South African Class 10 4-6-2

The South African Railways Class 10 4-6-2 of 1904 was a steam locomotive from the pre-Union era in Transvaal Colony.

CSAR Class 10 4-6-2 1904
South African Class 10 4-6-2
SAR no. 738 (ex CSAR no. 656) at Sydenham Loco depot, 4 September 1966
Type and origin
♠ Type XM2 tender - ♥ Type XP1 tender (No. 746)
Power typeSteam
DesignerCentral South African Railways
(P.A. Hyde)
BuilderNorth British Locomotive Company
Serial number16194-16203, 16226-16230
ModelCSAR Class 10
Build date1904
Total produced15
Specifications
Configuration:
​
 • Whyte4-6-2 (Pacific)
 • UIC2'C1'h2
Driver2nd coupled axle
Gauge3 ft 6 in (1,067 mm) Cape gauge
Leading dia.28 1⁄2 in (724 mm)
Coupled dia.62 in (1,575 mm) as built
63 in (1,600 mm) no. 745
Trailing dia.33 in (838 mm)
Tender wheels♠ 33 1⁄2 in (851 mm) as built
34 in (864 mm) retyred
♥ 34 in (864 mm)
Wheelbase56 ft 4 in (17,170 mm)
 • Engine30 ft 2 in (9,195 mm)
 • Leading6 ft (1,829 mm)
 • Coupled10 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 couplers64 ft 6 3⁄4 in (19,679 mm)
Height12 ft 10 in (3,912 mm)
Frame typePlate
Axle load15 LT 10 cwt (15,750 kg)
 • Leading13 LT 10 cwt (13,720 kg)
 • 1st coupled15 LT (15,240 kg)
 • 2nd coupled15 LT 10 cwt (15,750 kg)
 • 3rd coupled15 LT 10 cwt (15,750 kg)
 • Trailing13 LT 5 cwt (13,460 kg)
 • Tender bogieBogie 1:
♠ 24 LT 4 cwt (24,590 kg)
♥ 27 LT 10 cwt (27,940 kg)
Bogie 2:
♠ 25 LT 3 cwt (25,550 kg)
♥ 23 LT 11 cwt (23,930 kg)
 • Tender axle♠ 12 LT 11 cwt 2 qtr (12,780 kg)
♥ 13 LT 15 cwt (13,970 kg)
Adhesive weight46 LT (46,740 kg)
Loco weight72 LT 15 cwt (73,920 kg)
Tender weight♠ 49 LT 7 cwt (50,140 kg)
♥ 51 LT 1 cwt (51,870 kg)
Total weight♠ 122 LT 2 cwt (124,100 kg)
♥ 123 LT 16 cwt (125,800 kg)
Tender type♠ XM2 (2-axle bogies)
♥ XP1 (2-axle bogies)
XC, XC1, XD, XE, XE1, XF, XF1, XF2, XJ, XM, XM1, XM2, XM3, XM4, XP1, XS permitted
Fuel typeCoal
Fuel capacity♠♥ 10 LT (10.2 t)
Water cap♠ 4,000 imp gal (18,200 l)
♥ 4,250 imp gal (19,300 l)
Firebox typeBelpaire
 • Firegrate area35 sq ft (3.3 m2)
Boiler:
​
 • Pitch7 ft 4 in (2,235 mm)
 • Diameter4 ft 6 3⁄4 in (1,391 mm)
 • Tube plates18 ft 6 1⁄2 in (5,652 mm)
 • Small tubes92: 2 1⁄4 in (57 mm)
 • Large tubes18: 5 1⁄4 in (133 mm)
Boiler pressure190 psi (1,310 kPa)
Safety valveRamsbottom
Heating surface1,588 sq ft (147.5 m2)
 • Tubes1,463 sq ft (135.9 m2)
 • Firebox125 sq ft (11.6 m2)
Superheater:
​
 • Heating area384 sq ft (35.7 m2)
CylindersTwo
Cylinder size19 1⁄2 in (495 mm) bore
28 in (711 mm) stroke
Valve gearWalschaerts
Valve typePiston
CouplersJohnston link-and-pin
AAR knuckle (1930s)
Performance figures
Tractive effort24,470 lbf (108.8 kN) @ 75%
Career
OperatorsCentral South African Railways
South African Railways
ClassCSAR & SAR Class 10
Number in class15
NumbersCSAR 650-664, SAR 732-746
Delivered1904
First run1904
Withdrawn1972
The 2nd coupled axle had flangeless wheels

