Toto, are you still in Kansas? Recently I removed a fan from a Husqy rider transmission shaft. Don't know your model, but after trying a 2 point spanner wrench inserted into the fan hub holes and having the wrench jump out while trying to unscrew the retaining nut I went to a "strap wrench" on the pulley. It did not work. Finally ....fasten a vice grip GENTLY" onto the bottom lip of the pulley such that the vice grip abuts part of the transmission casting. The nylok nut then unscrewed easily. The "gently" part is to avoid bending the pulley.