cefinkjr Didn't some roads have locomotives with the Elesco "bundle" on the pilot deck? Seems to me I've seen that but can't recall which road it was.
Didn't some roads have locomotives with the Elesco "bundle" on the pilot deck? Seems to me I've seen that but can't recall which road it was.
.
The Elesco, Coffin, and Worthington feed water heater systems consisted of water pump or pumps - one sometimes two - and the heat exchanger. The pump was often on the pilot deck but sometimes on the side of the locomotive - the early ones were huge. The all important heat exchanger - which was of the "open type" or "closed type" - was usually ahead of the stack. The "open type" mixed exhaust steam with the cold water feed into the boiler, the "closed type" did not mix but used a system of hot pipes to heat the cold boiler intake water.
Both of these systems were common to many late ATSF steam locomotives like ATSF Hudson 3463 in Topeka KS - Worthington "open system" with water pump on the pilot deck - and many other railroads.
An examination of ATSF 4-6-2 Pacific 3415 does indeed show what appears to be the Elesco bundle - "closed system" on the pilot deck. Can't say I have seen many in this location. Looks good though!
Doc
Dr DA feed water heater must be located so that it can work - what does it work on but exhaust steam from the cylinders as it is on the way to the stack. It is diverted to a chamber or bundle where cold tender water may be heated. There would be no purpose for placing this on the engine pilot deck.
Dr D Wizlish, Glad to see you chime in on this discussion, but when did throwing out a bunch of technical names and vague comments constitute a legitimate retort?
Wizlish,
Glad to see you chime in on this discussion, but when did throwing out a bunch of technical names and vague comments constitute a legitimate retort?
Ye gods, just the kind of discussion I love, and I have been missing it completely! Let me take up some of the points with a bit more detail. I keep thinking that because I've seen technical detail, it's self-evident to others with serious interest and knowledge of steam practice... that's a dumb assumption. As my great-grandmother used to say, 'ignorance is not stupidity'. (Except when it is ignorance as shown by me in assuming everyone knows the esoteric stuff!)
... I cannot come to believe that a modern engineering and computer design "poppet valve" concept could not overcome all of these limitations cost effectively.
Much of the effective limitation was solved in between the PRR efforts in '47-'48 to fix the T1 problems (many of these, like better centrifugal casting of the valves, were never implemented) and the system on ATSF 3752 that is described in Vernon Smith's One Man's Locomotives. The 'catch' is that even the simplified used in Franklin type D (which uses a kind of wire-drawing effect to produce the effect of cutoff as speed increases) has complicated gears and shafts that require close alignment and careful maintenance. With the advent of comparatively cheap CAD/CAM, many of the objections to designing and fabricating the 'nightmare boxes' are reduced. But there is still much more involved in providing all those valves and seats and springs and cams when the alternative is a (comparatively) simple articulated, multiple-ring long-lap long-travel piston valve (or Willoteaux valve if you need the equivalent of multiple ports opening in parallel)/ driven by a simple pin-jointed linkage like Baker gear.
"Sleeve valve" as used in early automobiles and in Ricardo's work
These have almost as grim a history as rotaries in steam-locomotive practice. About the closest I think they came to workability was the setup used in Bulleid's Leader, where a Meehanite sleeve with a great plurality of ports was used, between the piston and the cylinder wall. This design had probably the lowest possible dead space of any workable arrangement, and (naturally!) very good theoretical high-speed steam admission. But the design showed also a remarkable capability to start leaking steam if even one of the very substantial number of sealing rings cracked or wore -- and even a cursory examination of the required lubrication arrangements would convince you that 'cost-effective' was an adjective to describe the setup. (I am tempted to point out that when Bulleid attempted a Leader-style arrangement later, in Ireland, he used more-or-less conventional piston valves.)
"Rotary valve" as used in some internal combustion motor designs such as CSRV.
And they work, if anything, even worse than they did in IC engines. Two words for you: Paget locomotive. Differential expansion vs. required tight sealing makes for an operational disaster in typical railroad service.
A possible way around this is to adapt an idea from a British design called an 'asynchronous compound' -- have the rotary valve always work with a slight clearance, and use the 'slip' together with the exhaust steam in a compound arrangement of some type. But the simplicity you gain from the absence of sealing -- or inadvertent interference fits -- will be bought at a comparatively high price... in a number of respects.
I won't go into how you keep a rotary valve exposed to highly superheated steam lubricated, while keeping lubricant out of the exhaust (or using enough antifoam in the water treatment!) so you can use an open FWH.
"Reed valve" as in two stroke interal combustion and modern compressors.
I'll bite -- just how would you propose using these on a high-pressure steam locomotive?
I for one cannot think of any other common valve designs applicable to power producing machinery...
