South African Class 5 4-6-2

South African Class 5 & 5R 4-6-2

Class 5R no. 781 retired at De Aar, 15 April 1978

Type and origin ♠ Class 5 as built with a Belpaire firebox ♥ Class 5R rebuilt with a Watson Standard boiler Power type Steam Designer Cape Government Railways (H.M. Beatty) Builder Vulcan Foundry Serial number 2774-2777 Model CGR Karoo Class Build date 1912 Total produced 4

Specifications Configuration 4-6-2 (Pacific) Driver 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 30 1⁄2 in (775 mm) Coupled dia. ♠ 61 in (1,549 mm) ♥ 62 in (1,575 mm) Trailing dia. 34 in (864 mm) Tender wheels 33 1⁄2 in (851 mm) as built 34 in (864 mm) retyred Wheelbase 55 ft 10 1⁄4 in (17,024 mm)  • Engine 29 ft 5 in (8,966 mm)  • Leading 6 ft 2 in (1,880 mm)  • Coupled 10 ft 8 in (3,251 mm)  • Tender 16 ft 9 in (5,105 mm)  • Tender bogie 4 ft 7 in (1,397 mm) Length: ​  • Over couplers ♠ 64 ft 1⁄2 in (19,520 mm) ♥ 64 ft 1 7⁄8 in (19,555 mm) Height ♠ 12 ft 10 in (3,912 mm) ♥ 12 ft 11 in (3,937 mm) Frame type Bar at front, Plate at rear Axle load ♠ 15 LT 15 cwt (16,000 kg) ♥ 16 LT 9 cwt (16,710 kg)  • Leading ♠ 10 LT 10 cwt (10,670 kg) ♥ 15 LT 1 cwt (15,290 kg)  • 1st coupled ♠ 15 LT 10 cwt (15,750 kg) ♥ 15 LT 5 cwt (15,490 kg)  • 2nd coupled ♠ 15 LT (15,240 kg) ♥ 16 LT 9 cwt (16,710 kg)  • 3rd coupled ♠ 15 LT 15 cwt (16,000 kg) ♥ 15 LT 5 cwt (15,490 kg)  • Trailing ♠ 11 LT 10 cwt (11,680 kg) ♥ 10 LT (10,160 kg)  • Tender bogie Bogie 1: 24 LT 4 cwt (24,590 kg) Bogie 2: 25 LT 3 cwt (25,550 kg)  • Tender axle 12 LT 11 cwt 2 qtr (12,780 kg) Adhesive weight ♠ 46 LT 5 cwt (46,990 kg) ♥ 46 LT 19 cwt (47,700 kg) Loco weight ♠ 68 LT 5 cwt (69,350 kg) ♥ 72 LT 9 cwt (73,610 kg) Tender weight 49 LT 7 cwt (50,140 kg) Total weight ♠ 117 LT 12 cwt (119,500 kg) ♥ 121 LT 16 cwt (123,800 kg) Tender type XM2 (2-axle bogies) XC, XC1, XD, XE, XE1, XF, XF1, XF2, XJ, XM, XM1, XM2, XM3, XM4, XP1, XS permitted Fuel type Coal Fuel capacity 10 LT (10.2 t) Water cap 4,000 imp gal (18,200 l) Firebox type ♠ Belpaire ♥ Round-top  • Firegrate area ♠ 34.2 sq ft (3.18 m2) ♥ 36 sq ft (3.3 m2) Boiler: ​  • Model ♥ Watson Standard no. 1  • Pitch ♠ 7 ft 5 in (2,261 mm) ♥ 8 ft (2,438 mm)  • Diameter ♠♥ 5 ft (1,524 mm)  • Tube plates ♠ 17 ft 9 in (5,410 mm) ♥ 17 ft 8 5⁄8 in (5,401 mm)  • Small tubes ♠ 184: 2 1⁄4 in (57 mm) ♥ 76: 2 1⁄2 in (64 mm)  • Large tubes ♥ 24: 5 1⁄2 in (140 mm) Boiler pressure ♠ 200 psi (1,379 kPa) ♥ 190 psi (1,310 kPa) Safety valve ♠ Ramsbottom ♥ Pop Heating surface ♠ 2,066 sq ft (191.9 m2) ♥ 1,620 sq ft (151 m2)  • Tubes ♠ 1,924 sq ft (178.7 m2) ♥ 1,497 sq ft (139.1 m2)  • Firebox ♠ 142 sq ft (13.2 m2) ♥ 123 sq ft (11.4 m2) Superheater: ​  • Heating area ♥ 366 sq ft (34.0 m2) Cylinders Two Cylinder size ♠ 19 in (483 mm) bore ♥ 20 in (508 mm) bore ♠♥ 28 in (711 mm) stroke Valve gear Stephenson Valve type ♠ Richardson balanced slide ♥ Piston Couplers Johnston link-and-pin

Performance figures Tractive effort ♠ 24,860 lbf (110.6 kN) @ 75% ♥ 25,750 lbf (114.5 kN) @ 75%

Career Operators South African Railways Class Class 5 & 5R Number in class 4 Numbers 780-783 Nicknames Karoo Delivered 1912 First run 1912 Withdrawn 1969

The 2nd coupled axle had flangeless wheels

The South African Railways Class 5 4-6-2 of 1912 was a steam locomotive.

In 1912, four Enlarged Karoo Class 4-6-2 Pacific type passenger steam locomotives which had been ordered by the Cape Government Railways the year before were placed in service by the newly established South African Railways. The locomotives were therefore numbered directly onto the South African Railways roster and designated Class 5.

The Cape Government Railways (CGR), Natal Government Railways (NGR) and Central South African Railways (CSAR) had all prepared designs and placed orders for new locomotives shortly prior to 1912, when the South African Railways (SAR) locomotive classification and renumbering scheme was implemented.

The CGR's Enlarged Karoo, designed by H.M. Beatty, the Cape Government Railways Chief Locomotive Superintendent and built by Vulcan Foundry of Newton-le-Willows, was one of the locomotive types which were designed and ordered before the SAR was established and which ended up being delivered to the newly established national railways of the Union of South Africa. The locomotives were designated Class 5 and numbered in the range from 780 to 783. They entered service during November 1912.

The Class 5 was a larger and heavier version of the Class 5B, with a higher pitched boiler, Belpaire firebox, larger diameter leading and coupled wheels and larger cylinders.

The cylinders were arranged outside the bar frames, with balanced Richardson type D slide valves arranged above the cylinders and actuated by Stephenson valve gear through rocker shafts. The hind frame of the engine was of the plate type and was widened out to receive the Belpaire firebox, which itself was a notable departure from the usual practice of the CGR to use round-topped fireboxes.

In the 1930s, many serving locomotives were reboilered with a standard boiler type, designed by then Chief Mechanical Engineer A.G. Watson as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification.

During 1935, only one of the Class 5 locomotives, no. 781, was reboilered with a Watson Standard no. 1 boiler and reclassified to Class 5R. The most obvious difference between the Class 5 and Class 5R is the absence of the Belpaire firebox hump between the cab and boiler on the reboilered locomotive.