Steam questions

NW Mailing List nw-mailing-list at nwhs.org
Wed Nov 11 11:35:11 EST 2009


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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