Steam questions

[NW Mailing List]

I understand that front-end throttles were used to keep steam in the  
superheater tubes when the throttle was closed to cut down on  
superheater tube burning.  The throttle valves were between the  
superheater output and the cylinders.  Dome throttles were usually  
upstream of the superheaters, so the superheater tubes were dry when  
the throttles were closed.  I think there were some other space and  
access advantages as well.

I think that there was some discussion of this a while back on this  
site.

pete groom
On Nov 11, 2009, at 10:12 AM, NW Mailing List wrote:


> I have a question!   In regards to the Y5's with a Bradford Front  

> End throttle, why was it there and not in the steam dome? Did it  

> provide a shorter path to the front engine when in Simple?

>

> MArk Lindsey

> Stuck in the 1930's

>

> On Nov 11, 2009, at 10:39 AM, NW Mailing List 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

>>

>> ________________________________________

>> NW-Mailing-List at nwhs.org

>> To change your subscription go to

>> http://list.nwhs.org/mailman/options/nw-mailing-list

>> Browse the NW-Mailing-List archives at

>> http://list.nwhs.org/pipermail/nw-mailing-list/

>

>

> --------------------------------------------------------------------------------

>

>

>

> No virus found in this incoming message.

> Checked by AVG - www.avg.com

> Version: 8.5.425 / Virus Database: 270.14.53/2486 - Release Date:  

> 11/07/09 07:38:00

>

> ________________________________________

> NW-Mailing-List at nwhs.org

> To change your subscription go to

> http://list.nwhs.org/mailman/options/nw-mailing-list

> Browse the NW-Mailing-List archives at

> http://list.nwhs.org/pipermail/nw-mailing-list/

>

>

>

>

> ________________________________________

> NW-Mailing-List at nwhs.org

> To change your subscription go to

> http://list.nwhs.org/mailman/options/nw-mailing-list

> Browse the NW-Mailing-List archives at

> http://list.nwhs.org/pipermail/nw-mailing-list/