Locomotives Compound
"Type français"

André Chapelon, toujours , Mis à jour avril 2021
André Chapelon. 26 octobre 1892 - 22 juillet 1978

Surnommé "Le petit" par ses amis et collègues

"Le travail accompli par Chapelon en transformant des locomotives qui étaient loin d'être neuves et en apportant d'incroyables améliorations à leurs performances justifie une opinion qui fait de lui le plus grand ingénieur en matière de locomotives depuis Robert Stephenson. Si cela est vrai, c'est que lui seul a semblé être capable d'embrasser l'entière signification des interactions biologiques entre les divers organes de la machine et de les traiter d'une manière scientifique, d'une façon telle qu'il était même en mesure de prédire les résultats extraordinaires qu'elles donneraient. Ses locomotives atteignirent un rapport poids / puissance et un rendement thermique jamais vu auparavant avec des locomotives à vapeur, et elles ne donnèrent pas lieu à plus d'incidents en service que ceux qui en étaient en charge ne l'avait voulu."

J.T. Van Riemsdijk & K. Brown, "The pictorial history of steam power", chapitre "Steam on the railways", Octopus Books, London 1980 and Gallery Press, 1984.

PLEASE NOTE: Every paragraph will become a link to a specific page in a (more or less) close future... These are only short introductions. More hours per day, please! Come back from time to time, I sometimes add a few details here.


The beginning of his engineering career:

His first creation: The KYLCHAP exhaust system, one of the first examples of high efficiency "fluid engine"

What was exactly his contribution and theories to compound locomotives design: Mainly the to relegate of rule-of-thumb and voodoo-inspired theories and design rules to the "cul de basse-fosse", deep holes were thrown and forgotten alive persons in ultimo punishment some centuries ago, in favour of the real scientific knowledge of his time and by a systematic checking of theories by the use of extensive tests of engines in real conditions and with the help of correctly used modern metering equipment such as, for example, high speed stroboscopic cameras he used to study steam flowing. Details and more by clicking HERE someday may be

His compound locomotives:

Very innovative work on single expansion engines too:

Narrow gauge single-expansion  locomotives designed for Brazilian's railroads after he left the S.N.C.F., french nationalized railroad company: Plans of machines for the fifties-sixties, never build, mainly because of the "All nuke", leading to "everything electrical" politic favoured by generations of our mad politicians:  Chapelon had sincerely a great admiration for industrial capacities of the United States and also for the resulting quality of U.S. engineering. Also, Timken roller bearings, cast chassis, Union Pacific type rods, mechanical firing and more yet U.S. engineering habits were parts of the specifications of the projects of Chapelon. Most of them were most than planned but fully designed up to execution drawings, even two set of cylinders for the 2 10 4's were cast as well as boiler parts built. Co-designed engines (S.N.C.F. era): Although Chapelon was really affected to be compelled to collaborate to their design because the specs. of those, imposed by S.N.C.F. management was in total contradiction with thermodynamics knowledge of the time as well as with his pre-S.N.C.F. work, successes again. The scientifical and theoretical ressearches made by Chapelon

An invention curiously unrecognized made by an assistant of Chapelon: The Willoteaux's piston valve, used on the 242 A 1, 141 E 113, and a on a great number of machines designed by other french engineers. Its major advantages if it is compared to a Trick piston valve are that it twices flow sections for bot inlet and exhaust, another being its lightness. If you know application of those in other countries, please send me some infos.

Il y en a d'autres!

Applications of Chapelon's theories and creations to other french railroad companies' locomotives:


And to other countries' locomotives by foreign designers. But why they didn't went deeper in Chapelon's way?

International opinions about the work of André Chapelon, some texts also containing interrogations and RIGHT answers about the evident negation of this work made by nationalized railroads management against unanimous technical staff opinion leading to premature withdraw of most then to the total destruction of Chapelon's highly subversive engines. Straight hooliganism

I think only some engineers and scientists around the world can figure out to how much non scientific or technical but administrative, hierarchical and thus human difficulties Chapelon was faced to all along his career. It's not only my opinion, it's shared here and elsewhere by everyone knowing the topic and seems thus reach the status of Historical truth. Unfortunately, it seems to be a constant of the life of engineers and researchers in France still today (3000 engineers left France for foreign countries in 1996, an official figure in constant and regular increase)



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