South African Class NG15 2-8-2

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South African Class NG15 2-8-2
SAR Class NG 15 124 (2-8-2).JPG
NG15 no. 124 on the Van Stadens river bridge, 26 October 1985
Specifications
Power type Steam
Designer South African Railways
Builder Henschel and Son
Société Franco-Belge
Serial number Henschel: 21905-21907, 24475-24479, 29585-29589 [1]
Franco-Belge: 2667-2671, 2682-2686
Model Class NG15
Build date 1931-1957
Total produced 21
Configuration 2-8-2 "Mikado"
Gauge 610 mm (2 ft)
Leading wheel
diameter
21 in (533 mm)
Driver diameter 33.875 in (860 mm)
Trailing wheel
diameter
21 in (533 mm)
Wheelbase Total: 44 ft 7.625 in (13.605 m)
Engine:
9 ft 7 in (2.921 m) coupled
20 ft 2.9375 in (6.171 m) total
Tender:
4 ft (1.219 m) bogie
15 ft (4.572 m) total
Length 54 ft 3.1875 in (16.540 m)
Height 10 ft 5 in (3.175 m)
Frame Plate frame
Axle load 6.7875 long tons (6.9 t) on 4th driver
Weight on drivers 26.4375 long tons (26.9 t)
Locomotive weight 56.6 long tons (57.5 t) w/o
70,473 lb (32.0 t) empty
Tender weight 31.2 long tons (31.7 t) w/o
28,423 lb (12.9 t) empty
Locomotive and tender
combined weight
87.8 long tons (89.2 t) w/o
98,896 lb (44.9 t) empty
Tender type 2 axle bogies
21 in (533 mm) wheels
Fuel type Coal
Fuel capacity 5.5 long tons (5.6 t)
Water capacity 2,860 imp gal (13,000 l)
Boiler 3 ft 11.75 in (1.213 m) inside diameter
13 ft 1.5 in (4.001 m) inside length
5 ft 8.875 in (1.749 m) pitch
Boiler pressure 171 psi (1,180 kPa)
Firegrate area 16.7 sq ft (1.551 m2)
Heating surface:
– Tubes
94 tubes 1.75 in (44.4 mm) diameter
15 tubes 4.71875 in (120 mm) diameter
728 sq ft (67.633 m2)
– Firebox 68 sq ft (6.317 m2)
– Total 796 sq ft (73.951 m2)
Superheater area 180 sq ft (16.723 m2)
Cylinders Two
Cylinder size 15.75 in (400 mm) bore
17.75 in (451 mm) stroke
Valve gear Walschaerts
Tractive effort 16,610 lbf (73.9 kN) at 75% boiler pressure [2]
Career
Railroad(s) Otavi Mining and Railway Company
Tsumeb Copper Corporation
South African Railways
Class Class NG15
Number in class 21
Number 17-19, 117-124, 132-136, 144-148
Nicknames Kalahari
Delivered 1931-1958
First run 1931

The South African Class NG15 2-8-2 of 1931 is a South African steam locomotive from the South African Railways era.

In 1931 three narrow gauge locomotives with a 2-8-2 Mikado wheel arrangement, similar in design to their existing Class Hd and Class NG5 locomotives, were acquired for the Otavi Mining and Railway Company in South West Africa. More were purchased for the Otavi and for the Tsumeb Copper Corporation during the subsequent years, eventually bringing the total number of these locomotives up to twenty-one by 1958.[3]

When the narrow gauge Otavi Railway was regauged to Cape gauge in 1960, all twenty-one locomotives were taken over by the South African Railways. They were classified as Class NG15 and transferred to the Eastern Cape for further service on the narrow gauge line from Port Elizabeth to Avontuur.[3]

Manufacturers[edit]

The Class NG15 2-8-2 narrow gauge steam locomotive was designed by the South African Railways (SAR) and built by Henschel and Son for the Otavi Mining and Railway Company. The company operated a 352 miles (566 kilometres) narrow gauge line across the Namib Desert from Swakopmund on the Atlantic coast to Tsumeb and Grootfontein in South West Africa (SWA, now Namibia). The first three locomotives were delivered in 1931, numbered in the range from 17 to 19, followed by three more in 1939, numbered in the range from 117 to 119.[1]

Ten more of these locomotives were built for the Otavi line by Société Franco-Belge and delivered in two batches of five in 1950 and 1953, numbered in the ranges from 120 to 124 and 132 to 136 respectively.[3]

In 1958 five more of these locomotives, once again built by Henschel, were delivered to the Tsumeb Copper Corporation, numbered in the range from TC1 to TC5, for use by the SAR in terms of an agreement between the SAR and the Corporation.[1][2][3]

Evolution[edit]

The Class NG15 2-8-2 locomotive was a development of the Otavi Class Hd and SAR Class NG5 locomotives of the Otavi Mining and Railway Company in SWA.

Otavi Class Hd[edit]

Three Otavi Class Hd 2-8-2 locomotives, built by Henschel with builder's works numbers 10720 to 10722, were supplied on lease to the Otavi Mining and Railway Company in Deutsch-Südwest-Afrika (DSWA, now Namibia) by the German government in 1912. They were numbered 40 to 42 in the Otavi fleet. These locomotives had piston valves and, at 59 long tons (59.9 tonnes), they were considerably larger than earlier main line Otavi locomotives, which were typically less than 23 long tons (23.4 tonnes) in full working order.

