Can someone provide me with the best method to use to disassemble a gear that was interfernece fitted to a shaft by means of thermal variance of the parts ?
Thermal variance again can work, but it depends on how effectively you can chill the shaft while applying heat to the gear, with the assembly in a press.
For modest interference fits, force and heat can work.
Producing a large enough temperature gradient usually requires that the heat be applied rapidly, by a serious heat source, like a flame.
If the interference is substantial, it becomes more difficult to salvage both parts. If one is to be replaced anyway, it may be better to destroy it to save the other.
Easiest way is to give the assembly to an experienced mechanic and go out for coffee. You may not want to watch his process.
