S-1 and S-2 Engine Brake Valves on N&W

[nw-mailing-list at nwhs.org]

Abram,

The "DCV" pipe connection designation almost certainly stands for "Double Check Valve."  A double check valve is fitted between the engine brake valve and the engine's triple valve so that air from either source is routed to the brake cylinder instead of blowing out the exhaust of the other valve.

Gordon Hamilton
  ----- Original Message ----- 
  From: nw-mailing-list at nwhs.org 
  To: N&W Mailing List 
  Sent: Sunday, April 02, 2006 9:37 PM
  Subject: S-1 and S-2 Engine Brake Valves on N&W


  From rummaging through the N&W photos in the VTU image base, it is apparent that da Comp'ny didn't start photographing the mechanical aspects of engines until around 1922 (probably at the time the photo lab was set up by the Motive Power Department.)

  What a shame.  It means we have no backhead shots of the really interesting older engines.

  Attached is a photo of an S-1 (or perhaps it is an SA-2) early engine brake valve.  (They were not called "independent brakes" at that time.)  These valves were the standard engine brake until well after the No. 6 automatic brake came out sometime early in the Twentieth Century.  The S- or SA- ("SA" for "straight air") engine brake was furnished  as the standard engine brake until a modification was made to the No. 6 automatic brake equipment by the application of a new top segment under the valve, containing an equilizing piston.

  The handle is not oriented horizontally, like today's engine brake valves, but rather sticks straight up in the air.  This photo looks from the "back" of the valve toward the "front" (from the boiler toward the engineman.)  Shoved all the way forward (to the right) is "application."  Pulled partly back (to the left, where the handle stands in this photo) is "lap."  Pulled all the way forward toward the engineman (left, in this photo) is "release."  The three pipe connections are marked "MR" (main reservoir,) "EX" (exhaust) and "DCV" (meaning???)  The valve stands 14" tall and when moved through its entire quadrant, the handle circumscribes an arc of about 14".

  How'd you like to switch cars all day using one of these babies ?  What an arm-buster !

  So, my question is... How long did the S- series engine brake valves last on the N&W?  I have found no photographic records in the VTU image base, but I have heard that some of these valves remained in service until around 1950.

  Anyone know...?

  -- abram burnett,
              der Tinkerer

  (PS - I'm in the market for an S-6 independent brake valve, which attached to the top "segment" under the No. 6 automatic brake valve, if anyone knows where one is available...)




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