My ignorance knows no bounds it seems.
I now find that it would be appropriate to learn how steam engines work, not just what fuels the nuclear reactors, but all the dohickies and gizmos on the engines that model railroaders call details.
So I’m looking for a book or books or other reference materials that shows the history, development and implications of all said dohickies.
Know what I mean?
BTW: I know how to utilize inter-library loans.
Gidday Chip, here’s a couple of basic videos to wet your whistle, so to speak.
I’m not sure if there is a definitive book so to speak, but have been lucky enough to have been given several handbooks for the operation of several NZR steam locomotives which go into more specific details. I have also been given handbooks on the operation of the Walschaerts, and Baker valve gear.
I would presume that similar handbooks would have been issued to US railroad enginemen.
Cheers, the Bear.[:)]
Keep in mind that there are at least two stages to this: initially learning the history of steam power, and then learning the ‘fine points’ of detail design.
Both of these are separate from learning the actual thermodynamics of how steam works, and then why thermodynamics alone can be a lousy guide for practical locomotive design, and then why the ‘most efficient’ locomotive designs might not be the ones practically best for actual railroad service…
This being separate from the history, and the design, and sometimes the corporate shenanigans, of the various ‘doohickeys’ (often patent, specialized, and ‘invented here’) over the years. Much of this is imperfectly told and has to be put together from the literature rather than found in one or a couple of definitive books.
In my personal opinion you should start with a piece of overkill: get as many of the carefully labeled drawings that show ‘parts of the steam locomotive’ as you can. Offhand I remember seeing good ones for a NYC Hudson and a German locomotive as the later types, and one for a ‘typical’ American type from the late 19th Century (when what was ‘good practice’ could be wildly different from later developments!). Then find some of the labeled backhead photos and keep them as reference on what to start looking up – and unlabeled ones to compare.
The closest thing I can think of to a list of auxiliaries in one place is the Ransome-Wallis Encyclopedia of World Railway Locomotives. That was published right at the effective end of big steam, at a time when I think most of the ‘powers that be’ expected steam in Britain to persist decades longer. On the other hand, the actual listing of auxiliaries in the ‘encyclopedia’ part is wildly incomplete in many respects, while colossally overdetailed in others (British injectors in particular)
For what is actually involved in designing a working steam locomotive, I c
Many of the earlier references are, through the miracle of Google Books, free to download (as PDFs) or to print out. The trick is knowing what they are, which is not in one place (as it probably should have been by now, and for all I know actually is). There is a very good article from ~1849 on the development of early (!) valve gear which is fascinating both for what it says and for understanding what is practical about ‘steam distribution’ – be prepared to break out the Anacin as you get into the subject of modern radial gear for piston valves, and then the merry world of poppet valves from Caprotti on. Take copious notes on what you read … and on what you don’t (yet) understand … then follow up on what you don’t ‘get’ and repeat the exercise.
I have not yet found a better ‘on video’ explanation than the one ATSF prepared, as I recall circa 1922, using the then relatively new technique of animation to show with technical correctness some of what was going on. Fortunately at least some of this was preserved by Herron Rail Videos and a portion of it can be seen here:
https://m.youtube.com/watch?v=QYNRhL0ddDQ
Regrettably this was the ‘silent film’ era and the accompanying discussion, which would have contained additional important details such as why 2-cylinder double-acting locomotives need two cylinders in quarter, and why the ‘compression’ noted is important in operation, has apparently been lost.
Periodically as you learn more about steam technology you can come back to this illustration to clarify it. For example the development of the ‘combustion chamber’ lengthens the distance to that ‘rear tubesheet’ to give increased radiant uptake; the precise motion of the piston valves involves longer travel than ‘necessary’ as well as long lap for good reasons; the behavior of the boiling water is very different from what is pictured, in significant ways; the plates and screens in a Master Mechanic front end are arranged differently from the illustration in important respects.
