South African Class NG4 4-6-2T

NGR Class N 4-6-2T 1911 South African Class NG4 4-6-2T
No. NG16, restored at Sandstone Estates, 4 May 2013
Type and origin Power type Steam Designer Natal Government Railways (D.A. Hendrie) Builder Kerr, Stuart and Company Serial number 1207-1208, 1294-1295, 1342-1344 Model Kerr Stuart Side-tank Build date 1911-1914 Total produced 7
Specifications Configuration: ​  • Whyte 4-6-2T (Pacific)  • UIC 2'C1'n2t Driver 2nd coupled axle Gauge 2 ft (610 mm) narrow Leading dia. 18 in (457 mm) Coupled dia. 30 in (762 mm) Trailing dia. 21 in (533 mm) Wheelbase 17 ft 9 in (5,410 mm)  • Leading 3 ft 6 in (1,067 mm)  • Coupled 5 ft 9 in (1,753 mm) Length: ​  • Over couplers 24 ft 11 in (7,595 mm) Height 9 ft 4 1⁄2 in (2,858 mm) Frame type Plate Axle load 6 LT 3 cwt (6,249 kg)  • Leading 6 LT 19 cwt (7,062 kg)  • 1st coupled 6 LT (6,096 kg)  • 2nd coupled 6 LT 3 cwt (6,249 kg)  • 3rd coupled 6 LT 1 cwt (6,147 kg) Adhesive weight 18 LT 4 cwt (18,490 kg) Loco weight 29 LT 14 cwt (30,180 kg) Fuel type Coal Fuel capacity 21 long hundredweight 2 qtr (1.1 t) Water cap 820 imp gal (3,730 l) Firebox type Belpaire  • Firegrate area 11 sq ft (1.0 m2) Boiler: ​  • Pitch 4 ft 9 in (1,448 mm)  • Diameter 3 ft 3 1⁄2 in (1,003 mm)  • Tube plates 11 ft 2 1⁄8 in (3,407 mm)  • Small tubes 128: 1 3⁄4 in (44 mm) Boiler pressure 165 psi (1,138 kPa) Safety valve Ramsbottom Heating surface 700.9 sq ft (65.12 m2)  • Tubes 655.4 sq ft (60.89 m2)  • Firebox 45.5 sq ft (4.23 m2) Cylinders Two Cylinder size 11 1⁄2 in (292 mm) bore 15 in (381 mm) stroke Valve gear Walschaerts Couplers Johnston link-and-pin
Performance figures Tractive effort 8,183 lbf (36.40 kN) @ 75%
Career Operators Natal Government Railways South African Railways Class Class NG4 Number in class 7 Numbers NGR no. 10-11 SAR no. NG10-NG16 Delivered 1911-1914 First run 1911 Withdrawn 1948 Preserved No. NG16

The South African Railways Class NG4 4-6-2T of 1911 was a narrow-gauge steam locomotive from the pre-Union era in the Colony of Natal.

In 1911, shortly before being amalgamated into the South African Railways, the Natal Government Railways placed the first two of seven 4-6-2 Pacific type narrow-gauge tank steam locomotives in service. In 1912, when these two locomotives were assimilated into the South African Railways, they retained their engine numbers, but with an "NG" prefix added.

Five more of these locomotives were delivered to the South African Railways in 1913 and 1914. When a system of grouping narrow-gauge locomotives into classes was eventually introduced somewhere between 1928 and 1930, they were all designated Class NG4.

By 1906, the Natal Government had realised that light railways were essential as feeders to open up fertile districts which were distant from the existing main- and branch lines, particularly when the intervening stretches of country were difficult from an engineering point of view.

The third narrow-gauge railway line in Natal was the Alfred County Railway which ran from Port Shepstone on the South Coast to Harding. The first section to Paddock was opened on 8 November 1911.

Like their two predecessor locomotive types, the Hunslet Side-tank of 1906 and the Hawthorn Leslie Side-tank of 1907, this third batch of narrow-gauge 4-6-2T Pacific locomotives of the Natal Government Railways (NGR) were also built to the design of NGR Locomotive Superintendent D.A. Hendrie, using the Hawthorn Leslie drawings for the Class NG3. The majority of their parts were interchangeable with those of the earlier engines.

Between 1911 and 1913, the High Com­mis­sioner for the Union of South Africa placed three orders for altogether seven of these locomotives with Kerr, Stuart and Company.