Yes, there are inside side rods on the Champelon 2-10-2. And the rear cylinders are not located per “standard” American practice. They are at a considerably raised elevation, quite probably to allow space for the inside side rods. Likewise quite probably were the “slide rule guys” at Altoona to adapt this modification to the PRR T1s, they could go just a couple inches or so higher and put all the siderods outside the frame !!!
The 330,000 lb drawbar of the D11R is NOT an extrapolated figure. Among other things, it is an engineering design requirement. Every component in the D11R is designed strong enough that it can do what it needs to do for that drawbar figure. There are two track groups, one right side and one left side, each providing 165,000 lb of the drawbar. Each drive sprocket is capable of handling 165,000 lb. Each track link is capable of handling 165,000 lb. Painting them other than Caterpillar yellow does not decrease their strength. Installing them on a steam powered “vehicle” with PRR lettering does not decrease their strength. There is a rather famous photograph from the 1920s showing a tug-of-war between a then-new Milwaukee Road electric locomotive and two Milwauke Road steam locomotives. The electric locomotive won. And the results would have been the same if the length of chain used were replaced with of a length of D11R track links. It’s still the same 165,000 lb strong. And D11R track links would not have broken were two Milwaukee Road electrics been on one side and 2.5 PRR T1’s on the other. (So OK, use 2 T1s and one E6 and I’ll leave the good guys at Caterpillar to demonstrate how their D11R can produce a 330,000 drawbar.)
There are problems with all of these solutions. None of these solutions could have been used with the “existing” T1 frames. Of course GSC could have produced new frames that incorporated whatever changes the “slide rule guys” at Atloona wanted. Of course GSC would expect to be paid. The cost of the new frames is most probably a smaller
I’m not questioning the strength of the CAT components, what I’m questioning is whether the D11R can actually develop that much pull in the real world. I’ve been around plenty of construction sites and have operated smaller CAT dozers in the past. The treads do increase the traction, however, dozers can, and will spin their treads on a hard push/pull.
Like I said, I don’t believe the physics supports the D11 producing 143% pull over its operational weight.
N&W J’s did not have lead added to the frames. This was done to the low pressure engine of the Y5-Y6’s when the booster valve was added in the early 1950’s. The engine weight was increased from about 582,000 lbs to about 611,000 lbs. The J’s always had 288,000 lbs on the drivers, no lead necessary.
For Leon Silverman’s, and anyone else’s, benefit who is interested, the 4-10-2 at the Frankline Institute is quite unique: In addition to being a 3-cyl. job, it has a water-tube boiler – exactly the reverse of the vast majority of railroad locomotives but quite common in marine use. If memory serves, this boiler was rated at 330 pounds of pressure! Which was huge for its day.
I understand that the reason the Franklin locomotive did not sell was road resistance to the water-cooled concept, and not rejection of 3-cylinder design (the maintenance problems of that were not appreciated until later). As I understand the opposition, the fear was that a water-tube boiler, in a railroad application, could not (for all the vibration) be maintained with integrity. Sooner or later, the thing would leak, and irreparably.
In the marine application, the machine is riding on a cushion of water, not on unyielding steel rails, so the vibration problem does not arise, at least to the same magnitude. Water-tube boilers are quite good at pushing ships around.
A third strike might have been that it was compounding, a feature that wasn’t very popular in the U.S.
First, the 60000 was water-tubed, not water-cooled.
It embodied too many radical concepts in one machine. From a maintenance standpoint, the particular design of water-tube firebox on the 60000 used something in excess of 200 washout plugs, each of which would have to be removed and replaced once a month at boiler wa***ime. The normal firetube boiler on a large engine might have 30 or so such plugs.
The center cylinder was always a maintenance problem in the US, more so than overseas. It’s possible that it was as much a culture problem as anything else; enginehouse workers in Britain were always accustomed to going in between the frames to accomplish maintenance chores which were always outside in full view and handy to get at on a two-cylinder locomotive with outside valve gear. There is a 4-6-0 on display in one of the London museums that shows on each side a main rod, crossheads and piston rods to a set of outside cylinders, and of course the side rods. But reading the mechanical description of the locomotive reveals that it is a 4-cylinder compound with Walschaert valve gear; this means that not only are there two more cylinders, piston rods, crossheads and main rods connected to a crank axle, but there are two complete sets of Walschaert valve gear between the frames.
