South African Class 15C 4-8-2

South African Class 15C (15CB) 4-8-2

Class 15C Big Bill, as delivered, c. 1925

Type and origin ♠ With 57 inch (1,448 mm) coupled wheels ♥ With 60 inch (1,524 mm) coupled wheels ♣ Copper firebox - ♦ Steel firebox - ʘ Reboilered ʘ 23x28 Cylinders - ʘ 24x28 Cylinders Power type Steam Designer Baldwin Locomotive Works Builder Baldwin Locomotive Works Serial number 58307, 58308, 58708-58717 Model Class 15C Build date 1925-1926 Total produced 12

Specifications Configuration 4-8-2 (Mountain) Driver 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 30 in (762 mm) Coupled dia. ♠ 57 in (1,448 mm) ♥ 60 in (1,524 mm) Trailing dia. 33 in (838 mm) Tender wheels 34 in (864 mm) Wheelbase 65 ft 3 1⁄4 in (19,895 mm)  • Engine 35 ft 8 in (10,871 mm)  • Leading 6 ft 10 in (2,083 mm)  • Coupled 15 ft 9 in (4,801 mm)  • Tender 20 ft 5 in (6,223 mm)  • Tender bogie 6 ft 2 in (1,880 mm) Length: ​  • Over couplers 73 ft 2 1⁄4 in (22,308 mm) Height ♠ 12 ft 10 in (3,912 mm) ♥ 12 ft 11 1⁄2 in (3,950 mm) Frame type Bar Axle load ♠♣ 17 LT 13 cwt (17,930 kg) ♠♦ 17 LT 2 cwt (17,370 kg) ♥♣ 17 LT 19 cwt (18,240 kg) ♥♦ 17 LT 8 cwt (17,680 kg)  • Leading ♠♣ 18 LT 3 cwt (18,440 kg) ♠♦ 19 LT 5 cwt (19,560 kg) ♥♣ 18 LT 3 cwt (18,440 kg) ♥♦ 19 LT 5 cwt (19,560 kg)  • 1st coupled ♠♣ 17 LT 13 cwt (17,930 kg) ♠♦ 17 LT 1 cwt (17,320 kg) ♥♣ 17 LT 16 cwt (18,090 kg) ♥♦ 17 LT 4 cwt (17,480 kg)  • 2nd coupled ♠♣ 17 LT 12 cwt (17,880 kg) ♠♦ 17 LT 2 cwt (17,370 kg) ♥♣ 17 LT 18 cwt (18,190 kg) ♥♦ 17 LT 8 cwt (17,680 kg)  • 3rd coupled ♠♣ 17 LT 13 cwt (17,930 kg) ♠♦ 17 LT 2 cwt (17,370 kg) ♥♣ 17 LT 19 cwt (18,240 kg) ♥♦ 17 LT 8 cwt (17,680 kg)  • 4th coupled ♠♣ 17 LT 9 cwt (17,730 kg) ♠♦ 16 LT 18 cwt (17,170 kg) ♥♣ 17 LT 15 cwt (18,030 kg) ♥♦ 17 LT 4 cwt (17,480 kg)  • Trailing ♠♣ 16 LT 6 cwt (16,560 kg) ♠♦ 15 LT 19 cwt (16,210 kg) ♥♣ 16 LT 6 cwt (16,560 kg) ♥♦ 15 LT 19 cwt (16,210 kg)  • Tender bogie Bogie 1: 33 LT 18 cwt (34,440 kg) Bogie 2: 35 LT 10 cwt (36,070 kg)  • Tender axle 17 LT 15 cwt (18,030 kg) Adhesive weight ♠♣ 70 LT 7 cwt (71,480 kg) ♠♦ 68 LT 3 cwt (69,240 kg) ♥♣ 71 LT 8 cwt (72,550 kg) ♥♦ 69 LT 4 cwt (70,310 kg) Loco weight ♠♣ 104 LT 16 cwt (106,500 kg) ♠♦ 103 LT 7 cwt (105,000 kg) ♥♣ 105 LT 17 cwt (107,500 kg) ♥♦ 104 LT 8 cwt (106,100 kg) Tender weight 69 LT 8 cwt (70,510 kg) Total weight ♠♣ 174 LT 4 cwt (177,000 kg) ♠♦ 172 LT 15 cwt (175,500 kg) ♥♣ 175 LT 5 cwt (178,100 kg) ♥♦ 173 LT 16 cwt (176,600 kg) Tender type KT (2-axle bogies) Fuel type Coal Fuel capacity 14 LT (14.2 t) Water cap 6,000 imp gal (27,300 l) Firebox type Round-top, combustion chamber  • Firegrate area 48 sq ft (4.5 m2) Boiler: ​  • Pitch ♠ 8 ft 6 in (2,591 mm) ♥ 8 ft 7 1⁄2 in (2,629 mm)  • Diameter 6 ft 2 1⁄4 in (1,886 mm)  • Tube plates 20 ft 1⁄2 in (6,109 mm)  • Small tubes ♠ 143: 2 1⁄4 in (57 mm) ʘ 117: 2 1⁄4 in (57 mm)  • Large tubes ♠ 30: 5 1⁄2 in (140 mm) ʘ 34: 5 1⁄2 in (140 mm) Boiler pressure ♠ 200 psi (1,379 kPa) ♥ 210 psi (1,448 kPa) Safety valve Coale Pop Heating surface ♠ 2,777 sq ft (258.0 m2) ʘ 2,584 sq ft (240.1 m2)  • Tubes ♠ 2,554 sq ft (237.3 m2) ʘ 2,361 sq ft (219.3 m2)  • Arch tubes 23 sq ft (2.1 m2)  • Firebox 200 sq ft (19 m2) Superheater: ​  • Type Schmidt  • Heating area ♠ 716 sq ft (66.5 m2) ʘ 670 sq ft (62 m2) Cylinders Two Cylinder size ʘ 23 in (584 mm) bore ʘ 24 in (610 mm) bore ʘʘ 28 in (711 mm) stroke Valve gear Walschaerts Valve type Piston Couplers Bell link-and-pin AAR knuckle (c. 1930s-1950s)

