[gowings97]

Fair point, but from what I've read the preliminary cause identified pertains to an axle (not braking) issue?

[TylerE]

The idea is that you stop quicker, before the axle actually fails.

[gowings97]

So the train initiated a stop, the axle broke, and they did not stop in time? Why did they initiate the stop?

First I've heard of this.

*Update - NTSB is saying it was bearing failure - https://www.ntsb.gov/news/press-releases/Pages/NR20230214.as...

ctrl+f for 'axle' or 'brake' from the NTSB statement - zero results

[TylerE]

What do you think the bearing is containing?

[MrOwnPut]

That doesn't mean it was the brake. The bearing contains the brake. The axle contains the bearing. The train contains the axle.

Not enough information to determine what caused the bearing to fail, bearing failures account for 5.9% of all train derailments[1].

Though we can look at common train bearing failures to get a likelihood...

Most likely it was a simple lack of maintenance. It's possible to prevent this with more sensors[2] and tighter maintenance checks.

[1] https://www.wisnerbaum.com/blog/2016/september/the-most-comm...

[2] https://www.southampton.ac.uk/engineering/research/projects/...

[TylerE]

No, you e got it backwards. The train contains the bogey which contains the bearing which contains the axle.

[MrOwnPut]

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.

[eggy]

Containing? Discs for braking are mounted and fixed to the axle. Bearings allow for rotation of the axle and are offset from the disc brake mount and constrained on other axes. I don't know what kind of train or brake system was used on this train, so I can't speak to whether brakes or Donald Trump ;) are to blame for this.