i read the 4014 made frequent stops for inspections.
while i assume 4014 may require some 21st century safety features and may not have been built exactly as it was 50+ years ago, i wonder if it uses any 21st century technology for monitoring and maintenance?
i notice in the video that the cars it pulled were lit, doors open(?) and occupied. Assume they had radio communication with the cab.
Were those inside monitoring the performance of the engine using electronic temperature, pressure and load sensors and PC displays?
greg - Philadelphia & Reading / Reading
Having followed this project for several years, I know that the 4014 was rebuilt to burn oil instead of coal. UP management choose to do this change because it is a lot easier to support logistically.
As far as safety equipment (trip recorder, cab cameras, etc.), I believe they are required on all locomotives operating on main lines.
Just wondering-- are ditch lights not required for mainline operation?
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
Nope.
From https://www.law.cornell.edu/cfr/text/49/229.125
(h) Any locomotive subject to Part229, that was built before December 31,1948, and that is not used regularly incommuter or intercity passenger service,shall be considered historic equipmentand excepted from the requirementsof paragraphs (d) through (h) ofthis section.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
Thanks.
N&W 611 must get an exemption, because I seem to recall N&W J 611, as well as 612 and 613, being constructed in May and June of 1950, which of course is after December 31, 1948.
And that begs the question: If (if) new-build Pennsylvania T-1 5550 does get built and becomes operational, will it need ditch lights?
kgbw49N&W 611 must get an exemption, because I seem to recall N&W J 611, as well as 612 and 613, being constructed in May and June of 1950, which of course is after December 31, 1948. And that begs the question: If (if) new-build Pennsylvania T-1 5550 does get built and becomes operational, will it need ditch lights?
I suspect the ruling wording is 'not used in regular passenger or commuter service', but then again I am no a member of the enforcing agency.
Never too old to have a happy childhood!
The question in my mind is, if they can exempt a steam lcomotive built prior to 1948 from a ditch light installation, WHY can't they be exempted from PTC?
After all, the purpose of PTC as I understand it is to provide a back-up if the head-end crew aren't keeping their minds on their work, to put it simply.
On a mainline steam run there's more than the usual head-end crew in the cab. Company officials, photographers, road pilots, you name it. Not likely the engineer's going to lose his focus with an "audience" watching his every move.
No disrespect intended to any of you professional railroaders out there. I for one have always considered PTC as nothing more than example of "panic legislation" at it's worst.
Flintlock76 Company officials, photographers, road pilots, you name it. Not likely the engineer's going to lose his focus with an "audience" watching his every move.
Some woudl argue the opposite. Having that many people in the cab can be a huge distraction.
Maybe. We'd have to ask veteran steam excusion engineers like Doyle McCormack, Rich Melvin, Paul Nicini, Steve Sandberg, Steve Lee and others for their input.
Anyway, the point I was trying to make is anyone running a steam locomotive under the circumstances I described isn't likely to be fooling around with a Smartphone, texting or otherwise, or nodding off, or whatever.
And if what I've read is true, and it probably is, before any Class One lets a steam preservation group out for a romp on their mainline they have to demonstrate they're more professional than the professionals, and that's saying something!
Again, NO disrespect to the professionals.
What about brake equipment? Latest brake stands have better (?) functions, at least different.
Technical questions
1. What is each axel load on the track ?
2. Does UP have a lower rail weight limit for 4014 and 844?
3. Does UP have a slower warm up time to prevent distorting any of the loco's parts ? Also the cool down time ?
4, Higher elecctrical power needs ? What additions ? Does it have inverters and battery back ups ?
5. Turn out considerations especiall compound of close together turn outs ?
6. Did UP resurface any of the loco's route lately?.
7. Repeat == brake stand?
gregc i read the 4014 made frequent stops for inspections. while i assume 4014 may require some 21st century safety features and may not have been built exactly as it was 50+ years ago, i wonder if it uses any 21st century technology for monitoring and maintenance? i notice in the video that the cars it pulled were lit, doors open(?) and occupied. Assume they had radio communication with the cab. Were those inside monitoring the performance of the engine using electronic temperature, pressure and load sensors and PC displays?
Had a nice close look at 4014 yesterday. No signs of any test instrumentation anywhere. Some pix here: https://flic.kr/s/aHsmD6o4sr
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
oltmanndHad a nice close look at 4014 yesterday. No signs of any test instrumentation anywhere. Some pix here: https://flic.kr/s/aHsmD6o4sr
Still what I think is evidence of considerable blow on the right side of the forward engine in that last picture. That might show markedly heavy consumption of cylinder oil well-atomized and emulsified.
