Some generator armatures are connected to the engine cracnkshaft via mating conical surfaces. The end of the engine is typically the male cone and the generator the female cone. A small keyway is included and a long bolt through the center of the generator armature holds it to the engine crank. Try loosening the bolt a few turns and while applying a separating force between the armature and cracnkshaft, tap on the center bolt to dislodge the crank.

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