Could steam make a comeback?

[wsherrick]

Routine engine house expenses probably included regular maintenance items such as the 30 day boiler wash which is mandated by the FRA, fire cleaning, keying up wedges, replacing worn brasses and bearings etc which on a large fleet of engines was done on a constant basis vs. heavy repairs which were done as needed or about every 5 years.

Most of these maintenance tasks were eliminated on the newest locomotives that were equipped with force fed lubrication and roller bearings throughout.

The 30 day boiler wash has remained unchanged for time immemorial.

If I skipped anything I'm sure somebody will point it out.

[Norman Saxon]

 

Regarding "enginehouse" expenses, Johnson's review of costs in general shows how statistics were manipulated at the time, and have become embedded in the perceptions regarding Steam. It is true that routine enginehouse expense for Steam ($4,592) was nearly six times the cost of that for the Diesel-electric ($800). A difference of $3,792. This compares 2-8-4 locomotives with a 3,600 hp Diesel-electric, doing the equivalent work.

 

But, it was in maintenance that the cost differentials really stood out, the Diesel-electric costing $77,726 annually, compared to the Steam engine at $47,393, a difference of $30,333, which completely drowned the savings obtained in fuel costs.

Michael, could you explain the difference between "routine enginehouse expense" wherein steam was $3,792 more expensive than diesel, and "annual maintenance" wherein a diesel was $30,333 more expensive than steam?

I take it the routine enginehouse expense number is not an annual expense but rather occurred a number of times per year depending on builder reccommended maintenance cycles?

[MichaelSol]

And to think that there were a few who thought this discussion should be put to rest. 

Being condemned to spend my Fourth of July in Detroit, and endure a lengthy layover in Chicago O'Hare, I took my copy of "The Steam Locomotive" by R.P.Johnson along to re-read. The book is an engineering look at the status of Steam locomotion circa 1942. Lots of engineering diagrams, equations, and a back pocket of blueprints of various component designs.

Johnson noted that "the modern steam engine is capable of making continuous runs of up to 1500 or 2000 miles. It can remain in constant service and under steam for a month at a time ... obtaining annual mileages of from 75,000 to 100,000 miles per year."

Sixty five years later, BN's current Diesel-electric fleet averages 90,000 miles per year.

"During the month of November, 1933, an engine on the Chicago, Milwaukee, St. Paul & Pacific Railroad made 18,930 miles. This was done without the aid of any special arrangements. The locomotive simply made ten regular round trips between Minneapolis and Harlowton, a distance of 1893 miles round trip. The locomotive received only ordinary attention at terminals during the whole month. This locomotive was part of a fleet ... [that averaged] an annual rate of 124,788 miles per year for each locomotive."

Interestingly, railroad practice at the time created higher crew costs for the Diesel-electric, as railroads had adopted the practice for the diesel, in addition to the engineer and the fireman, of a "Maintainer" who lounged around in the engine compartment keeping an eye on things.

Regarding "enginehouse" expenses, Johnson's review of costs in general shows how statistics were manipulated at the time, and have become embedded in the perceptions regarding Steam. It is true that routine enginehouse expense for Steam ($4,592) was nearly six times the cost of that for the Diesel-electric ($800). A difference of $3,792. This compares 2-8-4 locomotives with a 3,600 hp Diesel-electric, doing the equivalent work.

The comparison looks quite dramatic.

Fuel for the Steam engine ($34,723) cost twice as much as the diesel fuel ($15,800) for the same work, naturally at the price differential then existing for coal and diesel fuel. The difference was $18,923.

These differences are the ones that seem stuck in the public conciousness, and perhaps is a testament to the power of advertising, at which GM excelled.

As other data was examined, the picture changed. The Diesel-electric used nearly seven times as much lubricant as the Steam engine, $4000 vs. $800, a difference of $3,200. This alone nearly swallowed up the advantage in engine house service.

