South African Class 16 4-6-2

The South African Railways Class 16 4-6-2 of 1914 was a steam locomotive.

South African Classes 16 & 16R 4-6-2
Class 16 no. 800, Braamfontein, c. 1930
Type and origin
♠ Class 16 as built with a Belpaire firebox
Class 16R rebuilt with a Watson Standard boiler
Steel firebox - Copper firebox
Power typeSteam
DesignerSouth African Railways
(D.A. Hendrie)
BuilderNorth British Locomotive Company
Serial number20430-20441
ModelClass 16
Build date1914
Total produced12
Specifications
Configuration:
  Whyte4-6-2 (Pacific)
  UIC2'C1'h2
Driver2nd coupled axle
Gauge3 ft 6 in (1,067 mm) Cape gauge
Leading dia.30 in (762 mm)
Coupled dia.60 in (1,524 mm)
Trailing dia.33 in (838 mm)
Tender wheels34 in (864 mm)
Wheelbase55 ft 11 34 in (17,062 mm)
  Engine29 ft 5 12 in (8,979 mm)
  Leading6 ft 2 in (1,880 mm)
  Coupled10 ft 9 in (3,277 mm)
  Tender16 ft 9 in (5,105 mm)
  Tender bogie4 ft 7 in (1,397 mm)
Length:
  Over couplers64 ft 4 18 in (19,612 mm)
Height♠ 12 ft 10 in (3,912 mm)
12 ft 11 14 in (3,943 mm)
Frame typePlate
Axle load♠ 18 LT (18,290 kg)
17 LT 15 cwt (18,030 kg)
  Leading♠ 16 LT 3 cwt (16,410 kg)
16 LT 10 cwt (16,760 kg)
  1st coupled♠ 18 LT (18,290 kg)
17 LT 13 cwt (17,930 kg)
  2nd coupled♠ 18 LT (18,290 kg)
17 LT 15 cwt (18,030 kg)
  3rd coupled♠ 17 LT 18 cwt (18,190 kg)
17 LT 15 cwt (18,030 kg)
  Trailing♠ 13 LT 12 cwt (13,820 kg)
13 LT 8 cwt (13,620 kg)
  Tender bogieBogie 1: 27 LT 10 cwt (27,940 kg)
Bogie 2: 23 LT 11 cwt (23,930 kg)
  Tender axle13 LT 15 cwt (13,970 kg)
Adhesive weight♠ 53 LT 18 cwt (54,760 kg)
53 LT 3 cwt (54,000 kg)
Loco weight♠ 83 LT 13 cwt (84,990 kg)
82 LT 19 cwt (84,280 kg)
Tender weight51 LT 1 cwt (51,870 kg)
Total weight♠ 134 LT 14 cwt (136,900 kg)
134 LT (136,200 kg)
Tender typeMP1 (2-axle bogies)
MP, MP1, MR, MS, MT, MT1, MT2, MX, MY, MY1 permitted
Fuel typeCoal
Fuel capacity10 LT (10.2 t)
Water cap4,250 imp gal (19,300 l)
Firebox typeBelpaire - Round-top
  Firegrate area 37 sq ft (3.4 m2)
Boiler:
  ModelWatson Standard no. 2B
  Pitch♠ 7 ft 9 in (2,362 mm)
8 ft (2,438 mm)
  Diameter♠ 5 ft 4 58 in (1,641 mm)
5 ft 7 12 in (1,714 mm)
  Tube plates♠ 18 ft 3 in (5,563 mm)
18 ft 4 in (5,588 mm)
18 ft 3 58 in (5,578 mm)
  Small tubes131: 2 14 in (57 mm)
87: 2 12 in (64 mm)
  Large tubes24: 5 12 in (140 mm)
30: 5 12 in (140 mm)
Boiler pressure 190 psi (1,310 kPa)
Safety valveRamsbottom
Pop
Heating surface♠ 2,186 sq ft (203.1 m2)
1,978 sq ft (183.8 m2)
  Tubes♠ 2,040 sq ft (190 m2)
1,836 sq ft (170.6 m2)
  Firebox♠ 146 sq ft (13.6 m2)
142 sq ft (13.2 m2)
Superheater:
  Heating area♠ 515 sq ft (47.8 m2)
472 sq ft (43.9 m2)
CylindersTwo
Cylinder size22 in (559 mm) bore
26 in (660 mm) stroke
Valve gearWalschaerts
Valve typePiston
CouplersJohnston link-and-pin
AAR knuckle (1930s)
Performance figures
Tractive effort 29,890 lbf (133.0 kN) @ 75%
Career
OperatorsSouth African Railways
ClassClass 16 & 16R
Number in class12
Numbers790-801
Delivered1914
First run1914
The 2nd coupled axle had flangeless wheels

In 1914, the South African Railways placed twelve Class 16 steam locomotives with a 4-6-2 Pacific type wheel arrangement in passenger train service.[1][2][3]

