Tonnage Ratings and Weather Reductions for Locomotives

NW Mailing List nw-mailing-list at
Tue Dec 25 18:00:22 EST 2018

Hello John,

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 
train crews.

 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 
substantial factor.

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,
Grant Carpenter

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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