The Otavi Class Hd locomotives came into SAR ownership in 1923 when the Otavi Railway was nationalised. Ex Otavi Railway locomotives retained their pre-SAR running numbers, but had the prefix SW (for South West) added to their existing numbers to distinguish them from SAR narrow gauge locomotives that bore the same running numbers.

  • Number SW40 is believed to have been the last locomotive in steam on the narrow gauge Otavi Railway during September 1961, shortly before the demolition of the line was completed. It was then placed on display at Usakos station, which had become the southern terminus and works location of the narrow gauge line after World War I.
  • Number SW41 was retained with the intention to display it in a museum in Windhoek. In 1960 it was plinthed at Otjiwarongo station.
  • Number SW42 was sold as scrap in 1962.

Class NG5[edit]

Six similar Henschel built locomotives were placed in service in 1922, subsequently classified as Class NG5 by the SAR who had become responsible for operating all railways in SWA after World War I.

These locomotives had slide valves instead of the piston valves that were used on the Class Hd and the driving wheel suspension arrangement also differed. One of these Class NG5 locomotives was sent to the Avontuur line in South Africa for trials, but since it jammed on the tighter curves in the Langkloof despite having one set of flangeless driving wheels, it was returned to SWA.

All six Class NG5 locomotives were sold as scrap in 1962.

Class NG15[edit]

The drawing board work for the Class NG15 has been attributed to the one time Chief Mechanical Engineer (CME) of the Otavi Railway, a German engineer known in SWA as Mr. Peters, who was employed as a draughtsman by the SAR. The usual practice of the SAR in the steam era was to design locomotives in their own drawing offices and to then go out and find a builder.

Since the earlier trials with the Class NG5 locomotive, the sharpest curves on the Avontuur line had been eased and the experience gained in the process was taken into consideration during the design of the Class NG15. The leading pair of driving wheels of the Class NG15 have a limited amount of sideplay and are linked to the leading pony truck, while the axle of the leading driving wheels still remain parallel to the other three driving axles at all times.

This linking of a pony truck and driving axle is known as a Krauss-Helmholtz bogie, an invention of Richard von Helmholtz who was the chief designer at the Krauss works in Munich from 1884 to 1917. On standard gauge railways in Europe the inclusion of a Krauss-Helmholtz bogie has allowed the use of large 2-10-0 locomotives on sharply curved mountain sections. Some early electric locomotives also used Krauss-Helmholtz bogies.

Relocation[edit]

Number plate with "NG" prefix to number
Number plate without a number prefix

In SWA the Otavi Class Hd, Class NG5 and Class NG15 Mikado locomotives operated in a common pool. In 1960, when all the SWA narrow gauge lines were widened to Cape gauge, the Class Hd and Class NG5 locomotives were retired, while the twenty-one Class NG15 locomotives were all purchased by the SAR and relocated to the Langkloof line between Port Elizabeth and Avontuur. In the Langkloof the Class NG15 was nicknamed "Kalahari", inappropriately so since its previous stamping ground was across the Namib desert, not in the Kalahari.[3]

When it was first introduced on the Avontuur line, the Class NG15 was not allowed to work beyond Humansdorp from Port Elizabeth because of a lack of turning facilities in the Langkloof. This was rectified by the construction of a triangle at the end of the line at Avontuur, something that until then had not been required in the Langkloof since it had been the domain of bi-directional Garratt locomotives.

In the last years of steam traction on the Avontuur line the Class NG15 was unique in being the only non-Garratt steam locomotive working in the Langkloof. Outside the apple season the Class NG15 became well known for hauling the Apple Express from the Humewood Road railway station in Port Elizabeth to Loerie and back every Saturday to cater for tourists. It gained further fame when the Apple Express instituted an annual train race marathon where athletes could compete against an Apple Express filled with spectators.[4]

The builders, works numbers and SAR renumberings of the Class NG15 locomotives are set out in the table below.[1]

End of the line[edit]

During the 1970s steam traction in the Langkloof began to be replaced by diesel power with the introduction of the General Electric built Class 91-000 diesel-electric locomotive in 1973. Diesel and steam served the Langkloof together for some years, but by the mid 1980s road transport had triumphed over rail transport on the apple route as well, and the narrow gauge steam fleet was retired.[5]

Current locomotive status[edit]

Since the preservation of heritage locomotives is always dependent on the attitude and disposition of the current incumbents of positions of authority, the current status as set out below should be considered as a snapshot of the situation at a point in time, in this case circa 2007.

Service illustrated[edit]

The main picture shows Franco-Belge-built number 124, equipped with smoke deflectors, crossing the Van Stadens River with the Apple Express on 26 October 1985.

See also[edit]

References[edit]

  1. ^ a b c d Henschel-Lieferliste (Henschel & Son works list), compiled by Dietmar Stresow
  2. ^ a b South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
  3. ^ a b c d e Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 10–11, 108. ISBN 0869772112. 
  4. ^ Durrant, A E (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. p. 125. ISBN 0715386387. 
  5. ^ 100 Years of Being at the Heart of It All, Spoornet brochure, Circa 2003

Other sources[edit]

  • Namib Narrow Gauge, by S.M.Moir and H.Temple. Crittenden, The Oakwood Press.
  • 24 Inches Apart, by Sidney Moir. Janus Publishing, 1981.
  • The Locomotive in South Africa, by T.J.Espitalier and W.A.J.Day. South African Transport Services Museum, 1989.
  • The Kei Explorer 1989, South African Transport Services Museum and Railway Society of S.A.
  • The Steam Locomotive, A History, by David Ross. Tempus Publishing Limited, 2006

External links[edit]