Overmod oltmannd Had a nice close look at 4014 yesterday. No signs of any test instrumentation anywhere. Some pix here: https://flic.kr/s/aHsmD6o4sr Still what I think is evidence of considerable blow on the right side of the forward engine in that last picture. That might show markedly heavy consumption of cylinder oil well-atomized and emulsified.
oltmannd Had a nice close look at 4014 yesterday. No signs of any test instrumentation anywhere. Some pix here: https://flic.kr/s/aHsmD6o4sr Still what I think is evidence of considerable blow on the right side of the forward engine in that last picture. That might show markedly heavy consumption of cylinder oil well-atomized and emulsified.
Agree - a lot of oil blow-by, discolored everything it touched.
gregc,
I think that if you review the UP video releases done by Ed Dickens you will note that they made several changes in the functioning of the 4014 spring rigging particularly to some caged coil springs done to equalize the functioning of the suspension. Also some passing comments on the use of ball bearings in place of bushings in the same suspension components.
Ed also commented on the effort to have the engine brakes function flawlessly on UP4014. I could not tell from his quick discriptions just how exactly they effected this.
If you review the videos you might pick up a few other modifications which would include the replacement of the asbestos insulation with newer material as well as material changes in the joints of the steam distribution piping.
Previous videos of the UP844 project noted the addition in the supporting of the superheater bundles with a newly designed spring steel clip setup inside the boiler flues. Likely these were used on UP4014 also.
In reviewing the operation of the UP4014 videos I also seemed to notice the telltale exhaust steam from two steam turbo generators on the top of the boiler providing additional engine electrical power. I have seen this done on other locomotives also.
Dr. D
I didn't notice the added turbo generator, but I did see that the #844 has two in someone's video on YouTube that I watched the other day.
Doesn't surprise me with the added electronics on board.
what are they inspecting during the stops they make out on the mainline?
greg,
Any newly rebuilt machinery - especially a railroad steam locomotive - requires a period of "break in" or "run in" that is extremely important to the life of the locomotive.
The massive size of the UP4014 hides the tolerances of the moving parts. Especially if roller bearings are involved. For example the engine is designed around a set of blueprints. In those days these were massive paper drawings sometimes several feet long. These indicated the sizes and designs of the parts of the locomotive.
As in anything in this world there are the design ideas and "what is actually built." Sometimes small errors in the parts are unavoidably made. These manufacturing errors can not always be corrected and so it is inevitable that no machine is "perfect" as it was designed.
Because of these variations in tolerances when new machines are built it is advisable for them to go through a period of "running in" or "break in" where various bearings and pipe fittings and bolts are checked and rechecked over a period of time to assure everything is performing as it should and to take care of any problems.
This is why UP4014 was driven slowly around for days with a tool car and crew and a diesel engine attached. Especially important on the "break in" period is the continual greasing of the side rod bearings. Some engines like NW611 have side rod drive with ball bearing equipment. The tolerances of the parts on these engines must be very precise - say on the order of .002 to .020 depending on the parts and the bearing design. To hold these tolerances over a locomotive that is the size of a railroad steam locomotive is a real challenge.
Union Pacific Railroad Mechanical department decided decades ago not to participate in the roller bearing side rod technology that Norfolk and Western did. Hence the brass bushing riding on steel pin "plain bearing" drive of the UP4014 and UP844. These engines hold a tolerance of 1/16 to 1/8 inch in the operational clearances of the moving parts of the locomotive side rods.
Still it is a challenge to get the drive wheels spaces exact distances apart and operating on the same plain as well as quartering the wheel drive pins to exactly 90 degrees and the wheel centers running true without wobble or out of round conditions.
So you can see why a new locomotive is "broken in" gradually to allow parts that bind and rub against each other as they are not designed to - to allow these surfaces to "run in" to a effective operating clearance and condition. Lots of grease helps as does the old technique of "slapping rods" which is touch the bearing areas to see if they are too hot! Today of course you would not do this by hand but use a new tech "heat gun" to read the temperature.
I can refer you to S. Kip Farrington Jr's book on the Santa Fe Big Three, which describes the railroads long efforts to break in the locomotives on that railroad back in the pre WWII days. It is amazing how much work went into developing an effective motive power department of a major railroad.