Well, you left out a biggie -- the 'bash valve'. Arguably the simplest valvetrain you can have -- a projection on the piston crown lifts a ball off its seat against spring restoring force. I'd agree that poppets are better than these for large railroad locomotives, but if you are converting a locomotive diesel prime mover to run on steam (as in Perry Shoemaker's approach) the bash valve remains an interesting potential approach.
... Possibly the Wardale articulated design with Baker action was a workable compromise for commonly accepted maintaince schedules Wardale was confronted in maintaining Red Devil.
Wardale himself has been forthright in saying that he considers proper piston valves to be a better solution in practice, for a working locomotive, than poppets. Note that the advantages of the Franklin System only prevail at high speed AND high delivered power -- examine the performance of, say, the T1 with Franklin OC valve gear vs. the T1a with piston valves and Walschaerts gear.
The multi roll bearings and diesel piston rings on piston valves is novel considering the problem with "carbon sticking piston valves" that high demand situations created (such as when Pennsy borrowed a N&W 600 for tests and stuck the valves).
Note that 'Multirol' is a trade name for a particular make of needle bearing. And they are diesel-style rings, not repurposed actual diesel-engine piston rings -- the metallurgy and characteristics are usually different.
The carbon sticking the rings is, of course, derived from superheated steam coking the lube oil needed to keep rings sliding. There are approaches that ought to reduce this -- the Spilling company, for example, makes engines that can use upward of 1000-degree steam without using oil lubricant. A useful thing here is to look up the old enginion AG "zero emission engine" -- which I still find an intriguing design -- and examine how its tribology was arranged.
"Trofimov valves as improved by Meiningen, or Wagner bypass valves!" I cannot believe you would introduce a subject title like this without some explanation of them. They represent quite an insight into new thoughts on piston valve design.
Well, actually not all that new. The Trofimov valve is a functional improvement on an older design (the Nicolai valve, which had an interesting history) -- it provides automatic bypass action when the locomotive is drifting. There are, or were, operating instructions for the system on the Web -- look for references to locomotive 3025, which had them. Perhaps this link to a .pdf will still work.
Here is a picture of a Wagner bypass valve (as fitted to a large ATSF locomotive expected to run at high speed):
A point that was raised in discussion is that Trofimov valves can be fitted to most any locomotive with piston valves -- the Wagner bypass requires its own housing in the cylinder casting.
I also cannot believe you would bring up "compression control" and its importance without some discussion because it is the subject of choice to continue this thread. Walschearts design and Baker designs primarily failed because they kept back the tremendous efficiencies that could have been realized in reciprocating steam locomotives when operated at "limited cut off."
The compression control is really more about reducing momentum effects at high speed than it is about suppoosedly "tremendous efficiencies" to be gained by limited cutoff. I would refer you to the people responsible for the Duke of Gloucester, a locomotive that can reliably operate at over 95% cutoff without mechanical damage -- there are practical limits to how much cutoff can be used while still making the required power to propel the engine at speed, and those are nowhere near what the valve gear can reliably produce.
I don't know if the thermodynamic and water-rate improvements of Jay Carter-style compression control (look it up on the SACA 'phorum' if you have to) would be valuable enough on large locomotives to justify their use over the simpler Okadee valves that just vent excessive compression.
Wardale and his support by South African Railway hardly compares to what Pennsylvania Railroad pursued with the T-1 duplex drive development or that New York Central under Paul Kiefer was attempting in similar situation to Wardale with the NYC 6000 series Niagaras. Time was indeed running out.
With the cost of diesel fuel in the present age some doubt remains that the diesel electric locomotive could have displaced reciprocating steam locomotive if it had been allowed to continually develop to its full potential.
Even with diesel fuel at ten times the cost it was in the Forties, it is highly likely that some form of diesel traction would have become highly adopted. Remember that very few people (outside GM-EMD, of course!) were expecting steam to disappear anywhere near as quickly as it did in North America. The various unavoidable inefficiencies of big steam -- starting, perhaps, with all the problems and issues related to water, which the diesel avoided entirely, and finishing up with all the manpower reductions that dieselization facilitated -- were one of the major factors, as was the 'critical mass in reverse' when it became increasingly impractical for specialty manufacturers of essential steam-locomotive systems to stay in business. When superheater elements can't be built or rebuilt to order quickly and easily by experts, and arch brick is no longer made or delivered when needed, or you can't get parts to your fancy FWH pumps -- even a large theoretical saving in fuel gets eaten up pretty quickly.
And I'd expect the UMW to be increasing the cost of decent steam coal
And then there is the environmental pollution issue. Smoke was already a serious concern by the late '40s. Things like total-loss lubrication, ash dumping, ejection of fines in the exhaust, or continuous blowdown dribbling nice alkaline water all over the railhead would not have been tolerated if there had been a substantial number of working mainline steam locomotives left.
Our community is FREE to join. To participate you must either login or register for an account.