Feb

23

Starts at Minute 4:00: A Failed Defect Detector and the Train Derailment at East Palestine

The achievement of railroads is that they can carry massive loads thousands of miles with an economic efficiency that no other form of ground transport can come close to matching. To do this they have to violate the first rule of all practical mechanical engineering and have metal scrape against metal without any lubrication. The wheels and rails are steel against steel. If an air brake fails for a wheel, it stops it dead and the wheel becomes a giant flint throwing sparks and then flames. The only solution to this problem is to slow the train to walking speed and move it to a siding. If the train continues at speed (30-40 mph in developed areas), that car will eventually derail. The unanswered question for this incident is why the train crashed in the pattern of an emergency stop by the engine, not the derailment of a single car. That could have been caused by the engineer not having the skill and temperament required to avoid literally slamming on the brakes because "the train is on fire". But, that is pure speculation by those of us sitting safe in the bleachers.

Bud Conrad writes:

Thank you for the explanation in bigger picture context. There seems to be something much more unusual about this particular incident, than just a mechanical failure, of a type that must happen frequently because steel is riding on steel.

Jeffery Rollert comments:

Modern rail cars have systems that brake all cars at once (locomotives included). It’s done by a radio signal or wire, and no longer a pneumatic propagation. I know, because a very good friend designed and built the system decades ago. Cars derail, when the locomotive derails and effectively becomes the brake. So why did the locomotive derail?

I haven’t seen the video, but strongly suspect something in the tracks or a switch was improperly diverted that the locomotive couldn’t handle the redirection at that speed.

Henry Gifford explains:

Steel rolling on steel is a great idea because there is such a small amount of friction. An adult human can allegedly push a fully loaded (200,000 Pounds or more) railroad car along a level track (but not get it started – another story). Rubber covered wheels, in contrast, require much more energy because heat is generated as the rubber flexes (internal friction from molecules rubbing on each other). But, if the railroad train car bearings seize up, steel is sliding on steel – still lower friction than rubber rubbing on a road, thus the locomotive(s) can drag it along until derailment…

Read the full discussion here.


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