Empty (tare) weight of 611's Auxiliary Tender?

Wed Jul 8 15:31:22 EDT 2015

Gentlemen,

The 611 is as good now as ever.

I have Bob Pilchers graph he plotted of the A, J and Y-6b’s which are more detailed than I was able to reproduce in the Giant book.  The J could develop a continuous 4500 DBHP or greater between 25 and 65 MPH with a maximum of 5150 at 40 MPH.  His graph and curve show the J at 26 MPH generating 4575 DBHP.  You mentioned that the N&W was conservative – yes and no.  Pilcher, as Engineer of Tests for steam, wanted to show what the locomotive could do day in and day out, not just what it could do under ideal conditions.  Also the railway wanted to know what the locomotive could do at the drawbar and thus when you see the drawbar HP curves for the A and Y-6b’s, they showed what they were capable of behind the A-tank.  The curves for the J’s were computed before they were placed in freight service using A-tanks during the last year of their revenue service and of course the excursion service.

This latest testing shows that the 611 is as good now as ever which is a credit to those who designed and built her, and to those that prepared her for present service.

Good job.

Bud Jeffries

From: NW Mailing List via NW-Mailing-List 
Sent: Wednesday, July 08, 2015 2:07 PM
To: nw-mailing-list at nwhs.org 
Cc: NW Mailing List 
Subject: Re: Empty (tare) weight of 611's Auxiliary Tender?

Based on the information from Ken, below, and Dave Stephenson in his response, I calculate that the auxiliary tender required about 370 drawbar horsepower to be kept moving at 26 mph on the 1.34% grade.  This includes the following assumptions:
- The "Modified Davis" train resistance formula gives a reasonable answer (it's sort of the "industry standard", so that should be safe...)
- The Auxiliary Tender was still full
- The measurement was on tangent track (this assumption is mandatory since I had no information regarding specific location with respect to a curve) OR the quoted grade was compensated.
- Yes, of course I added grade resistance to the rolling resistance.

Added to the 4400 DBHP the NS Research Car is quoted as having measured, this compares favorably with the slightly over 4500 DBHP  in the N&W curve reproduced in Col. Jeffries' book, and is just about on (as close as you can read the curve) the curve Classic Trains published (on-line) in conjunction with their special issue on 4-8-4s.

Several relevant conclusions, in no particular order:
- There have for years been "whispered" thoughts that the N&W's published capabilities for the J were...um...conservative.
- Spencer did a super job!
- "The Old Girl" hasn't lost a step!

Thanks to Ken and Dave for their assistance!

Dave Phelps

In a message dated 7/8/2015 1:41:37 P.M. Eastern Daylight Time, nw-mailing-list at nwhs.org writes:
  Dave 

  The best I can do is off NS' diagram sheet for the 250001 and 250002, last updated was 1-22-1991, which states an average light weight of 143,650 pounds.

  Ken Miller

  On Jul 8, 2015, at 10:31 AM, NW Mailing List via NW-Mailing-List wrote:

    Could some kind soul please provide the empty (tare) weight of 611's current auxiliary tender?

    I need the information to complete the input data to calculate, using the modified Davis train resistance formula, how much the addition of the auxiliary tender impacts the drawbar horsepower measurements reported from the NS Research Car during the recent excursions.  Then, a valid comparison can be made with the N&W curve reproduced in Col. Jeffries' book, and the curve Classic Trains published (on-line) in conjunction with their special issue on 4-8-4s.

    Thanks in advance,

    Dave Phelps
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