Tonnage reduction with temperature falling

NW Mailing List nw-mailing-list at
Mon Dec 17 10:49:16 EST 2018



“Trains with Head End Brake Pipe Supply Only”.  What trains on the NW would NOT meet this criteria in the 1973 timeframe (i.e. what trains would fall outside these special instructions)?


John Garner, Newport VA


From: NW Mailing List [mailto:nw-mailing-list at] 
Sent: Monday, December 17, 2018 7:46 AM
To: NW Mailing List <nw-mailing-list at>
Subject: Re: Tonnage reduction with temperature falling



On 12/16/2018 10:01 PM, NW Mailing List via NW-Mailing-List wrote:

I was under the impression that the reason the tonnage went down with temperature was thermodynamics of water evaporation to get the needed pressures of steam. The point about oil and grease viscosity makes good sense as well. 

Mike Shockley 

Not so, Mike. The following chart is from Shenandoah Div. ETT #5 effective Sunday, May 20, 1973.

Jimmy Lisle

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