Bavarian S 2/5

The Class S 2/5 express locomotives of the Royal Bavarian State Railways (Königlich Bayerische Staats-Eisenbahnen) were the first steam engines in Germany to be built with full-length bar frames (durchgehendem Barrenrahmen). The prototypes for this type of frame were the two locomotives imported in 1900 from Baldwin Locomotive Works in the USA, that had been similarly classified as the S 2/5.

Bavarian S 2/5 DRG Class 14.1
Bavarian S 2/5
Number(s)	DRG 14 141–145
Quantity	10
Manufacturer	Maffei
Year(s) of manufacture	1904
Retired	by 1927
Wheel arrangement	4-4-2
Axle arrangement	2'B1' n4v
Type	S 25.16
Track gauge	1,435 mm (4 ft 8 ^1⁄2 in)
Length over buffers	19,275 mm
Empty weight	62.2 6
Service weight	68.6 t
Adhesive weight	32.0 t
Axle load	16.0 t
Top speed	110 km/h
Driving wheel diameter	2,000 mm
Leading wheel diameter	950 mm
Trailing wheel diameter	1,206 mm
No. of cylinders	4
LP cylinder bore	570 mm
HP cylinder bore	340 mm
Piston stroke	640 mm
Boiler Overpressure	16 bar
No. of heating tubes	278
Grate area	3.27 m^2
Radiative heating area	14.5 m^2
Tube heating area	191 m^2
Evaporative heating area	205.50 m^2
Tender	Bavarian 2'2' T 21
Water capacity	21.0 m^3
Fuel	7 t
Train control	Walschaerts (Heusinger)

History

In 1904, Maffei built ten engines that shared many of the same components as the S 3/5, which was developed in parallel. For example, they did not use a wider firebox, which would have been possible given the wheel arrangement, in order to be able to use one that could be used on the S 3/5. So the firebox was only around 90 mm wider than the bar frame of the locomotive. For manufacturing reasons the sole bar was still not made of one piece, but forged from several bars.

For the first time in Bavaria a driving wheel diameter of 2,000 mm was chosen instead of the 1,870 mm diameter hitherto the norm for express train locomotives. Like the locomotives imported from the United States, they had a four-cylinder compound engine. However the usual European (von Borries) configuration with two inside and two outside cylinders was used instead of the Vauclain compound system.

On test runs, one of the locomotives reached 135 km/h; in normal use, 110 km/h was the top speed. The locomotives were initially stabled at Munich I shed and hauled such famous trains as the Orient Express and the North-South Express, amongst others. But, as on all German Atlantics the traction of the two driven axles was soon insufficient. The S 2/5 was not blessed with a long time in service, although the locomotive had very good riding qualities and was seen as a genuinely fast runner.

In 1910 the locomotives went across to the Palatine network to Ludwigshafen shed and also to the Nuremberg repair shop. In 1922 only eight S 2/5 engines remained. The Deutsche Reichsbahn took over just five locomotives as the Class  14.1, numbered 14 141–145. They were retired in 1927.

The locomotives had Bavarian 2'2' T 21 tenders.

See also

• Royal Bavarian State Railways
• List of Bavarian locomotives and railbuses