--- In STMFC@yahoogroups.com, Frank Greene <frgreene290@...> wrote:
Thanks for checking the ETT's. Where is it written about the cars being labeled RB equipped? I wonder if it was an AAR rule? Or each railroad did their own thing?
At the low speeds of a hump yard, a roller bearing equipped car would roll much further, and could reach the string of cars at the end of the track at a much higher speed.
For an automatic retarder, I would expect the amount of retarding would need to be changed for a roller bearing equipped car versus a plain bearing equipped car (I think automatic retarders were already adjusting for car weight). Over on OpSig a professional railroader indicated that modern hump yard retarders now take wind speed/direction into account because the cars are so free wheeling.
I suspect it would also require very different handling by a hump rider manually controlling the brake (although one would expect quick adaptation if the riders were instructed in the difference.) Perhaps C&O was reacting to damaged cargo from too-high hump impacts, or possibly injuries to riders?
So I suspect the Southern RB marking was to at least help someone working a hump yard (retarder controls or riders - either one).
Were hump riders ever outlawed? Or did the railroads find them too expensive (in pay or in damaged contents)?