Ed Dickens is to congradulated for his masterful handling of the great Union Pacific Steam show.
By the way, this is why UP844 is double heading with UP4014 - so the "Big Boy" doesn't have to shoulder all the work this time around!
----------------
As an aside I might mention that the average new automobile also requires a similar "break in." The difference between a properly "run in" automotive engine can be a great deal of performance and vehicle milage. Even new automotive rubber tires are to be broken in below 50 mph for 50 miles. Think about it.
thanks for the explanation.
my dad was a machinist and showed me blueprints marked with corrections in red. Are you telling us that the existing Big Boy prints may not reflect how the locomotives were actually built and never updated?
is it also fair to assume that beside the bearings in side rods, drivers and valve gear, various steam fitings and packings were also being inspected?
i understand how bronze bearings can easily be replaced allowing the continued use of existing steel parts that hopefully don't wear much. The same with tires. Do the cylinders use sleeves that were easily replaced?
gregc ... my dad was a machinist and showed me blueprints marked with corrections in red. Are you telling us that the existing Big Boy prints may not reflect how the locomotives were actually built and never updated?
You may recall the very famous example of the PRR, which obtained 'blueprints' of the C&O T-1 2-10-4s that did not contain the (many!) redlines and changes made to the engines after their construction. Woeful was the subsequent learning curve!
I do not think this is an issue for Dickens & Co., for at least two reasons. First, he is working with the inherited drawings from Union Pacific shops, so presumably all the necessary changes (both good and bad!) are either documented or could be deduced. Second, the top-down quality focus in the "new" steam organization involves careful documentation and, where appropriate, redesign 'for maintenance' of all the components of the locomotive, so any 'refinements' based on experience should have been backstopped by analysis, careful specification of materials and techniques, etc. (It was mentioned in past threads that the experiences with rebuilding 844 were useful in many respects for the 4014 project.)
Is it also fair to assume that beside the bearings in side rods, drivers and valve gear, various steam fittings and packings were also being inspected?
You betcha!
Now, I suspect that part of this question has a bit of an edge to it, since a massive steam blow was observed on the forward engine during 'initial hurry-up break-in' and there is still some doubt whether the engine is pulling at full capacity. There is some controversy about the best ways to make metallic packing with modern materials, and I don't know if UP has made arrangements with specialty firms (like Hunt-Spiller in the olden days) or has tried 'rolling their own'. I am sure, however, that the tools, talent, and perhaps most importantly the motivation and championing are all present in their organization to fix the problem, not just expediently but methodologically.
I understand how bronze bearings can easily be replaced allowing the continued use of existing steel parts that hopefully don't wear much. The same with tires. Do the cylinders use sleeves that were easily replaced?
In most locomotives, the cylinders do use sleeves; in my experience they should be made of a bronze alloy and are called 'bushings'. I am less sure that I'd use the expression 'easily replaced' to describe getting them out for replacement, though; there are some interesting horror stories on RyPN of the attempts to get recalcitrant bushings out without destruction, or in some cases even with destruction (the 'revealed wisdom' being that laying weld beads in the circumference usually breaks them loose when all else fails...)
There have been some arguments as to whether 'modern' practice (e.g. of valves with articulated heads and multiple 'diesel-style' thin rings) actually benefits from bushings rather than careful line-boring and surface-hardening of, say, cast-steel cylinders. The tribology between the ring faces and the bore, in an environment ranging from wet atmosphere to superheated steam, is the chief thing of interest here, and in some respects it may be difficult to figure this out without some empirical raps over the nose with a rolled-up newspaper.
As an alternative, the Russell Brown 'asynchronous compound' doesn't use formal contact piston rings at all; the HP cylinders work with very small clearance, the pistons supported on tailrods, and the blowby is calculated into the steam budget for the LP turbocompounded alternator. You would almost certainly not need the expense or complications of bushings in such a design; any wear or corrosion would be periodically line-bored true (as in IC engine practice) and the dumb rings on the pistons adjusted accordingly.
P.S. Alfred Bruce's book on American locomotive practice contains a very good description of both the theory and practice behind UP's decision to go with bronze floating rings instead of roller bearings in high-speed practice. I strongly recommend that you find a copy and read carefully through that section.
gregc thanks for the explanation. my dad was a machinist and showed me blueprints marked with corrections in red. Are you telling us that the existing Big Boy prints may not reflect how the locomotives were actually built and never updated?
