Württemberg AD

The Württemberg AD was a German steam locomotive built for the Royal Württemberg State Railways. It was an express train engine with a 4-4-0 wheel arrangement and was built from 1899 by the Maschinenfabrik Esslingen ('Esslingen Engineering Works'). Up to that point the railway only had increasingly elderly locomotives with a 2-4-0 configuration.

Württemberg AD/ADh DRG Class 13.16/13.17
1506 at Tübingen in March 1905
Number(s)	AD: KWStE 451–500, 1501–1538 DRG 13 1601–1624 ADh: KWStE 1541–1557 DRG 13 1701–1714
Quantity	115
Manufacturer	Maschinenfabrik Esslingen
Year(s) of manufacture	1899–1909
Retired	1932
Wheel arrangement	4-4-0
Axle arrangement	AD: 2′B n2v ADh: 2′B h2
Length over buffers	15,427 mm (50 ft 7 1⁄4 in)
Service weight	50.2 tonnes (49.4 long tons; 55.3 short tons)
Adhesive weight	29.2 tonnes (28.7 long tons; 32.2 short tons)
Axle load	14.6 tonnes (14.4 long tons; 16.1 short tons)
Top speed	100 km/h (62 mph)
Driving wheel diameter	1,800 mm (70 7⁄8 in)
Leading wheel diameter	850 mm (33 1⁄2 in)
No. of cylinders	Two
Cylinder bore	ADh: 490 mm (19 5⁄16 in)
LP cylinder bore	AD: 670 mm (26 3⁄8 in)
HP cylinder bore	AD: 450 mm (17 11⁄16 in)
Piston stroke	560 mm (22 1⁄16 in)
Boiler Overpressure	AD: 14 kg/cm2 (1.37 MPa; 199 psi) ADh: 12 kg/cm2 (1.18 MPa; 171 psi)
Grate area	2.00 m2 (21.5 sq ft)
Evaporative heating area	129.10 m2 (1,389.6 sq ft)
Tender	wü 2 T 10, wü 3 T 15.5
Water capacity	10.0 or 15.5 m3 (2,200 or 3,400 imp gal; 2,600 or 4,100 US gal)

The vehicles were equipped with a two-cylinder, compound engine. The most striking feature was the large, horizontal pipe connecting the two steam domes. Ninety eight engines of this class were built by 1907; they initially had flat slide valves, but from 1903 piston valves were installed.

In 1907 two locomotives were tested with two-cylinder, superheated steam engines. This reduced the boiler overpressure to 12 kg/cm² (1.18 MPa; 171 psi) and generated an improvement in performance of about 20%. As a result, 17 more locomotives were built to this configuration up to 1909 and were designated as Class ADh.

Both classes began to be retired in the early 1920s.

The Deutsche Reichsbahn took over 24 of the compound locomotives as DRG Class 13.16 with numbers 13 1601 to 13 1624, and 14 superheated locomotives as DRG Class 13.17 with numbers 13 1701 to 13 1714. The first ones were retired in 1928, the last in 1932.

The locomotives were equipped with Württemberg wü 2 T 10 and wü 3 T 15,5 tenders.