South African Class NG G13 2-6-2+2-6-2

South African Class NG G13 2-6-2+2-6-2

NG G13 no. 49 at Sandstone Estates, 9 April 2006

Type and origin Power type Steam Designer Hannoversche Maschinenbau AG Builder Hannoversche Maschinenbau AG Serial number 10549-10551, 10598-10599, 10629-10635 Model Class NG G13 Build date 1927-1928 Total produced 12

Specifications Configuration: ​  • Whyte 2-6-2+2-6-2 (Double Prairie) Driver 3rd & 4th coupled axles Gauge 2 ft (610 mm) narrow Leading dia. 21 in (533 mm) Coupled dia. 33 in (838 mm) Trailing dia. 21 in (533 mm) Minimum curve 150 ft (46 m) Wheelbase 42 ft 9 in (13,030 mm)  • Engine 13 ft 2 in (4,013 mm) each  • Coupled 6 ft 3 in (1,905 mm) each Pivot centres 23 ft 9 in (7,239 mm) Length: ​  • Over couplers 48 ft 5 1⁄4 in (14,764 mm) Height 10 ft 4 in (3,150 mm) Frame type Bar Axle load 7 LT 1 cwt 2 qtr (7,189 kg)  • Leading 6 LT 10 cwt 1 qtr (6,617 kg) front 6 LT 1 cwt 1 qtr (6,160 kg) rear  • 1st coupled 7 LT 1 cwt 2 qtr (7,189 kg)  • 2nd coupled 6 LT 18 cwt 1 qtr (7,023 kg)  • 3rd coupled 6 LT 14 cwt (6,808 kg)  • 4th coupled 6 LT 16 cwt 1 qtr (6,922 kg)  • 5th coupled 6 LT 17 cwt 3 qtr (6,998 kg)  • 6th coupled 6 LT 13 cwt 2 qtr (6,782 kg)  • Trailing 4 LT 0 cwt 2 qtr (4,090 kg) front 4 LT (4,064 kg) rear Adhesive weight 41 LT 1 cwt 1 qtr (41,720 kg) Loco weight 61 LT 13 cwt 1 qtr (62,650 kg) Fuel type Coal Fuel capacity 4 LT (4.1 t) Water cap 1,285 imp gal (5,840 l) front 540 imp gal (2,450 l) rear Firebox type Round-top  • Firegrate area 19.5 sq ft (1.81 m2) Boiler: ​  • Pitch 5 ft 5 in (1,651 mm)  • Diameter 4 ft 7 3⁄4 in (1,416 mm)  • Tube plates 9 ft 3 5⁄8 in (2,835 mm)  • Small tubes 152: 1 3⁄4 in (44 mm)  • Large tubes 15: 5 1⁄2 in (140 mm) Boiler pressure 180 psi (1,241 kPa) Safety valve Pop Heating surface 921.1 sq ft (85.57 m2)  • Tubes 839 sq ft (77.9 m2)  • Firebox 82.1 sq ft (7.63 m2) Superheater: ​  • Heating area 149 sq ft (13.8 m2) Cylinders Four Cylinder size 12 in (305 mm) bore 16 in (406 mm) stroke Valve gear Heusinger Valve type Piston Couplers Bell-and-hook (Cape) Johnston link-and-pin (Natal)

Performance figures Tractive effort 18,850 lbf (83.8 kN) @ 75%

Career Operators South African Railways Class Class NG G13 Number in class 12 Numbers 49-50, 58-60, 77-83 Delivered 1927-1929 First run 1927 Withdrawn 1973

The South African Railways Class NG G13 2-6-2+2-6-2 of 1927 was a narrow gauge articulated steam locomotive.

Between 1927 and 1929, the South African Railways placed twelve Class NG G13 Garratt articulated steam locomotives with a 2-6-2+2-6-2 Double Prairie type wheel arrangement in service on the Langkloof and Alfred County Railway narrow gauge lines.

In 1927, Hannoversche Maschinenbau AG (Hanomag), in consultation with the South African Railways (SAR), designed a locomotive which was to become the standard 2 feet (610 millimetres) narrow gauge Garratt locomotive in South Africa for the next forty years.

How Garratts, to which Beyer, Peacock and Company held the patent, came to be designed and built by the German firm of Hanomag was the result of the coming into power of the Pact Government in South Africa in 1924. With strong anti-British sentiments amongst Afrikaners in the new government still lingering after the Second Boer War, British manufacturers were avoided whenever possible.

The initial order was for three Class NG G13 locomotives, numbered in the range from NG58 to NG60, which were delivered and placed in service in November 1927. Performance trials of the Class NG G13 proved it to be both powerful and free steaming despite having a smaller grate area than the predecessor Class NG G11. This resulted in an immediate order for another two locomotives, numbers NG49 and NG50, and even before these two were delivered, another seven numbered in the range from NG77 to NG83. The second and third orders were both delivered in 1928 with the third order locomotives entering service during January 1929.

The locomotive was greatly improved from the Class NG G11, with trailing wheels added to each engine unit, outside bar frames instead of plate frames, round-topped fireboxes instead of Belpaire fireboxes, and larger dimensions in most respects except the grate area. They were superheated and sported an extremely compact arrangement of Walschaerts valve gear and outside bar frames. The leading wheels were arranged as conventional pony trucks, while the inner carrying wheels were built to the Gölsdorf system which allowed the axle some lateral movement.