Tonnage Ratinds and weather Reductions for locomotives

NW Mailing List nw-mailing-list at
Tue Dec 18 21:17:05 EST 2018

Still seems odd to me that the 1953 ETT for the Pokey Div. instructs train
tonnage to be reduced in cold weather solely to successfully complete a
terminal brake test and has no relation to over the road performance.


Broken rails due to cold probably not as common when rails were jointed.


Curious. What year did you hire?


Thanks for your thoughts/experiences,  John Garner


From: NW Mailing List [mailto:nw-mailing-list at] 
Sent: Tuesday, December 18, 2018 12:36 PM
To: NW Mailing List <nw-mailing-list at>
Subject: Re: Tonnage Ratinds and weather Reductions for locomotives


On 12/18/2018 9:47 AM, NW Mailing List wrote:


I understand that. Your train length chart is from 1973 (dynamic-brake
diesel era).

I'm trying to understand the possible reasons behind tonnage reduction
instructions shown in a 1953 steam era NW time table. I think the list has
figured out the reasons for diesel era train length reductions well enough.
All I've gotten so for cold weather tonnage reduction is 1. Increased
likelihood of broken knuckles 2. Increased rolling resistance of friction
bearings 3. And maybe decreased braking capacity due to leakage. Are there
other factors?

 John Garner


    I think it is all about the same thing, keeping the proper air pressure
on the rear of the train. Note the portion below from a 1935 ETT where it
states that a train could be given over tonnage not to exceed car limit.
Also note the very close resemblance between the two charts regarding
temperatures and percentages. 
In my experience, tonnage was not a concern. Not by the Yardmasters or the
Chief Dispatchers. It was a case of..."Don't worry about the mule, just load
the wagon!" And, we never had a reduction in tonnage just because of
temperature. However, I do remember a time or two where they took cars off
of us in Roanoke Terminal in order to get the proper air pressure on the
rear. If you can't get the proper air pressure, you can't make a proper
brake test. If you can't make a proper brake test, you are going anywhere!
    I will say one other thing about cold temperatures, rails will break
before knuckles will!

Jimmy Lisle

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