Richard Feynman explains: What keeps a train on the track?

**Jon** · Jun 5, 2019, 12:22 PM

Feynman notes available online, with viewer app so you can see the original written notes: Feynman's Notes for The Feynman Lectures on Physics . There is enough here for some Feynman wallpaper.

**mklotz** · Jun 5, 2019, 02:03 PM

Or you could use them to create your own version of the Feynman van...

Elementary physics diagrams would probably have better appeal to the motoring public than Feynman diagrams...

https://en.wikipedia.org/wiki/Feynman_diagram

**Paul Alciatore** · May 22, 2020, 11:59 PM

The same effect is also one of the reasons why traditional barrels are fatter in the middle and smaller at the top and bottom. In the days before every warehouse had a forklift or, at least, a pallet jack, barrels were moved around the warehouses and moved in and out of trucks and RR cars by setting them on wood rails on their sides. Then they could be rolled for great distances on those rails and they would stay on the rails due to the self steering effect that they share with RR wheels. You can see this at work in old films of barrels running on wood rails. They would wobble first to one side and then to the other, but they would always correct their course and stay on the rails.

Something our grandfathers knew, but we have forgotten. Well, some of them, anyway.

**mklotz** · May 23, 2020, 09:22 AM

Originally Posted by Paul Alciatore

The same effect is also one of the reasons why traditional barrels are fatter in the middle and smaller at the top and bottom. In the days before every warehouse had a forklift or, at least, a pallet jack, barrels were moved around the warehouses and moved in and out of trucks and RR cars by setting them on wood rails on their sides. Then they could be rolled for great distances on those rails and they would stay on the rails due to the self steering effect that they share with RR wheels. You can see this at work in old films of barrels running on wood rails. They would wobble first to one side and then to the other, but they would always correct their course and stay on the rails.

Something our grandfathers knew, but we have forgotten. Well, some of them, anyway.

Ah, but, Paul, this beggars the question of

Did they know about this effect before they started building barrels or did they discover it after they had worked out a technique of building a liquid-tight wooden container from slats?

I don't know the answer but barrels are older than railroads so I doubt they got the idea that way.

An associated question that has always intrigued me...

The ancients quarried and transported over long distances huge, heavy blocks of stone for their mega-constructions. Archaeologists theorize they used sledges dragged on rollers for the most part*. However, it's known that the Romans (and probably others) built cylindrical wooden structures around stone slabs and rolled those, possibly on temporary tracks laid for the purpose.

Now steering these monstrously heavy cylinders would have been difficult at best. Is it possible that they accidentally discovered the self-steering properties of the barrel shape?

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*Exceptions include "walking" the giant moai of Easter Island and the use of purpose built ice roads by the Chinese during the construction of the Forbidden City.

**Frank S** · May 23, 2020, 10:13 AM

Originally Posted by mklotz

Ah, but, Paul, this beggars the question of

Did they know about this effect before they started building barrels or did they discover it after they had worked out a technique of building a liquid-tight wooden container from slats?

I don't know the answer but barrels are older than railroads so I doubt they got the idea that way.

An associated question that has always intrigued me...

The ancients quarried and transported over long distances huge, heavy blocks of stone for their mega-constructions. Archaeologists theorize they used sledges dragged on rollers for the most part*. However, it's known that the Romans (and probably others) built cylindrical wooden structures around stone slabs and rolled those, possibly on temporary tracks laid for the purpose.

Now steering these monstrously heavy cylinders would have been difficult at best. Is it possible that they accidentally discovered the self-steering properties of the barrel shape?

---
*Exceptions include "walking" the giant moai of Easter Island and the use of purpose built ice roads by the Chinese during the construction of the Forbidden City.

Quite probably the discovery of rolling barrels on rails may have been the result of trying to figure out how not to drop a barrel off of a gangway while unloading them from a ship.
Large pottery jars predates wooden barrels but they were difficult to transport when made very large. Wooden buckets may have predated barrels as well. handles could be installed in them and they could be carried in multiples on yolks like smaller pottery jars, but buckets are difficult to seal preventing spillage in the holds of ships also they are difficult to stack unless and empty bucket were placed upside down on the one below it then another row cold be stacked on top. the shape of 2 buckets stacked together and large pottery jars resemble that of a barrel hence the advent of a barrel now they had something they could fill seal and lay on its side and roll up a gangway. However off loading posed problems the fat bellied barrels were difficult to control while descending and would roll off the edge of the gangway so a barrier would be required. The barriers it soon may have been discovered could keep the barrel rolling in a straight line as long as the belly of the barrel did not touch the gangway. This may have been accidental when the barrels became larger making them longer than the gangway was wide. the advent of the railway and the subsequent shape of the train wheels may have been borrowed from the learned process of rolling barrels on the side barrier rails of the gangway