OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers SB Drive Assembly

I'm working my way through restoration of an old SB.
How do I remove the drive assembly from the crankshaft? The attached pic shows a locking nut that is now loose.
On later SB's it looks like they have a cotter pin but this is either screwed or pressed on.

Thanks
Ian