Friday, April 12, 2013

How Do Trains Stay on the Track?

Jason Kottke posts a Richard Feynman video in which he explains that question, after he tells us why trains can go with solid axles and no differential.

What I now want to know is when was the method invented?  And why didn't Conestoga wagons need a differential (I assume because the wheels could slip?)

[Updated:  turns out the conical shape also contributes to the sway of a railway car.  See this wikipedia article on "hunting oscillation" ,which is a generic name for the phenomena.  And this article goes into more detail than the Feynman video.  It also briefly mentions an alternative to the coned wheel--canting the track.  Not quite clear on how that works--a canted racetrack presumably uses gravity to counterbalance centrifugal forces.  Is that the effect of a canted rail track, or does it also reduce the difference in distance traveled by outside and inside wheels?  Still nothing on when coned wheels were invented.]

1 comment:

Anonymous said...

Since trains have been in existence for over 100 years, the technology has been there longer than any of us have been around. It is cool how the train never (or almost never) de-rails due to the curve.......

I'm more curious about all the different types of switches there are, like when 4 or 6 tracks all come together. Who thought that up.