But, it was in maintenance that the cost differentials really stood out, the Diesel-electric costing $77,726 annually, compared to the Steam engine at $47,393, a difference of $30,333, which completely drowned the savings obtained in fuel costs.

These numbers did not account for the financing charges accrued for the Diesel-electric, of $22,667 per year, but it was clear early on -- 1942 -- that if the Diesel-electric was going to be the preferred motive power type, that there would be a significant economic penalty to the industry resulting from the transition to that motive power.

The significance of Johnson's work, dating as it was at 1942, is that he predicted the ultimate cost penalty of dieselization to the railroads. The significance of H.F. Brown's landmark study in 1960, after the data was complete, was that Johnson's predictions proved to be accurate.

And these weren't "outsiders looking in". Johnson and Brown were the industry's motive power specialists. The interesting story, then, may be how the railroad industy's genuine motive power specialists were ultimately overruled by the marketing and head office people who did not have the length and breadth of experience, or any at all, with motive power.

Today, the singular, distinctive advantage that the Diesel-electric enjoyed over Steam -- cost of fuel -- has not only completely vanished, but been inverted to where the Steam engine would produce the equivalent service for one-half to one-third the cost of fuel.

 

[jmlaboda]

And to think that there were a few who thought this discussion should be put to rest.  After a bit of a lull in activity I have managed to learn considerably more about several different things involved within this thread and I do appreciate the input!!!

[Autobus Prime]

-The ACE 3000 was supposed to have a fluidized bed firebox -- blowing steam into the firebox to react with coal to produce gas, which would then be burned with excess air. This technology is used in power plants, and was installed in the SAR "Red Devil".

Is that what a fluidized bed is?  I thought what you describe is a gas producer firebox.  I thought a fluidized bed is a bed of coal and limestone with air being jetted into it from below.

B:

Right. It was a gas producer firebox. The (exhaust) steam wasn't just blown into the firebox (as with overfire jets) but into the underside of the fire bed, so the gas production would actually occur in a fluidized bed of coal, steam, and air. It wasn't a firebed, strictly speaking.

...steam, mostly from the cylinder exhaust with the remainder made up from the air pump exhaust and blower, is fed in under the fire and is drawn through the firebed along with the primary air, cooling the fire to below the temperature at which clinker forms, in an endothermic reaction, which produces combustible Carbon monoxide and Hydrogen gas (producer gas). This gas is thoroughly mixed with more, secondary air, above the fire, where it is burnt cleanly with no smoke and a minimum of excess air, this fact of admitting the majority of the air required for combustion above the fire also means there is significantly less gas rising through the firebed to entrain and carry away small coal particles. This last is what gives the GPCS such an increase in efficiency over conventional combustion at high rates of steaming...

VERY interesting, no? Retrieved from this cool page:
http://www.5at.co.uk

On the subject of steam and modern diesels, I find it interesting that diesels like the ES44 are emulating their external-combustion forebears, in a way. They can produce much more engine horsepower than they are capable of applying to the rail. You have a lot of power in one unit that's relatively light for the power available, usable at speed, not usable without slippage when starting. In steam's case, this was controlled by careful sizing of cylinders and wheels; on the diesel, it is controlled by automatically limiting the wheelslip.

It would be impossible today to replicate the NYC and others' tests of steam vs. diesel. We don't have brand-new modern steam. Any 60 year old mechanism will require lots of TLC. We don't have the infrastructure in place. Yes, our excursion steam takes armies of support personnel, but that army back then would have finished with one loco, then gone on to another.

I would love to see some work done with the NYC study results under modern conditions. Assuming the infrastructure was all put in place and brand new steam with all the latest and best could be obtained and brought in line with efficiency and cleanliness requirements (to take care of the usual objections) , there would still be differences - diesels had to have a fireman back then, but steam as usually done always needs one. There might be added liability insurance, since steam with a firetube boiler has at least 1 more catastrophic failure mode than a diesel. :( Fuel prices would of course be vastly changed.