Manufacturer

The Class 16 4-6-2 Pacific type passenger locomotive was designed by D.A. Hendrie, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1910 to 1922. It was built by the North British Locomotive Company in Glasgow, Scotland, who delivered twelve locomotives in 1914, numbered in the range from 790 to 801.[1][2][3][4]

Characteristics

D.A. Hendrie

The design of the Class 16 closely followed that of Hendrie's Class 15 4-8-2 Mountain type which was introduced at the same time from the same builders and many parts were made interchangeable.[1][3]

The cylinders were arranged outside the plate frames, with the piston valves above the cylinders and actuated by Walschaerts valve gear. The boilers were equipped with superheaters and had Belpaire fireboxes. The engines were delivered new with Type MP1 tenders with a 10 long tons (10.2 tonnes) coal capacity and a 4,250 imperial gallons (19,300 litres) water capacity.[1][2][3][5][6]

Power comparison

When it was built in 1914, the Class 16 was considered to be a very large and powerful express locomotive, even when compared to British locomotives which were built to run on 4 feet 8 12 inches (1,435 millimetres) broad gauge. As built, with 60 inches (1,524 millimetres) diameter coupled wheels, the ratio of wheel diameter to rail gauge was the same as that of a broad gauge locomotive with 81 inches (2,057 millimetres) diameter coupled wheels. Their tractive effort of 29,890 pounds-force (133.0 kilonewtons) at 75% boiler pressure exceeded the 27,800 pounds-force (124 kilonewtons) at 85% boiler pressure of Churchward's The Great Bear Pacific on the Great Western Railway and equalled, also at 85% boiler pressure, that of Gresley's later Great Northern Pacifics. This made the Class 16 the most powerful express passenger locomotive design yet to have been built in Great Britain at the time.[7]

Watson Standard boilers

During the 1930s, many serving locomotives were reboilered with a standard boiler type designed by A.G. Watson, CME of the SAR from 1929 to 1936, as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification.[3][5][6]

Eventually all twelve Class 16 locomotives were reboilered with Watson Standard no. 2B boilers and reclassified to Class 16R. Early conversions were equipped with copper and later conversions with steel fireboxes. In the process, they were also equipped with Watson cabs with their distinctive slanted fronts, compared to the conventional vertical fronts of their original cabs.[3][5][6]

Their original Belpaire boilers were fitted with Ramsbottom safety valves, while the Watson Standard boiler was fitted with Pop safety valves. An obvious visual difference between an original and a Watson Standard reboilered locomotive is usually a rectangular regulator cover, just to the rear of the chimney on the reboilered locomotive. In the case of the Class 16 and Class 16R locomotives, two even more obvious differences are the Watson cab and the absence of the Belpaire firebox hump between the cab and boiler on the reboilered locomotives.[3][5][6]

Service

The Class 16 was intended for fast passenger trains in Transvaal, the Orange Free State and the upper sections of Natal where the gradients were not as severe. They were placed in suburban passenger service, working between Pretoria and Johannesburg, and in mainline service on the section from Johannesburg to Volksrust on the line to Natal. In later years, after being withdrawn from mainline passenger service, many of these locomotives remained employed in suburban passenger working and shunting service.[1][2][3][7]

Preservation

NumberWorks nmrTHF / PrivateLeaselend / OwnerCurrent LocationOutside South Africa?
794THFKrugersdorp Locomotive Depot

Illustration

The main picture shows Class 16 no. 800 at Braamfontein c. 1930, as built with a Belpaire firebox and Type MP1 tender, on interurban service with a destination board for Pretoria below its headlight.

References

  1. Holland, D. F. (1972). Steam Locomotives of the South African Railways. 2: 1910-1955 (1st ed.). Newton Abbott, Devon: David & Charles. p. 27. 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, August 1945. p. 594.
  3. Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 10-11 & 64. ISBN 0869772112.
  4. North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  5. South African Railways & Harbours/Suid Afrikaanse Spoorweë en Hawens (15 Aug 1941). Locomotive Diagram Book/Lokomotiefdiagramboek, 3'6" Gauge/Spoorwydte. SAR/SAS Mechanical Department/Werktuigkundige Dept. Drawing Office/Tekenkantoor, Pretoria. p. 43.
  6. South African Railways & Harbours/Suid Afrikaanse Spoorweë en Hawens (15 Aug 1941). Locomotive Diagram Book/Lokomotiefdiagramboek, 2'0" & 3'6" Gauge/Spoorwydte, Steam Locomotives/Stoomlokomotiewe. SAR/SAS Mechanical Department/Werktuigkundige Dept. Drawing Office/Tekenkantoor, Pretoria. pp. 6a-7a, 41, 43.
  7. Durrant, A. E. (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. pp. 92–93. ISBN 0715386387.
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