Dear Juniatha:
Dear, you might consider a tad less stylized writing; it gets a bit murky sometimes. But charming.
As for the N & W's steam program, if you look it "deep in the eyes", you really DO find that the diesel's advantages are, [alas!] overwhelming. But let me add another, seldom mentioned reason to dieselize:
If you were a successful steam-powered railroad who wanted to expand your territory by buying a small but equally successful regional railroad, if you went to your financial backers to secure the funds necessary for the transaction, then might they not demand COLLATERAL for their financial aid?? And what can you offer as collateral - a clutch of steam engines, along with immoveable coaling towers and water cranes, plus machine facilities tailored to maintenance of steam engines?
WHAT THE HELL GOOD IS THAT if you default on your loan, and you have to break up the railroad? What are all the other railroads, who have already dieselised, going to do with your steam-powered assets?
Face it, your little toy steam engines, no matter how efficient, are WORTHLESS to anyone but YOU.
And so, if you want to be a "player", you have to KEEP UP - if everyone else dieselizes, the YOU must dieselize - unless you wish to have your motive power assets regarded as quaint and worthless.
If you routed the spent steam back to the boiler, then how would you maintain draft thru the flues? A problem with steam locomotives was that you had to expend that final bit of energy forcing the flue gases thru the petticoat and up the stack, where, of course, it's gone. The exception was with the condensing engines used in South Africa and other desert climes - but then, how do THEY work?
>> I'm crushed! Crushed I tell you! <<
Hi Firelock
Wait , wait , don't - just ask = J = ! To de-crush you :
Big Boy was the one locomotive type with the largest number of axles between couplers , i e engine plus tender , of any steam locomotive on earth , Mallet or single frame concept , namely 19 . However 'he' wasn't the longest steamer between couplers - this was long tall Sally-One , PRR 6100 . BB also wasn't the one with the heftiest down thrust on rails , that was the Lima 2-6-6-6 BigFoot , exactly the Virginian RR version which was a little heftier than the previously built Carbon&Oxide version . As concerns applicable tractive effort it makes little difference in principle if you have - to simplify ! - 2 x 4 axles loaded at 30 tons each or 2 x 3 axles loaded at 40 tons each .
Since the ALCO Boys scaled at some 32 tons while the Lima Virgins kept 'diet' just below 40 tons per driven axle , you might want to suggest the Boys could grind some extra effort onto ramp rails , yet the Virchesty Halleygenny had an extra stamina for speed with a long train running because of 'her' large and deep firebox of unhampered proportions behind the drivers , rather than above them , which allowed to much better suit combustion . Another question if Lima plain nozzle double chimney draughting was up to Jabelman's 2x4 nozzle double chimney design which again was far from perfect and certainly no match for an equivalent Kylchap design if properly executed .
The longer articulated chassis didn't help the UP-Boys , at least not with conventional boiler design as it was then used in standard type steam locomotives in the US in the 1940s with basic decisions even such as between A type and E type superheater concepts still unresolved . The earlier Triplex types should be considered as basically 2-8-8-0 with driven 0-8-2 or 0-8-4 tender and thus - other than for sheer total number of driven wheels - were not competitive for 'biggest' just as they weren't output-wise . The special series of 2-10-10-2s for the Virginian were formidable ramp roamers , yet again would just count for number of driven axles , neither for output nor speed nor length nor total number of axles between couplers . Neither did the Y-6 . Why not ? Output was not high in comparison to engine mass since tractive effort collapsed pretty progressively as speed rose . The Y at 63 mph ? Thanx , I wouldn't want to have it ! Because of use of compounding ? Yes and no - rather because of limitations of concept and design in the engine as realized than by principle of expansion .
André Chapelon rode the cab of one on his visit to US railroads in 1938 and wrote quite appreciating of the engine . Yet , when he calculated output reached on this regular trip over rising grades figures showed to have been comparatively moderate , speed readings on ramps were generally very slow and pretty moderate even on the level . The Ys were really heavy grade climbers , not tonnage rollers - that was where the A class came in . Chapelon was an integral gentleman who was positively prepared to appreciate other engineer's achievements and that's how he reported on his voyage to American RRs . Remarkable , how in his following designs he integrated a number of major American design features , such as one piece engine bed ( in this case as a fully welded construction ) combining the best from both sides of the Atlantic to compose a new design quality of advanced and versatile steam locomotive .