You would be surprised how often plans don't get updated. One place I worked had plans dated in the 1800s. They would pull the blueprints for the parts for a machine and send them to the manufacturing floor. The machinists would mark them up (like your dad) to make it possible to construct or to fix a dimension so the parts would fit together. Those marked up prints would generate a revision request so the original transparency would be updated for the next time this part got built. The day I left (unvoluntarily) I was working the revision desk. It was a large, 8'x4' drafting table covered in stacks of manufacturing revisions still waiting to be reflected on the originals. Most stacks were 3' tall!
Time is money and there was no money to waste updating plans, because it might be a one-off. So, in essence, they were building things wrong every time for 100 years. It's not a stretch to see the same mind-set in the railroad business.
OvermodThere have been some arguments as to whether 'modern' practice (e.g. of valves with articulated heads and multiple 'diesel-style' thin rings) actually benefits from bushings rather than careful line-boring and surface-hardening of, say, cast-steel cylinders.
wouldn't the piston need to be replaced/refabricated if the cylinder walls are cut and made larger?
what is an "articulated head"? (no luck with google)
OvermodIn most locomotives, the cylinders do use sleeves; in my experience they should be made of a bronze alloy and are called 'bushings'.
i was referring to the surface of the cylinder with a diameter of ~24" having a sleeve. I would think the much smaller opening the cylinder rod extends thru would have a bushing but also needs to be steam tight
To answer your question about the locomotive cylinders - yes the bore does wear out with time and use. My experience with Pere Marquette 1225 was that the cylinders did need to be bored straight. At the time we did this the Southern Steam Program was still in operation under the supervision of the Claytor brothers who were corporate leaders of the Southern Railroad and later Norfolk and Southern Railroad. One of the brothers also was the head of AMTRAK.
Southern Steam Program was a great team and would lend equipment out to other groups restoring steam locomotives. I believe they had developed a boring bar setup that used the studs on the front of the locomotive cylinder to attach the tooling and then using a small electric motor the cylinder could be rebored on the locomotive.
Consider this. That in the early 1920's the American railroad locomotive generally used a frame of built-up beams and cross braces to which the cylinders individually were bolted together and bolted onto the frame. This composite setup did "work loose" with time and stress requiring constant repair and replacement of cracked or broken parts, missing bolts and rivits etc. It was not uncommon for an engine to recieve an entirely new engine cylinder should one be broken in a catastrophic accident. The much smaller British locomotives continued to be built this way into the modern era.
About the mid 1920's in the United States technology for large steel castings developed so that railroads began to have the entire railroad locomotive engine frame cast in one piece including the individual cylinders - all the attaching brackets for appliances and yes - with hidden internal air chambers that could function as the train brake air resevoirs.
This was a remarkable structural improvement to an already fairly complicated machine as the steam railroad locomotive was. However damage to this new cast steel frame could require extensive welding to repair it, as the parts could no longer be simply replaced if necessary. Also the machine tool operations required to create this one piece frame became an imense industrial operation.
Consider that the frame had to be cast in the foundry by sand cast technique and then cleaned - then the central datum line for its construction had to be established - from which all the machining and alignment operations were measured. The saddles for the drive wheel axles were acurately laid out, as well as the bores for the valve gear and pistons. Also the valve gear hangar casting carefully machined in relation to the cylinders and axle locations. If the engine was to be roller bearing equipped, the measurements of all these dimensions were required be within several thousandths of an inch.
Also such a large steel casting of that size is not completely stable but expanded and contracted with temperature change. Also the simple supporting of the casting by its weight could sag on the ends to some minor degree. All these machining tendencies had to be calculated so that the finished product when measured would have the locations of the parts in proper alignement.
So a large locomotive builder like ALCO or Baldwin this work was all part of the regular business day. However, to repair or modify or reproduce these parts was a significant challenge.
Hopefully when Ed Dickens took apart UP4014 he found it had never been wrecked or damaged in some fashion or that in shopping the engine frame and parts would not be found out of alignment. Or when repairs were done in backshopping the machinists were able to keep everything within necessary tolerance and alignment.
Also with in the fleet of locomotives parts were interchanged so that UP4014 does not have its original tender and likely might not have original side rods wheel sets etc. Everything got kind of mixed together at the end of steam in the 1950's when all the locomotives were on the way to scrapping.
