While researching the NKP Berkshires in an effort to do a somewhat accurate live steam model, I’ve occasionally run across design items that puzzle the engineering mind, at least mine. Perhaps some on this board may be able to shed some light on these issues.

About higher steam domes;
I’ve always wondered why the C&O T-1’s, NKP & W&LE Berkshires, and one order of the PM Berkshires, had the steam dome mounted in the unconventional position of being on the first course of the boiler. This would be the best place to preclude having water carryover into the dry pipe, particularly when working hard upgrade where the water level would be at its lowest point in the boiler. The downside is that this is also the coolest part of the boiler.

The ALCO erecting drawings for the W&LE 2-8-4’s and the NKP S class, along with the NKP (Lima) erecting drawings for the S-1 class, show the dry pipe going up into the steam dome.

Now comes along the NKP (Lima) erecting drawing for the S-2 class engines. The drawing has a table which shows that the first order (1179) of the S-2 (740-754) class will not have the elbow going up into the steam dome but will have an “extended” dry pipe that does not terminate in the dome. The “extended” dry pipe goes toward the rear of the boiler and had kind of a scoop arrangement from which extended two smaller tubes to feed the two connections on the cab turret header. At the steam dome location was simply a hanger arrangement for this dry pipe. The scoop was located approximately where the seam is between the 2nd and 3rd boiler courses, about where the steam dome would be on a C&O 2-8-4.

The table on the erecting drawing shows that the second order of S-2 class engines (755-769) will have the dry pipe elbow with the dry pipe terminating in the dome. The specification sheet for order 1184 says “Top of dry pipe elbow fitted with extension to take advantage of height of the special dome cap as shown on RR drawing.”
The AMC issues a drawing to coincide with this order that shows a taller, or more dished out, dome cap that is four inches taller than the old, flatter one. The next day the AMC also issues a sketch showing a dome case or cover which is four inches taller than the old ones and applies to all S class engines. Thus we see all S class engines getting taller steam dome covers during their careers.

Then on 3-13-47, the AMC again changes their mind and issues a drawing calling for the extended dry pipe for all S class engines. An NKP drawing is issued on 3-28-51 calling for the flatter dome cap to be applied to all S class engines. There is not a drawing that I can find that says reduce the size of the taller steam doom covers.

The S-3’s were built with the “extended” dry pipe.

The NKP then has another reversal in their thinking about this by issuing a drawing on 2-6-57 which says that all S-2 and S-3 class engines, during their class 3 shopping, will receive the taller dome and cap and the dry pipe will terminate in the steam dome.
Since this was late in the steam era, only 16 Berkshires received this final modification to include the 763, outshopped on August 8, '57, and the 755, outshopped on March 19, '58. When the dome cover is removed from the 763 I would expect to see the dry pipe terminating in the dome. The 765 did not receive this modification which I noticed when we pulled the steam dome cover off in the early eighties.

Bottom line is, from an engineering standpoint, what were people like T.C. Shortt who was the NKP CMO during the Berkshires construction, or A.G. Turnbull of the AMC, thinking?
The sixteen Berkshires that received the dry pipe change were; 763, 777, 762, 761, 759, 757, 756, 755, 752, 750, 749, 748, 747, 746, 742, 740. The 763 was outshopped on August 8, '57, and the 755 was outshopped on March 19, '58.
If I remember right, all S class engines, except the S-3's, were getting the taller steam dome covers even though they might not have received the taller steam dome dry pipe installation yet. I surmise that this happened because the taller steam dome cover drawing was issued on 6-5-44 before the S-3's existed and therefore applied to only the S, S-1's, and S-2's. The drawing was never rescinded and therefore the railroad kept applying the new cover.
By the time the S-3's were built, the NKP was installing the taller covers on only the S-3's that received the dry pipe modification. The only S-3 to receive the taller cover would have been the 777 since it is the only one to receive the dome dry pipe installation. It was outshopped from a class 3 on April 5, '58.

The other thing that I’ve wondered about is the application of coil springs on the main and rear drivers for the NKP S-2 and S-3 class engines. I have found only one other class (there may be more?) of engines that had coil springs on the drivers and that was for one order of C&O 2-8-4’s and only on the main driver.
The NKP S-2 class were built in 1944 and the S-3 class in 1949. In the interim there was not any widespread application of these coil springs but yet the NKP came back and applied them again in ’49.
Any ideas as to why?

Maybe I should watch more TV!?!

