Hi Tom it's an interference fit relying on thermal expansion -carefully using a blow torch heat the drive gear ring to expand it, going round all the sides, then carefully knock/prise it off the thin lathed shoulder on the hub it butts up against, use wood where possible don't generally need excessive force at all.
Now be careful, don't want to over-heat the hub itself as it may crack during the process. Aluminium, even T6 heat treated/ tempered stuff will give you no indication the metal is melting under the surface, it cracks and breaks up like a thick cheesecake long before it melts properly at around 700c + so care is required. A Butane burner is a good tool for the job as it blows cooler than propane or oxy... you'll have it off in less than 2 mins.
Or pop the hub and attached gear on a baking tray and place in middle shelf of a pre-heated oven at 200c deg for 10 minutes, (180c for 8 mins fan assisted), remove with mrs's best oven gloves and tap off with a wooden block and allow to cool before serving
* baking times may vary.
(Same as you would do for fitting/removing an Iron cylinder liner from a Muff, so per lb...hmm.. about 15 mins for that...BTW don't grease the tray, and only do it when Mrs is not around)