I believe the "No hump" was due to concerns about bearing
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damage if couplings were harsh. The car end away for joint tends
to go straight up and then comes down hard on bearings. In
today's railroading if a loaded car (roller bearing of course)
is derailed the bearings on the derailed axles must be inspected
and/or changed due to the pounding the bearings absorb when
bouncing over ties, etc. Empty cars car go about half a car
length derailed before inspection needed.
In STMFC@yahoogroups.com, "Dave Evans" <devans1@...> wrote:
--- In STMFC@yahoogroups.com, Frank Greene <frgreene290@> wrote:
On 10/14/2012 12:21 AM, Dave Evans wrote:
... 1b) The C&O cars included a fat white strip under part of Chesapeake and Ohio to indicate they were roller bearing equipped. Steve Lucas has a 1958 ETT that makes note of this mark, and instructs crews in special handling of RB equipped cars, since the slippery little devils will roll a lot more at low speeds than plain journal bearing equipped cars. It would be useful to know if other ETT's of the late STMFC era had similar notations, and if that might mean specific marks need to be included on 1950's STMFC models from railroads other than the C&O.
Scanning through several Southern Railway ETTs from 1954-'58 did not
identify any special instructions for roller bearing equipped cars. On
roller bearing equipped boxcars and covered hoppers, Southern Railway
stenciled "[brand name] ROLLER BEARINGS" in 2 1/2" letters on the side
sill near the right bolster.
2a)The limited deployment of RB's in the STMFC era had little impact on freight train performance, although it did impact some individual car handling tasks, such as the C&O ETT instruction to not hump RB equipped cars and apply special practices for spotting RB equipped cars. It would be interesting to know if other ETT's and/or rulebooks had similar rules/guidance.
Why not hump roller bearing equipped hopper cars?
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)?