South African Class 2 4-6-2

NGR Class A 4-6-2 1905 South African Class 2 4-6-2
NGR Class A no. 326, SAR Class 2 no. 763
Type and origin Power type Steam Designer Natal Government Railways (D.A. Hendrie) Builder North British Locomotive Company Serial number 16192-16193 Model NGR Hendrie A Build date 1904 Total produced 2
Specifications Configuration: ​  • Whyte 4-6-2 (Pacific)  • UIC 2'C1'n2 Driver 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 28 1⁄2 in (724 mm) Coupled dia. 51 in (1,295 mm) Trailing dia. 30 in (762 mm) Tender wheels 30 in (762 mm) Wheelbase 51 ft 1 3⁄8 in (15,580 mm)  • Engine 27 ft 10 in (8,484 mm)  • Leading 6 ft (1,829 mm)  • Coupled 9 ft 4 in (2,845 mm)  • Tender 15 ft 6 in (4,724 mm)  • Tender bogie 4 ft 6 in (1,372 mm) Length: ​  • Over couplers 58 ft 4 1⁄8 in (17,783 mm) Height 12 ft 6 in (3,810 mm) Frame type Plate Axle load 15 LT (15,240 kg)  • Leading 11 LT 15 cwt (11,940 kg)  • 1st coupled 14 LT (14,220 kg)  • 2nd coupled 15 LT (15,240 kg)  • 3rd coupled 14 LT 15 cwt (14,990 kg)  • Trailing 10 LT 16 cwt (10,970 kg)  • Tender bogie Bogie 1: 18 LT 18 cwt (19,200 kg) Bogie 2: 19 LT 1 cwt (19,360 kg)  • Tender axle 9 LT 10 cwt 2 qtr (9,678 kg) Adhesive weight 43 LT 15 cwt (44,450 kg) Loco weight 66 LT 6 cwt (67,360 kg) Tender weight 37 LT 19 cwt (38,560 kg) Total weight 104 LT 5 cwt (105,900 kg) Tender type SH (2-axle bogies) SH, SK permitted Fuel type Coal Fuel capacity 6 LT (6.1 t) Water cap 3,225 imp gal (14,700 l) Firebox type Belpaire  • Firegrate area 28 sq ft (2.6 m2) Boiler: ​  • Pitch 7 ft 3 in (2,210 mm)  • Diameter 5 ft 3⁄4 in (1,543 mm)  • Tube plates 16 ft 4 3⁄4 in (4,997 mm)  • Small tubes 246: 2 in (51 mm) Boiler pressure 180 psi (1,241 kPa) Safety valve Ramsbottom Heating surface 2,231 sq ft (207.3 m2)  • Tubes 2,112 sq ft (196.2 m2)  • Firebox 119 sq ft (11.1 m2) Cylinders Two Cylinder size 19 in (483 mm) bore 24 in (610 mm) stroke Valve gear Stephenson Valve type Balanced slide Couplers Johnston link-and-pin AAR knuckle (1930s)
Performance figures Tractive effort 22,940 lbf (102.0 kN) @ 75%
Career Operators Natal Government Railways South African Railways Class NGR Class A SAR Class 2 Number in class 2 Numbers NGR 325-326 SAR 762-763 Nicknames Hendrie A Delivered 1905 First run 1905 Withdrawn 1936
The 2nd coupled axle had flangeless wheels

The South African Railways Class 2 4-6-2 of 1905 was a steam locomotive from the pre-Union era in the Colony of Natal.

In 1905, the Natal Government Railways placed two Class A steam locomotives with a 4-6-2 Pacific type wheel arrangement in service. In 1912, when these locomotives were assimilated into the South African Railways, they were renumbered and designated Class 2.

In 1904, orders were placed with the North British Locomotive Company (NBL) for two 4-6-2 Pacific type locomotives for the Natal Government Railways (NGR). They were designed by NGR Locomotive Superintendent D.A. Hendrie for passenger traffic on those sections of the mainline between Ladysmith and Charlestown which did not have very severe gradients. When they were delivered and placed in service early in 1905, they were designated the NGR Class A, also commonly known as the Hendrie A, and numbered 325 and 326.

The boiler of this Class was noted for its free steaming qualities. The engines used saturated steam, had Stephenson valve gear and were built on plate frames. The cylinders were inclined 1 in 18 and were arranged outside the plate frames, while the balanced slide valves were arranged inside the frames. After these two engines, Hendrie adopted Walschaerts valve gear and outside valves on all his subsequent locomotive designs for its greater accessibility.

The locomotives had Belpaire fireboxes with firebar rocking finger grates. To accommodate the wide and deep firebox, Hendrie made use of a bridle casting along the same lines as the one which was first introduced by H.M. Beatty on his Cape Government Railways (CGR) 6th Class 2-6-2 of 1903, later the Class 6Y on the South African Railways (SAR).

With a bridle casting, the widening of the locomotive frame at the back end was accomplished by uniting the narrow front part of the frame and the wider rear part by the heavy steel casting. This method of widening the frames for the firebox continued on the SAR until the general adoption of bar frames for mainline locomotives by 1927 rendered it no longer necessary.