Steam & Excursion > T&P 2-8-0

Hardly seen or photoed, Texas & Pacific did buy 10   2-8-0 class F-1 engines.  Originally saturated engines with 200 LBS steam and tractive effort of around 46000 lbs but later rebuilt witho two inch larger cylinders with super heated steam reduced to 180 lbs with not much change in tractive effort.  The engines were mostly asigned to yard service in the smaller yards such as Big Spring,  El Paso, and Odessa.  Other wise they were assigned to small local and work trains system wide.  Long before diesels became main line power some of the engines were sold to other railroads so to use the new NW-2 diesel switchers.
 



Edited 1 time(s). Last edit at 12/18/24 11:06 by tomstp.

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Fat boiler.

Built originally as 'saturated'....

In thermodynamics... 'saturated' means that the steam is as hot as 
its ever gonna get.... when confined to the boiling water..

Steam is always the same temperature as the water that boiled it --- 
as long as both remain in contact.... upon leaving the boiler, steam only flows 
towards the lower pressure..... lower pressure means lower temperature, 
so, some gas-state water (steam) condenses, and is partially liquid-state
water  --- arriving at the much cooler steam chest and pistons.

As steam pushes the pistons further down the cylinders...more and more 
of it turns to warm water, and no longer powers the pistons.

It can still be above 212F, but confined, it's pressure is vastly reduced 
from when in the boiler.  So, at each 'chug' you'll see the vapor cloud
above the train.  The cloud in the sky is, technically, NOT steam ---
in terms of thermodynamics.

Superheating meant routing the saturated steam through piping, directly 
into the the path of the flames and hot combustion gasses.  Steam confined 
and separated from boiler water, adds heat --- meaning that the steam molecuies 
are separated further apart... as long as the steam has room to expand.

So, when drawing hot fire into the flues containing superheating units.
and when the superheated steam gets to the cylinders, it's temperature
is stll well above the nearly 400 F of the boiling water in the boiier.
That hot steam continues to expand and power the piston during the entire
stroke., and NOT condensed to any degree.
Superheated Steam will typically be 550F to 700F.
Above 700F, the steam burns rhe valve-oil lubrication, and turns it
into a solid, hard, black mass.

So, steamers typically have limited upper steam temperatures. 

The change to superheated steam in these locomotives makes that large 
boiler a very good superheated engine, and very easy to fire, compared to
the days when they were running on saturated steam..

​W.


 



Edited 1 time(s). Last edit at 12/17/24 19:27 by wcamp1472.

#407 eventually wound up on the Evangeline Gravel Co. RR at Turkey Creek, LA.  Biggest and heaviest loco that they ever had.

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