The reference for locomotives and railcars


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Prussian S 4
German Reichsbahn class 135
Germany | 1902 | 104 produced
„Locomotives of all Nations”, Sonderausgabe Locomotive Magazine Weihnachten 1901

In order to take advantage of superheated steam technology that was just emerging, an example of the S 3 was converted in 1898 to test this technology. It was the world's first express locomotive of this type and the flame tube superheater used was the first variant of the superheater to be used. This consisted of a 445 mm thick tube, which was arranged in the boiler barrel and contained the tube bundle for superheating the steam.

Since this first construction was not yet completely convincing, but showed a very promising approach, two more examples were converted over the next two years. These had the superheater in the smoke box and ultimately led to the production engines of the S 4.

In 1902, production of these engines began, which in reality were completely new designs. Although they weighed the same as the S 3, the power could be increased by about a third. While the predecessor could pull 320 tonnes at 75 km/h on the level, it was now 80 km/h with 420 tonnes. In tests with only three cars, an S 4 was even able to reach 136 km/h. From 1906, a smoke tube superheater was finally used, which later became state-of-the-art.

Prototype with smokebox superheater
Prototype with smokebox superheater
Die Lokomotive, June 1910

Nevertheless, production was ended in 1909 after just 104 units, since the underlying design was already outdated and the S 6 was a much more modern locomotive on offer. As with other, older locomotives, the Reichsbahn took over significantly fewer locomotives in 1925 than had been envisaged in the original renumbering plan a few years earlier. The number had already halved about five years after the end of production, so that the Reichsbahn just planned 44 engines as 13 501 to 13 544. In the end, just four locomotives were taken over, which had also disappeared by 1927.

Variantsmokebox superheatersmoke tube superheater
ManufacturerBorsig, Henschel, Linke-Hofmann, Humboldt
Axle config4-4-0 (American) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Length59 ft 8 15/16 in
Wheelbase23 ft 7 7/16 in
Fixed wheelbase8 ft 6 3/8 in
Service weight120,086 lbs110,672 lbs
Adhesive weight70,548 lbs70,327 lbs
Total weight228,112 lbs
Axle load35,274 lbs35,164 lbs
Water capacity3,434 us gal
Fuel capacity11,023 lbs (coal)
Power sourcesteam
Indicated power952 hp (710 kW)987 hp (736 kW)
Optimal speed30 mph31 mph
Top speed62 mph
Starting effort20,257 lbf
Power Plant
Driver diameter78 in
Boiler pressure174 psi
Expansion typesimple
Cylinderstwo, 21 1/4 x 23 5/8 in
Grate area24.4 sq ft25 sq ft
Firebox area114.1 sq ft114.6 sq ft
Tube heating area972.4 sq ft1,011.3 sq ft
Evaporative heating area1,086.5 sq ft1,125.9 sq ft
Superheater area331 sq ft365 sq ft
Total heating area1,417.5 sq ft1,490.9 sq ft
Calculated Values
steam locomotive
last changed: 01/2022

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