South African Class 10A 4-6-2

CSAR Class 10-2 4-6-2 Saturated
South African Class 10A & 10BR 4-6-2

Class 10BR, ex Class 10A no. 751, ex CSAR Class 10-2 no. 669

Type and origin ♠ Class 10A as built with a Belpaire firebox ♥ Class 10BR rebuilt with a Watson Standard boiler Power type Steam Designer Central South African Railways (G.G. Elliot) Builder North British Locomotive Company Serial number 18971-18975 Model CSAR Class 10-2 Build date 1910 Total produced 5

Specifications Configuration 4-6-2 (Pacific) Driver 2nd coupled axle Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 28 1⁄2 in (724 mm) Coupled dia. 62 in (1,575 mm) Trailing dia. 33 in (838 mm) Tender wheels 34 in (864 mm) Wheelbase 55 ft 8 in (16,967 mm)  • Engine 30 ft 2 in (9,195 mm)  • Leading 6 ft (1,829 mm)  • Coupled 10 ft 10 in (3,302 mm)  • Tender 16 ft 9 in (5,105 mm)  • Tender bogie 4 ft 7 in (1,397 mm) Length: ​  • Over couplers 63 ft 10 3⁄4 in (19,475 mm) Height ♠ 12 ft 10 in (3,912 mm) ♥ 12 ft 11 in (3,937 mm) Frame type Plate Axle load ♠ 15 LT 18 cwt (16,160 kg) ♥ 16 LT 8 cwt (16,660 kg)  • Leading ♠ 14 LT 5 cwt (14,480 kg) ♥ 15 LT 6 cwt (15,550 kg)  • 1st coupled ♠ 15 LT 9 cwt (15,700 kg) ♥ 15 LT 9 cwt (15,700 kg)  • 2nd coupled ♠ 15 LT 18 cwt (16,160 kg) ♥ 16 LT 6 cwt (16,560 kg)  • 3rd coupled ♠ 15 LT 13 cwt (15,900 kg) ♥ 16 LT 8 cwt (16,660 kg)  • Trailing ♠ 12 LT 10 cwt (12,700 kg) ♥ 13 LT 11 cwt (13,770 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 ♠ 47 LT (47,750 kg) ♥ 48 LT 3 cwt (48,920 kg) Loco weight ♠ 73 LT 15 cwt (74,930 kg) ♥ 76 LT 2 cwt (77,320 kg) Tender weight 49 LT 7 cwt (50,140 kg) Total weight ♠ 123 LT 2 cwt (125,100 kg) ♥ 125 LT 9 cwt (127,500 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 ♠ 34.6 sq ft (3.21 m2) ♥ 36 sq ft (3.3 m2) Boiler: ​  • Model ♥ Watson Standard no. 1  • Pitch ♠ 7 ft 4 in (2,235 mm) ♥ 8 ft (2,438 mm)  • Diameter ♠ 4 ft 6 3⁄4 in (1,391 mm) ♥ 5 ft (1,524 mm)  • Tube plates ♠ 18 ft 6 1⁄2 in (5,652 mm) ♥ 17 ft 9 in (5,410 mm)  • Small tubes ♠ 154: 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) ♥ 180 psi (1,241 kPa) Safety valve ♠ Ramsbottom ♥ Pop Feedwater heater Trevithick exhaust steam type Heating surface ♠ 1,810 sq ft (168 m2) ♥ 1,620 sq ft (151 m2)  • Tubes ♠ 1,682 sq ft (156.3 m2) ♥ 1,497 sq ft (139.1 m2)  • Firebox ♠ 128 sq ft (11.9 m2) ♥ 123 sq ft (11.4 m2) Superheater: ​  • Heating area ♥ 366 sq ft (34.0 m2) Cylinders Two Cylinder size ♠ 18 1⁄2 in (470 mm) bore ♥ 20 in (508 mm) bore ♠♥ 28 in (711 mm) stroke Valve gear Walschaerts Valve type Piston Couplers Johnston link-and-pin AAR knuckle (1930s)

Performance figures Tractive effort ♠ 23,180 lbf (103.1 kN) @ 75% ♥ 24,390 lbf (108.5 kN) @ 75%

Career Operators Central South African Railways South African Railways Class CSAR Class 10-2, SAR Class 10A Number in class 5 Numbers CSAR 665-669, SAR 747-751 Delivered 1910 First run 1910 Withdrawn 1974

The 2nd coupled axle had flangeless wheels

The South African Railways Class 10A 4-6-2 of 1910 was a steam locomotive from the pre-Union era in Transvaal.

In 1910, the Central South African Railways placed ten Class 10-2 4-6-2 Pacific type steam locomotives in service, of which five were built with and five without superheaters. In 1912, when the five saturated steam locomotives were assimilated into the South African Railways, they were renumbered and designated Class 10A.

Ten heavy 4-6-2 Pacific type passenger locomotives, designed by Central South African Railways (CSAR) Chief Mechanical Engineer G.G. Elliot and based on the Class 10 design of his predecessor, CSAR Chief Locomotive Superintendent P.A. Hyde, were ordered from the North British Locomotive Company and delivered in 1910. They had plate frames, Belpaire fireboxes and Walschaerts valve gear and were delivered in two variants, with five of them using saturated steam while the rest were superheated. They were all designated Class 10-2 by the CSAR, numbered in the range from 665 to 674, and entered service in March 1910.

The Class 10-2 saturated locomotives were similar to the Class 10, except that their boilers were arranged 7 ⁷⁄₈ inches (200 millimetres) further forward and their firebox throats and back plates were sloped instead of being vertical. This modification brought the chimney in line with the cylinders and avoided a "set" in the blastpipe. The cylinders were arranged outside the plate frames. Like the Class 10, the locomotives had 62 inches (1,575 millimetres) diameter coupled wheels, the largest yet used in South Africa at the time.

The Walschaerts valve gear was controlled by a vertical type of steam reversing engine which was attached to the right-hand side of the boiler, just below the dome. It consisted of a 5 ¹⁄₂ inches (140 millimetres) diameter steam cylinder and a 4 inches (102 millimetres) diameter oil cylinder, fitted with a common piston rod with a crosshead which was machined integral with the piston rod. This crosshead was connected to a lever fitted to the reversing shaft. After 1912, these reversing engines were replaced with Hendrie steam reversers.