South African Class 23 4-8-2

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South African Class 23 4-8-2
SAR Class 23 2556 (4-8-2) 1.JPG
No. 2556 plinthed in Gideon Joubert park, Touws River, 8 January 2010
Type and origin
Power type Steam
Designer South African Railways
Builder Berliner Maschinenbau
Henschel and Son
Serial number Berliner:
10738-10744, 10816, 10985-10999, 11001-11015
Henschel:
23742-23754, 24155-24239
Model Class 23
Build date 1938
Total produced 136
Specifications
Configuration 4-8-2 "Mountain"
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Leading dia 34 in (864 mm)
Driver diameter 63 in (1,600 mm)
Trailing dia 34 in (864 mm)
Minimum curve 300 ft (91,440 mm) radius
Wheelbase Total, 2552-2571: 77 ft 8.5 in (23,686 mm)
Total, 3201-3316: 78 ft 2.5 in (23,838 mm)
Engine:
7 ft 2 in (2,184 mm) bogie
16 ft 6 in (5,029 mm) coupled
37 ft .5 in (11,290 mm) total
Tender:
8 ft 8 in (2,642 mm) bogie
30 ft 8 in (9,347 mm) total
Length 87 ft 2.25 in (26,575 mm) total
Height 12 ft 11.5 in (3,950 mm)
Frame Bar frames
Axle load 18.85 long tons (19.2 t) on 2nd driver, 2552-2571
18.7 long tons (19.0 t) on 2nd driver, 3201-3316
Adhesive weight 73.2 long tons (74.4 t) 2552-2571
72.5 long tons (73.7 t) 3201-3316
Loco weight 110.95 long tons (112.7 t) 2552-2571
111.1 long tons (112.9 t) 3201-3316
Tender weight 105,928 lb (48.0 t) empty
104.25 long tons (105.9 t) 2552-2571 w/o
107.7 long tons (109.4 t) 3201-3316 w/o
Loco & tender weight 219,744 lb (99.7 t) empty
215.2 long tons (218.7 t) 2552-2571 w/o
218.8 long tons (222.3 t) 3201-3316 w/o
Tender type EW
* 3 axle bogies
* 34 in (864 mm) wheels
* Length 43 ft 10 in (13,360 mm)
Fuel type Coal
Fuel capacity 18 long tons (18.3 t)
Water cap 9,200 imp gal (42,000 L) 2552-2571
9,500 imp gal (43,000 L) 3201-3316
Boiler 6 ft 2.25 in (1,886 mm) inside diameter
22 ft 6 in (6,858 mm) inside length
9 ft (2,743 mm) pitch
Boiler pressure Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value).
Firegrate area 63 sq ft (5.853 m2)
Heating surface 3,400 sq ft (315.870 m2)
 • Tubes 136 tubes 2.5 in (64 mm) diameter
36 tubes 5.5 in (140 mm) diameter
3,168 sq ft (294.317 m2)
 • Flues 26 sq ft (2.415 m2)
 • Firebox 206 sq ft (19.138 m2)
Superheater:
 • Heating area		 676 sq ft (62.802 m2)
Cylinders Two
Cylinder size 24 in (610 mm) bore
28 in (711 mm) stroke
Valve gear Walschaerts
Performance figures
Tractive effort 43,200 lbf (192 kN) at 75% pressure
Career
Operators South African Railways
Class Class 23
Number in class 136
Numbers 2552-2571, 3201-3316
Delivered 1938-1939
First run 1938
Retired 1983

The South African Railways Class 23 4-8-2 of 1938 is a South African steam locomotive from the South African Railways era.

In 1938 and 1939 the South African Railways placed one hundred and thirty-six Class 23 steam locomotives in service. The Class 23 was the last and the largest 4-8-2 Mountain type locomotive to be designed by the South African Railways.[1][2][3]

Manufacturers

The Class 23 4-8-2 Mountain type steam locomotive was designed by W.A.J. Day, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1936 to 1939. It was intended as a general utility locomotive capable of operating on 80 pounds per yard (40 kilograms per metre) rail, and was built in two batches by Berliner Maschinenbau and Henschel and Son in Germany. The original order in 1938 was for twenty locomotives, of which Berliner built seven, numbered in the range from 2552 to 2558, and Henschel thirteen, numbered in the range from 2559 to 2571.[1][4][5]

The urgency brought about by the rapidly deteriorating political climate in Europe at the time led to a further one hundred and sixteen locomotives being ordered even before the first batch could be delivered and tested. Of these, Henschel built eighty-five, numbered in the range from 3201 to 3285, and Berliner thirty-one, numbered in the range from 3286 to 3316. The last locomotive of this second order was delivered in August 1939, just one month before the outbreak of World War II.[1][4][6]