I suspect however that UP4014 and UP4023 and others were saved because they represented the "sweethearts" of the railroad. Engines that everyone knew ran so well. The railroad intended to save UP4023 and stored it indoors for decades because it was the lowest milage and newest engine and the best candidate for preserving. Unfortunately in an era of ignorant managment UP4023 was placed outside and exposed to the ravages of the winter which caused Ed Dickens to retrieve UP4014.
Anyway Ed Dickens and crew were able to bore the cylinders oversize on the locomotive and there are several videos showing the equipment in place for the job.
As a further point engine cylinders were designed with extra materal for continual boring in the shopping process but in the event of damage or overboring beyond the design limits the cylinders were sleeved to size.
Finally, New York Central Railroad with its fleet of passenger Husdon 4-6-4 locomotives which were first built with composite locomotive frames. Because the cast steel one piece frame technology developed after the first engines were built the railroad went on a rebuilding program where in the shopping process the original frames were scrapped out and new cast steel frames were ordered and the engines rebuilt in this fashion. New York Central was also famous for building the locomotives with Walscharts Valve Gear and later converting them to Baker Valve gear which required completely different valve gear hangar framing.
The one New York Central Hudson lost in service was wrecked at Little Falls NY at speed early one winter morning. The locomotive went into a rock embankment after derailing at speed. It went over on its side and the boiler exploded out from the firebox bending the frame wheels and rods completely around like the frame was folded in half. The railroad scrapped the locomotive as a new one could be build easier than the cost of the repair.
In sum there are fairly standard procedures for repairing most of what in necessary on the steam locomotive. Reboring cylinders, replacing piston packing etc. is not usually that big of a deal.
gregc Overmod There have been some arguments as to whether 'modern' practice (e.g. of valves with articulated heads and multiple 'diesel-style' thin rings) actually benefits from bushings rather than careful line-boring and surface-hardening of, say, cast-steel cylinders. wouldn't the piston need to be replaced/refabricated if the cylinder walls are cut and made larger?
Overmod There have been some arguments as to whether 'modern' practice (e.g. of valves with articulated heads and multiple 'diesel-style' thin rings) actually benefits from bushings rather than careful line-boring and surface-hardening of, say, cast-steel cylinders.
Not necessarily; the ring construction can accommodate steam tightness and only the 'steam edges' need to be built out - and that only slightly with minimal axial force on them.
I believe David Wardale has a good discussion of the advantages of diesel-style rings, and ...
what is an "articulated head"?
Think of a typical piston-valve spool with its various rings and edges. This is a long, stiff thing operating through several regions with temperature gradients, being pushed and pulled from one end. Wardale proposed articulating the two heads on a piston valve so they could 'float' and self-align individually in their bores, without any tendency to scuff, with a separate (and more easily adjusted) piece locating them axially. (I think there is a drawing showing the construction somewhere either on Hugh Odom's Ultimate Steam Page or Martyn Bane's site.) It may help to think of the construction as two piston heads with a connecting rod between them.
Overmod In most locomotives, the cylinders do use sleeves; in my experience they should be made of a bronze alloy and are called 'bushings'.
Here is some of the notes I had on file from the PM1225 restoration I was involved with in Michigan some 38 years ago. About the details of servicing the Lima berkshire.
First the engine was delivered to Michigan State University for display purposes and the piston rod packing and piston rings were removed from the engine to prevent these items from corroding and the engine becoming immovable in the future.
We had to restore the cylinder packing without having any parts on hand to verify what was built into the engine. Likewise we had piston rings made without originals to guide us, only the blueprints.
Also, these locomotives were delivered to Pere Marquette with cast steel frames but the cylinder castings were individual bolt on castings as in the days of "built up frame" locomotive construction.
The locomotive repair tolerances given by the Pere Marquette standard maintenance equipment instructions were as follows:
WEAR LIMITS
Cylinder bore taper - max allowable - 1/16 inch
Cylinder bore out of round condition - max allowable - 1/16 inch
Cylinder bore diameter variation between right and left sides - 1/2 inch
In the lifetime of use by Pere Marquette Railroad the cylinders had been bored oversize to 26 and 1/2 inch - the original bore was 26 inches.
The engine power cylinders were manufactured with removable cast iron sleeve linings held in place by shoulders in the cylinder block casting and kept from rotating by two brass plugs in each cylinder. The rear cylinder heads were welded to the cylinder block casting and the front cylinder heads were bolted on by 26 studs each 1 1/2 inch in diameter.
