4-8-0 M-2 class

[nw-mailing-list at nwhs.org]

Re: 4-8-0 M-2 classPete,

I likewise expected experts to expound on the esoterics of M2 "relief" valves, but I think that you covered the bases just fine.  One added comment: a check of drawings in our archives covering the M2 and other classes of N&W locomotives shows that the N&W used the terminology, "bypass valve" instead of "relief valve."

Gordon Hamilton
  ----- Original Message ----- 
  From: nw-mailing-list at nwhs.org 
  To: N&W Mailing List 
  Sent: Monday, July 12, 2004 4:20 PM
  Subject: Re: 4-8-0 M-2 class


  A number of RRs used that type of relief valve - ATSF's newer power comes to mind.

  I believe that relief valves relieved pressure buildup in the cylinders when the loco was coasting and the valve gear was "hooked up" so that steam couldn't move from one end of the cylinder to the other.  (They may also have helped to keep cinders, etc., from being sucked into the cylinders while coasting.)  Without them, I believe that engineers had to keep the throttle cracked a little so that the loco was working very lightly, even though the train may have been braking.

  I chimed in because no one else had; I'm sure that others have more definitive comments.

  Pete Groom

  On 7/11/04 7:33 PM, "nw-mailing-list at nwhs.org" <nw-mailing-list at nwhs.org> wrote:


      Hi,
       I have a question about the cylinders on some 4-8-0 M-2 class locos, the 1150-1160 numbers. On the cylinders of some, there is a protrusion off the side of the middle of the cylinder, with square ends.
       . . .

    Sorry Tony, 
    They are pressure relief valves. 
    . . . 

    Mark Lindsey

----------------------------------------------------------------------------
    ________________________________________
    NW-Mailing-List at nwhs.org
    http://list.nwhs.org/mailman/listinfo/nw-mailing-list






------------------------------------------------------------------------------


  ________________________________________
  NW-Mailing-List at nwhs.org
  http://list.nwhs.org/mailman/listinfo/nw-mailing-list
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://six.pairlist.net/mailman/private/nw-mailing-list/attachments/20040717/29b0c5ba/attachment-0001.htm