On an american four cylinder would the cylinders be on the outside or would two cylinders be on the inside as on a three cylinder locomotive. Gary
Omitting the duplex-drive concept where all four cylinders would be on the outside (but not in the same locations) or other experimentals that didn’t amount to much I don’t see how an American four cylinder engine could have ignored the European approach and have not located the two additional cylinders inboard of the other two.
I can’t think of anything else that might have worked with any degree of practicality.
They were mounted in just about anyway you can imagine. There were “Tandem Compounds” with the cylinders mounted one in front of the other sharing the same piston rod. Another type of four cylinder steam locomotive was the “Vauclain Compound” named for Samuel Vauclain the head of locomotive production at Baldwin Locomotive Works. These had the high-pressure cylinders mounted below the low-pressure cylinders outside the frames.
There is always the “L.F. Loree” arrangement.
It could be set up as a simple rather than a compound…
American High-Pressure Steam Locomotives (douglas-self.com)
(scroll down)
I could imagine the “George H Emerson” with the duples pairs coupled by conventional rods, and converted to burn oil to save the abrasion from coal dust at the rear cylinders.
Duplex Drive Locomotives. (douglas-self.com)
(scroll down)
You have a four cylinder 4-8-4…
Peter
That is not dissimilar from the ACE3000 approach (with the ‘coupling by conventional rods’ following Withuhn’s approach to conjugation) – that design retained both ‘run-of-mine-coal’ firing and compounding.
The only real ‘abrasion’ issue on the B&O duplex was piston rods, and my suspicion is that it was nicking of the rods rather than progressive wear to the glands. The solution in the '80s was to have been to use a ‘boot’ (like that on a long-excursion 4x4 shock absorber) with appropriate condensate and lubricant handling. As noted before, SP used ‘back-pedaling’ engines for many years and didn’t report particularly showstopping problems with piston rods – of course that was at much slower speeds.
I was an early fan of the de Glehn-du Bousquet arrangement which divides the drive longitudinally, with the HP normally on the outside (where inspection is easier) and the LP displaced forward (which makes it easier to fit larger cylinders) acting on the forward driver axle. This was tried early, but the engines were apparently built too light for our service, and no one chose to build one ‘strengthened’.
The original Vauclain compound (as used on the fastest locomotives in the world just before the turn of the 20th Century) was a mechanically clever arrangement that put the HP cylinder above the LP cylinder (very seldom was the HP under the LP, generally for reasons of space, as on Manitou & Pikes Peak), driving an outside main through a common crosshead. This was an early use of a piston valve, with preternaturally contorted porting to do the job of admission and release to both cylinders on one side with a single spool; the cylinder blocks are a triumph of casting.
Guess the first 4-cyl engines in the US were Vauclain compounds, with low-pressure cylinders above or below the high-pressure, on the outside of the engine’s frame. Does the name mean Baldwin was the only one that made them?
Maybe tandem compounds were next, with the axes of the HP and LP cylinders coinciding. HP was always ahead of LP? They were always slow freight engines?
Balanced compounds (HP cylinders inside the frame) started … around 1905? A few 4-cyl balanced simple engines were built; no one got more than a couple of simples, but 4-cyl balanced compounds weren’t rare – SFe had hundreds: 4-4-2s, 2-6-2s and 4-6-2s.
Wonder when the last 4-cyl engine in the US ran – were they all scrapped, or converted to 2-cyl by 1929?
I don’t think the Vauclain compounds lasted too long after the concept of superheating was proven. While those compounds worked they were pretty maintanance intensive, and American railroaders were alway very averse to maintanance intensity.
The original kind were on their way out long before Schmidt figured out practical superheating; I suspect this was at least part of the reason Sam went to balanced compounding at Baldwin and did not change the name.
Note that you can’t adjust a Vauclain compound the way you can a de Glehn-du Bousquet engine, to equalize thrust in the HP and LP. Theoretically (very theoretically) you could rig up some sort of riding cutoff that would vary admission on the LP ports to match what the HP was developing (and this would be done ‘by feel’, so changes in HP performance would be balanced too) but I could not figure out a way to do this with the valve as Baldwin constructed and placed it. While the task may be no easier with the revised arrangement (I believe the common piston valves and complicated passage coring were retained) certainly the differential-wear issues were solved.
Famously, compounding in the presence of superheat, which seems almost like a no-brainer for economy, was tried very little in the United States in the decade after superheat was demonstrated to ‘work’ – which is great support for your position. And there does not appear to be a lack of experimentation with both superheat and compounding in the early years of the Superheater Company … perhaps the combination of the licensing fee and cost of the superheater plus the added cost and complication of misunderstood compound expansion did the business effectively enough!
Even more, very little of the use of three cylinders, even simple, even though as stoutly advocated by Alco a few years later as ‘the answer’ to increasing engine size and power, did not; cert
The Shaw, and I think some other kinds of balanced engine design, considerably predate the Vauclain compound. You might look to see if the PRR experiments with de Glehn-du Bousquet effectively predate extensive use of the Baldwin arrangement – but there’s little doubt that the perceived advantages of the Vauclain arrangement, while they remained obvious, would make the much greater investment of machinery and training to use it effectively for a de Glehn type less attractive.