Jim Kreider

Just from briefly churning my mind, my thoughts from what you describe would seem to have been a desire for hotter steam. While all of what is in the boiler proper would theoretically be same temperature, drier steam (higher energy) would achieve higher superheat in same superheat area than wetter steam. Maybe they thought closer to firebox provides drier steam. Perhaps the thought was crews were competent enough to not run high water coupled with the fact that NKP seems to be mostly flatter territory (no constant up and down mountains).

That's just what I visualize, if I'm understanding what you describe correctly. After rereading your post, I should point out that I'm referring to the extension. And after doing some more thinking, a more general locomotive design practice seems to have the dry pipe inlet mostly central in the boiler relative to average center of mass of boiler water. This would be to keep most steady steam quality for territory gradient changes. Would assume the scoop location would have been similar? Also the scoop you describe, is it similar to the trough for the foam meters, were the locomotives such equipped? This could be why the extension was put in and removal of such equipment could call for removal of the extension that you also describe.

I've been all over 765, its dry pipe is at the firebox end. There might be some reasoning about deciding where to place the input. Theres a discussion on the nkp email yahoo about having a 4-8-4 passenger engine, a high stepping smaller boilered 4-8-4, but since the line was not heavy grades, a 4-6-4 worked out fine, perhaps a larger 4-6-4 would be the order as the NKP hudsons were smaller.

So an engine like 765 might be kept on the lesser grades lines while 755 with a middle dome might be placed on parts of the line with heavier grades.

But remember these engines have the superheaters to dry and heat that steam even further. Are there live steam engines with superheaters? dunno, but for your model put your input at the safest location as you might be traveling your engine to various sites who have grades. The model is much smaller and heat variance between the front and rear of the engine may not be as great as the real thing.

I believe 765 is all leaf springs on the drivers.

good luck with your engine.

according to the list, only 2 existing engines today have the extended dry pipe, 765 and 779. if anyone at steamtown knows and can chime in, pipe up about 759, 763 may be brought back to operation if they read this perhaps they can tell us if its at the dome.

4 inches is a rather small distance to tell the difference between dome and extended dry pipe from a casual side track observation, I think theres a cover for the steam dome anyways to prevent seeing that anyways.

Someone from the 765 group has posted that the extended drypipe was removed during one of the locomotive's overhauls, the drypipe reverting to the original design. Supposedly this was done to make the locomotive more suitable for operating in hilly territory, such as its trips on former Southern and C&O trackage.

All good points there Mr. Kreider - interesting details. I must say that the temperature of all areas of the steam space will be nearly the same. Remember to think of your boiler pressure gauge as a boiler thermometer. The coolest part of the boiler is below the water line in the belly at the throat sheet where the cooler feedwater has travelled and is about to feel the heat of the firebox.
TO dinwitty: "I've been all over the 765 and the dry pipe is at the firebox end".
Sorry, but you're wrong on both points.
When we first restored the 765, she had the "extended dry pipe" around the steam dome and back towards the firebox. We did remove this in 1982, I believe, to return with the elbow up into the steam dome ending about 1" below the dome lid. And, yes, we did this to reduce the amount of priming we were experiencing when operating the locomotive on "foreign" roads with larger hills than the NKP. Also, we usually fired the engine with a half glass or more in the boiler - just to be on the safer side of things. I know many NKP veterans ran the Berks across an entire division and only saw the water wink ocassionally in the bottom of the glass.
Many NKP shop men told us the "extended dry pipe" was a feature only to save the manpower cost of removing the elbow from the dome at every required inspection.
Also, I can't imagine a locomotive assignment to a certain division of the railroad
to be determined by the locationof the dry pipe.
TO dinwitty: " I believe the 765 is all leaf springs on the drivers."
The 765 was built with the coil springs Mr. Kreider refers to on the #3 and 4 drivers.
765 has always had them and they are still there today. We replaced them with new in 1986. We called ALCO Spring in Chicago and they still had the original specs on file and produced them for us perfectly.
Best regards;
Gary P. Bensman, FWRHS
Supervisor of Standard Practices

And on the 759: she has a dry pipe elbow up into the dome. As witnessed during Diversified Rail Services' work with the asbestos abatement contract at Steamtown 3 years ago. We were ALL OVER the 759 and I'm proud to say we left her better than we found her.

I might be misworded, the input was at the firebox end (the extended version) not at the dome.

Awful lot of waffling in the designing, heh. Maybe a short dome at the firebox end would help in those thoughts, but anyways. Steam engine design works on tried and true designs and again some suppositions and experimentation in progress, and mod as you go.

Today with a lot of high tech we aughta be able to design the near perfect steamer.

dang diesels...

