The S 2/5 was an Atlantic express locomotive that was developed at the beginning of the century together with the S 3/5. Both implemented learnings from the locomotives borrowed from Baldwin and were the first German locomotives with a continuous bar frame.
The bar frame consisted of much thicker metal than the plate frames used up until then and therefore had a lower installation height. The result was not only a sleeker look with see-through undercarriage, but also much better accessibility to the internal parts of the chassis. Especially in locomotives with more than two cylinders, the inside cylinders could be serviced more easily.
Compared to the 1,870 mm coupled wheel diameter of the S 3/5, the wheels of the S 2/5 had a diameter of 2,000 mm, making it suitable for longer journeys on flat land at high speed. Due to the larger diameter, however, the last coupled axle had to be replaced with a trailing axle, which reduced the possible traction. As a result, the S 2/5 was able to run up to 135 km/h in tests, but the permitted speed was set at 110 km/h like its sister. Initially it also pulled high-value international trains, but soon its tractive power was no longer sufficient for the increased loads and so it was replaced by the S 3/5 and S 3/6.
Schematic drawing with dimensions
Die Lokomotive, May 1906
A total of ten engines were delivered in 1904, which were relocated to the Palatinate network in 1910. After it was founded, the Reichsbahn still registered half of the stock, which was given the numbers 14 141 to 14 145 in 1925. They were phased out in the next two years.