South African Class NG5 2-8-2

South African Class NG5 2-8-2

Class NG5, circa 1960

Type and origin Power type Steam Designer Henschel and Son Builder Henschel and Son Serial number 18578-18583 Model Class NG5 Build date 1921 Total produced 6

Specifications Configuration 2-8-2 "Mikado" Gauge 600 mm (1 ft 11 5⁄8 in) narrow gauge Leading dia Driver diameter Trailing dia Wheelbase Total: 38 ft 6.625 in (11,751 mm) Engine: 9 ft 7 in (2,921 mm) coupled 17 ft 0.6875 in (5.20 m) total Tender: 3 ft 3.375 in (1,000 mm) bogie 11 ft 5.75 in (3,499 mm) total Length 49 ft 9.25 in (15,170 mm) Height 10 ft 9.9375 in (3,300 mm) Frame Plate frame Loco weight 32.85 long tons (33.4 t) Tender weight 25.5875 long tons (26.0 t) Loco & tender weight 58.4375 long tons (59.4 t) Tender type 2 axle bogies wheels Fuel type Coal Fuel capacity Water cap 2,860 imp gal (13,000 L) Boiler 3 ft 11.75 in (1,213 mm) inside diameter 13 ft 1.5 in (4,000 mm) inside length 5 ft 8.875 in (1,749 mm) pitch Boiler pressure Firegrate area 16.7 sq ft (1.551 m2) Heating surface 948 sq ft (88.072 m2)  • Tubes 114 tubes diameter 12 tubes ext dia 880 sq ft (81.755 m2)  • Firebox 68 sq ft (6.317 m2) Superheater:  • Heating area 145 sq ft (13.471 m2) Cylinders Two Cylinder size bore stroke Valve gear Walschaerts Loco brake Vacuum Train brakes Vacuum

Performance figures Tractive effort 16,610 lbf (74 kN) at 75% pressure

Career Operators South African Railways Class Class NG5 Number in class 6 Numbers NG71-NG76 Delivered 1922 First run 1922 Withdrawn 1960

The South African Railways Class NG5 2-8-2 of 1922 is a narrow gauge steam locomotive.

In 1922 the South African Railways placed six narrow gauge steam locomotives with a 2-8-2 Mikado type wheel arrangement in service on the Otavi branch in South West Africa. When a system of grouping narrow gauge locomotives into classes was eventually introduced somewhere between 1928 and 1930, they were classified as Class NG5.

Manufacturer

Six narrow gauge steam locomotives with a 2-8-2 Mikado type wheel arrangement were built for the South African Railways (SAR) by Henschel and Son in Germany in 1921. They were built to the same design as the three Class Hd locomotives that had been built in 1912 for the German administration in Deutsch-Südwest-Afrika (DSWA, now Namibia) for leasing to the Otavi Mining and Railway Company. The locomotives, numbered in the range from NG71 to NG76, were delivered in 1922.

Characteristics

Like their predecessor Class Hd, they were superheated, with Walschaerts valve gear and outside plate frames. The new locomotives differed from the Class Hd in having different boilers, which were of the same dimensions but with a different tube arrangement and, consequently, a slightly reduced total heating surface.

In keeping with SAR practice at the time, they had vacuum train brakes instead of the air brakes that the Class Hd was equipped with. In addition they had slide valves instead of the piston valves used on the Class Hd. Their driving wheel suspension arrangement also differed.

Classification

In service, these six locomotives and the three Class Hd locomotives were operated in a common pool. The system of grouping narrow gauge locomotives into classes was only adopted by the SAR somewhere between 1928 and 1930 and at that point these six locomotives as well as the three Class Hd locomotives were all classified as Class NG5.

Service

The 1922 vintage Class NG5 was placed in service on the 352 miles (566 kilometres) narrow gauge line from Swakopmund on the Atlantic coast to Tsumeb and Grootfontein in South West Africa (SWA). They spent their whole service life in SWA, except for a brief period when one of them was sent to the Avontuur line in the Eastern Cape for trials. However, since it jammed on the tighter curves in the Langkloof despite having one set of flangeless driving wheels, it was soon returned to SWA.

They were all withdrawn from service when the SWA system was regauged to Cape gauge in 1960. Since they were unsuitable for use in the Langkloof, all six 1922 vintage Class NG5 locomotives were sold as scrap in 1962.