RepairClinic Item #1604705 | Tecumseh Genuine OEM Part #611004
Tecumseh flywheel key (woodruff key). The flywheel key aligns the flywheel in the correct position on the crankshaft. If the engine stops suddenly due to hitting a hard object, the flywheel key shears in half to prevent damage to the engine. If the flywheel key is broken, the engine won't start.