South African Class 15A 4-8-2

South African Class 15A & 15AR 4-8-2

Class 15AR no. 1788, Graaff Reinet, 4 April 1978

Type and origin ♠ Class 15A as built with a Belpaire firebox ♥ Class 15AR rebuilt with a Watson Standard boiler ♣ Steel firebox - ♦ Copper firebox Power type Steam Designer South African Railways (D.A. Hendrie) Builder North British Locomotive Company Beyer, Peacock and Company J.A. Maffei Serial number NBL 20556-20560, 20843-20850, 21054-21063, 21436-21441, 21502-21505, 21718-21737, 22736-22750 BP 5955-5974, 5978-5987 Maffei 5625-5645 Model Class 15A Build date 1914-1925 Total produced 119

Specifications Configuration 4-8-2 (Mountain) Driver 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 28 1⁄2 in (724 mm) Coupled dia. 57 in (1,448 mm) Trailing dia. 33 in (838 mm) Tender wheels 34 in (864 mm) Wheelbase 60 ft 6 3⁄4 in (18,459 mm)  • Engine 33 ft 8 in (10,262 mm)  • Leading 6 ft 2 in (1,880 mm)  • Coupled 15 ft (4,572 mm)  • Tender 16 ft 9 in (5,105 mm)  • Tender bogie 4 ft 7 in (1,397 mm) Length: ​  • Over couplers 68 ft 11 1⁄8 in (21,009 mm) Height ♠ 12 ft 10 in (3,912 mm) ♥ 12 ft 11 3⁄4 in (3,956 mm) Frame type Plate Axle load ♠♥♣ 16 LT 11 cwt (16,820 kg) ♥♦ 16 LT 14 cwt (16,970 kg)  • Leading ♠ 15 LT 14 cwt (15,950 kg) ♥♣ 16 LT 1 cwt (16,310 kg) ♥♦ 16 LT 6 cwt (16,560 kg)  • 1st coupled ♠♥♣ 16 LT 10 cwt (16,760 kg) ♥♦ 16 LT 13 cwt (16,920 kg)  • 2nd coupled ♠ 16 LT 10 cwt (16,760 kg) ♥♣ 16 LT 9 cwt (16,710 kg) ♥♦ 16 LT 6 cwt (16,560 kg)  • 3rd coupled ♠♥♣ 16 LT 11 cwt (16,820 kg) ♥♦ 16 LT 14 cwt (16,970 kg)  • 4th coupled ♠♥♣ 16 LT 9 cwt (16,710 kg) ♥♦ 16 LT 11 cwt (16,820 kg)  • Trailing ♠ 12 LT 6 cwt (12,500 kg) ♥♣ 12 LT (12,190 kg) ♥♦ 12 LT 7 cwt (12,550 kg)  • Tender bogie Bogie 1: 27 LT 10 cwt (27,940 kg) Bogie 2: 23 LT 11 cwt (23,930 kg)  • Tender axle 13 LT 15 cwt (13,970 kg) Adhesive weight ♠ 66 LT (67,060 kg) ♥♣ 65 LT 19 cwt (67,010 kg) ♥♦ 66 LT 4 cwt (67,260 kg) Loco weight ♠ 94 LT 16 cwt (96,320 kg) ♥♣ 94 LT 6 cwt (95,810 kg) ♥♦ 94 LT 17 cwt (96,370 kg) Tender weight 51 LT 1 cwt (51,870 kg) Total weight ♠ 145 LT 17 cwt (148,200 kg) ♥♣ 145 LT 7 cwt (147,700 kg) ♥♦ 145 LT 18 cwt (148,200 kg) Tender type MP1 (2-axle bogies) MP, MP1, MR, MS, MT, MT1, MT2, MX, MY, MY1 permitted Fuel type Coal Fuel capacity 10 LT (10.2 t) Water cap 4,250 imp gal (19,300 l) Firebox type ♠ Belpaire, combustion chamber ♥ Round-top  • Firegrate area ♠ 40 sq ft (3.7 m2) ♥ 37 sq ft (3.4 m2) Boiler: ​  • Model Watson Standard no. 2A  • Pitch ♠ 7 ft 9 in (2,362 mm) ♥ 8 ft 1⁄2 in (2,451 mm)  • Diameter ♠ 5 ft 4 5⁄8 in (1,641 mm) ♥ 5 ft 7 1⁄2 in (1,714 mm)  • Tube plates ♠ 19 ft (5,791 mm) ♥♣ 21 ft 8 in (6,604 mm) ♥♦ 21 ft 7 5⁄8 in (6,594 mm)  • Small tubes ♠ 113: 2 1⁄4 in (57 mm) ♥ 87: 2 1⁄2 in (64 mm)  • Large tubes ♠ 21: 5 1⁄2 in (140 mm) ♥ 30: 5 1⁄2 in (140 mm) Boiler pressure ♠ 185 psi (1,276 kPa) ♥ 190 psi (1,310 kPa) Safety valve ♠ Ramsbottom - ♥ Pop Heating surface ♠ 2,026 sq ft (188.2 m2) ♥ 2,313 sq ft (214.9 m2)  • Tubes ♠ 1,834 sq ft (170.4 m2) ♥ 2,171 sq ft (201.7 m2)  • Firebox ♠ 192 sq ft (17.8 m2) ♥ 142 sq ft (13.2 m2) Superheater: ​  • Heating area ♠ 478 sq ft (44.4 m2) ♥ 537 sq ft (49.9 m2) Cylinders Two Cylinder size 22 in (559 mm) bore 28 in (711 mm) stroke Valve gear Walschaerts Valve type Poppet (No. 2100), Piston (Others) Couplers Johnston link-and-pin AAR knuckle (1930s)

