South African Class 10B 4-6-2

CSAR Class 10-2 4-6-2 Superheated
South African Class 10B & 10BR 4-6-2

Class 10B no. 756, ex CSAR Class 10-2 no. 674

Type and origin ♠ Class 10B 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 Beyer, Peacock and Company Order number BP 0268 Serial number NBL 18976-18980 BP 5483-5487 Model CSAR Class 10-2 Build date 1910-1911 Total produced 10

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 14 cwt (15,950 kg) ♥ 16 LT 8 cwt (16,660 kg)  • Leading ♠ 14 LT 16 cwt (15,040 kg) ♥ 15 LT 6 cwt (15,550 kg)  • 1st coupled ♠ 15 LT 12 cwt (15,850 kg) ♥ 15 LT 9 cwt (15,700 kg)  • 2nd coupled ♠ 15 LT 14 cwt (15,950 kg) ♥ 16 LT 6 cwt (16,560 kg)  • 3rd coupled ♠ 15 LT 14 cwt (15,950 kg) ♥ 16 LT 8 cwt (16,660 kg)  • Trailing ♠ 12 LT 13 cwt (12,850 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 ♠ 74 LT 9 cwt (75,640 kg) ♥ 76 LT 2 cwt (77,320 kg) Tender weight 49 LT 7 cwt (50,140 kg) Total weight ♠ 123 LT 16 cwt (125,800 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) Generator Pyle National Turbo Firebox type ♠ Belpaire - ♥ Round-top  • Firegrate area ♠ 35 sq ft (3.3 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 ♠ 92: 2 1⁄4 in (57 mm) ♥ 76: 2 1⁄2 in (64 mm)  • Large tubes ♠ 18: 5 1⁄4 in (133 mm) ♥ 24: 5 1⁄2 in (140 mm) Boiler pressure ♠♥ 180 psi (1,241 kPa) Safety valve ♠ Ramsbottom ♥ Pop Feedwater heater Trevithick exhaust steam type Heating surface ♠ 1,588 sq ft (147.5 m2) ♥ 1,620 sq ft (151 m2)  • Tubes ♠ 1,463 sq ft (135.9 m2) ♥ 1,497 sq ft (139.1 m2)  • Firebox ♠ 125 sq ft (11.6 m2) ♥ 123 sq ft (11.4 m2) Superheater: ​  • Type Schmidt  • Heating area ♠ 384 sq ft (35.675 m2) ♥ 366 sq ft (34.003 m2) Cylinders Two Cylinder size ♠♥ 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 ♠♥ 24,390 lbf (108.5 kN) @ 75%

Career Operators Central South African Railways South African Railways Class CSAR Class 10-2 SAR Class 10B & 10BR Number in class 10 Numbers CSAR 670-674 (NBL) SAR 752-761 (NBL & BP) Delivered 1910-1912 First run 1910 Withdrawn 1974

The 2nd coupled axle had flangeless wheels

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

In March 1910, the Central South African Railways placed ten Class 10-2 steam locomotives with a 4-6-2 Pacific wheel arrangement in service, of which five were built with and five without superheaters. In 1912, when the five superheated locomotives were assimilated into the South African Railways, they were renumbered and designated Class 10B. During 1912, the South African Railways placed five more Class 10B locomotives in service.

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 with Schmidt type superheaters. 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 superheated 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.