Od102

KWStE 479 (Esslingen 3188/1901), Crailsheim depot, July 1908. Later this locomotive became DRG 13 1614 and was withdrawn in April 1928. Source: www.commons.wikimedia.org.

Side drawing of class AD. Source: Lokomotiv-Archiv Württemberg (see References).

KWStE 1506 (Esslingen 3265/1903), photographed in Tübingen in March 1903. In 1920 this engine was rebuilt and fitted with steam superheater, but was soon withdrawn from use. Source: www.commons.wikimedia.org.

KWStE 1504 (Esslingen 3263/1903), location and date unknown – possibly a factory photo. Source: Die Lokomotive September 1904.

In order to replace elderly express locomotives with the 1-2-0 axle arrangement, Königlich Württembergischen Staats-Eisenbahnen (KWStE) ordered new 2-2-0s running on saturated steam with compound engines from Maschinenfabrik Esslingen. Prototype (3027/1899) was followed by 59 examples, classed AD; they were assigned service numbers from 441 to 500. Next batch, starting from No. 1501 (Esslingen 3260/1903), featured piston valves instead of slide ones previously used and numbered 38 examples, delivered until 1907. Class designation remained unchanged. Next two engines (Esslingen 3432/1907 and 3433/1907, KWStE 1539 and 1540, later re-numbered 1541 and 1542) were fitted with single-expansion steam engines and ran on superheated steam, with boiler pressure reduced from 14 to 12 bar. As they proved superior to earlier compounds in terms of tractive effort and economy, further fifteen examples were delivered in the superheated variant, classed ADh. Last of them was Esslingen 3520/1909. Both AD and ADh had two steam domes connected with a horizontal tube of large diameter; this feature was characteristic for many Austrian engines, but seldom encountered in Germany. They were coupled with two-axle 2T10 or three-axle 3T15.5 tenders.

Despite comparatively young age of these locomotives, withdrawals started in early 1920s. DRG finally retained only 24 ADs (re-classed 13¹⁶, written off until 1928) and fourteen ADhs (re-classed 13¹⁷, withdrawn until 1932). One AD engine (No. 1506, Esslingen 3265/1903) was rebuilt in 1920 and fitted with steam superheater; further conversions, however, did not follow and No. 1506 was even not impressed into DRG. Polish railways had only one locomotive of this type, of the compound variety (former KWStE 1538, Esslingen 3431/1907 – the last example built before switching to superheated ADh). As its axle arrangement was the same as that of Prussian class P4² and overall characteristics were similar, it was initially classed P4^W, where upper index indicated the land of origin. In 1926 it was re-designated Od102-1. This locomotive was still in use in 1927, but disappeared before 1931. Not a single engine of this type has been preserved.

Main technical data^*)

No.	Parameter	Unit	Value
1.	Years of manufacture	-	1899 – 1907
2.	Total built / used in Poland	-	98 / 1
3.	Tender class	-	12C102
4.	Axle arrangement	-	2-2-0
5.	Design maximum speed	km/h	100
6.	Cylinder bore	mm	450 / 670
7.	Piston stroke	mm	560
8.	Engine rating	kW/hp
9.	Tractive effort	kG	5 500
10.	Boiler pressure	MPa	1.43
11.	Grate dimensions	m X m	2.0 m^2
12.	Firebox heating surface	m^2	9.8
13.	Distance between tube plates	mm	3 705
14.	Number of flue tubes	-	250
15.	Heating surface of flue tubes	m^2	119.3
16.	Number of smoke tubes	-	-
17.	Heating surface of smoke tubes	m^2	-
18.	Evaporating surface, total	m^2	129.1
19.	Superheater heating surface	m^2	-
20.	Diameter of drivers	mm	1 800
21.	Diameter of idlers front/rear	mm	850 / -
22.	Total weight, empty	kg	44 900
23.	Total weight, working order	kg	50 200
24.	Weight on drivers, working order	kg	29 200
25.	Weight with tender, empty	kg
26.	Weight with tender, working order	kg	82 300
27.	Maximum axle load	T	14.6
28.	Axle base (with tender)	mm	12 705
29.	Overall length (with tender)	mm	15 470
30.	Brake type	-	Westinghouse, steam

^*) Data refer to class AD only.

References and acknowledgments

- LP;

- www.pl.wikipedia.org;

- www.de.wikipedia.org;

- Lokomotiv-Archiv Württemberg by Hermann Lohr and Georg Thielmann (Transpress, Berlin, 1988).