The 242 AT was the first of four series of 4-8-4T tank locomotives that the PLM had built to accelerate the suburban trains that departed from the Gare de Lyon in Paris. They replaced the tank locomotives 232 AT and 232 BT. A total of three manufacturers delivered 120 locomotives between 1926 and 1929.

They had a Belpaire firebox with a steeply sloped grate between the wheels of the third and fourth driving axles. Power was transmitted via four compound cylinders of the de Glehn system. Over the years it often became apparent that the frames were too weak for the long wheelbase.

They were classified by the SNCF as 5-242 TA. After the war, they were distributed across several regions and received region-specific adjustments, for example smoke deflectors. They were decommissioned by 1968.

Schematic drawing with dimensions

Die Lokomotive, June 1935

From 1933, the ČSD had tank locomotives built by Škoda and ČKD for express trains in the mountains. They received assemblies from existing locomotives. The chassis was designed in such a way that curves with a radius of 150 meters or more could be negotiated. When the Sudetenland was annexed, 15 locomotives came to the Reichsbahn and became the class 68⁰. In Czechoslovakia they were only retired between 1973 and 1981.

For suburban trains, the ČSD developed a tank locomotive with a 4-8-4 wheel arrangement, which was developed using the latest design principles. It was based on the single class 475.0 tank locomotive and the four class 476.0 tank locomotives. At the time of delivery, they were the largest tank locomotives in Europe.

The boiler had a combustion chamber, a mechanical stoker, a rocking grate and a double Kylchap blastpipe. There were also Trofimoff valves, power reverser and roller bearings. The three cylinders worked with simple expansion. Visually, the locomotives were clearly reminiscent of the German standard locomotives, especially with their Witte smoke deflectors and the steps at the front.

The first 38 locomotives were put into service as class 476.1. Due to the water reserves, they were very rear-heavy, which caused an uneven distribution of the loads on the driving axles. On the remaining 22 locomotives, the rear storage tanks were shortened by 30 cm and the side water tanks were lengthened to the front. To optimize the boiler's performance, the combustion chamber has been lengthened, thereby shortening the tubes and flues. These locomotives were designated as the class 477.0 and all earlier ones were rebuilt in the same way.

They were primarily used in the area of large cities in front of passenger trains, but also in front of freight trains if necessary. During test runs, speeds of up to 115 km/h were reached and 96 km/h were possible on flat land with an 800-tonne train. The same weight could be transported at 0.5 percent at 53 km/h and at one percent at 35 km/h.

The class 477.0 was not phased out until 1971. With the electrification of many lines and the introduction of more and more diesel locomotives, they gradually disappeared until 1981 when none were in use anymore. Three are still operational today, the 477.060 had even been in the Augsburg railway park for a few years since 2009.