weak output, while investigating other causes, the tightening status of these screws should also be checked. Timing of replacement: As long as the hydraulic pump is disassembled for major repairs, regardless of the appearance of the screws, it is strongly recommended to replace them with brand new original screws, as their pre tightening force may decrease after repeated use and there may be fatigue damage that is not visible to the naked eye.