I do not see this in their current production list and you’ll probably have to e-mail or contact them to find out how to get a full version:
I haven’t seen this manual, but it may be the go.
https://www.amazon.com/Locomotive-Enginemans-Manual-W-James/dp/1935327828
Cheers, the Bear.[:)]
Here is a list of locomotive firing references found valuable by people at RyPN (some of which contain important details of locomotive or auxiliary-device design).
http://www.rypn.org/forums/viewtopic.php?f=1&t=30012&view=print
The PRR T1 Trust has made this excellent training book available as a .pdf file. It is quite worthwhile.
https://prrt1steamlocomotivetrust.org/bookclub/download.php
Good Luck, Ed
This reminds me that CSR/SRI went to some trouble a decade ago, when they were developing their ‘Project 130’, to prepare some white papers on modern steam technology, which can still be found with a little looking. Here is an example:
Depends on what you mean by “how a steam engine works”.
For me the puzzle has always been the valve gear. The boiling of water and the path the steam takes is pretty straightforward. How steam can drive the pistons is also pretty straightforward.
Speed control, torque control and direction of travel were the really important elements of the engineering that George Stephenson and his engineers figured out.
Again, for me, the lightbulb moment was to realize that at full power the pistons are pushed directly by the full steam pressure developed by the boiler. The expansion ratio utilized the entire volume of available steam. That would be equivalent to wide open throttle on a supercharged internal combustion engine at maximum boost pressure. The cylinders become effectively much bigger than their physical dimensions. No internal combustion engine can do that even if supercharged. Diesel electrics do this by decoupling engine rpm from wheel rpm using the generator and electric motor to allow very wide difference in relative speed. In effect, the diesel electric multiplies the effective displacement of the engine by increasing rpm while road speed doesn’t change, effective even at zero speed. Steam locomotives do the opposite, they really can increase the effective cylinder displacement while at zero rpm.
It was the mechanism and control of “part throttle” that made the steam locomotive work as a practical device. The valve control mechanism permits the engineer to cut off the pressure of the full steam volume available which then reduces the power to the level of the expansion capacity of the cylinder. The steam is captive inside the cylinder and power then results only from the expansion of that fixed volume of steam. Very fine power control can be exerted by a skilled engineer. That’s the really interesting part.
I would start by looking at how the engineer can use the valve control mechanism to r
You almost couldn’t be more wrong. Among other things, you are neglecting the ‘other half’ of necessity, the getting rid of the steam mass once you’re done using it for expansive thrust.
Interestingly, the ACTUAL cutoff that produces highest speed in well-designed reciprocating locomotives with piston valves lies in a surprisingly narrow band, between about 40 and 43%. Far more ‘interesting’ are the effects of compression, both necessary and undesired, after the moment of exhaust cutoff back around to subsequent admission.
It is almost impossible to overstate the importance of the innovation of long-lap long-travel piston valves in true high-speed locomotives. Some very late designs so valued high speed at the ‘steam edge’ that they used exaggerated valve travels at full – see the nominal travel on de Caso’s last 4-6-4s for example.
Much more ‘fun’ can be had in looking at precisely why poppet-valve installations can progressively increase high-speed performance even though their nominal very short cutoffs become worthless in practice over as low a speed as 100mph. The art involves getting the expansive steam mass into the cylinder very quickly (compared to the event length of a stroke at high cyclic) where it can then proceed to work its expansive magic proportional to the mechanical advantage of the ‘crank’ in the drive. It also involves holding the exhaust open either to a larger net opening or a longer duration than that provided by ‘symmetrical’ radial valve gear, while still fine-tuning compression.
For true fun, look up the Franklin type D patent, where wire-drawing, that traditional ancient enemy of reciprocating-locomotive efficiency, becomes a necessary part of the contr
as an engineer interested in developing a software model of a steam locomotive, i’ve been disappointed by the books I’ve read: Semmens (2000), White (1968), Bruce (1952). All provide a historical perspective and how designs evolved, but none provided a more thorough qualitative, much less quantitive description of steam locomotive design.
i also contacted someone invoked with the 5AT project which was investigating a modern design of a steam locomotive. While some were looking at detailed fluid dynamic models of the flow of steam thru various piping of an engine, i never found a more general desrciption.
originally i failed to recognize the purpose of the reverser. the reverser is a linkage in the valve gear that causes it to provide steam on the opposite side of the cylinder cycle so the engine can move in either direction. but a significant secondary effect is to cut off the flow of steam to the cyclinder part way through it’s cycle. this has two advantages.
the first is it extracts energy more efficiently from what steam is used by allowing the steam to expand in the cylinder rather than wasting the energy when exhausted. The 2nd is to conserve steam which will be consumed more quickly at higher speeds. i think setting the reverser is more crit
I always wondered why the engineer was always playing with the reverser in all the Royal Hudson videos I watch. Well I learned my one thing for today and I am still on my first cup of coffee.[Y]
Yeah, but I was hoping for enough to get started.