It would be an interesting read. Any grad students out there?

[Anonymous]

-The ACE 3000 was supposed to have a fluidized bed firebox -- blowing steam into the firebox to react with coal to produce gas, which would then be burned with excess air. This technology is used in power plants, and was installed in the SAR "Red Devil".

Is that what a fluidized bed is?  I thought what you describe is a gas producer firebox.  I thought a fluidized bed is a bed of coal and limestone with air being jetted into it from below.

[Autobus Prime]

Folks:

Not really interested in arguing today, but did want to bring up a few points / answer a few questions:

-A rail vehicle with a low center of gravity is indeed harder on the track than one with a high center, all else being equal. It's not hard to see why- inertial forces apply at the center of mass. As this gets closer to the railhead, more is laterally applied to the rail, less can be absorbed by rocking on the springs. Instability on curves is less troublesome than in, say, your daily-driver SUV, because trains tend to stick to more predictable paths. :D
SO there may well have been some trading of hammerblow for these other effects. The heavy axle-hung motors also add a lot of unsprung weight, although traction motors have gotten lighter over the years.

-The ACE 3000 was supposed to have a fluidized bed firebox -- blowing steam into the firebox to react with coal to produce gas, which would then be burned with excess air. This technology is used in power plants, and was installed in the SAR "Red Devil". The idea is sound; I would wonder how it coped with periods of heavy demand, when coal-fired steamers tend to smoke heavily.

-The ACE 3000 was also supposed to have a duplex drive to reduce the mass of reciprocating parts and counterweights, lowering hammerblow. The reversed rear cylinders weren't a huge success on the PRR Q1.

I really wonder how the ACE would have turned out. There were some neat ideas, and some that just seemed inexplicable.

[MichaelSol]

TH&B:

l wonder then why places such as Japan or China aren't developing hi-tech steam?

How much coal does Japan have? That will answer one of your questions, and perhaps frame for you why it may be a reasonable question in the United States, as to considering the economic advantages of coal-fired locomotion, and not a reasonable question for most of the nations of the earth -- that don't have massive coal reserves.

China rarely does leading edge research in anything. Their MagLev is German.

And, I don't know whether it's useful to ask or not, but how do you know there are no coal-fired locomotive development projects underway?

[MichaelSol]

TH&B:

l believe that if there was anything to get out of steam somebody in the world would be doing it.   

Slow down. Think. By this logic, we would have never dieselized, since the rest of the world was generally staying with steam and electric. We led the way, didn't we? So how do you  account for that?

[TH&B]

l wonder then why places such as Japan or China aren't developing hi-tech steam? They seem to be going for such far out things like mag-lev trains.  l believe that if there was anything to get out of steam somebody in the world would be doing it.  Whoever would develope hi-tech steam should get an edge on the rest of us. 

 

Do you trust deisel electrics?  They are much the same, just the diesels are a little more complicated locomotives compared to the most basic electric engine like a low voltage DC engine.

[carnej1]

ELECTRICS - I DON'T TRUST THEM, PERIOD. 

.

MARK.

Really?...Why Not?

[MichaelSol]

Some of the fundamental problems with steam, both back in the transition era and today, are much more psychological and political than they are economic and mechanical---

All true, and there is a key economic driver that is often overlooked: cheap money.

Typically, after a war, there was a period of economic letdown. The U.S. Government, charged with not only its own economic well-being, but Europe and Japan as well, urgently expanded the money supply to avoid the usual post-war recession.

Dieselization began when new equipment was available for 1% interest charges. The shorter economic service life of the Diesel-electric did not seem threatening when a railroad company could buy 20 diesel-electrics on credit for the same annual expenditure as the capital outlay for one steam engine.

