yes, it IS a push ring.  I'm not worried about ruining the ring since I'm assuming I can just get another one for a 1/2" shaft, but I am worried about breaking the wheel.  Any suggestions for just getting it off would be helpful.  I could try cutting it off with wire cutters.  I'm pretty sure prying it off will result in breaking something else.  The shaft has a groove on it to hold it on to make it even worse for getting off.