The reference for locomotives and railcars
French State Railway 242 A
France | 1943 | only one produced
242 A 1 on an old postcard
242 A 1 on an old postcard

When the French State Railways were already planning the complete conversion to electric and diesel locomotives, André Chapelon designed an express steam locomotive with an output of 4,000 hp at the drawbar. As a basis, he used the Est 241-101, which had not made it into series production, and modified it accordingly. He converted the simple three-cylinder engine into a compound engine and provided the locomotive with optimized steam pipes and a Kylchap exhaust system.

The result was the most powerful steam locomotive ever built in Europe, producing between 5,230 and 5,430 hp (3,900 and 4,048 kW), depending on the source. While the original locomotive only had 2,550 hp on the drawbar, over 4,000 hp were now achieved and express trains heavier than 1,000 tonnes could be pulled. Up to 158 km/h were reached on test runs and approval was given for 130 km/h. The machine was put into service in 1951, but was only used sporadically due to the decision to electrify the network and was scrapped in 1961.

Axle config4-8-4 (Northern) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Length89 ft 8 in
Length loco58 ft 3 7/16 in
Empty weight299,387 lbs
Service weight326,284 lbs
Adhesive weight185,188 lbs
Total weight496,040 lbs
Axle load46,297 lbs
Water capacity8,982 us gal
Fuel capacity25,133 lbs (coal)
Power sourcesteam
Indicated power5,230 hp (3,900 kW)
Optimal speed59 mph
Top speed81 mph
Starting effort56,787 lbf
with start valve68,144 lbf
Power Plant
Driver diameter76.8 in
Boiler pressure296 psi
Expansion typecompound
Cylindersthree, HP: 23 5/8 x 28 3/8 in
and LP: 26 3/4 x 29 15/16 in
Grate area53.8 sq ft
Evaporative heating area2,720 sq ft
Superheater area1,294 sq ft
Total heating area4,014.1 sq ft
Calculated Values
steam locomotive
André Chapelon
last changed: 08/2023

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