This is the best demonstration I’ve seen for how train wheels = rails work, and why the wheels are slightly tapered. The taper here is greatly exaggerated for clarity:
When you find the old black and white filmed under a boxcar, you’ll be truly amazed as the weight of the car does keep the wheels centered, even though the tread slope is less than 5 degrees.
The BART system has used cylindrical wheels since its inception, and it has been a constant source of problems. I have lost track of the status, but there is a program underway to change them all to a tapered profile.
Bart’s status - New wheel tech quiets screeching rails
and - BART: Redesigned wheels make for quieter ride, but real improvement will take years
See what happens when you reinvent the wheel? (https://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)(https://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-undecided.gif)
I’m looking at the comments and wondering why some of these people are allowed to think in public.