Locomotive number 3301 received an out of sequence works number, Berliner 10816 instead of 11000, since works number 11000 was reserved for a new 4-6-2 Pacific type locomotive for the German State Railways. The table shows the Class 23 engine numbers, builders and works numbers. On the builders’ works lists all the locomotives are recorded as having been built in 1938.[1][2][5]

Design considerations

Watson Standard boiler

As originally designed, the locomotive would have had 66 inches (1,676 millimetres) coupled wheels, which would have required a newly designed boiler to accommodate the extra length brought about by the longer coupled wheelbase. The increasing political turmoil in Europe and the resulting urgency, however, prohibited time being spent on designing a new boiler. As a result, the existing Watson Standard no. 3B boiler was incorporated in the design, with an extra long smokebox to partially compensate for the shorter boiler. This boiler was one of the range of standard type boilers designed by Day’s predecessor as CME, A.G. Watson, as part of the latter’s standardisation policy.[1]

Coupled wheel diameter

In order to enable them to negotiate 300 feet (91.4 metres) radius curves, the leading coupled wheels were given a 1 inch (25 millimetres) side-play. In addition, largely also as a result of the decision to use the shorter Watson Standard boiler, it was decided to reduce the coupled wheel diameter from 66 inches (1,676 millimetres) to 63 inches (1,600 millimetres), which shortened the coupled wheelbase and would further ease passage on sharp curves.[1][4]

These decisions appear to have been taken at quite a late stage, since the cylinders were cast to suit the larger wheel diameter. To compensate for the decreased wheel diameter, the maximum boiler pressure was raised to Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value)., at the time the highest yet used on the SAR.[3]

Tender

Since these locomotives were intended for working in the Karoo where good quality water is a scarce resource, they were equipped with very large tenders with a high water capacity that rode on six wheeled bogies. They were the largest tenders to have been used in South Africa up to that time and as designed, they would have had a water capacity of 10,000 imperial gallons (45,000 litres).[1][4]

Axle load restrictions, however, led to the water capacity being reduced to 9,200 imperial gallons (42,000 litres) for the first order of twenty locomotives. This was increased to 9,500 imperial gallons (43,000 litres) for the second order of one hundred and sixteen. Four vacuum cylinders operated clasp brakes on all tender wheels.[1][4]

Streamlining

During the 1930s the streamlining of locomotives was fashionable in Europe and the United States of America. It was proposed to adopt streamlining on some of the Class 23 locomotives, but investigation showed that it would increase the cost by £500 per locomotive and increase the weight by approximately 2 long tons (2.0 tonnes). Those factors, coupled to the negligible performance benefit of streamlining at normal goods train speeds as well as the reduced accessibility of working parts on a streamlined locomotive, led to this idea being abandoned.[1][4]

Service

In general appearance and power the Class 23 locomotive is very similar to the Class 15E and 15F. In their first few years of service the Class 23 fleet formed the bulk of the motive power on the lines from Touws River to Beaufort West and from De Aar to Welverdiend via Kimberley and Klerksdorp.[4]

The arrival of the new Class 25 and Class 25NC in 1953 caused them to be transferred to Bloemfontein, to work from there to Kimberley to the west and Kroonstad to the north.[4]

Due to metal fatigue cracks that developed in their 5 inches (127 millimetres) thick rolled steel bar frames, they were withdrawn from mainline service considerably earlier than the similar Class 15F. They were all retired by 1983, many of them in the process donating their large Type EW tenders to increase the range of the Class 15F. At least one of these tenders, that of number 3209, was later rebuilt to a water-only tender.[3][4]

Illustration

The main picture shows Berliner-built number 2556, which was plinthed next to the High School in Gideon Joubert Park in Touws River on occasion of that Railway town’s centenary in 1977. It was officially presented to the town by SAR chief executive Dr. Kobus Loubser on 24 September 1977.[7]

  • SAR Class 23 3300 (4-8-2).jpg

    Berliner-built no. 3300 at Koppies, Orange Free State, between Sasolburg and Kroonstad, 6 October 1989

  • Class 23 no. 3282 Vrystaat.jpg

    Henschel-built no. 3282 "Vrystaat" on the Orange Express, stopped at Perdeberg on the line between Petrusburg and Kimberley

  • SAR Class 23 3209 (4-8-2) Tender.JPG

    No. 3209’s Type EW tender, rebuilt to a water-only tender, at Worcester, Western Cape, 20 October 2009

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 South African Railways and Harbours Locomotive Diagram Book, 2’0” & 3’6” Gauge Steam Locomotives, 15 August 1941, as amended
  3. ↑ 3.0 3.1 3.2 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 Henschel & Son works list, compiled by Dietmar Stresow
  6. ↑ Touws River, Municipality - SAR Class 23 No 2556
  7. ↑ Touwsrivier – Daos Ab – 1877-1977 (J.H. Stassen, 1977), pp79, 83-85
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