Tonnage Ratings and Weather Reductions for Locomotives

NW Mailing List nw-mailing-list at
Thu Dec 27 12:35:58 EST 2018

Yes, John,

I thought it interesting yet another topic that brings out differences 
between divisions on the railroad (See recent reply on word usage.) and 
crewmen concerns based on perspective.

Timing of change from train tonnage to length would suggest roller 
bearings. One engineer said you could feel the drag and roller bearings 
were better, but it didn't matter much. No matter the conditions, he 
would just give it some gas until they started to move.

The conductor sweated the math to adjust tonnage, if just a feeling 
based on experience. To Ed and Harry's point, the most prevalent factor 
had to do with overloads--70-tonners looking loaded to 90 with coal 
piled high and overflowing the side sheets. I can even remember the 
rolling noise going by seemed an octave lower. Sometimes, you could tell 
who was loading by the heap profile. I referred to this as load level, 
because loads could be low, too. Cars were not weighed until at least 
Bluefield or Portsmouth, so conductors on every train until there had to 
guess/estimate tonnage.

Brakes were more the concern of mine runs as most runs were downgrade to 
the main where loads could be set off for road crews to deal with. 
Stalls on the main were a bad thing and Elkhorn crews (Bluefield men) 
had to consider margin for overloads when picking up heading eastbound 
upgrade towards Bluefield. Apparently, effects from cold temps fell into 
the margin for error.

Eastbound time freights may have been trimmed for cold before they got 
on the Division, but they normally ran lean to maintain speed. A pusher 
was usually put on, so again margin could have minimized effects of cold 

River crews picking up loads, like most westbounds, started in Bluefield 
Yard on a -1.22 percent grade and kept descending nearly all the way to 
Williamson, so train length was mostly limited by air and how it was 
affected by cold temps.

John, I wonder if your dad had done any research, had any input at the 
time, or thoughts on the topic. Hello and Happy New Year to the family.

Grant Carpenter

On 12/26/2018 8:20 PM, NW Mailing List wrote:
> Grant,
> I hoped you would chime in on this. I did look in Pokey ETT thru 1963. 
> Tonnage reduction charts continued to be included. So as you say it 
> was not a function of steam or diesel (or electric). I suspect it was 
> more a function of friction bearings. Whether these charts (or ETT) 
> were adhered to or not is another matter. Operating management at some 
> point obviously thought tonnage reduction was important. It would be 
> interesting to see when the temperature charts switched from being 
> tonnage based to being train length based.
> Merry Christmas indeed.
> John Garner
> *From:*NW Mailing List [mailto:nw-mailing-list at]
> *Sent:* Tuesday, December 25, 2018 6:00 PM
> *To:* nw-mailing-list at
> *Subject:* Re: Tonnage Ratings and Weather Reductions for Locomotives
> 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 affected.
> 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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