Yanmar YM129900-21600 Flywheel Ring Gear

The Yanmar YM129900-21600 flywheel ring gear is a precision-machined steel component designed for press-fit installation onto the flywheel assembly. It features 114 teeth cut to OEM profile specifications for reliable starter motor engagement. This ring gear serves Yanmar 4TNE94, 4TNE98, 4TNV94L, and 4TNV98 engine series, which are factory-installed in Komatsu 4D92E-1, 4D94E-1, and 4D98E-1 power units. The part is a direct replacement for Komatsu OEM numbers YM129900-21600 and 129900-21600. It is engineered to withstand repeated high-torque cranking cycles and thermal expansion differentials between the ring gear and flywheel hub. Applications span Komatsu hydraulic excavators (PC75-1, PC80MR-3), wheel loaders (WA65-3, WA75-3), crawler loaders (CK20-1, CK35-1), and forklift models (BX20, BX50).