Baldwin had a number of key patents on the arrangement, notably on the valve design. Making that cylinder arrangement work with slide valves would be comical in a number of respects, especially some of the passage lengths; the situation is not much improved if you allow slide valves working in other than horizontal seating (as many English locomotives of the period used). Whether Baldwin would have licensed the arrangement to other builders at all is unclear; in the event, the amalgamated American Locomotive Company pursued its own distinctly different solutions.
This may depend on other things. One of the engines tested on the original PRR plant as erected at the St. Louis exposition was a Santa Fe 2-10-2 with the tandem-compound arrangement and considerable test data were recorded for it – I don’t have a copy of the results but I believe it’s now easily obtained on line for study. It was not considered either a failure or particularly ominous maintenance nightmare in 1904.
Where you put the HP vs. LP probably involved the steam circuit more than having
Owing to current circumstances, I have been hitting the Renew button on my loans from the “U”, and the Alfred Bruce book remains on my nightstand.
Bruce explains that the “tandem compound” became maintenance expensive, both from the need to renew the gland isolating the HP from the LP cylinder and also the need to take the whole, fine thing apart to do that. Bruce points on the “crane attached to the smokebox” (essentially a metal arm that pivots outward) to aid in that task.
There is that sole-remaining Swedish steam turbine locomotive that uses some form of mechanical jackshaft drive from turbine to siderods to wheels.
Look starting at 16:45 for a view of the drive arrangement.
The problem is that the rod drive mechanism of a steam locomotive is already overconstrained and hence sensitive to binding if the drivers are the least bit “out of quarter” or if the frame is the least bit skewed from either assembly tolerances or frame damage.
The Stanier-designed “Turbomotive” on the LMS railway in England along with the Pennsy S2 turbine had a quill drive, to one drivers for the Turbomotive and to two drivers with the S2? The other drivers are connected with siderods, which have the further advantage that they don’t need (as much) reciprocating balance, although Overmod pointed out that the drive arrangement wasn’t in perfect balance owing to the effects of different rotation planes.
The Swedish M3t turbine locomotive, however, uses a jackshaft drive – the turbine drives a “dummy wheel” (the jackshaft) that is connected by siderods to the actual driving wheels of the locomotive. To me, such a jackshaft could be turned by a high-speed multi-cylinder steam engine in place of a turbine.
Alfred Bruce (who else?) covers this type of drive used in steam trams and low-speed street-railway switch engines, and his criticism of it is binding and friction and wear in the drive.
I guess at high speeds and as the locomotive body bounces in relation to the drive wheels with its springs, this introduces a small angularity between the jackshaft wheel and the first driving wheel? If that is a problem, why isn’t the angularity of a driver hitting a joint in the rail, displacing it in relation to neighboring drivers not a p
The Swedish M3t turbine locomotive, however, uses a jackshaft drive – the turbine drives a “dummy wheel” (the jackshaft) that is connected by siderods to the actual driving wheels of the locomotive. To me, such a jackshaft could be turned by a high-speed multi-cylinder steam engine in place of a turbine.
I guess at high speeds and as the locomotive body bounces in relation to the drive wheels with its springs, this introduces a small angularity between the jackshaft wheel and the first driving wheel? If that is a problem, why isn’t the angularity of a driver hitting a joint in the rail, displacing it in relation to neighboring drivers not a problem? Is it that the deflection of drivers relative to each other, for reasonably smooth track, much smaller than the “bouncing” deflection of the jackshaft attached to the locomotive in relation to the drivers in contact with the rail? (Paul Milenkovic)
The Swedes were very attached to jackshaft drive for electric locomotives. Until the 1970s, they preferred a jackshaft drive to coupled axles for heavy freight traffic, particularly on the Narvik iron ore line.
SJ Dm3 - Wikipedia illustrates a sort of electric Triplex which lasted until the introduction of current variable frequency AC traction motor technology.
High speed multi cylinder steam engines tended to use flexible drive to single axles as shown by French High-Pressure Locomotives. (douglas-self.com) (scroll down to 232P1 entry) and
Hi Gary
You might have mentioned what you want four cylinder for?
One thing is for sure: it won’t be easy to fit in!
American locomotive design is so much developed around and for the two cylinder engine that you have to change a lot to accomodate inside cylinders - and we are not talking of double cluster of cylinders outsides asides each other, neither am I talking of cylinders both ends of the coupled wheels. Cylinders belong to near the smoke box - full stop. A three cylinder engine would be much easier to realize.
It is a paradox situation: although heavy engines would in the first place more ask for multi-cylinder designs, they are at the same time the ones where it is more difficult to realize. Also, cylinder size comes to a practical limit and in a four cylinder simple expansion engine it is hardly possible to use identical cylinder dimensions inside and out.
Oh, no, let’s drop that thought as fast as it came up: no staggering of cylinders and two drive axles inside - no! Those wierd forces evoked by such a non-symetric design!
It is a different proposal if four cylinder engine(s) are combined with a Duplex arrangement: this way cylinder dimensions come down to handy sizes and piston forces are also milder. Still the old European aesthetical and technical ideal of the deGlehn compound (with inside LP) will hardly be realized.
Except you dare to explore the really high boiler pressures: 400+ psi …
Juniatha