The 'North-Western' folks , as I like to call them , at Roanoke knew what to ask of their steam locomotives and they knew how to realize it . They had a concise concept of design and an efficient organization of steam traction - that's why alleged diesel economies could not be realized as advertised by comparison of Old Steam against Modern Diesel as then invariably hammered down by EMD sales dept - slogan which , although of inherently ill logics , has since become petrified and ever repeated . In fact , when N&W were about to become the only one RR retaining steam , they had a film produced to explain how those 'diesel advantages' were already realized by their three major steam classes , the J , the A and the Y-6 in combination with the way they were run .
However , admittedly , diesels still could be regarded much more economic if you only looked at it the right way : basically , they didn't use steam - and for RRs like the Santa Fe that *was* a ponderous argument !
Don't worry - be happy !
Regards
Juniatha
P.S.: side remark : I wonder what if Roanoke shops had decided to swap to motor cycle construction - Harley Davidson might as well have closed down ? Just listen what a name for a Big Bike , if you let it roll off your tongue :
Have a ride on your Rrroanoke !
*gee*
Ulrich Maybe you could help me with this...why can't the steam, once its done its work in the cylinder, be routed back to the boiler for reheating instead of being disipated to the atmosphere? This would be a closed loop where the steam would be reheated and reused. So far I'm told that it would be impossible to get the low pressure used steam back into the boiler where the pressure is higher.
Maybe you could help me with this...why can't the steam, once its done its work in the cylinder, be routed back to the boiler for reheating instead of being disipated to the atmosphere? This would be a closed loop where the steam would be reheated and reused. So far I'm told that it would be impossible to get the low pressure used steam back into the boiler where the pressure is higher.
It wouldn't work because the boiler is a pressure vessel. Any steam leaving the boiler is going to lose pressure as it goes through the pipes. The pressure is highest right when it leaves the throttle valve. After that it is all downhill from there. By the time it leaves the cylinders it has lost much of it's pressure which is why mallets had to have a considerably larger piston for the second expansion cycle.
You simply couldn't put 90 psi of steam pressure back into a 200 psi boiler. You couldn't even put 200 psi into a 200 psi boiler. You would have to raise it to probably 205 or 210 psi to inject it into the boiler.
All this talk about steam sure makes me wonder what we would have seen if steam could have lived another 10 years or so. Was there ever a locomotive that was built that had a second steam locomotive behind it, which was only serving as a auxiliary boiler to supply steam to the primary locomotive? Has this ever been tried? You would need a steam pipe connecting the two locomotives but it would give you a unlimited steam supply as it would be basically two boilers providing steam for one locomotive.
You mean the Big Boy WASN'T the biggest and best loco ever made??? I'm crushed! Crushed I tell you!
Firelock76I KNOW the N&W hauled more than coal! J-M-J! Gimme a little credit here, would ya? I LOVE the N&W and the "Holy Trinity" of steam. Jeez!
.
I KNOW the N&W hauled more than coal! J-M-J! Gimme a little credit here, would ya? I LOVE the N&W and the "Holy Trinity" of steam. Jeez!
OK, coal isn't going to spoil if it doesn't get to market yesterday.
I know we've had speed discussions in the past, and what it really boils down to is application to the circumstances.
Certainly not every train was expected to run near the 100mph mark, very few were in fact, it gets down to the application. If a Y6 on the N&W wasn't meant to run any faster than say, 40 to 50 miles per hour, or frequently slower, that was OK, coal isn't going to spoil if it doesn't get to market yesterday. On the other hand, the Erie grabbed a lot of perishable freight business when they started running Berkshires that were comfortable running over the 50 mph mark. See where I'm going with this?
And passenger use? A passenger wants to get where he's going quickly, that was the original attraction of the railroads to begin with, so for passenger use you're going to need a, well for lack of a better term, "speedster". It was true in 1840 and it's true now.
