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Steam Locomotion in the 21st Century

The Recent History of Steam Locomotive Development

Modern "Live Steam" Engineers

updated 28 January 2022

While most of these pages cover the development of "full sized" steam locomotives, another field of steam technology development exists. Coincident with the decline of mainline steam activity in the 1950's a new hobby sprang up. All over the world, enthusiasts began building miniature working steam locomotives to satisfy their "thirst for steam". "Live steam" clubs formed and built tracks where enthusiasts could operate their locomotives. These locomotives are actual fuel-burning, smoke-belching, steam engines and exhibit all the properties (good and bad) of their full-sized counterparts. A very common scale for these miniature engines is 1-1/2 inches to the foot, which gives engines which are big enough to pull several cars carrying adult passengers.

Traditionally, most live steam locomotives are technologically simple. Craftsmen build their engines in garages or workshops, and hence simple construction, easy operation and good reliability are sought-after qualities. Accessories such as superheaters, feedwater heaters, and efficient exhaust systems are rarely used. Fuel efficiency is generally disregarded due to the relatively small size of these engines relative to that of the operators.. The full-sized fireman has no trouble stoking the firebox, regardless of how inefficient the engine is.

Despite this, several live steam enthusiasts have been interested in building more-complex models. For instance, one in the UK has constructed an authentic replica of one of Chapelon's compound French Pacifics. Other enthusiasts have seen the practical value of implementing the improvements developed by Chapelon, Porta, Wardale, et al to their miniature steam locomotives. They also see the possiblity of using miniature locomotives as research platforms for developments which can be applied to full-size steam locomotives.

Michael Guy

Googling "Lempor exhaust" will turn up information on quite a few Lempor installations on live steam locomotives around the world. This is chiefly due to the work of Michael Guy of Canada, who not only fit his own locomotive with a Lempor, but developed a spreadsheet for sizing the components of a Lempor for any locomotive.   You can read more about Michael's work, see photos of several live steam Lempor installations, and access his Lempor Exhaust spreadsheet here:

John Davies ( Model Engineer )

(Information provided by John Davies) While the building of miniature steam locomotives might be far removed from full size rail operation, and be considered to be expensive toys for rich boys, there is a serious side to this hobby. Engineering of the highest standards is often practiced, which has the potential to allow steam locomotive development to be conducted at a fraction of the cost associated with full size operations.

In 1991 a single garage was converted into a simple workshop and with the minimum equipment a start was made to build a 1/6 scale Lynton and Barnstable locomotive (LEW). During the next six years every component was redrawn (the plan was to a different scale) and manufactured. As boilers do not scale this major item was re-designed using model boiler calculation guidelines.

John's first experimental steps were taken by casting the cylinders and axle bearings using aluminium (aluminum) alloy, which has worked well on this saturated steam locomotive which is seen below.

Lady Carol - The sole motive power at the Secunda Steamers in South Africa for the last 3 years. Has pulled heavy trains, covering a distance of 15 000 scale Kilometres in the process. While the building and running of this locomotive and the training of many drivers, was an enjoyable hobby, a greater challenge was sought.

During 1998 John acquired a copy of David Wardale's The Red Devil. An in-depth study of this very informative volume left him convinced that the steam locomotive at the height of its reign, was not only grossly under-developed, but that the standard Stephenson layout severely limited the potential to compete with the diesel. He had found the doorway to a new journey in steam. A miniature locomotive of a different concept would be the way forward to prove that steam can be competitive in this modern world.

After reading The Red Devil, John was particularly intrigued with the idea of the Gas Producer Combustion System (GPCS) developed by L. D. Porta and applied by Wardale to locomotives in South Africa. Lady Carol had experienced problems with "clinkering" of her fire and this sometimes caused problems during operations at the Secunda Steamers track. The GPCS seemed to offer major benefits for operation of this locomotive. Further, John reasoned that if the GPCS system, which needed a deep coal bed, could be made to work in a miniature locomotive, that most, if not all characteristics of the steam locomotive could be scaled in both directions. If this were true, then a cheap, cost efficient way had been found for steam locomotive development. With advice from a small group of knowledgeable enthusiasts ( the S-TEAM ), Lady Carol was modified to use incorporate GPCS combustion via relatively simple modifications. This trial was conducted with success on a grate of 42 square inches and a firebed depth of 3 inches. This story is covered in more detail in the paper "The Miniature Steam Locomotive" (1999).