Performance figures Power output ♠ʘ 38,980 lbf (173.4 kN) @ 75% ♠ʘ 42,440 lbf (188.8 kN) @ 75% ♥ʘ 38,880 lbf (172.9 kN) @ 75% ♥ʘ 42,340 lbf (188.3 kN) @ 75%

Career Operators South African Railways Class Class 15C, 15CB Number in class 12 Numbers 2060–2071 Nicknames Big Bill Delivered 1925-1926 First run 1925 Withdrawn 1976

♠ The leading coupled axle had flangeless wheels

The South African Railways Class 15C 4-8-2 of 1925 was a steam locomotive.

In 1925, the South African Railways placed two American-built Class 15C steam locomotives with a 4-8-2 Mountain type wheel arrangement in service. Another ten locomotives were ordered and delivered a year later. In 1926, these locomotives were reclassified to Class 15CB.

On 15 December 1924, after an official tour of investigation to the United States of America by G.E. Titren, the Superintendent Motive Power of the South African Railways (SAR), an order was placed with the Baldwin Locomotive Works (BLW) of Philadelphia for four experimental locomotives, two of which were of a 4-8-2 Mountain type wheel arrangement. These locomotives, both types specially designed for the long runs of the Union Limited and Union Express passenger trains between Cape Town and Johannesburg, were delivered in 1925.

These locomotives conformed to SAR requirements as far as practicable, but also incorporated the latest American railway engineering practices. They introduced several features which were new to the SAR at the time, such as top feeds to the boiler, self-cleaning smokeboxes, Sellar's drifting valves and grease lubrication to the coupled wheel axleboxes, crank pins and connecting rod big ends. Their fireboxes were equipped with flexible side stays and water siphon arch tubes to support the brick arch and to improve circulation. Their Type KT tenders, arranged with self-trimming type coal bunkers, had a coal capacity of 14 long tons (14.2 tonnes) and a water capacity of 6,000 imperial gallons (27,300 litres), which was considered sufficient for the engines to travel 100 miles (161 kilometres) without having to replenish water.

The locomotives represented a considerable advance in power over the Classes 15, 15A and 15B. They had 5 inches (127 millimetres) thick bar frames and their boilers were larger in proportions than that of any existing SAR locomotive, while their boiler pitch was raised 10 inches (254 millimetres) higher than that of anything else in service at that time. The boilers were equipped with three Coale pop type safety valves and a Schmidt type superheater. To reduce the length between boiler tube plates, a 2 feet 3 inches (686 millimetres) long combustion chamber was provided in the firebox. The locomotive's size quickly earned it the nickname Big Bill, while its contemporary Class 16D 4-6-2 Pacific type, which arrived from the same builders in the same shipment, was nicknamed Big Bertha.