And OK, if the N&W designers were good enough to get the Y6 to run at up to 63mph reliably, well good for them! It only confirms what geniuses they were. If other 'roads didn't want to follow N&W's lead on this I'm sure they had their reasons, some good, maybe some not so good. Personally, I think a lot of locomotive builders were secretly jealous, maybe insanely so, that those "hillbillies" down in Roanoke were better at the craft than they were!
Firelock76 A compound MALLET wasn't a speedster on account of the difficulty of balancing those massive cylinders and assorted running gear behind the pilot.
But back to Firelock76's remark; Why other roads didn't persue developement of the compound mallet like the N&W did with their Y class, I have no idea. However as a former N&W steam engineer related to me, "You didn't want to run the Y6's much over 63mph. After that they started getting a little shakey". Now, is that "balancing those massive cylinders and assorted running gear" enough?
beaulieu Firelock76 By the way, anyone ever hear the old firemans saying? "If you wouldn't drink it, don't put it in the tender!" So a bottle of Jack Daniel's into the tender if the Trainmaster is walking towards the cab would be OK?
Firelock76 By the way, anyone ever hear the old firemans saying? "If you wouldn't drink it, don't put it in the tender!"
By the way, anyone ever hear the old firemans saying? "If you wouldn't drink it, don't put it in the tender!"
So a bottle of Jack Daniel's into the tender if the Trainmaster is walking towards the cab would be OK?
Why not? Steam engines wanna feel good too, ya know!
erikem Ulrich Maybe you could help me with this...why can't the steam, once its done its work in the cylinder, be routed back to the boiler for reheating instead of being disipated to the atmosphere? This would be a closed loop where the steam would be reheated and reused. So far I'm told that it would be impossible to get the low pressure used steam back into the boiler where the pressure is higher. What you are describing is similar closed cycle gas turbine using steam as the working fluid instead of air or some other gas. The spent steam would have to be compressed before it could heated again and that compression takes a lot of energy - typical figures for a gas turbine is that ~75% of the power produced by the turbine is used in the compressor. Condensed steam (liquid water) is much less energy intensive to pump up to high pressure than a gas (it's very dense and almost incompressible). The downside is that you do throw away a lot of energy in condensation. - Erik
I would also add that the gas turbine (which operates using the Brayton cycle), steam power plants (Rankine cycle), steam engines (Rankine cycle), Stirling engines (Stirling cycle), etc. are heat engines. All heat engines must reject heat to a low temperature reservoir. Thus, heat rejection to the atmosphere is necessary regardless of the working fluid, including pure steam. Note that heat rejection for open gas turbine cycles is accomplished by dumping the working fluid into the atmosphere.
Anthony V.
Marine steam engines (on ocean-going vessels anyway) operated with condensers almost from the very beginning, salt water being absolutely the last thing you want in a boiler. Exhaust steam was condensed, then routed back into the boilers. Boiler pressure is just way too high to get the used steam back in in an uncondensed state.
Oh, and so no-one gets the wrong impression, I never said compounding and speed were mutually exclusive! I'm well aware of Vauclains, DeGlehns, and Chapelons compounds. A compound MALLET wasn't a speedster on account of the difficulty of balancing those massive cylinders and assorted running gear behind the pilot.
...O-M-G !!
That's a complex story - lots has been written about it , lots of it is plain rubbish .
Even professional engineers of steam locomotive builders and railroads often seem to have had but rather limited understanding of what really can be obtained by compounding , what it's for and what it takes to make it work . Occasionally , even today there are examples of people springing up exposing but fantastic ignorance when happily offering what seemingly they believe should be new relevations .
No insult intended .
With regards
As I recall, the exhaust steam has lubricating oil, from the cylinders, mixed with it, and this should be removed before the condensed steam is reintroduced into the boiler (though this detail did not seem to bother the designers of the triplexes, as the exhaust from the cylinders under the tender went into the tank); was the equipment necessary to take care of this a part of the complex condensation system on the SAR condensing engines (which had a blower to maintain the draft)?
Johnny
Ulrich Why couldn't the steam, once its done its work in the cylinders, be routed back to the boiler for reheating and reuse? Instead of spending so much energy in turning water to steam wouldn't reheating the steam that's been used already (and adding a little water as needed) be more efficient?
