1873101420 Original Excavator 6WG1 Engine High-pressure Oil Pump Coupling Shaft Repair Kit 

Part number 1873101420 (also spelled as 1-87310142-0/AE23698) is a Hitachi original - Isuzu 6WG1 series engine high-pressure fuel supply pump (fuel injection pump/common rail fuel supply pump) drive coupling repair kit (Coupling Repair Kit/Spider Build Kit). It is used as a flexible connection component between the pump and the crankshaft output end of the engine, mainly suitable for large Hitachi excavators equipped with 6WG1 engines, such as ZX850-3, ZX870H-3, ZX870LCH-3 and other models (some channel information also indicates that it can be used for same family large tonnage machines on ZX450/ZX470 platforms).
 

The core of this repair kit is the elastic transmission component of the pump driven flexible coupling (flex/spider coupling). The 6WG1 oil supply pump is driven by the crankshaft end gear → transition shaft → coupling (rubber/polyurethane spider block+metal spring plate/pressure plate). This package provides a complete set of disposable wear parts such as elastic blocks, loss gaskets, retaining springs, locating pins, etc. that are subjected to shear/fatigue, restoring the coupling's ability to cushion torsional vibration and coaxiality tolerance. The hardness, rebound, and oil resistance (diesel/engine oil mist/heat) formula of the original specifications of the elastic block are controlled, with high dimensional tolerances and installation groove matching. After installation, it can maintain the alignment of the pump input shaft and transition shaft, reduce additional loads, avoid pump bearing eccentric wear, abnormal noise, and timing related failures - it essentially ensures smooth transmission and pump life, rather than "increasing pressure or flow".
 

It should only be replaced when the pump/transition shaft assembly is disassembled or the coupling is disassembled: it does not need to be touched in daily life. Typical symptoms include low-frequency "thumping" on the pump side, increased shaking during no-load/variable load, broken edges and debris on the rubber block of the coupling, and shiny metal parts; If these are found, stop the machine first and don't force the fragments into the gear chamber. Key points for disassembly and assembly - first release pressure and fix the pump shaft to prevent self rotation → take photos to record the direction of the pressure plate/bolt → replace all vulnerable parts in the package, and do not reuse old elastic blocks; The installation should ensure that the two halves of the coupling are coaxial, the spacing is correct, and the bolts are tightened in the order of crossing and the specified torque. After installation, manually rotate and confirm that there is no jamming or interference.