Steam Loco Experts - a question about LIMA super power?

[ATLANTIC CENTRAL]

OK, I have been trying to find the answer to this question for a while, and no one seems to know.

The following Super Power 2-8-4 locos where built from the same design and are nearly identical (except for small road specific items, headlights, tender sizes, etc.):

NKP S class

Pere Marquette  N class

C&O K-4 class

Virginian BA class

All the same frame, boiler, cylinders, etc, etc, EXCEPT for one major functional feature. Among these locos there are three different steam dome/sand box configurations - WHY? does anyone out there know?

The C&O locos all have a forward sand box.

The NKP locos all have a forward steam dome.

The first groups of PM locos are the same as the NKP locos, later PM locos are like the C&O locos.

The Virginian locos have the steam dome "burried" in the sand box.

Date of construction is not the answer, some of the earliest where NKP, the last one built was a NKP.

The DT&I heavy 2-8-2's, which were built during this same period, and which are very similar in design, have the forward sand box.

All these locos had front end throttles so steam dome location should not have had much effect on performence? Or does it?

Inquiring minds want to know? Does anyone have any factual data on this? Or, any thoughts?

Sheldon

[wjstix]

Most likely the differences are because that's what the railroads ordered.

You have to remember, steam locomotive building was the opposite of diesel building. Diesels from the outset have worked like cars - you look at what models the builder offers and pick the model you want, then pick from a list of options (dynamic braking, steam boiler for passenger service, etc.). Steam engines were more like ordering a suit from a tailor.

A railroad and a manufacturer might spend months working back and forth with blueprints, diagrams, etc. until they came to a design that exactly matched what the railroad wanted. Things like speed required, grades, clearances in tunnels, etc. all were a factor. (For example, New York Central had some low clearances so their largest steam engines often had recessed domes that barely were noticeable above the boiler.) 

Once the design was approved, the builder went ahead and built the engines. In some cases, a railroad might order 10 engines from Alco, and then go back a year later for 10 more only to find Alco was booked up. They could then take their blueprints to Baldwin or Lima and have them build the engines instead. The Baldwin or Lima engines might be virtually identical to the earlier Alco ones.

[ATLANTIC CENTRAL]

Stix,

I am well aware of all those factors about steam loco construction. This is a more specific question, and those who are familiar with these specific locos know how much they were the same - except for this item.

I posted this in the Classic Trains forum after only getting a few responses here:

http://cs.trains.com/TRCCS/forums/t/182037.aspx

Sheldon

[CAZEPHYR]

This is an interesting subject.

I thought you might like to see some of the data on the different locomotives, all almost twins, but none actually were built exactly like the others.  They did all share the same boiler in general but the railroads used different amount of super heater area and flues according to their specifications.   The C&O used Boosters on the trailing truck on all of their 2-8-4's to add TE for starting.  All railroads had a family look to their steam power and the headlights and domes were normally taylored to that look.

There is no facts or data in any of my books describing how a railroad chose their headlight position or any of the options that a steam locomotive might have.   The larger cylinders gave a higher starting TE but used more steam in general.  

The NKP 2-8-4's were the first to be developed and the original ALCO built S class sort of set the stage and followed the scaled down C&O version of the 2-10-4. 

NKP  69" drivers   25" D X 32" stroke and 245 psi 428,900 for the S class later S3  444,290 Lb 

C&O 69" drivers   26"D X 32" stroke and 245 psi  engine weight  469, 880 lbs     Booster option on all

Virg   69" drivers   26" D X 32"  stroke and 245 psi  engine weight  460,400 lbs

RF&P 69" drivers 25" D X 32" stroke and 245 psi  engine weight  433,200

PM    69" drivers  26" D X 32" stroke and 245 psi   engine weight  448,000   later engines weighed more

The cab sizes were different also and the tenders were ordered to fit into scheme of the particular railroad facilities.  

It is interesting to see how much the repeat orders of the same engine for each railroad differed.  

As for the C&O changing the position of the sand dome and steam dome, the only clue I have is the C&O had some heavy grades on some of their coal runs and having the steam dome in a different position might have been their choice for that operation.  The actual location of the C&O steam dome was much closer to the middle of the length of the boiler than the NKP.  The virginian retained the same basic steam dome location and had the large sand dome built around the steam dome.  That would have equalized the weight better on the locomotive but cut down on the overall amount of sand that they could carry. 

CZ 

 

 

 

 

 

 

 

[ATLANTIC CENTRAL]

CZ, Thanks for the interest and the info. I have all that data and then some, and have studied these locos in great depth. Most recently I am reading "Lima Super Power Steam Locomotives" by Thomas Dixon and Kevin Kohls.

While there are lots of small differences including the ones you pointed out, no one seems to know the "why" of the steam dome/sand box location question.

Interestingly I don't run any Berkshires on my freelanced ATLANTIC CENTRAL, but became more interested in the development of these locos when researching the DT&I 800 class 2-8-2's and the plausablity of my freelanced heavy Mikes.

After much study I concluded that a 69" driver Mikado version of these locos could have built, had some railroad  asked for them. It would have had a higher TE and a higher factor of adheasion, but also would have pushed axle loads to near limits - but so did the Great Norhern O-8 Mikados.

Back to the steam dome question - So far, the steam dome placement relative to use on grades is the only idea that seems to fit.

Again, thanks for your thoughts.

Sheldon

[wjstix]

I'd be tempted to look at other engines those railroads had - did the C&O always put the sand dome in the same relative spot on the boiler for example?? If so, how far back did they do it?? It might at least give you a lead to find out why they did it that way.

[KCSfan]

ATLANTIC CENTRAL

Inquiring minds want to know? Does anyone have any factual data on this? Or, any thoughts?

Sheldon

I was born in 1932 so I saw and was around the steam engines of many different roads but I never gave any thought to sand or steam dome locations. I lack any factual data but a thought comes to mind that could possibly explain the dirrerences. Perhaps the location of  coaling tower chutes, water plugs and sand hoppers played a role. A RR might have a practice of locating these facilities at some or even most of its major engine terminals  so its road engines could take on coal, water and sand all at the same time without having to move the engine. The location of the sand dome on the new engines it ordered might have been dictated by a desire to continue this practice without having to relocate any of the service facilities. A sand dome could be located virtually anywhere atop the boiler from far forward to far back. If the sand dome needed to be located forward to enable "one stop servicing" then the steam dome was obviously located to its rear (and vice versa).

This could be a plausible explanation but I have no idea if in fact this was the case.

Mark

was located forward them it was logical to Once the location of the sand dome was specified the steam dome could