H.F. Brown notes that, for the first time in its history, N&W took on debt to obtain motive power when it dieselized -- $86 million. Seemed like a bargain at the time, only $860,000 in interest charges for all new motive power. But, if that annual charge is cost adjusted for more expensive replacements later, when interest rates reached 4%, it was a $4.1 million annual charge, at 8%, a $10 million charge, and by the mid-1970s when financing charges for SD-40-2s reached 14%, a $21 million charge.

Don't know what the N&W earned those years, but a hypothetical of $50 million and a 8% annual rate of return, the increased charges reduced N&W's earnings to 7.8%, 7.3%, 6.4% and 4.7% with each ratchet of the interest rates. And the railroads couldn't do anything about it, and likely other pressures on their earnings only leveraged the dieselization costs even more negatively.

The net effect of dieselization was to take 8% railroads and make 4% railroads; taking 4% railroads and making 2% railroads, 2% railroads and making 1% railroads -- and the bankruptcies commenced.

And this had nothing to do with the motive power type, but rather was the result of an investment strategy new to railroads which imposed future escalating, unavoidable costs: the railroads had become the industrial equivalent of credit card junkies.

 

[Modelcar]

...."Lewis Rukeyser"....Now there was a fellow worth listening to....Miss him.

[tomikawaTT]

quote user="TH&B"

W Germany used 125 mph electric locos and steam engines in the 1970s, South Africa , India and finaly China used steam lately but did not take any large foreward steps in its technoligy, remaining labour intensive around steam while embasing hi tech electrics and diesels.

This to me must reflect some fundamental problem with steam.   All these countys have such different ways to economise.

close quote

Some of the fundamental problems with steam, both back in the transition era and today, are much more psychological and political than they are economic and mechanical---

• Steam is, "Old technology."  During and right after WWII the general mindset was, "Out with the old, in with the new!"  Add to that, the aggressive marketing of diesel manufacturers, some of whose claims (since called into serious question, if not disproved outright) would have made a used car salesman blush.
• The Powers That Be, finding themselves embarrassed by Andre Chapelon, simply prevented him from building more efficient steamers - they had decided to electrify, and that was that.  His highly successful rebuilds were quietly swept under the rug.
• In the third world, the demise of the steam manufacturers meant no more spare parts would be forthcoming.  (The same thing, plus Stuart Saunders, killed steam on the N&W.)  If you can't get parts for your Baldwins, you buy diesels - and regret it.
• In several countries where central government control dictated/dictates national priorities, the politicians have decreed diesel or electric power.  In most of those places, arguing with city hall can seriously endanger your health.
• Present-day corporate management is captive to a bunch of Wall Street stock analysts and investment specialists, whose vision doesn't extend beyond the present quarter's bottom line and growth rate.  Try doing anything that doesn't have a positive net return by this time next week, and the Elves (Lewis Rukeyser's term) will engineer a stockholders' rebellion before you can say, "Long-Term."

It's easy for those of us, standing on the sidelines, who don't have to contend with the financiers, government regulators, environmental 'experts' and NIMBYs, to see how a sea change in motive power would have desireable results.  Tell it to the analyst from Morgan Stanley, or a technologically challenged Wall Street Journal reporter.

Chuck

[MichaelSol]

This to me must reflect some fundamental problem with steam.  

Oil was cheap compared to coal. Whether or not that satisfies your idea of a "fundamental problem" -- or an advantage-- that was the main difference.

Times have changed.

Does that mean, by the criteria used 60 years ago -- cost of fuel -- that there is now a "fundamental problem" with the diesel-electric locomotive?

Depends on your religion.

[TH&B]

You guys make it sound like maybe there is something in steam locomotives.  But how come nobody , nowhere in the world has developed modern steam engines beyond a few mods to the classic side piston type.  Not every region of the world has the same "economoic formula" as the US, and they do come up with different results including straight electric and diesel hydraulic and even old school steam. 

 

W Germany used 125 mph electric locos and steam engines in the 1970s, South Africa , India and finaly China used steam lately but did not take any large foreward steps in its technoligy, remaining labour intensive around steam while embasing hi tech electrics and diesels.