I don’t know that the compounding feature of the 60000 would have been found that objectionable;
But that particular boiler design and the center cylinder would have been, and obviously were, enough to kill the thing commercially.
Old Timer
I remember reading in Trains many years ago about the T1 and the N&W. The quote from the N&W man was “We tried to make an engine out it, but we couldn’t.” I think this was reality winning over theory.
I think the problem with the T-1 was to do with eqalisation. What the T-1 should have been was two 4-4-0 locos back to back. The adhesion and riding properties of these is a matter of record. What you actually got was the equalisation for a 4-8-4 applied to two separate locos, a recipe for disaster. Check for yourselves, the equaliser between the second and third drivers is easy to see.
I take it you’re refering just to the wheel arrangement, and not suggesting a sort of center cab configuration with two separate sets of fireboxes, boilers, etc?
I think you’re onto something, but what I would suggest is a pair of “reversed” 4-4-0’s (0-4-4’s?) back to back, with the two sets of pistons centered back to back, or even one larger set of pistons driving both the forward pair and trailing pair of drivers.
Sorry, but from my viewpoint, equalizing the two engines together would make for smoother riding than two sets of equalizers. Could you please explain you conclusion :)?
Sincerely,
Daniel Parks
As I understand, Johnstone wants to put one 4-4-0 on the track and behind it a second 4-4-0, but turned around (0-4-4), its cylinders then moved forward & turned back around again and the 4 wheel lead truck replaced by a 4 wheel trailing truck. On top of this is to be installed a high temperature pressure vessel, commonly called “a boiler”. Been there. Done that. Two frames under one boiler is always called an ARTICULATED steam locomotive, regardless of wheel arrangement. Someone is obviously missing that the PRR T1 was NOT articulated. It had ONE FRAME, running the full length of the locomotive. Most likely because that was what the “slide rule guys” in Altoona wanted.
One thought from futuremodal is scary – “…one larger set of pistons driving both…”. By jove, he’s got it !!! Discard the front pair of cylinders, enlarge the bore of the center cylinders by about the square root of two, and change to a piston rod that comes out of both ends of the cylinder (back era 1890? this was called a balanced cylinder or piston - so, nothing new.) The rear of that rod drives the two rear driving axles and the front of the rod drives the two front driving axles. Scary because this is the first thought that will work !!! Eliminates one pair of cylinders and associated valve gear, retains the light-weight rods feature and positively prevents the problem of half of the drivers slipping. Now, like any good 4-8-4, they either don’t slip or they all gotta slip togeather. No more “half” stuff. And it keeps the Altoona guys happy with only one frame.
Were one to apply the Wythe classification system by counting drivers and not counting cylinders, the PRR T1 has four guide wheels, 8 driving wheels and 4 trailing wheels, thus making it a 4-8-4. Note that the drivers probably don’t care where the power comes from, they are going to run all the same. And so all the springs, spring hangers, drop bars, equalizer bars, all the rest, will be basically the same on all 4-8-4s and it don’t matter how many
wccobb,
What is your opinion of an opposed piston arrangement where each side has a piston fore and aft of the drivers, with both connected to the same side rod? Is there any advantage/disadvantage of such an arrangement over the T1’s standard arrangement or the centered piston idea? Would there be a timing problem?
Futuremodal - The wildest Loree D&H compound was a 4-cylinder 4-8-0 with two cylinders in front and two behind the drivers, all driven by a rotary-cam poppet valve arrangement. Both front and back main rods drove the same crankpin. Take a look at a picture of it and you’ll quickly know why it wasn’t approved for fleet application . . .
Old Timer
Took a look at it…
http://www.dself.dsl.pipex.com/MUSEUM/LOCOLOCO/USAhp/USAhp.htm
…and yes, I can see why that prototype didn’t work, but that doesn’t explain why the concept wasn’t improved upon. What I don’t understand about the Loree triple expansion was why they went with the unbalanced high and intermediate cylinders on the cab end (with the hp on the right side of the cab and the ip on the left side), rather than having two cylinders of the same pressure? The T1 cylinders weren’t compound, were they? Why not take the T1 principal and combine it with the opposed cylinder concept? Or if possible, a six cylinder concept, with two cab end, two centered, and two forward, and with the centered cylinders connected with both the front and rear cylinders in an opposed fashion?