During 1999 the concept of a locomotive with 100% adhesive weight, allowing a high TRACTIVE EFFORT to weight ratio, which could run at moderate speeds on poor track beds would be ideal for oil starved developing countries. The ability to use any available solid fuel was called for. Furthermore local construction with the maximum possible local content, which would boost the countries manufacturing industry would be necessary. A fully modular construction using simple technology would be necessary to avoid prolonged downtime during maintenance would be essential to allow competition with diesel traction.

With the help of the S-TEAM, the year 2000 saw the birth of the concept, this steam locomotive will have the appearance of a diesel and provide similar crew comfort. The locomotive will run on self-steering bogies having from two to four axles. These bogies will be powered by a piston valve four-cylinder steam engine placed above them. The boiler will be of high efficiency producing superheated steam and including a preheater and fired by a GPCS firebed, which will be drafted by a Lempor exhaust system. The modular system will allow fuel and water to be carried on board for short-range duties or to be fitted with a tender for long range operation in the cab forward mode. The dry walled fire bed area can be changed for different fuels used.

Construction drawings for a 7-1/4 inch gauge prototype were begun. Construction was expected to begin during 2001 and was expected to take between 3 and 5 years. (Not known if this was accomplished.) A sketch of the proposed locomotive can be seen below. After a period of testing and tuning, further development is expected to be an ongoing process. Will this exercise lead to a new generation of commercial steam locomotives? Time will tell!

John also developed a coal-fired cooking stove using the Gas Producer Combustion System principal to reduce smoke an emissions.  Read more about it here:

Live steam enthusiasts and others interested in this project may contact John via e-mail at:

Wolf Fengler

Wolf Fengler has a masters degree in mechanical engineering from UCLA and currently serves as a principal and mechanical engineer at FMW, LLC. Wolf's serious involvement with steam locomotives began at the age of 11 at the local live steam track. Since that time, he has helped to build a locomotive, operated numerous model steam engines, spent much time researching steam locomotive developments and corresponds with steam locomotive experts from around the world. In addition to his involvement in the Live Steam hobby, he is also active with the San Bernadino Railroad Historical Society, which maintains and operates former AT&SF 4-8-4 #3751. He is also the first to admit that he has a lot to learn.

The year 1985 was quite pivotal in the development of his interest in steam locomotives. This was the year that he convinced his Dad that they should build a live steam locomotive. It was also the year that Ross Rowland and the ACE 3000 team took ex C&O 4-8-4 #614 out on the mainline to acquire test data. An issue of Railfan & Railroad from May of that year contained a wonderful article on the months long testing back East that fired his imagination. It also contained a small two (2) page report on the work of a young engineer named David Wardale In South Africa on a locomotive nicknamed the "Red Devil."

The inspiration for the improvements to the locomotive came from reading that article and others about Chapelon, Porta and Wardale, as well as experience garnered operating the engine coupled with engineering knowledge from other fields.

The coal-fired locomotive features:

  1. A thermic syphon
  2. Smokebox throttle, upstream of the superheaters (would be better downstream, but there were space constraints)
  3. A large diameter, streamlined dry pipe and steam supply lines to the cylinders
  4. Two, full firebox depth arrowhead type stainless steel superheater elements of the same diameter as the main dry pipe
  5. An Inconel grate
  6. A feedwater heater consisting of a copper pipe coiled around the inside diameter of a portion of the smokebox
  7. Radiused exhaust ports a la New York Central Niagaras
  8. Individual streamlined exhaust passages which collect in a central blast pipe
  9. A four-lobed exhaust nozzle sized per the recommendations of Jos Koopmans and L.D. Porta
  10. A triple-venturi petticoat arrangement for the exhaust which somewhat emulates a Kylchap 1-C
  11. A conical stack extension which serves to keep cinders and fumes away from the operator and helps extend the diffuser length
  12. A master mechanics self-cleaning smokebox arrangement was fitted for a time. It was quite effective, but was removed to facilitate cleaning and an increased draft for testing the gas producer combustion system (GPCS). A simple wire screen around the petticoats now serves as a spark arrester.
  13. Synthetic, lube-free bearing material for the connecting rods and needle bearings on the main rods. Miniature roller bearings were tried in the Walshaerts valve motion and work alright except in the die block, where they have been replaced with more conventional bearing material
  14. Automotive style seal rings for the pistons
  15. An arch (several types of different shapes and materials have been tried)
  16. GPCS firebox: a needle valve tapped off the turret supplies clinker control steam, which works quite well when coupled with the occasional stir. Secondary air was provided via control of the fire door opening and several short steel tubes which came up through the grate. This work predated the publishing of David Wardale's book, so the primary/secondary air ratios were purely guess work as no technical advice was readily accessible at that time. The tubes quickly burned out and no further work has been completed due to time constraints. However, when the tubes
    were still functional, a noticeable improvement in firing was detected. A coal crusher was also constructed to provide "scale" sized coal pieces to obtain the necessary firebed depth, once that information was available. This improved GPCS operation, but increased the occurrence of caking.

