Refers to article: http://www.straightdope.com/columns/000218.html
I’m sure this is true, since Cecil says it, but what practical reasons does he mean?
You would need some sort of play for the wheel. Just MHO.
[[I’m sure this is true, since Cecil says it, but what practical reasons does he mean?]]
I’m pretty sure it had to do with increasing or reducing friction on the wheels of the train.
Jill
I’d say it was probably to carry more weight. A 2-inch track would mean narrower wheels, not able to carry as much. 2.5 inch track should allow 25 percent heavier cars.
To forward another guess, maybe the cars had more tendency to derail on narrow track.
I think we need an authority on this one. Since Cecil said he’d continue to pursue the story, maybe he’ll cover this in the update.
“If you prick me, do I not…leak?” --Lt. Commander Data
Well, the wider rail explanation doesn’t make sense, since that would tend to narrow the gauge, not widen it. (Gauge is the distance between the rails.) The friction and play answers are possible, but vague. Do we assume that this Stephenson fellow built a bunch of trains, later found out that they didn’t run quite smoothly enough on the tracks he’d laid, and so decided to widen the tracks rather than rebuild the trains? It’s possible, but it seems a bit far-fetched.
I’m guessing that the material he was using for axles may have had something to do with it. Say, he finds that he gets four axles and two inches of waste from the stuff the ironworks sends him. That’s four cuts. All he has to do to elliminate one cut is to widen the gauge by half an inch. Now he can get four axles with only three cuts.
This is a little technical, but you asked for it. A problem in early railroad design was how to deal with track curvature, since (a) train wheels don’t rotate on their axles but rather are fixed in place, and (b) the inner wheel on a curve travels less distance than the outer wheel. In autos, this problem is solved using the differential. On early railroad rolling stock, one wheel had to slip, which caused squealing and excessive wear.
So Stephenson and his associates - I’m not exactly sure who dreamed this up - came up with the idea of using train wheels that were conic sections. This is difficult to explain without diagrams, but on a curve the outer wheel rides up on the flange, where the circumference is greater, while the inner wheel rides out on the “tire,” where the circumference is less. This reduces the need for slippage (although it doesn’t eliminate it, since trains squeal and cause excessive wear on curves to this day). The conic section of the wheels also makes the wheel/axle unit self-centering on tangent (straight) track, reducing the likelihood of derailments.
Anyway, to make the whole thing work, there needed to be some room for the wheels to slop back and forth on the rails. Thus the need for the extra half inch.
Once again proving there’s no answer like a Cecil answer. Thank you great master!