One thing I’ve been meaning to ask, in terms of total power output, was there any difference between two or four cylinder locomotives if the total displacement was the same, e.g. are four (or more) cylinders better than two? Seems to be true in spark ignition engines.
Sorry to be pessimistic, but in the words of Han Solo, “This isn’t going to work.”
You have two problems:
1.) Without two pistons at 90 degree differences, you could definitely get into some tricky spots…
2.) You couldn’t keep the lightweight driving rods, because the force from the cylinder would be doubled, so the running gear would have to be enlarged accordingly.
3.) Might get sort of jerky, and the strains would probably be great.
Nope–two cylinders is a decided advantage.
Sincerely,
Daniel Parks
wcccobb seems to have answered the questions.
Total power output in a simple locomotive is going to be tied to the ability of the boiler to boil water, the cylinders merely convert the potential energy in the steam into kinetic mechanical energy. A compound locomotive, be it a Mallet, cross compound, de Glehn compound, or whatever, uses the same steam more than once. It would be theoretically more efficient than a simple locomotive but, as the D&H compounds showed, could be a maintenance nightmare.
Four cylinders are theoretically better than two for the same total power output. The main reason is two large cylinders use correspondingly large volumes of steam and the valves and passages have problems handling the flow and mass of steam. Four smaller cylinders give the same amount of steam more of a chance to get into the cylinders, do some work, and get out. This is one possible reason for the conjecture that the PRR T1a (5547?) equipped with Walschaerts gear, was enough experimentation for one locomotive. According to the enginemen who ran it, there was little difference in its overall performance compared to the others. With the small cylinders, normal valves and valve gear would have been able to handle the smaller amounts of steam effectively. The poppet valves didn’t have much effect on operating economy until relative high rotational speeds were reached. In comparative tests on N&W in 1948, a T1 (5511) was less economical in terms of coal and water usage per unit of output than the N&W’s Class J until about 70 mph. Most of this was likely caused by the extremely short stroke which reduced cylinder efficiency at lower speeds. The T1 performed OK within its capacity during those tests, but used larger amounts of fuel and water to bring it off.
Anyone here really understand the principle behind compound expansion? To a first order approximation, the important value is the expansion ratio (related to valve cutoff). The higher the expansion ratio, the higher the work done by a pound of steam, until you get to the low pressure limit imposed by cylinder back pressure.
There are second order effects involved in why compounding may help. One example of compounding was the Wright R3350tc aircraft engine from the Lockheed Super Constellation, the DC-7, the P2 Neptune, and I also believe the Douglas Skyraider (called “spad” by the jet pilots in Vietnam). After expansion in the cylinders, further expansion took place in turbines, which were connected to the main power shaft through automotive-style fluid couplings.
Pistons are pretty high friction so once you expand past a certain point you are just overcoming piston friction. I am guessing turbines are much lower friction, but leaky compared to pistons, especially at high pressures. By combining pistons and turbines in this way, you are getting the best of both worlds, of course at the expense of a very complex (and trouble-prone engine – I heard that the Lockheed Constellation was known as the best 3-engine airliner in which to cross the Atlantic).
In steam locomotives you are typically using pistons for both stages of expansion. I suppose the low pressure piston can be less tight-fitting to reduce friction at the lower pressures? I tried to make sense of some of the Web pages describing Champelon and Porta’s work on this subject. There was some kind of story about the latent heat of condensation being a power robber – does compound expansion keep the high pressure cylinder hot, the low pressure cylinder not quite so hot, and get efficiency by not cooling the steam to where it condenses and robs you of all of the remaining power?
Is compound expansion of value because with single expansion it is hard to get valve cutoff for very high expansion ratio
Poppet valves, which are the type used in the cylinder heads of Ed’s Hemi engine, are a distinct improvement over piston valves in controlling the flow of steam. On North American steam, they were controlled by either rotary cam or oscillating cam mechanisms. They improved performance on almost every locomotive that was equipped with them but were not popular because they often became oddballs in a fleet equipped with piston and slide valves.