Dave ,thats right,but the tunnels ,bridges and loading gauge etc., was set not because of the size of locos but because as I wrote earlier that the land owning classes wanted minimal visual railway impact on their lands. Railways weren't loved by landowners in those days. They were seen as a blight on the landscape but a necessary unstoppable evil. A case of the NIMBYattitude. "not in my back yard" I wasn't around in the 1800s but thats according to the rail-history books I've read anyway. MARK.... just copied this extract on Andre Chapelon's locomotive in question...QUOTE : SNCF 242A1
The lone SNCF 242A1 prototype, rebuilt from an unsuccessful Etat three-cylinder 4-8-2 simple expansion locomotive 241.101 into a 4-8-4 compound locomotive. This remarkable locomotive achieved both extraordinary power outputs and efficiencies in coal and water use,[18] but no further examples were built as SNCF focused on electric traction for its future motive power development. 242A1 was trialed on many test runs which showed that this locomotive was equal in power output as the (then) existed SNCF electric locomotives. Here, for the first time in Europe, was a steam locomotive with a 20-ton axle load which not only was at least as powerful as the most powerful high-speed electric locomotive but which could repeatedly develop its maximum power without any mechanical trouble. Developing 5,300 ihp (4,000 kW)[vague] in the cylinders and with 65,679 lbf (292.15 kN) of peak tractive effort, 46,225 lbf (205.62 kN) mean tractive effort—nothing in Europe could touch it. While Nr.242A1 being tested the electrical engineers were designing the locomotives for 512 km (318 mi) Paris - Lyon line, which was to be electrified. An electric locomotive slightly more powerful than the successful Paris - Orléans 2-D-2 type electric locomotive was contemplated. But when the test results of the test of 242A1 become known, the design was hurriedly changed to incorporate the maximum capacity possible within a 23-ton axle load, and then the 144-ton 9100 class http://commons.wikimedia.org/w...:SNCF_Class_2D2_9100 was produced with over 1.000 hp (0.746 kW) more than the originally designed. Thus the performances of the Mistral and other heavy passenger express trains would not have been so outstanding if 242A1 had not existed.
Therefore Andre Chapelon indirectly influenced French electric locomotive design. In addition 242A1 demonstrated the suitability of the Sauvage-Smith system of compounding for French conditions and the designs for future French steam locomotives, prepared but unfortunately stopped, were of Sauvage-Smith compounding system.
In ordinary service 242A1 was allocated at Le Mans depot (SNCF Region-3 Ouest and hauled express trains in 1950 - 1960 between Le Mans and Brest 411 km. Nr. 242A1 did not last long, it was withdrawn from service and hurriedly scrapped in 1960.
Builder details:
- SNCF 242A1 2D2-h3v (1)600x720 (HP) / (2)680x760 (LP) 1950 148 tons Marine Homecourt 339 / 1945 (rebuilt from 2D1-h3 Fives Lille 4800 / 1932) Written off from books 10 / 1960.