Regarding the present status of N&W 1218 and 2156, what is your opinion on which of these would be easier to restore to operating condition?
lois
Lois, welcome back! Where ya been?
OK, in my own uninformed opinion it would probably be easier to bring 1218 back to life before 2156. Considering 1218 was restored to service in the early 80’s while 2156 has been dormant for fifty-plus years with 1218 we have some idea of what we’re dealing with. 2156, who knows what lurks within? The “Shadow”? Maybe.
Just my opinion.
Firelock is probably right.
If the two locos were in roughly equivalent condition, the Class A would probably be the better candidate because the Y6a was intended as a lower speed engine, and was built as a compound. The Y6a’s great power would be wasted.
Tom
Mostly managing my Friends of the 611 Facebook group.
However, one thing that many fans are not aware of is that the Y6 class, even though built for low speed freight operation, could run at higher speed when necessary. They had to keep to schedule on time freights on the Shenandoah and Pocahontas divisions, and that meant occasional 50-plus mph running. The Y6 could never match the A in the fast freight department but still could be relied on to bring a train in on time if necessary. It was the “locomotive of all trades” of its time, and was called upon to do what was necessary by the railway.
lois
Something to remember, though, is that the efficiency – and, by extension, the expected water rate – falls off dramatically on a Y locomotive above its designed operating range. (Where was the speed range above which a NYC Hudson would produce more DBHP?) I’d be concerned that you’d need multiple A-tanks
Also, even if it is possible to run (relatively) quickly by adjusting the booster valve to balance the LP engine, that adjustment would have to be made carefully each time the power demand changed at high speed, with perhaps relatively low tolerance for error either in the quickness or the direction in which the correction was made.
If this is something being seriously considered, with the actual permission of MoT (about which I am not going to speculate on a public forum) I would be extremely prompt about finding anyone living who has actually run a Y at speeds of 40mph or higher, and ask them in great detail what they did, and what to watch for. Barring that, I don’t think it is an impossible task to design some form of at least semiautomatic IP injection for high=speed operation, or developing a training program for “younger” engineers to know how to use it safely. I don’t know whether it would be feasible to adapt the as-built booster valve for that purpose, so this would essentially be a new ‘program’ within a restoration effort. Personally I would consider it a critical one if the engine is expected to operate safely at the ‘necessary’ speeds to fit in with other traffic.
Keep in mind that the booster was intended for use boosting power on mountain grades, not across the entire speed range. Not as economical as pure compound operation, but, more economical than pure simple operation. Train speed increasing from a grinding 8mph to 12 - 15mph.
Just as he says. (There is an account in Jeffries’ N&W: Giant of Steam and Louis Newton describes it in ‘layman’s terms’ on p.657 of Rails Remembered vol.3
Remember that Big Jim previously noted that by intent it was the ‘heat’ (more specifically, reheat) put into the LP steam that was the most important characteristic of Pilcher’s ‘booster’, rather than pressure normalization per se between the HP and LP engines.
I do think, however, that the idea of an intermediate degree of ‘simpling’ that normalizes performance from the LP engine is a logical followon that is within the scope of what a booster valve can do.
Copies of the updated version of N&W: Giant of Steam are available at the N&W HS Commissary. See nwhs.org.
lois
Before it was shut down in 1994 the old Norfolk-Southern steam program had a speed limit of 45 miles an hour on the excursions.
I don’t know if the speed limit’s still in force, but if it is it would make it a moot point of how fast 2156 could be pushed. There’d be no need to push it hard anyway.
It’d be a hell of a thing to see at any rate!
It was actually restricted to 40mph.
That I do not know. I have heard on a few occasions of 630 going over 40 mph. Don’t know about the 765.
lois
It’s in the timetable.
OK Big Jim, 40 it was. Even less reason to worry about a Class Y in excursion service, assuming that 40mph rule still stands.
The Y6 developed maximum power at 40 mph, so that is right in its territory. Imagine the size of excursion train that it could pull. 30 coaches would seem like a walk in the park.
lois
I don’t believe I have ever seen a report that says the DBHP for a modern Y class peaked at any speed higher than about 26mph. I can’t remember the reference that pointed out a NYC Hudson’s DBHP curve crossed that of the Y somewhere in the mid-30mph range, but someone here will know and provide it. There is the advantage, of course, that a Y will definitively start any train it can pull up to 40mph. But 30 cars at 40mph is not likely to be ‘in the envelope’ if there is much uphill working… even relatively slight uphill working…
Lois,
You really should know better than that.
There is a note on the ‘improvements’ in Dixon, Parker, and Huddleston’s book on the Y class locomotives, pp.107-108. They mention a distinction between the function of the ‘improved’ reducing valve and the booster valve.
As they put it, the booster put a “shot of superheated steam” into the IP receiver. The reducing valve was changed from a “normal” semi-automatic simpling valve to one that was entirely “under the control of the engineer” – by which I assume, until someone like Dave Stephenson says differently, that the degree of simpling rather than just the point of transition was capable of adjustment. I think there is a difference between what the two devices do: the reducing valve adjusts the amount of throttled steam being added to the forward engine, the booster valve adds reheat (and some pressure, but probably not adjustable pressure) to the LP steam when working full compound.
I have not seen the mechanical devices used for either function, but presume that both survive on 2156, and could be ‘reverse engineered’ if necessary. I am checking the NWHS drawing archives to see what’s currently online or available regarding them.
Is this what you are looking for?
Actually, much better than what I would have been looking for. I would not have figured that the ‘booster valve’ would be arranged as it is just by looking at the fabrication drawings of the reducing valve.
Note that the physical “booster” valve actually does the opposite of what I had been assuming it did. If I am reading the drawings in the instructions correctly, when in compound mode the feedback loop between receiver and piston on the reducing valve ALREADY is set to work with full ‘boosted’ pressure – the booster valve’s supplied steam closes the reducing valve further than the feedback system would (and effectively disabling the feedback system when it does so), so it is actually an ‘economy’ valve in terms of its direct action (which I would not have expected!) Of course, to the locomotive’s engineer this would not matter if they were following directions. As a matter of ‘interaction design’ semantics, it would seem sensible that physically opening a “booster” valve (following the usual valve convention that turning its stem counterclockwise increases flow) would produce greater boosting. And indeed that is the effect here… because Pilcher et al. were smart enough to construct the valve ‘backward’ so that it is closed when fully unscrewed…
Note the purpose of the constriction in the control-steam feedback loop from the receiver to the reducing valve.
I think a Wagner-style fluidic valve controlling the reducing-valve actuating piston would make modulation of the reducing valve position easier when running ‘servo’ with booster ‘enabled’ (note how I carefully avoid ‘open’ and ‘closed’ – shades of the troubles at Three Mile Island!). As constructed, I think it would be effectively impossible to use an intermediate setting of the booster valve
I believe the 40 mph speed limit was for insurance purposes after the wreck at Great Dismal Swamp. My experience with NW611 after that, was that “official speed limit” and “actual practice” varied greatly. Chasing from Fort Wayne IN to Detroit MI - I could not catch NW611 running well over 70mph. This was likely never reported.
UP844, however, seems to hold fairly close to 75mph.
Dr. D