In July 1904, the Central South African Railways placed fifteen Class 10 steam locomotives with a 4-6-2 Pacific type wheel arrangement in service. In 1912, when they were assimilated into the South African Railways, they were renumbered but retained their Class 10 designation.[1][2][3][4]

Manufacturer

Fifteen 4-6-2 Pacific type passenger locomotives, designed by Central South African Railways (CSAR) Chief Locomotive Superintendent P.A. Hyde, were ordered from the North British Locomotive Company (NBL) and delivered in 1904, numbered in the range from 650 to 664. They were designated Class 10 by the CSAR.[1][2][4][5][6][7]

Characteristics

The Class 10 was designed by Hyde to take full advantage of the new 80 pounds per yard (40 kilograms per metre) track of the CSAR, which was gradually replacing the old 60 pounds per yard (30 kilograms per metre) sections on mainlines. The locomotive had plate frames, a wide Belpaire firebox, outside admission piston valves and Walschaerts valve gear, and was superheated. Its 62 inches (1,575 millimetres) coupled wheels were 2 inches (51 millimetres) larger in diameter than those of H.M. Beatty's Karoo Class Pacific which had entered service on the Cape Government Railways (CGR) the year before. At the time, the CSAR Classes 10 and 11 which were acquired simultaneously, were the heaviest and largest locomotives built for 3 feet 6 inches (1,067 millimetres) gauge.[1]

These locomotives were to form the basis for further development of the Pacific type, which was to become the standard express passenger steam locomotive type in South Africa. They were handsome locomotives and their appearance was enhanced by the use of planished steel plates to cover the boiler and cylinder lagging. They were equipped with two whistles of different tones and a steam turbine generator, mounted on the smokebox between the headlight and the chimney, to power the Edwards headlight.[1][2][8]

Firebox

The Class 10 was of an extremely advanced design for the day. At 7 feet 3 inches (2,210 millimetres) long, the firebox was somewhat shorter than usual practice, but much wider at 6 feet 1 1⁄2 inches (1,867 millimetres). It had a rocking firegrate with a drop grate at the front. The rocking grate was operated by a small steam cylinder of 4 inches (102 millimetres) bore and 6 inches (152 millimetres) stroke, arranged under the footplate. This arrangement became standard practice on all new locomotives, except on those equipped with mechanical stokers where it was found preferable to divide the grate into sections which could be shaken separately by hand gear.[1][8]

Boiler

The locomotive's most striking feature was the length of the boiler and smokebox. The boiler barrel was of telescopic design and was built up of three 6 feet 5 5⁄16 inches (1,964 millimetres) sections, with a lap of 4 1⁄2 inches (114 millimetres) and made of 5⁄8 inch (16 millimetres) thick plates. At 7 feet 4 inches (2,235 millimetres) above rail level, its boiler centre line or pitch was higher than that of any other locomotive in service in South Africa at the time.[1][4]

The boiler was fitted with Hornish type mechanical cleaners. Two were attached to the top of the foundation ring at the front and back, and a third to the front plate of the barrel, approximately at water level. The latter was intended for the removal of scum and was operated by a rod, attached to the cleaner cock and passed along the left side of the engine cab. When the scum cock was in operation, steam and water coming through the cock were carried to the front of the engine through a pipe. Both cleaners on the foundation ring were provided with separate hand-operated cocks. These fittings were not perpetuated on any subsequent locomotive designs.[1]

South African Railways

When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (CGR, Natal Government Railways and CSAR) were united under a single administration to control and administer the railways, ports and harbours of the Union. Although the South African Railways and Harbours came into existence in 1910, the actual classification and renumbering of all the rolling stock of the three constituent railways were only implemented with effect from 1 January 1912.[3][9]