Holy crap guys, this is great.
Part of the problem is that the 5AT people intentionally deprecated theoretical design in favor of ‘practical’ computations that even people in primitive parts of the world, or after a catastrophic EMP strike on the West, could use to design locomotives effectively. (This is some of the same principle that governed the reprinting of the Red Devil book – something you should have in your library right next to Johnson if you’re serious about steam design)
You need to invest in the full version of the FDCs (you may have to sweet-talk Chris Newman at the successor to the 5AT consultancy to arrange for a full set) and learn how to abridge and then run them for the design and scale of a ‘project’ locomotive. As I’ve previously noted, Fry’s analysis in the early 1920s was reasonable, but involved far too many unexplained empirical constants that were derived from specific norms of locomotive design at that time, norms that do not apply to most modern power or circumstances. This for example renders the lolog approach to heat transfer in the tubes almost functionally useless, especially if you have an erroneous conception of how Besler tubes and the like work.
Note that the original name for the device was ‘cutoff’ (when it was a Johnson-bar type device) and the reverse involved using a different set of hooks in the gear. We use the term ‘power reverse’ because it makes ‘lock-to-lock’ adjustments of radial gear like Walschaerts (where the link serves for both forward and reverse motion as well as cutoff adjustment) easier under po
He is actually ‘driving’ the engine doing that; he probably had the throttle full open by the time he got above 20mph and he will keep it open as long as he can, right up until he hits a downgrade and wants the engine to stop making power or ‘coast’ (and there is a whole master class of fun information about how he will do that).
More fun is video in which you see someone starting a large modern locomotive with a considerable train – see if you can find the very early sound film of an engineer working one of the NYC Hudsons along the Hudson River. You will notice just the fine coordination between ‘taps’ on the throttle and spins of the reverser wheel to get effective acceleration out of a locomotive with which he may have had only a few trips’ familiarity … and, as with most classes of steam locomotive, had very different throttle response or behavior from her ‘sisters’ and needed to be felt out in the first few miles. It’s in here somewhere:
https://www.youtube.com/playlist?list=PLqKGkdgzE1eMUUM-H1f-WYLXUvE6Ayeje
but I can’t get video to run on my current Mac system…
For fun listen to this, and hear the effect of fine changes in the throttle and reverse:
Hey Chip, I did not read all the responses, so sorry if this is repetitive.
When I was in High School I joined the Florida Live Steamers, a 1/8" (7 1/2" gauge) group that was very active down here. Over a few years I actually helped build a 4-4-2 Atlantic and a 2-6-0 Mogul.
This taught me more about how a steam locomotive works than I could have predicted. Actually building one, you cannot help but learn a lot.
I currently have “part of” a 2-8-2 in my backyard being neglected.
My suggestion would be, if at all possible, to look into live steam locomotive contsruction manuals and maybe find a group. These are sort of a “real thing”, and these guys love to chat about their builds.
I would probably be very ignorant of how steam works had I never joined that group.
-Kevin
This makes sense entirely even outside a ‘prototype’ discussion – and if you want to see a great piece of modeling, see if the detailed construction discussion of Ed Woodings’ PRR T1 model is still online somewhere. Every piece of that locomotive was built to scale, including the poppet valve gear…
Well this is all very interesting. Who knew that there was a fourth state unique to water. Not I, for certain.
Imagine my disappointment to learn that the driving cylinders are never opened to full boiler pressure and that pressure then allowed to expand, and that the cut off is always used to prevent this from happening.
Somebody might usefully point out the errors in this descriotion, for example:
https://the-contact-patch.com/book/rail/r0018-driving-a-train