 

This to me must reflect some fundamental problem with steam.   All these countys have such different ways to economise.

[Modelcar]

.....Wow, what a detailed drawing....Can appreciate that a bit from many years ago studying Architectural Drawing.

I see the design you fellows are talking about.  Never knew of such an arrangement existed in steam engine suspension systems...

I can liken that a bit to comparing transferring forces on an automobile suspension system of say....the rear suspension design that contains a "rear stablizer bar"....It transferrers force through the bar to counteract an action on the opposite side of the vehicle.  Example:  Helps prevent body lean as a vehicle rounds a curve.

Thanks for the input.

[Modelcar]

....Chuck and Bucyrus....Thanks for the info and effort of explanation...Very much appreciated.  Long church service and now on the way to find some lunch....Must find time later today to understand what you fellows have provided....

[MichaelSol]

I have been on a C&O Berkshire at 70 MPH on jointed track and it was quite smooth.  I have been over the same track with SD-40's at 40 MPH and you had to hang on for dear life.  The diesels pitching back and forth made me sea sick.

Milwaukee Road decided, for whatever reasons, to send their FP-45's west after the advent of Amtrak. Not sure why ... they didn't have dynamic braking so they were always put behind Little Joes. I was at East Portal Substation one day and we were in the office watching 261 work its way up the hill. Behind the Joes "something" was sure swaying back and forth. As the train got to the Substation we saw that it was one of the first FP-45s to operate on the PCE -- still in its passenger service Harriman Yellow. A handsome, graceful, BIG locomotive, but oh my gosh ... that thing was all over the place ...

 

[tomikawaTT]

Quentin,

To expand on the info Bucyrus supplied, the equalization system of an old-technology steam loco can be likened to a three-legged stool, which always has the same weight on each leg no matter how irregular the surface.

If the locomotive has a four wheel lead truck (4-4-0 up to and including Big Boy) that truck is one 'leg,'  supporting the frame at its kingpin.  There is no cross-connection between the spring-and-lever linkage connecting the drivers (and trailing wheels, if any) on each side of the locomotive - each of those is another 'leg.'

If the locomotive has a two wheel lead truck (2-anything) the lead truck is equalized with the front axle, the whole supporting the locomotive at the pivot of the fore-and-aft lever that connects the lead axle springs to a cross-lever between the springs of the lead driving axle.  The lead driving axle is not connected to the side equalization system of the other drivers.  (The illustration in MR Cyclopedia Vol 1, Steam Locomotives, shows the lead truck equalized to the two front driver axles, another possibility.)

Switchers would have the lead driver axle cross-equalized and the other driver axles equalized lengthways.

Looking at the boiler of an articulated, the lead engine unit is the front leg of the stool.  The drivers of the rear engine and the trailing truck axles are equalized longitudinally, but not cross-connected.

I would expect that a new-in-the-21st Century steam suspension system would incorporate shock absorbers, something the old steamers never had.

Hope this is informative.  An attempt to Google up an illustration came up dry.

Chuck

[Modelcar]

....Bucyrus....Thanks, will take a look when I get back from church....Gotta run, so the clock says.

[Anonymous]

....Any suggestions as to where {on here}, one might seek to find an illustration of the "equalizer suspension system".....?

Quentin, I can't find much reference on the web, but here is a drawing that shows equalization between two drivers of a 4-4-0: 

http://cprr.org/Museum/Science_of_Railways_1899/Steam_Locomotive.html

Scroll down to the bottom of the page where the image is blown up, and you can clearly see the leaf springs under the driver axles.  The springs load as the axles rise.  The end of each spring that faces out or away from the driver set is basically fixed to a bracket on the frame.  However the ends of each spring that are near each other are connected to a short link, and those short links are in turn connected to a rocking lever, which looks like an inverted teeter-totter.  That is the equalizer lever (Item #43, Driver Spring Equalizer). 

