hank Wrote:
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> I've often wondered why the Grande didn't put
> roller bearings under the 3' gauge cars int the
> 1920's. It was a mature technology by then, having
> been developed before WWI, and the saving of tons
> of friction on places like Marshall Pass or the
> Monarch branch would seem to have justified it for
> the gons used on the coal & rock trains if nothing
> else. Not to mention rollers are better in low
> temps.
> From what I've read, the big objection to putting
> roller bearings on freight cars was the idea that
> you'd spend a boatload of money on it and then,
> once the car was interchanged, you'd never see it
> again. Not a problem for the 3' gauge.
> Just musing,
> Hank
Not a whole lot of difference in rolling resistance between the bearing types once you're moving more than ~5 MPH until very high speeds. Difference at drag freight speeds was modest--part of why roller bearings took so long to catch on. There's some, but most of the perceived difference stems from Timken's very successful propaganda/advertising campaign (disparaging plain bearings as "friction bearings" and whatnot). Main benefits are in maintenance reduction, improved reliability via reduction of hotbox incidents and dramatically reduced starting resistance.
The "some" bit of difference does help going uphill, but in mountain railroading you have to go down as well as up, and the freer your train rolls, the more you have to use your brakes so the benefit in that sense more or less cancels itself out or becomes a potential liability. Even with plain bearings there were cases where trains took longer going downhill than up. Dynamic braking largely mitigates this downside.
During the steam era roller bearing cars would've been most helpful on flatland railroads since steam locomotives tend to have low starting tractive effort compared to equivalent diesels. There were cases on some flatland roads where locomotives needed help starting trains they could pull fine once moving.
Edited 1 time(s). Last edit at 05/29/2019 08:44PM by James.
