Steam questions

[NW Mailing List]

To expand on what Gordon Hamilton wrote about throttles - 

M's and W's and other engines whose cabs were mounted astraddle of the firebox had their throttles on top of the boiler for convenient handling by the engineer.  These throttles operated a rod that went directly above the top of the boiler into the back of the steam dome (through a packing gland)where the actual throttle was located.  The throttles described by Mr. Hamilton were on the E-2s, K-2 and K-2as M-2s and subclasses and earlier Mallets up through the Y-4s.

EdKing
---- NW Mailing List <nw-mailing-list at nwhs.org> wrote: 

> 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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