Why couldn't the steam, once its done its work in the cylinders, be routed back to the boiler for reheating and reuse? Instead of spending so much energy in turning water to steam wouldn't reheating the steam that's been used already (and adding a little water as needed) be more efficient?
The exhaust steam from the cylinder is too low pressure to reenter the boiler directly, and too hot for an injector to work. The exhaust steam could be used to preheat boiler water using a feedwater heater, so as to not waste the energy available in the exhaust steam, but you also need the steam pressure from the exhaust steam to make the boiler drafting work.
It's relatively easy to get water into the boiler by way of an injector or pumps. Getting low-pressure steam back into a high-pressure boiler is impossible.
Why does the steam need to be condensed first? The purpose of the fire and that huge boiler is to boil water to make steam...
Once the steam is boiled it does its work in the cylinders and then LEAVES the cylinders as steam and is disipated to the atmosphere. Why not take that used steam and route it back to the boiler for reheating? After all...reheating used steam would involve less energy output than heating water to produce steam. I understand about the condensor...the condensor takes the used steam and turns it back to water which is then routed back to the boiler for reuse. Why not take the condensor out of the loop and just reheat the used steam in the boiler?
South African Railways was famous for its condensing 4-8-4's, which were built to support steam operation through a desert where water was unavailable. The condensing gear, which was mounted in the tender, had its own maintenance needs above and beyond that of the rest of the locomotive. SAR also had otherwise identical conventional 4-8-4's for service elsewhere, which implies that the condensing gear existed only for a special situation.
The D&H high-pressure experimentals had water tube boilers - and water tube boilers have had an unhappy record when used on rails. Unlike the maritime environment, rail-borne boilers are subject to routine jolts and bounces that only happen to ships in combat.
Another problem for the Leonor F. Loree was that both cylinders on each side drove the same crankpin. That must have put a LOT of stress on that crankpin - with no way to use tandem rods or any other technique to spread the stress to a second axle box.
Finally, the design was a one-off, with all the disadvantages of non-standardization that status implied. It was a brainchild and pet project of its namesake. When Mr. Loree was no longer there to cheer it on, it was quietly scrapped in favor of conventional 4-8-4s and simple-expansion Challengers.
Chuck
Deggesty As I recall, the boiler design of the D&H engines was really strange to me--and it may well have contributed to the high maintenance requirements. I can picture one or two of these engines in my mind (they really looked strange to me, back in the fifties, when Trains had an article on these engines).
As I recall, the boiler design of the D&H engines was really strange to me--and it may well have contributed to the high maintenance requirements. I can picture one or two of these engines in my mind (they really looked strange to me, back in the fifties, when Trains had an article on these engines).
It was the June 1967 issue - which happened to be the first issue that I bought...
- Erik
The de Glehn compounds had four cylinders, two HP cylinders driving cranked axles inside the frames, two LP driving conventionally outside.
The inside drive was to the first driver and those cylinders were far forward in relation to the frame. The outside drive was to the second driver and those cylinders were mounted pretty far back, typically over the rear of the pilot truck instead of the center. The idea was that the inside and outside rods were the same length to keep things in balance mechanically.
The British "Castle class" locomotives had the de Glehn mechanical arrangement thought to be easy on the tracks owing to the mechanical balance, but they were simple expansion.
Part of what makes compounding complicated is the simple/compound transition valve. Compound locomotives often have an arrangement to operate in simple mode, perhaps admitting steam to the larger low-pressure (LP) cylinders through some pressure reducing valve. This helps with starting. Based on discussion on another thread on this forum, it was explained to me that this "simpling valve" is not just some turn of a handle kind of valve, but is this largish thing, usually tucked between the frames, to reroute steam and exhaust in the different modes and can be "servo driven" (power operated by applying steam to move the valve into the correct position).
Compounding can achieve greater expansion of the steam, but it is not clear how this is better than simply using a shorter cutoff with simple expansion. Another problem with compounding is that you have to extract exhaust steam through valves on the HP cylinders, port that steam into a receiver, and then supply that steam through another set of intack valves into the LP cylinders. The indicator diagrams I have seen show a substantial gap between the pressure-volume loop of the HP and LP cylinders representing the valve losses I speak of.
