Steam questions

[NW Mailing List]

Nathan,

In addition to what others have furnished on the two types of throttle 
levers on N&W steam locos, a few more comments  may help.

Older N&W steam locos used the "horizontal" throttle levers, which were 
pivoted to the left (toward the fireman) of the vertical centerline of the 
boiler and which were pinned to a rod (or stem) that typically passed 
through a stuffing box on the boiler backhead on the vertical centerline of 
the boiler and above the crown sheet.  This rod reached through the boiler 
to a bell crank under the steam dome, and the other arm of the bell crank 
raised or lowered the throttle valve when the rod from the throttle lever in 
the cab moved forward or backwards, respectively.  I can think of two 
problems with this throttle arrangement.  One, the sliding action of the rod 
in the stuffing box on the backhead probably caused more wear on the packing 
than the rotary action of the shaft in the stuffing box leading to a 
dome-mounted throttle operated by the outside throttle linkage (and a 
vertical throttle).  Two, with the throttle lever in the "off" position, 
expansion and contraction of the boiler might be different than the 
expansion and contraction of the rod through the boiler raising the throttle 
valve just enough to leak steam to the cylinders, which could cause the 
locomotive to "walk away."  This happened at times.  The more modern 
arrangement of the outside linkage associated with vertical throttle levers 
largely avoided this problem by incorporating a rocker lever mid way between 
the throttle lever and the throttle valve to provide compensation for the 
expansion and contraction of the boiler.

Gordon Hamilton

----- Original Message ----- 
From: "NW Mailing List" <nw-mailing-list at nwhs.org>
To: "NWHS" <nw-mailing-list at nwhs.org>
Sent: Sunday, November 08, 2009 12:33 AM
Subject: Steam questions



> Alright gang I'm back with more questions, Both are for the most part

> quick and hopefully simple. First what orientation did N&W prefer for

> the throttles of their steam locomotives? Horizontal or Vertical? I

> think the J and A both had Vertical oriented but I am not sure if that

> was N&W preference of just what they used on those locomotives for some

> reason.

>

> Second Question is a little harder but I feel it will be easy for

> someone to answer. In listening to Link's recording of  Y6 working

> Waynesboro, at time I hear a distinct "thump thump thump" that is

> rythimic then it quits then it does it again. It does not sound like a

> Cross Compound to me so I am buffaloed as to what it is, Feedwater pump

> perhaps? I head the same sound in Hooters on Blues ridge when there is a

> Y doing Switching at Blue Ridge. It happens while the locomotive is

> still moving but the throttle seems to be closed and the engine coasting.

>

> Thanks ahead of time,

> Nathan

>

> -- 

> Nathan Simmons

> trainman51 at gmail.com

> http://www.t-51.org

> KI4MSK

>

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