South West African Zwillinge

GSWA Zwillinge 0-6-0T
South West African Zwillinge 0-6-0T

Krauss picture of Zwillinge no. 73 B & A, c. 1899

Type and origin Power type Steam Builder Krauss & Company Henschel and Son L. Schwartzkopff Egestorf Maschinenbau Anstalt Humboldt Arnold Jung Model Zwillinge Build date 1899-1905 Total produced 182 pairs

Specifications Configuration: ​  • Whyte 0-6-0T (Six-coupled)  • UIC Cn2t Driver 3rd coupled axle Gauge 600 mm (1 ft 11 5⁄8 in) narrow Coupled dia. 580 mm (22.8 in) Wheelbase 1,300 mm (4 ft 3.2 in)  • Coupled 1,300 mm (4 ft 3.2 in) Length: ​  • Over couplers 8,200 mm (26 ft 10.8 in) pair  • Over beams 3,510 mm (11 ft 6.2 in) unit 7,200 mm (23 ft 7.5 in) pair Width 1,600 mm (5 ft 3.0 in) Height 2,700 mm (8 ft 10.3 in) Frame type Plate Adhesive weight 16,500 lb (7,500 kg) Loco weight 8,500 kg (18,700 lb) Fuel type Coal Fuel capacity 250 kg (550 lb) Water cap 830 l (180 imp gal) Firebox type Round-top  • Firegrate area 0.3 m2 (3.2 sq ft) Boiler pressure 220 psi (1,517 kPa) Heating surface:  • Tubes 14.29 m2 (153.8 sq ft) Cylinders Two Cylinder size 180 mm (7.1 in) bore 240 mm (9.4 in) stroke Valve gear Stephenson Valve type Murdoch's D slide Couplers Buffers-and-chain

Performance figures Maximum speed 20 km/h (12 mph) Power output 60 hp (45 kW) Tractive effort 12.2 kN (2,700 lbf) @ 60%

Career Operators Swakopmund-Windhuk Staatsbahn South African Railways Number in class 50+ pairs Nicknames Zwillinge or Illinge Delivered 1898-1905 First run 1898

1. Data for single engine unless indicated otherwise. 2. The total production of 182 pairs includes those built for use in other parts of the world.

The South West African Zwillinge 0-6-0T of 1898 was a narrow gauge steam locomotive from the German South West Africa era.

Between 1898 and 1905, more than fifty pairs of Zwillinge twin tank steam locomotives with a 0-6-0 wheel arrangement were delivered to the Swakopmund-Windhuk Staatsbahn (Swakopmund-Windhoek State Railway) in German South West Africa. By 1922, only two known specimens of these locomotives remained to be taken onto the roster of the South African Railways.

The first troops of the German Feldbahn-Baukommando (field railway construction commando) arrived in Swakopmund in German South West Africa (GSWA) on 11 September 1897. They were tasked to build a narrow gauge railway across the Namib Desert from Swakopmund to Windhoek, via Jakkalswater and Karibib. The 382-kilometre long (237-mile) Swakopmund-Windhuk Staatsbahn, later named the Northern State Railway or Nordbahn, was officially opened to traffic nearly five years later, on 1 July 1902.

The railway was initially intended for temporary military purposes only, to be worked by means of animal power such as Argentine mules or Cape donkeys, but steam traction was soon adopted. The track was laid on steel sleepers with 19 pounds per yard (9 kilograms per metre) rail and had very severe curves and gradients. Climbing out of the Khan River gorge, the gradient was 1 in 19 (5¼%) with curves of 180-foot radius (55-metre).

In 1905, a 14-kilometre long (9-mile) branch line was constructed from Karibib on the Nordbahn to Onguati near Usakos, where it connected with the new Otavi line from Swakopmund to Tsumeb. This created an alternative line from Windhoek to the Atlantic Ocean at times when the section through the Khan River gorge suffered from the occasional flooding. The Nordbahn section between Swakopmund and Karibib was later abandoned and, between 1911 and 1913, the 119-mile long (192-kilometre) section between Karibib and Windhoek was regauged to Cape gauge.