Steam questions

[NW Mailing List]

Ed,

Thanks for pointing out the other arrangement for the horizontal throttles. 
After I hit the send button I thought of the W's and M's with the firebox 
that extended so far back into the cab as to separate the engineer and 
fireman, and I realized that those throttles had to be ahead of the boiler 
backhead.

Gordon Hamilton

----- Original Message ----- 
From: "NW Mailing List" <nw-mailing-list at nwhs.org>
To: "NW Mailing List" <nw-mailing-list at nwhs.org>
Sent: Wednesday, November 11, 2009 11:35 AM
Subject: Re: Steam questions



> 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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