The piston rod is 77 and 5/8 inch long and weighed 428 lbs. This is held to the piston by a 4 and 3/4 inch nut which was rivited over to prevent its loosening. Each piston contained two rings and each ring was a two piece assembly of the Hunt-Spiller design and backed by a rolled piston ring expander. Each ring was also cut into seven segments. The piston rod was held into the Laird design multiple bearing crosshead with a tapered fit and key and the tapered fit holding the parts together not the key. The crosshead weighed 720 lbs and the wrist pin for the driving rod weighed 110 lbs.
Consider these weights when calculating the forces involved in a running locomotive. Newtons laws of motion F=MxA indicates where force equals mass times acceleration and gives some idea of the tremendous energy involved in stopping and starting the piston and crosshead at the beginning and end of each stroke as the engine moves.
When replacing the cylinder piston rod packing - such as is contemplated with UP4014 observing is blowby this month. The tapered key joining the piston rod end and crosshead is removed so the piston rod packing can be serviced. The packing consists of a lead alloy that is no longer commercally available as in the days of steam. This alloy was not available when PM 1225 was restored. Estimates of the cost of replacing these bushings was in the $5000 range at the time. The PM1225 project considered using a crushed aluminum product donated to us by Durametallic Packing Company until the Norfolk and Southern Steam program in Birmingham AL provided us with a supply of the original alloy for us to cast the parts.
A custom made cast iron gland ring was also made and with a small diameter coil spring fitted over it to hold the lead packing into position in the cylinder head. The piston rod taper was then fitted back into the crosshead and secured with the keyway which as I said is not the "load bearing member." All the power of the locomotive is transfered through the tapered fit joint in each crosshead! I cannot recall such taper fit joints being used in modern mechanical engine constructions.
I hope this gives you some idea of the technique and technology of the steam locomotive of the time and what Union Pacific Steam Program is so valiantly accomplishing.
numbers make more sense to me when I make comparisons
i read that automobiles have piston sleeves, diesel engines have liners and I'm told steam engine cylinders have bushings. I believe we're all talking about the same thing, a replaceable cylinder wall that avoids the need to refabricate a piston. The steam engine bushing has ports for the valves that must be aligned with the valve.
a Big Boy 24" cylinder at 300 psi produces a force of ~68 tons (300 * Pi * (24/2)^2). There are 4 cylinders, in pairs 90 degs apart, which I believe results in a consistent doubling of that force (136 ton) around an entire while rotation. I believe this force will accelerate a 5000 ton (100 * 50ton) train ~1 fps/sec
i read that the piston pressure in a diesel (truck) engine can be as much as 2700 psi, or a force of 17 tons/piston for a 4" piston
it was interesting to see Burt Lancaster in The Train recasting a rod bearing and moving the rod back to the locomotive using a gantry
gregcnumbers make more sense to me when I make comparisons ... a Big Boy 24" cylinder at 300 psi produces a force of ~68 tons (300 * Pi * (24/2)^2). There are 4 cylinders, in pairs 90 degs apart, which I believe results in a consistent doubling of that force (136 ton) around an entire while rotation. I believe this force will accelerate a 5000 ton (100 * 50ton) train ~1 fps/sec
We have had some threads on this (a couple involving Juniatha) and you need to start by amending some of the quoted numbers, even for the extreme case of starting at full throttle and longest cutoff.
There are losses in the admission pressure between the part of the boiler containing the pops and the valve inlets; there are some more between the valves and cylinder ports (e.g. wiredrawing) that affect both instantaneous pressure/thrust and achievable MEP. There is also the effect of fixed cutoff (which is not as extreme as, say, a PRR I1, but still substantial on any modern locomotive) mandating some expansion that tends to take the MEP down even if the peak pressure is still relatively high.
You must also take account of the rod angularity and the fact of quartering 'peaking' thrust on one side while the other is near zero; the most useful thing is to graph the resultant (preferably as seen at the wheelrim, where the torque that matters has its effect) every few degrees (I believe David Wardale has such a graph in the Red Devil book, I think for every 15 degrees). This is valuable enough that it should be posted on the Web somewhere for reference)
As with the discussion of boosters: you should conduct at least part of the analysis including the required mass flow of steam to produce the effect you're predicting. (Had this been done by the morons publicizing a "9000 horsepower" PRR steam turbine, there might have been better recognition of the inherent disaster before more development time and capital had been expended on the idea...)
