South African Class MJ 2-6-6-0

South African Class MJ 2-6-6-0

SAR Class MJ no. 1651, c. 1914

Type and origin ♠ Locomotive as built - ♥ Reboilered locomotive Power type Steam Designer South African Railways (D.A. Hendrie) Builder Maffei North British Locomotive Company Order number NBL L657 Serial number Maffei 3452-3461 NBL 21248-21255 Model SAR Class MJ Build date 1914 Total produced 18

Specifications Configuration 2-6-6-0 (Denver) Driver 3rd & 6th coupled axles Gauge 3 ft 6 in (1,067 mm) Cape gauge Leading dia. 28 1⁄2 in (724 mm) Coupled dia. 42 3⁄4 in (1,086 mm) Tender wheels 34 in (864 mm) Wheelbase 58 ft 11 1⁄4 in (17,964 mm)  • Engine 32 ft 8 in (9,957 mm)  • Coupled 8 ft 4 in (2,540 mm) per unit  • Tender 16 ft 9 in (5,105 mm)  • Tender bogie 4 ft 7 in (1,397 mm) Length: ​  • Over couplers 67 ft 5 1⁄8 in (20,552 mm) Height ♠♥ 12 ft 6 1⁄8 in (3,813 mm) Frame type Bar Axle load ♠ 13 LT 15 cwt (13,970 kg)  • Leading ♠ 7 LT 17 cwt (7,976 kg)  • 1st coupled ♠ 12 LT 12 cwt (12,800 kg)  • 2nd coupled ♠ 12 LT 13 cwt (12,850 kg)  • 3rd coupled ♠ 12 LT 19 cwt (13,160 kg)  • 4th coupled ♠ 11 LT 8 cwt (11,580 kg)  • 5th coupled ♠ 12 LT 16 cwt (13,010 kg)  • 6th coupled ♠ 13 LT 15 cwt (13,970 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 ♠ 76 LT 3 cwt (77,370 kg) Loco weight ♠ 84 LT (85,350 kg) Tender weight 51 LT 1 cwt (51,870 kg) Total weight ♠ 135 LT 1 cwt (137,200 kg) Tender type MP1 (2-axle bogies) MP, MP1, MR permitted Fuel type Coal Fuel capacity 10 LT (10.2 t) Water cap 4,250 imp gal (19,300 l) Firebox type ♠♥ Belpaire  • Firegrate area ♠♥ 40 sq ft (3.7 m2) Boiler: ​  • Pitch ♠♥ 7 ft 9 1⁄8 in (2,365 mm)  • Diameter ♠♥ 5 ft 1 1⁄2 in (1,562 mm)  • Tube plates ♠ 17 ft (5,182 mm) ♥ 17 ft 1⁄4 in (5,188 mm)  • Small tubes ♠♥ 151: 2 in (51 mm)  • Large tubes ♠♥ 18 5 1⁄2 in (140 mm) Boiler pressure ♠♥ 200 psi (1,379 kPa) Safety valve Ramsbottom Heating surface ♠♥ 1,913 sq ft (177.7 m2)  • Tubes ♠ 1,783 sq ft (165.6 m2) ♥ 1,780 sq ft (165 m2)  • Firebox ♠ 130 sq ft (12 m2) ♥ 133 sq ft (12.4 m2) Superheater: ​  • Type Schmidt  • Heating area ♠ 343 sq ft (31.9 m2) ♥ 350 sq ft (33 m2) Cylinders Four High-pressure cylinder 16 1⁄2 in (419 mm) bore 24 in (610 mm) stroke Low-pressure cylinder 26 in (660 mm) bore 24 in (610 mm) stroke Valve gear Walschaerts Valve type Piston Couplers Johnston link-and-pin AAR knuckle (1930s)

Performance figures Tractive effort ♠ 38,170 lbf (169.8 kN) @ 50% ♥ 37,950 lbf (168.8 kN) @ 50%

Career Operators South African Railways Class Class MJ Number in class 18 Numbers 1651-1660, 1674-1681 Delivered 1914-1921 First run 1914 Scrapped 1962

The South African Railways Class MJ 2-6-6-0 of 1914 was a steam locomotive.

Between 1914 and 1921, the South African Railways placed eighteen Class MJ Mallet articulated compound steam locomotives with a 2-6-6-0 wheel arrangement in branch line service.

The Class MJ 2-6-6-0 Mallet articulated compound steam locomotive was designed by D.A. Hendrie, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1910 to 1922, to meet the need for engines with a higher tractive effort to cope with heavy traffic on branch lines.

Ten of these branch line locomotives were ordered from Maffei of Munich but, as a result of the outbreak of the First World War, only two could be delivered from Germany in 1914, numbered 1651 and 1652.

The order for the remaining eight was then transferred to the North British Locomotive Company (NBL) in Scotland, who delivered them in 1917 and 1918, numbered in the range from 1653 to 1660. The entry for the Mallets in the NBL works register shows them as ordered on 20 April 1915 and delivered from February to March 2016. Those dates are probably ex works dates rather than actual delivery dates.

After cessation of hostilities in 1918, Maffei approached the SAR and requested that the balance of the original order, which had been built in 1914 but could not be delivered because of the war, also be accepted. These eight locomotives were delivered in 1921, numbered in the range from 1674 to 1681.

The locomotives had Walschaerts valve gear and were superheated, using the Schmidt type superheater. Unlike most of the other SAR Mallet classes, which had round-topped fireboxes, the Class MJ had Belpaire fireboxes. The four cylinders were arranged outside the 4 inches (102 millimetres) thick bar frames.

The locomotives were delivered with Type MP1 tenders with a coal capacity of 10 long tons (10.2 tonnes) and a water capacity of 4,250 imperial gallons (19,300 litres). The same tender was used by altogether fifteen other SAR locomotive Classes.

During 1939, while W.A.J. Day was the CME of the SAR, the Classes MJ and MJ1 were modified slightly to be reboilered with the same standard boiler, once again with Belpaire fireboxes.