Gary:
You are certainly correct in saying that the temperature is relatively constant in the steam space along the boiler. I was not entirely accurate by using the word “cooler”. SR6900 has hit the point in regard to what I meant to suggest and that is the “quality” (vapor mass/total mass) of the steam is less at the first course than in the back or in other words, more liquid is entrained in the saturated steam, especially since that is the point at which cold feedwater (relatively speaking of course) is introduced into the boiler, and that is also the point at which the tubes and flues are pretty well exhausted in regard to their transfer of heat into the water. I think that with the dry pipe terminating in the dome the superheaters have more work to do.
Your statement about what the NKP shop men had to say about the extended dry pipe certainly makes sense because the dry pipe diverted around the dome centerline, or was offset as you looked down the dome opening into the boiler. That certainly sheds some light on the subject. You may not recall but my observation about 765’s dry pipe came from the fact that I helped you pull the dome cap off in the early eighties. Where did time go?

Dinwitty:
The NKP was certainly territorial in regard to the distribution or assignment of engines to particular divisions. I don’t know how they determined their assignment list and as Gary suggested I do not think that it had anything to do with any particular design attribute or modification, or at least none that I could find in researching engineering drawings or notes. As you suggest there appears to be some “waffling” on this subject by NKP’s mechanical department.
Just off the top of my head we would regularly see on the Buffalo Division (among others I’m sure);
700, 707, 719, 726, 727, 743, 744, 745, 746, 748, 763, all the S-3’s
But we never saw the 755, 759, or 765 on the east end.
Of course, all or most of the 700’s would migrate to Conneaut for class repairs even though they would not operate out of there.
I would cross the NKP track on my way to school and I remember seeing the 776 go east about 7:30 in the morning. One of the guys who worked with my dad in the crossing towers in Erie kept a log book of all engines passing his location while he was on duty. I often visited with him on the way home from school and he showed me that the 776 went west earlier on the same day. My dad then told me that it went east again while he was on second-trick duty in the evening. I always thought that this kind of reinforced the idea that certain engines were strictly confined to certain divisions. BTW, I wish I had that log book.
BTW, the live steam models have been done for sometime now.

In regard to the coil spring installation on the main and rear drivers; coil springs would not have the damping capability of leaf springs so perhaps the NKP did this to soften the ride especially since the roads operating philosophy was to run these engines at a mile-a-minute pace or better. But if that was the case, why did other roads not adopt the design?

These issues, among others, are things I’ve run across in my research to try and do an accurate scale model. The prototype issues have no or little impact on a 1-1/2” scale model of course, but it got kind of interesting to see the kind of changes that took place, and what the mechanical department men were thinking, during the career of a certain class of modern steam locomotive, probably typical of what a lot of railroads did with their motive power.

Gary;
As a side note, I have wondered to what extent the ride quality of the 765 has improved due to the fact that the engine is now properly trammed and quartered with rod bushings and spring rigging rebuilt to spec. In chatting with Tom Stephens the other day (Tom was an engineer and CMO on 765 for a while), he indicated that the difference is significant. He had the opportunity to ride the cab on last weekend’s trips. Gary, I think it would be interesting to hear your evaluation of that also.
You guys at Fort Wayne have done an admirable job on the locomotive and she sure looked good to me when I peeked into the shop on my last visit to Fort Wayne about a month ago.

Jim Kreider

It might be easier on the paperwork to keep specific engines on the same work routes and runs, the engineers may have a feel for their engines, there may be those little quirks between differrent engines.

note some berks were outfitted for passenger use and 765 is one such engine, perhaps a lucky save, as 767 I believe was not.

Its pretty clear railroads ordered specific engines for specific use, N&W 4-8-0's were made for the heavy grades, one sold to another line later did not perform to their preferences.

I don't recall if the drypipe shuttled around the dome, but it would not be impossible to do. What I wonder with the re-establishment of the pipe at the dome that if they made a quick disconnect (well quicker) for access into the boiler for inspection, theres just enough room above the flues to scramble on top of them and peek at the boiler inside.

It is all about getting the hottest driest steam for the best performance, but 765 isnt in daily working performance requirements, so at the dome is fine, but remains to be a formidable steamer nonetheless.

The firebox has 2 huge what I'll call "Flumes" for now that help circulate water into the firebox area and get more heating, older engines have just piping floating into the firebox for the same purpose, so its an idea expanded.

More on engine assignments, I am modeling the South Shore/NKP interchange in Michigan City in HO, and I learn they never ran Berks up there or rarely, it was mostly run by the Mikes.