Future planned improvements included:

  1. A new arch featuring integral secondary air passages
  2. Wire coil type enhanced heat transfer surfaces in the fire tubes to improve heat transfer without interfering with tube cleaning
  3. A redesigned grate/ashpan better incorporating the findings of Wardale and the latest theories of Porta
  4. Improved insulation

In addition, initial designs are slowly being readied for a Kittson-Meyer/Garratt hybrid that will feature compounding, a Porta sectional boiler, combustion air pre-heaters, a form of dynamic braking, a newly designed valve gear system and, hopefully, some control systems that will point the way toward multiple unit steam locomotive operation.

After finishing his masters, Wolf worked in the fuel cell industry for several years. Later, he worked for noted rail enthusiast and American Coal Enterprises founder Ross Rowland, before becoming a co-founder of FMW (Fengler-Meador-Ward) Solutions, LLC. FMW is involved in both commercial and tourist industry rail work, including steam locomotive rebuilding and improvements. Wolf is also a volunteer with the Pennsylvania T-1 Steam Locomotive Trust, and is designing the all-welded boiler incorporating current code requirements and fabrication techniques for the project.

Andrew Matthews

(updated June 19, 2005) 

Andrew had sent me information on a couple of planned projects in 2002 (see below), and recently sent me info on some recent live steam progress in Australia. (Below photos by Andrew Matthews except as noted.)

Tootles 0-4-0ST


"Tootles" is a 7-1/4" gauge 0-4-0ST which was recently refitted with a new Lempor exhaust system, smokebox (all stainless steel construction) and streamlined steam circuit. The photo above shows the locomotive in pre-modified condition. Andrew provides this assessment of the modified locomotive's performance: "Suffice it say the loco in question has approximately 20% more horsepower and almost has a silent exhaust when not working hard earning a nickname similar to Wardale's modified 19D (an SAR 4-8-2) "Spooky". The following photos show the smokebox and exhaust during fabrication as well as the completed locomotive. Of great interest, Andrew notes that the Lempor exhaust has now become almost the "standard" system at their track with no less than 4 locomotives under construction with Lempor exhausts.

new smokebox with
                                            Lempor exhaust

new smokebox with
                                            Lempor exhaust

New Smokebox with Lempor Exhaust

New Smokebox with Lempor Exhaust

Lempor Exhaust Installed

"Tootles" with Lempor Exhaust

photo by David Head

Lempor-equipped Tootles on Train

Andrew submitted the attached highly detailed technical paper on the design, fabrication, and testing of the Lempor Ejector for Tootles. Highly recommended reading for live steamers and full-size steam enthusiasts alike:

Thermodynamic Improvements to an 0-4-0ST Engine in 7-1/4" Gauge

Andrew's original info follows:.

Live Steam

The following comes from Andrew Matthews, a live steamer from Australia:

"I have noticed on your website that you have included a section on "live steam" Engineers and thought that you may be interested in some projects that myself and another member of our model engineering club in South Australia, Roseworthy Railway have been working on. Between the two of us we currently have three high power designs that we are drawing for 7 1/4" gauge, One of which is under construction at present. These designs. are utilising many of the principles as explained by Porta, Wardale & Chapelon.   The wheel arrangements of these locos: are an 0-6-2T, a 2-6-0, and a 2-10-4.   The main features common to all are:  

