South African Class NG G12 2-6-2+2-6-2

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South African Class NG G12 2-6-2+2-6-2
SAR Class NG G12 57 (2-6-2+2-6-2).jpg
Class NG G12 no. 57, circa 1930
Type and origin
Power type Steam
Designer Beyer, Peacock and Company
Builder Société Franco-Belge
Serial number BP 6365-6366, FB 2506-2507 [1][2]
Model Class NG G12
Build date 1927
Total produced 2
Specifications
Configuration 2-6-2+2-6-2 "Double Prairie" Garratt
Gauge 2 ft (610 mm) narrow gauge
Leading wheel
diameter
21 in (533 mm)
Driver diameter 30 in (762 mm)
Trailing wheel
diameter
21 in (533 mm)
Wheelbase Total: 40 ft (12.192 m)
Engine units:
5 ft 9 in (1.753 m) coupled
12 ft 7.5 in (3.848 m) total
Length 45 ft 10 in (13.970 m)
Height 10 ft (3.048 m)
Frame Plate frame, 21 ft (6.401 m) between pivot centres
Axle load 3.75 long tons (3.8 t) per driver
Weight on drivers 22.5 long tons (22.9 t)
Locomotive weight 36 long tons (36.6 t)
Fuel type Coal
Fuel capacity 2 long tons (2.0 t)
Water capacity 800 imp gal (3,600 l) front
200 imp gal (910 l) rear
Boiler 3 ft 6.375 in (1.076 m) inside diameter
8 ft 6 in (2.591 m) inside length
5 ft 3 in (1.600 m) pitch
Boiler pressure 180 psi (1,240 kPa)
Firegrate area 10.5 sq ft (0.975 m2)
Heating surface:
– Tubes
73 tubes 1.75 in (44.4 mm) diameter
10 tubes 5.25 in (133 mm) diameter
378.5 sq ft (35.164 m2)
– Firebox 45 sq ft (4.181 m2)
– Total 423.5 sq ft (39.344 m2)
Superheater area 97.5 sq ft (9.058 m2)
Cylinders Four
Cylinder size 8.5 in (216 mm) bore
16 in (406 mm) stroke
Valve gear Walschaerts
Performance figures
Tractive effort 10,400 lbf (46 kN) at 75% pressure
Career
Operator(s) South African Railways [3]
Class Class NG G12
Number in class 2
Number(s) 56-57
Delivered 1927
First run 1927
Withdrawn 1952

The South African Class NG G12 2-6-2+2-6-2 of 1927 is a South African steam locomotive from the South African Railways era.

In 1927 the South African Railways placed two Class NG G12 Garratt articulated steam locomotives with a 2-6-2+2-6-2 Double Prairie type wheel arrangement in service. They were the smallest Garratt locomotives to see service in South Africa.[3][4]

Manufacturer[edit]

The South African Railways (SAR) placed orders for two light weight narrow gauge Garratt locomotives with a 2-6-2+2-6-2 Double Prairie type wheel arrangement with Beyer, Peacock and Company in 1927. Beyer, Peacock sub-contracted their construction and the two locomotives were delivered by the Belgian locomotive builders Société Franco-Belge later in 1927. They were allocated separate works numbers by Beyer, Peacock as well as Franco-Belge, and were numbered NG56 and NG57 upon delivery.[1][2][3][4]

The locomotives were superheated, with outside plate frames, Walschaerts valve gear and round top fireboxes. Designed for light 20 pounds per yard (9.9 kilograms per metre) rail, their lightness of construction made them popular with the fitters who had to maintain them.[4]

Classification[edit]

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 two locomotives were designated Class NG G12, with the letters "NG" indicating narrow gauge and the "G" prefix to the classification number identifying it as a Garratt locomotive.[3][4]

Service[edit]

The Class NG G12 was obtained for utilisation on the new narrow gauge lines from Fort Beaufort to Seymour and from Upington to Kakamas, since it had become obvious that the Class NG6 Lawleys that had been used during the construction of these lines would not be able to cope with the expected daily traffic once the lines were opened.[4]

Upon arrival, the two locomotives were first put to work in South West Africa (SWA) for a trial period, after which no. NG56 was assigned to Upington and no. NG57 to Fort Beaufort.[4]

While they both mostly remained with their assigned depots, they were at times temporarily assigned to branches in other areas of the country to assist with seasonal demands on those branches. In 1940, when the Seymour branch was regauged to Cape gauge, no. NG57 was also assigned to the Kakamas branch. Both remained there until 1949, when the Kakamas line was also widened to Cape Gauge and they were returned to SWA for a brief period. From there, no. NG56 was allocated to Port Shepstone in Natal and no. NG57 to Humewood Road in Port Elizabeth, where they remained until both were withdrawn from service in 1952.[4]

Both locomotives were subsequently sold to the Rustenburg Platinum Mines, no. NG56 in 1952 and no. NG57 in 1953, where they were renumbered 5 and 6 respectively. They were both scrapped in 1959.[5]

See also[edit]

References[edit]

  1. ^ a b Hamilton, Gavin N., The Garratt Locomotive - Garratt Locomotives produced by Beyer, Peacock, retrieved 10 November 2012 
  2. ^ a b Hamilton, Gavin N., The Garratt Locomotive - Garratt Locomotives from Other Builders, retrieved 10 November 2012 
  3. ^ a b c d South African Railways and Harbours Narrow Gauge Locomotive Diagram Book, 2’0” Gauge, S.A.R. Mechanical Dept. Drawing Office, Pretoria, 28 November 1932
  4. ^ a b c d e f g Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 106–107, 110. ISBN 0869772112. 
  5. ^ Middleton, John N. (1989). South African Railways Locomotive Allocations - 1989 (4th, 1989 ed.). Auckland Park, South Africa: Railway Preservation Group. p. 20. ISBN 0-620-13670-7