If one driver runs over a high spot on the track, it raises the inner end of its spring, which raises that end of the equalizer lever.  That lowers the opposite end of the equalizer lever, which lowers the inner end of the spring of the other driver.  So the equalization system keeps the weight born by each driver exactly the same, even though there are high spots on the track.  It also keeps the drivers in contact with the rail so the flanges remain engaged.

Typically, in larger locomotives with six, eight, or more drivers, the leaf springs are inverted from what is shown here, and placed above the axles, but the equalizer levers are basically arranged the same way.  The arrangement of springs and levers is also carried through to the lead and trailing trucks.  The levers that connect the system to these trucks do not pivot at their center like the levers between the drivers.  The off-center pivot modifies the leverage so that less weight is transferred to the lead and trailing trucks than is transferred between drivers.  The system also transfers weight from one side of the engine to the other by means of a transverse equalizer lever. 

So the system of levers controls equalization, and the springs absorb shocks as a system of suspension.  They are two independent systems, with each performing its own function.      

 

[ONEHAGGIS]

HI, FIRST TIMER HERE. I HAVE BEEN READING WITH GREAT INTEREST THE MANY PAGES ON THIS SUBJECT - STEAM VS. DIESEL VS. ELECTRICITY.

SO HERE IS MY 3 CENTS WORTH.

ONE THING I DON'T THINK THAT HAS TALKED ABOUT IS NOISE ISSUES. 

AS I LIVE WITHIN A 1/4 MILE OF NORFOLK SOUTHERNS MAIN LINE IN VIRGINIA WITH A FEW GRADE CROSSING WHERE IT GETS REAL QUIET AT NIGHT, WHAT WOULD YOU RATHER HEAR GOING PAST YOU MANY TIMES DURING THE DAY OR NIGHT, THE ROAR OF A DIESEL, THE HUM OF AN ELECTRIC MOTOR, OR THE CHUG OF A STEAM LOCOMOTIVE?

ELECTRICS - I DON'T TRUST THEM, PERIOD. 

AND DON'T GET ME STARTED ON THE STENCH OF THE DIESEL ENGINE AS THEY IDLE NEARBY AND THE NOISE THEY MAKE IN THE MIDDLE OF THE NIGHT WITH THEIR ENGINES AND HORNS. YES, THEY MIGHT BE MORE EFFICENT AND FASTER, BUT AT WHAT EXPENSE?

IF WE PUT STEAM BACK ON THE RAILS, WE WON'T BE SO DEPENDENT ON "OPEC". WE ALREADY HAVE THE COAL FIELDS HERE, SO IF WE STOP EXPORTING COAL TO FORIGN NATIONS AND KEEP IT FOR OURSELVES, WE WILL HAVE A UNLIMMITED SUPPLY OF FUEL.

AS FOR THE STEAM LOCOMOTIVE INFRASTRUCTURE, DON'T YOU THINK THAT IT WILL CREATE THOUSANDS OF NEW JOBS FOR THOSE WHO NEED WORK?

AS FOR THE NEED FOR SPEED. INSTEAD OF 100+MPH TRAINS, A SLOWER JOURNEY BEHIND A STEAM LOCOMOTIVE WILL GIVE US TIME TO CATCH OUR BREATH FROM THE RAT-RACE AND GIVE US TIME TO GET TO KNOW ONE ANOTHER BETTER.

AS FOR THE LOCOMOTIVE OF THE FUTURE - WHAT ABOUT NUCLEAR POWERED?

THIS IS JUST MY OPINION.

THANX FOR LISTENING.

MARK.

[Modelcar]

....Any suggestions as to where {on here}, one might seek to find an illustration of the "equalizer suspension system".....?

[tpatrick]

Erikem wrote:

Where large steam was at an undeniable disadvantage to diesels was in bridge loading. Where a pair of early SD's may put 800,000 llbm in 120', the Big Boy would put 1,200,000 lbm in 128'. The early 4 axle power had even less weight per foot.