But compounding may reduce the thermal losses by separating the expansion into stages. There may also be lowering of friction loss because the larger, LP cylinders don't need to maintain as tight a seal as the smaller HP cylinders exposed to higher steam pressure.
I am thinking the reason that compounding went out when superheat came along is that for the same boost in fuel economy, the railroads would rather maintain a superheater rather than deal with the more complex machinery of a compound. In France where coal was in short supply, the did both.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
The de Glehn system allowed for independent cut off of each of the high pressure and low pressure cylinders, thus allowing for a series of various working combinations. I have yet to see any indepth readings as to how this worked but apparently it was quite a system.
Deggesty Paul, was it the Vauclain that had a high pressure cylinder on one side and a low pressure cylinder on the other? Or did it have a high and low pressure cylinder on each side? I confess that I had not heard the name "de Glehn;" what was the cylinder arrangement?
Paul, was it the Vauclain that had a high pressure cylinder on one side and a low pressure cylinder on the other? Or did it have a high and low pressure cylinder on each side? I confess that I had not heard the name "de Glehn;" what was the cylinder arrangement?
You're thinking of a cross compound. Vauclain compounds had a high-pressure and low-pressure cylinder on each side (four total), two cylinders on each side one above the other on one crosshead. The de Glehn compound is a French design, I don't know the particulars.
tomikawaTT Since compounding in the United States was mostly in the form of Mallet locomotives, with their ponderous low pressure cylinders and low drivers, there is a general impression that compounds were inherently slow. `T`aint necessarily so. Some of the Cole and Vauclain compounds built around the turn of the last century were high-drivered 2-4-2 and 4-4-2 types, and were quite capable of a good turn of speed. More recently, there were compounds built on the far side of the Atlantic that could FLY! Back in the early '70s, Bill Withuhn designed a 4-cylinder triple expansion compound engine that used internally connected drivers to balance and all but eliminate dynamic augment. If built, it would have been capable of speeds comparable to a N&W J. One key difference between the Mallet and a four cylinder triple expansion loco is that three of the four cylinders are meant be the same size - greatly simplifying the balancing required. So, are such engines practical? Innumerable ocean-going ships had four cylinder triple expansion engines, including all the WWII Liberty ships. They were chosen for the latter because they were simple, reliable and didn't require reduction gears like a steam turbine. There was one such loco built in the US - the Delaware and Hudson's Leonor F. Loree. It was a low-drivered 4-8-0, basically a super-consolidation, not designed for speed. The limiting factor was driver size, not compounding. Chuck
Since compounding in the United States was mostly in the form of Mallet locomotives, with their ponderous low pressure cylinders and low drivers, there is a general impression that compounds were inherently slow.
`T`aint necessarily so.
Some of the Cole and Vauclain compounds built around the turn of the last century were high-drivered 2-4-2 and 4-4-2 types, and were quite capable of a good turn of speed. More recently, there were compounds built on the far side of the Atlantic that could FLY!
Back in the early '70s, Bill Withuhn designed a 4-cylinder triple expansion compound engine that used internally connected drivers to balance and all but eliminate dynamic augment. If built, it would have been capable of speeds comparable to a N&W J.
One key difference between the Mallet and a four cylinder triple expansion loco is that three of the four cylinders are meant be the same size - greatly simplifying the balancing required.
So, are such engines practical? Innumerable ocean-going ships had four cylinder triple expansion engines, including all the WWII Liberty ships. They were chosen for the latter because they were simple, reliable and didn't require reduction gears like a steam turbine.
There was one such loco built in the US - the Delaware and Hudson's Leonor F. Loree. It was a low-drivered 4-8-0, basically a super-consolidation, not designed for speed. The limiting factor was driver size, not compounding.
IIRC, the Ross Rowland's ACE3000 project proposed using the Withuhn system;an improvement on the "Duplex Drive" system used on the PRR's T1 and Q1/Q2 series of locomotives. I recall reading that it caused some dissagreements within the design team and later versions of the design may have abandoned it...
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
Our community is FREE to join. To participate you must either login or register for an account.