Performance figures Tractive effort ♠ 32,990 lbf (146.7 kN) @ 75% ♥ 33,880 lbf (150.7 kN) @ 75%

Career Operators South African Railways Swaziland Railway Class Class 15A & 15AR Number in class 119 Numbers 1571-1575, 1781-1828, 1839-1858, 1961-1970, 2011-2025, 2080-2100 Delivered 1914-1925 First run 1914 Withdrawn 1980s

Most leading coupled axles had flangeless wheels

External video

South African Train takes tragic plunge AP Archive - British Movietone News footage of the accident on the Elands River bridge at Waterval Boven on 24 November 1949, which involved no. 1796 and another. (54 seconds)

The South African Railways Class 15A 4-8-2 of 1914 was a steam locomotive.

Between 1914 and 1925, the South African Railways placed 119 Class 15A steam locomotives with a 4-8-2 Mountain type wheel arrangement in service, delivered in ten batches from three manufacturers.

The Classes 15 and 15A were the final development of the plate-framed 4-8-2 Mountain locomotive designed by D.A. Hendrie, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1910 to 1922. Of the whole Hendrie Mountain family, the Class 15A was the most numerous and proved to be his most useful.

The predecessor Class 15 locomotives had one flaw, their excessively long fire tubes. When more locomotives of the type were ordered, Hendrie improved the boiler by adding a combustion chamber in the firebox, which shortened the distance between tube plates from 21 feet 9 inches (6,629 millimetres) to 19 feet (5,791 millimetres). When the first five of these redesigned locomotives were delivered in 1914, they were designated Class 15A. Altogether 119 were ultimately built in ten batches by three manufacturers. Being wartime, initial production and delivery occurred in dribs and drabs.

The locomotives had 1 ¹⁄₄ inches (32 millimetres) thick plate frames and piston valves, actuated by Walschaerts valve gear.

To reduce the weight on the trailing wheels, steel fireboxes were originally used instead of copper. Some locomotives in Natal had been fitted with steel fireboxes years previously and the results were fairly good, but wherever water supplies were of poor quality, steel fireboxes gave a lot of trouble and necessitated the introduction of water treatment plants to prevent corrosion. This reintroduction of steel fireboxes eventually led to its widespread use on all the larger locomotive types, but it also forced the SAR to adopt locomotive water treatment as a general policy.

The first five locomotives of 1914 were delivered with steel fireboxes. In the case of the Classes 15 and 15A, it was still early days for water treatment and enough trouble was experienced to result in their steel fireboxes being replaced with copper fireboxes. Hendrie followed a conservative policy in this respect and the majority of the rest of the Class 15A fleet were originally fitted with copper fireboxes. Steel fireboxes were only to be fitted in large numbers by his successor, Colonel F.R. Collins DSO, and only the last batch of 1925, supplied by Maffei, were delivered with steel fireboxes.

The last Class 15A locomotive, Maffei-built no. 2100, was fitted with Lentz Rotary Cam Poppet valve gear as an experiment, but this was later replaced with Walschaerts valve gear and piston-valve cylinders, thereby turning no. 2100 into a standard Class 15A.