Entirely true, but Big Boys were the biggest, not really typical. Compare N&W's A (951,600lbs) or Y6 (961,500 lbs) and the gap closes significantly. On the diesel side a pair of C44s would outweigh the SDs, although maybe not by much. Still, they make a fairer comparison, I think. So your point is correct, but not as dramatic as you have suggested.  

 

 

[erikem]

The entire weight of a steam locomotive rests on a system of springs and moveable levers, which allows the weight to be distributed across the entire wheel set.  If one wheel rises or falls relative to the others, then the movement is transmitted through the spring and lever system to equalize the weight on all of the wheels at the same time.  Steam locomotive spring systems act like a three legged stool. Each leg will bear the weight of the stool on an uneven surface so that the whole is steady.

The lever and spring arrangement is common;y referred to as an equalizer, which are also found on many diesel locomotive trucks - especially visible in the old AAR type A trucks and the trucks used on the Alco PA's. One difference that both you and Michael were hinting at is the steamer will probably have a lower fraction of unsprung weight than a diesel or electric with a nose suspended traction motor - but probably does not have that advantage over an electric with a quill drive (e.g. Pennsy GG-1's, Milwaukee EP-3's and some of the NH locomotives).

Westinghouse made several types of electric locomotives with side rods, notably the Pennsy DD1's, the N&W electrics and the first generation VGN electrics. The Pennsy DD1 was an especially interesting case as testing showed it to exert less lateral force on the rail at speed than electrics with more conventionally mounted traction motors.

Where large steam was at an undeniable disadvantage to diesels was in bridge loading. Where a pair of early SD's may put 800,000 llbm in 120', the Big Boy would put 1,200,000 lbm in 128'. The early 4 axle power had even less weight per foot. 

[Modelcar]

....wsherrick:

I'm aware of the suspension springs....{muliti-leaf}, but not the "lever" system you mention on steam engines.

[wsherrick]

....Doesn't the diesel electric have all the flexibility needed to "soak" up a bit of the irregularities as well......?  Trucks have "loose fitting" parts and of course the springs that carry the loco's weight as well...

Am I correct...part of the traction motors are supported directly to the truck frame structure of the loco with some kind of moveable joint....?

Drivers and {part of the rods}, would be unsprung weight on a steamer.  Some of those driving wheels had massive counter weights that sure makes it difficult to imagine they would be "lighter" than the diesel's driving mechanism.

I'm certainly no authority on the subject but I sure am curious on it.

The entire weight of a steam locomotive rests on a system of springs and moveable levers, which allows the weight to be distributed across the entire wheel set.  If one wheel rises or falls relative to the others, then the movement is transmitted through the spring and lever system to equalize the weight on all of the wheels at the same time.  Steam locomotive spring systems act like a three legged stool. Each leg will bear the weight of the stool on an uneven surface so that the whole is steady.

 

[tomikawaTT]

eltraino,

Yeah, the railroads laid off pipefitters and boilermakers - and replaced them with diesel mechanics and electricians.  And, since they were competing for those skills with non-rail industry, probably had to come up with more $ per hour to attract and keep them.

When a railroad bothered to look at efficiency (most didn't) the cost versus availability of maintaining a steam fleet could be dramatically reduced.  Case in point - the N&W lubritoriums, which reduced turnaround time after a run by a couple of hours while dramatically increasing the productivity of the people using the neatly spotted oil fill hoses and grease guns.  Two less hours in the terminal getting prepared was two more hours on the road, making money.

Then, too, there have been 70 years plus of advances in mechanical design technology since the last steam loco came off the drawing board.  I suspect that a present day steamer, possibly using an updated version of the Withuhn machinery layout under a boiler and firebox with all the Chapelon/Porta/Wardale improvements, would be a lot easier to maintain than a machine whose design was frozen in 1942.  It could certainly be made easier on the track - and far more fuel and water efficient.

Chuck