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Real steam


No steam locomotive ever built included all the available proven techniques to maximize its performance in service.
This fact, more than any other factor, is what lead to the downfall of world steam.

Developments in a bird's view

On this page I try to give a brief overview of the developments since 1930. These developments continue until today in a small but devoted community.

André Chapelon (1892 - 1978)

In the era from 1930-1950 Chapelon has proved in France on large scale that raising a steam locomotive's efficiency by as much as 30% was feasible. Remarkably he never designed a new French locomotive but he always proved his ideas by rebuilding existing designs.

His most important points (but certainly not all):

Better gas flow   Flowing gas undergoes friction from the tube sides. Use of wide steam tubes and avoiding sharp bends, thus allowing free flowing of the hot gases ,lessened the flow resistance dramatically
Higher pressure in the cylinders   To his horror Chapelon noted that engineers had the habit of throttling down the steam pressure to control the locomotive. Driving with low pressure and large cut-off is for various reasons far less efficient than driving with high pressure and low cut-off. Retraining engineers had tremendous effect on efficiency.
Less condensation   Condensation of steam in the cylinders causes loss of power. By introducing steam channels in the block that were flushed with used steam condensation was reduced to a minimum.
Multiple expansion   By consistently using double (or even triple) expansion and mathematically optimizing the multiple expansion system he achieved amazing results. He proved that multiple expansion, as opposed to general belief, was quite suitable for superheated steam locomotives.
Less counter pressure in the exhaust system   To raise draft on the fire used steam from the cylinders was used to create a "vacuum" in the smokebox and to eject the hot gases through the stack. The operation of this used steam jet in the exhaust system caused back pressure in the cylinders thus causing loss of power. Chapelon designed an exhaust system (Kylchap ejector) that had minimum back pressure and left more power for the engine.

One of the disadvantages of Chapelon's work is that it often necessitates radical reconstruction (almost to down right rebuilding) of the locomotive to achieve the desired results.

Livio Dante Porta (1922 - 2003)

This apprentice of Chapelon took development steps further. His work, contrary to Chapelon's, is tuned toward more readily applicable improvements rather than complete rebuilding, because he already lived in a time were such rebuildings were not easily undertaken anymore.

Further optimization of the exhaust system   By developing the Lempor exhaust he was able to take Chapelon's calculations and results one step further. To date the Lempor exhaust system is probably the most efficient exhaust system so far.
Improvement of the internal water treatment


Porta developed a water treatment with environmentally friendly chemicals to make water better suitable as boiler water.

    • scale did not settle on tubes and firebox but remained in suspension.
    • uneven heating or local overheating due to scale forming became a thing of the past
  • pitting or hidden corrosion was minimized

  • priming of the boiler (the foaming of water that caused the escaping steam to drag water along out of the boiler into the super heater and in bad cases into the cylinders) was greatly reduced
  • heat transfer through metal to the water was hindered by, thus improving the overall thermal efficiency of the boiler

This all leads to less boiler wash outs, less off time, less maintenance, less repairs and eventually to longer lifetime of boiler and machine.

Gas Producer Combustion System  

The GPCS is a series of measures in the firebox to improve firing in solid fuel boilers. Air is not sucked through the fire bed but is mainly led from air ducts over the fire causing turbulence and mixing air and fire gases thoroughly. A GPCS leads

  • to less flight of small unburnt fuel particles
  • complete combustion of gases
  • less ejection of soot and cinders, so consequently less chance for line side fires
  • less wear on the surfaces in the boiler, including the rear tube sheet, rear tube ends, super heater ends, and internal parts of the smokebox by the abrasive action of the cinders
  • less clinkering
  • more even heating, resulting in less stress in the firebox,
  • less chance of burn out

this all meaning a far less demanding job for the fireman

Both Chapelon and Porta have founded their improvements on methodical reasoning and mathematical calculations.

David Wardale

The "Red Devil" a SAR Class 25, modified to the principles of modern steam by David Wardale (© Malcolm Best, under Creative Commons Attribution-Share Alike 3.0 Unported license)

David Wardale worked on the improvement of various steam locomotive in South Africa and China. His book"The Red Devil and Other Tales from the Age of Steam" is considered by many as the definitive work on modern steam. He was lately involved in the 5AT project which unfortunately has been suspended due to lack of funds.

Various developments

Roller bearings  

Roller bearings have gradually taken their place in steam locomotive building since the mid 40's. They offer

  • less rolling resistance and consequently more power available to pull the train or less fuel consumption
  • less maintenance
  • less chance of hot bearings
  • less attention for greasing and oiling needed
Electric preheating  

The classical steam locomotive had to be lit hours in advance. Steam had to raised carefully and slowly to minimize stresses in the firebox and boiler. The modern steam locomotive can be heated by an external electrical heating device resulting in

  • a short heating time and fast operation readiness
  • raising steam without attendance
  • less stress in boiler and firebox by more even heating, the turbulence of the water spreads the heat evenly in the boiler
  • no local pollution
  • no inconvenience for the neighboring houses during the night (or by day for that matter ;-)
  • immediate readiness of steam to operate the various pumps and installations of the locomotive to prepare it for operation.
Oil firing  

Oil firing is known and used since the 50's. Current technology enables a better and more efficient burning of liquid fuels.


  • a better availability (at least in the so called "developed" countries) of liquid fuels at a lower price per unit of heat
  • lower price per kilometer by better fuel efficiency
  • no more fuzz of loading, shoveling or stocking coal and worrying about the quality of the fuel
  • less maintenance to the firebox
  • better tuning of the fire to the need for steam
  • one man operation is possible