steam loco question

[nw-mailing-list at nwhs.org]

After passenger service, the superelevation was reduced on many curves as it lessened the rolling resistance of freight trains.

Ed King
  ----- Original Message ----- 
  From: nw-mailing-list at nwhs.org 
  To: nw-mailing-list at nwhs.org 
  Sent: Thursday, June 29, 2006 11:07 PM
  Subject: Re: steam loco question


  What might not be related is what was told me regarding the famous 13-degree curve at Cedar, WV, by Bob Saxtan. It is that the superelevation of this curve was lowered and the curve was tightened after the end of N&W passenger service- what would be the reason for these modifications?

  I might note something that happened on the night of January 23, 1956. The 611, running the Pocahontas westbound, wrecked there at 12:51 AM. During the wreck, the 611 tipped over on the curve, and seemingly "jumped" over the inside westbound rail of the curve, then grabbed one of the rails of the eastbound track, which she pulled with her on her way onto the bank. I might ask if any of you want to comment on how the 611 made this "jump" as she did, even with the little room (as I have seen) between the curve tracks and the bank as I have seen at Cedar.

  Lois J. Ponton

  Author of 611 wreck book "Midnight on the Pocahontas"



   


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    From:  nw-mailing-list at nwhs.org
    Reply-To:  NW Mailing List <nw-mailing-list at nwhs.org>
    To:  NW Mailing List <nw-mailing-list at nwhs.org>
    Subject:  Re: steam loco question
    Date:  Tue, 27 Jun 2006 22:31:35 -0700 (PDT)



    How was all of this effected by superelevation of the track?
       
    I have never totally understood why they used it but it sounds like it would enhance the effect of the conical wheels.  
       
    Thanks,
       
    Jim Hall

    nw-mailing-list at nwhs.org wrote:
       
           
         
      I won't repeat the answers given so far, which are all correct and well explained, but there's two more factors, as it's been explained to me over the years (I'm an old electron pusher, so I take these things on faith): were not most steam locomotives built with a certain amount of lateral motion allowed in 
      the journal boxes?  Even thought the frame and bearings would hold the driving axles parallel, the ability to shift laterally slightly would also help.  Secondly, while in the ideal case the conicity of the wheel sets would eliminate or minimize flange contact, in the real world there is flange contact.  As long as the angle of attack of the flange is small and the shape of the flange is correct, the wheel will not climb, but rather the flange will keep the wheel in place.  The geometry of the flange and rail head result in a measure called the "L/V" ratio, the ratio of the lateral force (which tends to cause flange climb) to the vertical force (which keeps the wheel in place).  I have read what a desired limit of the L/V ratio is but I confess I didn't commit it to memory. 
         

         
      Dave Phelps
         

         
      In a message dated 
      6/27/2006 9:16:08 P.M. Eastern    
         
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