Removing pulley wheel from fly wheel

The Lister D I recently acquired has, what looks to me like, a pulley wheel fixed to the fly wheel.  It's clearly been there a long time!  It has four screw fixings but having removed them it doesn't move.  Does it require pressure or is there something else I should do please?

Thank you.

As far as I'm aware the pulley was never mounted like that by Listers, it would have been mounted on the shaft. The pulley is aluminium and will expand quicker than the cast flywheel, heat the pullet around the bossand it might give a little, get a stout length of rope with a loop on one end, put around the pulley and pass the other end through the loop and tie off on a bench then turn the flywheel in the other direction so the loop tightens and grips the pulley, it might break free, the aluminium and steel have coroded together.

Maryalice

Thanks for the advice. Pulley wheel now safely removed. Gentle leverage moving around the rim little by little did it.