Tonnage Ratings and Weather Reductions for Locomotives
NW Mailing List
nw-mailing-list at nwhs.org
Tue Dec 25 18:00:22 EST 2018
I think the table heading may be a bit misleading, leaning on a
correlation between train tonnage and length, and implying the loco was
The normal tonnage rating was a function of the loco and applied to the
train weight, but the weather reduction was a function of ambient
temperature and applied to the train length, apparently. The same
percentage reduction applied to steam and diesel, suggesting steam was
not a factor.
Not that it mattered--the tables seemed to be ignored by Pocahontas Div
From the engineer's perspective, locomotive performance did not seem to
be affected by low temperatures (steam or electric). Stiff journals
might account for the derating, but again, had no significant affect on
train handling when combined with other factors. Understand that
enginemen were informed (by the conductor) of train length, not tonnage.
From the conductor's perspective, they figured tonnage and adjusted it
(based on experience and depending on the job) for all manner of
variables, including weather conditions, engine class, individual
engine, individual engineer, load level, even wet leaves, and weeds, in
at least one case. Low temperatures alone did not seem to be a
Cold temps did raise concern for brakes, train line length and getting
enough air to the rear for a full release. If not, they would get
permission to set over twenty cars and try again. A frozen line was
common and brakemen would carry a flask of "antifreeze" in their pocket
to pour in the hose of the first car.
Busy recently, but enjoy catching up on the List.
Merry Christmas to All,
On 12/15/2018 7:36 PM, NW Mailing List wrote:
> By time-table instructions train tonnage in the steam era was reduced
> as ambient temperatures fell. Reductions were as much as 25% at
> temperatures below 0 degrees F (Rating G).
> Were there multiple reasons for this reduction? Was the primary reason
> the increased rolling resistance of cars with friction bearings? Were
> other factors involved?
> Thanks, John Garner, Newport VA
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