I read that automobiles have piston sleeves, diesel engines have liners and I'm told steam engine cylinders have bushings. I believe we're all talking about the same thing, a replaceable cylinder wall that avoids the need to refabricate a piston.
Ah, not necessarily. The steam bushings are pressed in with little provision for 'easy replacement' and are, in my understanding, primarily there because the best alloy for the cylinder part of a casting (whether in a cast bed or 'separate cylinder section') is incompatible with the materials and tribology for best ring performance. If a cast cylinder is sleeved, I suspect there is little explicit provision to make it as easily replaced as proper diesel liners. (Piston sleeves in modern vehicle engines are very often very thin, as in the 'rebuild' cermet sleeves for high-mileage diesels) and will not be practically removable without damage (this is an understatement; you'll have to break them up to get them out). The corresponding technology for reciprocating-locomotive cylinders, as an alternative to in-cylinder deposited hard coatings, is a bit thicker but still "not particularly amenable to being pressed out".)
There is little advantage in 'not having to refabricate pistons' compared to the expense of changing liners; the idea in large diesels is to permit replacement upon either significant running damage or to allow a common stocking of one size of new piston. There are some good online videos (e.g. from MAN) regarding piston and liner servicing in large low-speed ship engines that you might want to watch -- look at the matchmarking details and other care to keep things aligned, even at this large scale.
The steam engine bushing has ports for the valves that must be aligned with the valve.
No, the ports in the bushing have to be aligned with the passages in the cylinder casting. A consequence is that the front-to-back alignment will have to be very exact, on the order of magnitude of precision of setting the 'steam edge' (which can be as fine as 1/128" in traditional English-measure practice, although usually coarser than 1/64" as achieved). The actual valve setting is made by adjusting the valve gear to put the valve (as machined) correct with respect to the bushing (as machined). (You'll see reference in some of the old 'engineer's handbooks' as to how to tinker with this on the road!)
I read that the piston pressure in a diesel (truck) engine can be as much as 2700 psi, or a force of 17 tons/piston for a 4" piston
That is likely peak pressure around firing, and may involve shock force 'artifacts' if the strain gage used is not properly set up or connected (as you are probably familiar). What you're looking for is the MEP, and ideally the MEP related to crank position and rod angularity; this is one of the things that can be 'fine tuned' with a good pilot-injection EFI system ... if you don't care as much about physical emission quality.
I'd be surprised to see meaningful duration of 2700psi outside one of those sled-pulling trucks with twins or triplets that are built to get north of 2000hp out of a Cummins 6BT. Do not expect to get a million miles out of something making that kind of pressure!
I have seen it posted that the replenishment water to the tenders is first run through a water treatment car behind the tenders. Does anyone know anything about this?
.
OvermodWe have had some threads on this (a couple involving Juniatha)
could you provide a link?
OvermodThere is also the effect of fixed cutoff ... mandating some expansion that tends to take the MEP down even if the peak pressure is still relatively high.
it would be great to see a reference with numeric data. By my calculations, mean effective pressure is never below 50% and ~98% for 80% cutoff.
OvermodYou must also take account of the rod angularity and the fact of quartering 'peaking' thrust on one side while the other is near zero
i did. I saw this plot in Semmens. The blue and red curves show the tangential force on the driver at various angles based on a normalized cylinder diameter of 1 unit. The peak is 0.78 (Pi * (dia/2)^2). But when you combine the force from both out of phase cylinders (green curve) and average it over an entire rotation, the effective force become ~1 (128% of peak)
the catskill site has an estimate for TE due to a single cylinder accounting for some loses with the factor of 0.85 (but a value of 0.75 may be also be used) which results in a value of 16.7 tons
I see I forgot to account for the ratio of the cylinder stroke and driver diameter 0.41 (28/69), ~31 tons for each pair of cylinders and ~62 tons for all 4.
given an adhesive weight of 270 tons, max TE is ~67 tons (1/4 balanced weight on drivers). I think my estimate is in the ballpark assuming there's little purpose in designing an engine that significantly exceeds the max TE.
while these numbers don't account for pressure losses and back pressure, they also don't account for super-heating which while intended to raise steam temperature to minimize condensation in the cylinder may increase steam pressure as well.
it would be great to get a numerical confirmation (to some extent I have from the someone at 5at.co.uk)
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