South African Class MJ1 2-6-6-0

The South African Railways Class MJ1 2-6-6-0 of 1918 was a steam locomotive.

South African Class MJ1 2-6-6-0
SAR Class MJ1 no. 1673, c. 1920
Type and origin
♠ Locomotive as built - ♥ Reboilered locomotive
Power typeSteam
DesignerMontreal Locomotive Works
BuilderMontreal Locomotive Works
Serial number58427-58434
ModelSAR Class MJ1
Build date1918
Total produced8
Specifications
Configuration:
​
 • Whyte2-6-6-0 (Denver)
 • UIC(1'C)Chv4
Driver3rd & 6th coupled axles
Gauge3 ft 6 in (1,067 mm) Cape gauge
Leading dia.28 1⁄2 in (724 mm)
Coupled dia.42 1⁄2 in (1,080 mm) as built
42 3⁄4 in (1,086 mm) retyred
Tender wheels34 in (864 mm)
Wheelbase60 ft 8 1⁄4 in (18,498 mm)
 • Engine32 ft 8 in (9,957 mm)
 • Coupled8 ft 4 in (2,540 mm) per unit
 • Tender17 ft 11 in (5,461 mm)
 • Tender bogie4 ft 7 in (1,397 mm)
Length:
​
 • Over couplers68 ft 7 1⁄8 in (20,907 mm)
Height♠♥ 12 ft 6 1⁄8 in (3,813 mm)
Frame typeBar
Axle load♠ 14 LT 2 cwt (14,330 kg)
 • Leading♠ 7 LT 10 cwt (7,620 kg)
 • 1st coupled♠ 13 LT 13 cwt (13,870 kg)
 • 2nd coupled♠ 13 LT 15 cwt (13,970 kg)
 • 3rd coupled♠ 14 LT 2 cwt (14,330 kg)
 • 4th coupled♠ 12 LT 11 cwt (12,750 kg)
 • 5th coupled♠ 13 LT 12 cwt (13,820 kg)
 • 6th coupled♠ 13 LT 7 cwt (13,560 kg)
 • Tender axle12 LT 14 cwt 2 qtr (12,930 kg) av.
Adhesive weight♠ 81 LT (82,300 kg)
Loco weight♠ 88 LT 10 cwt (89,920 kg)
Tender weight50 LT 18 cwt (51,720 kg)
Total weight♠ 139 LT 8 cwt (141,600 kg)
Tender typeLP (2-axle bogies)
Fuel typeCoal
Fuel capacity10 LT (10.2 t)
Water cap4,250 imp gal (19,300 l)
Firebox typeBelpaire
 • Firegrate area♠♥ 40 sq ft (3.7 m2)
Boiler:
​
 • Pitch♠♥ 7 ft 9 1⁄8 in (2,365 mm)
 • Diameter♠ 5 ft 2 3⁄4 in (1,594 mm)
♥ 5 ft 1 1⁄2 in (1,562 mm)
 • Tube plates♠ 17 ft 3⁄8 in (5,191 mm)
♥ 17 ft 1⁄4 in (5,188 mm)
 • Small tubes♠ 146: 2 in (51 mm)
♥ 151: 2 in (51 mm)
 • Large tubes♠ 22: 5 3⁄8 in (137 mm)
♥ 18: 5 1⁄2 in (140 mm)
Boiler pressure♠♥ 200 psi (1,379 kPa)
Safety valveRamsbottom
Heating surface♠ 2,042 sq ft (189.7 m2)
♥ 1,913 sq ft (177.7 m2)
 • Tubes♠ 1,906 sq ft (177.1 m2)
♥ 1,780 sq ft (165 m2)
 • Firebox♠ 136 sq ft (12.6 m2)
♥ 133 sq ft (12.4 m2)
Superheater:
​
 • Type♠♥ Schmidt
 • Heating area♠ 413 sq ft (38.4 m2)
♥ 350 sq ft (33 m2)
CylindersFour
High-pressure cylinder16 1⁄2 in (419 mm) bore
24 in (610 mm) stroke
Low-pressure cylinder26 in (660 mm) bore
24 in (610 mm) stroke
Valve gearWalschaerts
Valve typePiston
CouplersJohnston 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
OperatorsSouth African Railways
ClassClass MJ1
Number in class8
Numbers1666-1673
Delivered1918
First run1918
Withdrawnc. 1960

In 1918, the South African Railways placed eight Class MJ1 Mallet articulated compound steam locomotives with a 2-6-6-0 wheel arrangement in branch line service.[1][2][3][4]

Manufacturer

Because of the difficulties experienced by the usual British and German suppliers to build new locomotives during the First World War, orders for the Class MJ1 2-6-6-0 Mallet articulated compound steam locomotive were placed with Montreal Locomotive Works (MLW) in Canada. The locomotive was designed by MLW, based on the specifications for the Class MJ Mallet which had been designed by D.A. Hendrie, the Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1910 to 1922. Eight of these branch line locomotives were built and delivered by MLW in November 1918, numbered in the range from 1666 to 1673.[1][2][4]

Characteristics

The locomotives were superheated, had Walschaerts valve gear and, like the Class MJ Mallets, had Belpaire fireboxes, but slightly larger boilers. When compared to the Class MJ, a distinguishing feature of the Class MJ1 was the sandbox which was mounted on top of the boiler to the rear of the steam dome in North American style. In general appearance, they bore a family resemblance to the Class 14C and Class 15B 4-8-2 locomotives which were also built by MLW in 1918.[1][2][4]

During 1922, the coupled wheels were retyred and their diameter was increased from 42 1⁄2 inches (1,080 millimetres) to 42 3⁄4 inches (1,086 millimetres).[2]

Reboilering

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.[2]

Service

The Class MJ1 was the last Mallet locomotive class to be placed in service by the SAR. All the Railway’s subsequent new articulated locomotives were to be Garratts, Modified Fairlies and Union Garratts.[5]

The Class MJ1 was also intended for branch line working and joined the Class MJ Mallets in service in the Eastern Cape. All eight were still in service by March 1948, but they were all withdrawn from service by 1960.[1][4][5]

Illustration
  • No. 1668 at Butterworth, Eastern Cape, c. 1950
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References
  1. Holland, D. F. (1972). Steam Locomotives of the South African Railways. 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 36–37. ISBN 978-0-7153-5427-8.
  2. Espitalier, T.J.; Day, W.A.J. (1945). The Locomotive in South Africa - A Brief History of Railway Development. Chapter VII - South African Railways (Continued). South African Railways and Harbours Magazine, May 1945. p. 350.
  3. South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
  4. Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. p. 88. ISBN 0869772112.
  5. Durrant, A. E. (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. pp. 24–25. ISBN 0715386387.
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