When these locomotives were assimilated into the South African Railways (SAR) in 1912, they retained the Class 10 classification, but were renumbered in the range from 732 to 746.[3][4][5]

Modifications

Two of the locomotives were later modified by the SAR. No. 745 was equipped with 1 inch (25 millimetres) larger diameter tyres on its coupled wheels, while no. 746 was coupled to a modified Type MP1 tender. The intermediate draw and buffing gear of the tender, no. 1634 off a Class MC1 Mallet locomotive, was altered to suit no. 746. This modification converted tender no. 1634 to the sole Type XP1 tender. While it had the same coal capacity as the Type XM2 with which the locomotives were delivered, it had a 250 imperial gallons (1,140 litres) larger water capacity.[10]

The rest of the fleet remained unmodified and, unlike their Classes 10A, 10B and 10C successors, were never reboilered with Watson Standard boilers.[10]

Service

The Class 10 was placed in service to haul the fast passenger trains out of Johannesburg to Volksrust on the Natal line and to Klerksdorp on the new Cape line which was completed from Orkney to Fourteen Streams in 1906.[4][5]

In later years, some were relocated to work in the Noupoort area, while the rest were relegated to suburban work on the lines from Germiston to Kliprivier and the Springs-Nigel-Heidelberg branch, or for pick-up work on the Braamfontein-Klerksdorp line.[4][5][11]

Upon completion of the electrification projects from the Reef to Kroonstad and Witbank, the twelve surviving Class 10 locomotives at Germiston were transferred to Port Elizabeth on the Cape Midland during December 1959, for use on the Uitenhage suburban and other local services. They were eventually relegated to work as shunting engines until they were scrapped between 1971 and 1972, after 68 years in service.[4][5][11][12]

No. 744 was eventually mounted outside the main station building at Springs, one of the first engines to be plinthed as part of the SAR Museum policy.[11]

Preservation

Of the Class S2 ,three survived into preservation. By 2018

NumberWorks nmrTHF / PrivateLeaselend / OwnerCurrent LocationOutside SOUTH AFRICA?
735THFReefsteamersGermiston Locomotive DEPOT
744THFSprings Station

Illustration
  • CSAR Class 10 no. 651, SAR no. 733, c. 1904
  • SAR no. 741
  • No. 745 staged for preservation, November 1971

References
  1. Espitalier, T.J.; Day, W.A.J. (1945). The Locomotive in South Africa - A Brief History of Railway Development. Chapter VI - Imperial Military Railways and C.S.A.R. (Continued). South African Railways and Harbours Magazine, February 1945. pp. 97-100.
  2. Holland, D.F. (1971). Steam Locomotives of the South African Railways. 1: 1859–1910 (1st ed.). Newton Abbott, Devon: David & Charles. pp. 129–130. ISBN 978-0-7153-5382-0.
  3. Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer's Office, Pretoria, January 1912, pp. 9, 12, 14, 34 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  4. Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 51–52. ISBN 0869772112.
  5. Durrant, A. E. (1989). Twilight of South African Steam (1st ed.). Newton Abbott, London: David & Charles. p. 8. ISBN 0715386387.
  6. North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  7. North British Locomotive Co. (from J. Lambert)
  8. Soul of A Railway, System 8, Part 1: Pretoria: including local services, workshops and running sheds, Part 1. Introduction, Caption 13. (Accessed on 15 March 2017)
  9. The South African Railways - Historical Survey. Editor George Hart, Publisher Bill Hart, Sponsored by Dorbyl Ltd., Published c. 1978, p. 25.
  10. 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, 12, 45.
  11. Soul of A Railway, System 7, Part 14: Eastwards from Germiston, Part 2: Brakpan and Modder-B to Springs and Nigel. Preamble, Caption 18. (Accessed on 4 March 2017)
  12. Soul of A Railway, System 3, Part 11: The Midland Main Line, Part 3, Alicedale to Cradock. Captions 5, 6. (Accessed on 15 February 2017)
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