  • Ball races to all running surfaces where at all possible.
  • Minimisation of reciprocating and unsprung weight.
  • Porta high adhesion tyre profile. :
  • Computer modeled valve gear.
  • Improved cylinder porting.
  • Mechanical cylinder lubrication.
  • Use of modern contempary alloys for many parts.
  • Use of polymeric materials for some wear and sealing components.
  • Cylinders designed with smaller clearance volumes and large steam chest volume.
  • Enlarged, enhanced steam curcuit.
  • Steel loco type boiler to A.M.B.S.C. standard.
  • Very high superheat for a model utilising full radiant superheaters (350+ deg.C)
  • Large combustion volume firebox and arch tubes
  • Steel firebox arch
  • Feedwater heating (80 to 90 deg.C)
  • Fully compensated braking system.
  • Lempor exhaust.
  • Downstream high-flow smokebox throttle
  • Steam chest and exhaust back pressure gauges.
  • Smokebox manometer.
  • Turbo feedwater pump (centrifugal). (Note: This item I am currently researching as to it's feasibility in a small scale utilising NASA data gathered from their fuel pumps.)
  • Speedometer

The next list applies only to the 2-6-0 and 2-10-4.  

  • Gas producer Combustion system.
  • Steam heated cylinders.
  • Fully compensated suspension system.
  • Digital water gauge for night running.
  • Thermocouple telemetry of firebox, smokebox & superheat temperatures.
  • Long range tenders.
  • Heavy frame superstructure to increase tractive weight.
  • Exhaust equalising piston valves :Aircraft aluminium(7075) coupling and conrods.
  • Some aluminium motion parts
  • Multiple bearing crosshead.
  • Long travel baker valve gear.(needle roller throught running on nitrided pins).
  • Max. cutoff 72.5%.  

So far the material for the frames, smokebox saddle, axleboxes,wheels,and all bearings needed have been purchased and the saddle fabricated for the 0-6-2T.The design of the 0-6-2T is about 40% complete. I hope to have that running mid 2004. My next project after that will be the 2-10-4 which is still very early in the design process.

Originally, the tank engine was to have been an 0-6-0T however this was later revised to an 0-6-2T configuration. Firstly, moment of inertia calculations revealed that with the 0-6-0T configuration there was an inordinate amount of weight and therefore energy hanging over the back end of the loco. This would likely result in much bobbing up and down which any springing system would be hard pressed to absorb. Secondly, Andrew's father for saw an illustration of Porta's 0-6-2T and decided he wanted the same outline and layout hence the similarity. The 2-10-4 is based on nothing in particular but is very much a combination of all the desirable features Andrew likes in a locomotive. American,French and Australian practice are the main influences.

Live Steam

Just a little about myself. I am middle-aged and work as a toolmaker in the medical industry. I completed year 12 studying maths, physics, chemistry,and metalwork. I have been interested in steam locos since I was about 3 years old and the affliction gets worse every year!. I am currently the secretary for our club and also the club boiler inspector. "

It certainly sounds like Andrew and his model engineering club are doing some cutting edge live steam engineering down under. Updates on their progress will be posted as they become available.

Tony Hubner

I recently received some info and drawings on a proposed 3-1/2" gauge, 3/4" = 1' scale modern live steam locomotive from Tony Hubner of Victoria BC Canada. Tony is a lifelong steam enthusiast and has built several small steam locomotives. In addition he is presently working on a steam boat and a three-wheeled steam car. Tony and his son run Meg Steam Incorporated, which produces narrow-gauge 0-4-0's for 7-1/2" gauge. Even his wife is involved in the live steam hobby, currently working on an English inside cylindered 0-4-0.

Tony's proposal is for a B-B two-truck type steam locomotive with an engine hung on the sideframes of each truck. The rear engine would be high pressure; the front would be low pressure (compound expansion). Drive to the wheels will be by roller chains. An all-copper boiler provides steam at 120 PSI, with a radiant superheater providing highly superheated steam, routed through a heat exchanger to re-heat receiver steam while slightly cooling the steam for the HP cylinders. The boiler will be coal-fired and will have a firetube barrel with a watertube firebox. The various parts are to be mounted on a frame and cased in like a diesel, with a cab at the back at a firing station at about the mid-point. The smokebox projects from the front for appearance and ease of tube cleaning.

Tony goes on to say "The ultimate end of the project would be to take it to England for the annual International Model Locomotive Efficiency Competition or IMLEC." Sketches of the proposed locomotive are included below:

Proposed 3-1/2" gauge B-B Modern Steam Locomotive

This drawing shows one of the two enclosed steam "motors" for the prosed locomotive.
A top view of the steam motor, also showing the relative sizes of the HP and LP cylinders, and the valve gear arrangement.

I look forward to hearing more from Tony on this very interesting engine proposal.

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