SNCF 242A1

The 242 A 1 is a prototype SNCF steam locomotive which was put into service in 1946. This locomotive is considered the masterpiece of André Chapelon.
== History ==
Indeed, it results from the transformation of the Mountain 241-101 from the State Railways designed by OCEM at the request of Raoul Dautry for the State Railway Company network and built in 1932 by the Fives workshops in Lille. It was equipped with a three-cylinder single-expansion engine, a stoker and distribution by “Renaud” type rotary cam valves. Faced with the poor performance of the locomotive, it did little service either at the Batignolles depot or at the Le Mans depot. When the SNCF was created, this machine was renumbered 241B 101. The engineer André Chapelon, who had in no way participated in its definition, proposed in 1938 to improve it according to his plans and directives.
The lone prototype, numbered 242A1, of the Société Nationale des Chemins de fer Français (SNCF) was one of the five known classes of three-cylinder 4-8-4 locomotives. It also had the distinction, along with an experimental high pressure locomotive of the New York Central Railroad in the United States, of being one of the two compound 4-8-4s. It was rebuilt by Andre Chapelon from the unsuccessful 1932 three-cylinder 4-8-2 simple expansion locomotive no. 241.101 of the Chemins de Fer de l'État into a 4-8-4 compound locomotive. This remarkable locomotive achieved extraordinary power outputs and efficiency in coal and water consumption, but no further examples were built since the SNCF focused on electric traction for its future motive power development.
No. 242A1 was put through trials on many test runs which showed that this locomotive was equal in power output to the existing SNCF electric locomotives at the time. Here, for the first time in Europe, was a steam locomotive with a 20 tonnes (19.7 long tons; 22.0 short tons) axle load which was not only at least as powerful as the most powerful existing high-speed electric locomotive, but which could repeatedly achieve its maximum power without any mechanical trouble. Developing 5,300 indicated horsepower (4,000 kilowatts) and with 65,679 pounds-force (292 kilonewtons) of peak tr active effort and 46,225 pounds-force (206 kilonewtons) of mean tr active effort; nothing in Europe could match it.
While no. 242A1 was being tested, electrical engineers were designing the locomotives for the 512-kilometer-long (318-mile) line between Paris and Lyon, which was to be electrified. An electric locomotive that was to be slightly more powerful than the successful Paris to Orléans 2-D-2 type electric locomotive was being contemplated. When the test results of no. 242A1 became known, however, the design was hurriedly changed to incorporate the maximum capacity possible with a 23 tonnes (22.6 long tons; 25.4 short tons) axle load, resulting in the 144 tonnes (141.7 long tons; 158.7 short tons) 9100 class with a power output of more than 1,000 horsepower (750 kilowatts) more than that of the original design. 
The performances of the Mistral and other heavy passenger express trains would therefore not have been so outstanding if no. 242A1 had not existed and Andre Chapelon therefore indirectly influenced French electric locomotive design. In addition, no. 242A1 demonstrated the suitability of the Sauvage-Smith system of compounding for French conditions and the designs for future French steam locomotives that were prepared but never produced, were to make use of the Sauvage-Smith compounding system. This took just 3 minutes to reach 97 kph (60 mph) from a standing start when pulling a train weighing over 600 tons. Despite exceeding what his design has promised, this engine's future is always doomed. 
In service, no. 242A1 was allocated to the Le Mans depot and, between 1950 and 1960, it hauled express trains over the 411 kilometres (255 miles) between Le Mans and Brest. It did not remain in service long, however, and was withdrawn and was scrapped quietly in 1960 to avoid any embarrassment.
Category:SNCF locomotives
Category:4-8-4 locomotives
Category:4-8-4 steam locomotives
Category:Locomotives
Category:Steam locomotives
Category:Tender locomotives
Category:Prototype locomotives
Category:Scrapped locomotives
Category:Passenger locomotives
Category:French steam locomotives
Category:French locomotives