Err yes you're right on that.

My point though is the "bearing failing" is too generic to determine what on it failed.

Sometimes the brakes are fixed to the axle, are they not? In that case it couldn't be the brake.

I’m not waiting y the brake failed. It can take minutes for air brakes to respond on a long train. Once they become aware of the hot axle, if they could stop quicker, then the bearing doesn’t fail, which causes the axle to drop out, and thus the train to derail.

Think about pulling over as soon as you know you’ve taken a hit to a tire instead of continuing to drive until you’re on nothing but a rim and sparks.