South African Class 18 2-10-2

Builder's picture of the Class 18, c. 1927

Type and origin
Power type	Steam
Designer	South African Railways (Col F.R. Collins DSO)
Builder	Henschel and Son
Serial number	20787-20788
Model	Class 18
Build date	1927
Total produced	2

Specifications
Configuration:
• Whyte	2-10-2 (Santa Fe)
• UIC	1'E1'h3
Driver	3rd coupled axle
Gauge	3 ft 6 in (1,067 mm) Cape gauge
Leading dia.	30 in (762 mm)
Coupled dia.	57 in (1,448 mm)
Trailing dia.	33 in (838 mm)
Tender wheels	34 in (864 mm)
Minimum curve	320 ft (98 m)
Wheelbase	67 ft 7+3⁄4 in (20,618 mm)
• Engine	38 ft 2+1⁄4 in (11,640 mm)
• Coupled	21 ft (6,401 mm)
• Tender	20 ft 5 in (6,223 mm)
• Tender bogie	6 ft 2 in (1,880 mm)
Length:
• Over couplers	76 ft (23,165 mm)
Height	13 ft (3,962 mm)
Axle load	19 LT (19,300 kg)
• Leading	7 LT 9 cwt (7,570 kg)
• 1st coupled	18 LT 6 cwt (18,590 kg)
• 2nd coupled	18 LT 18 cwt (19,200 kg)
• 3rd coupled	19 LT (19,300 kg)
• 4th coupled	18 LT 4 cwt (18,490 kg)
• 5th coupled	18 LT 2 cwt (18,390 kg)
• Trailing	14 LT 12 cwt (14,830 kg)
• Tender bogie	Bogie 1: 33 LT 18 cwt (34,440 kg) Bogie 2: 38 LT 16 cwt (39,420 kg)
• Tender axle	19 LT 8 cwt (19,710 kg)
Adhesive weight	92 LT 10 cwt (93,980 kg)
Loco weight	114 LT 11 cwt (116,400 kg)
Tender weight	72 LT 14 cwt (73,870 kg)
Total weight	187 LT 5 cwt (190,300 kg)
Tender type	HT (2-axle bogies) Mechanical stoker
Fuel type	Coal
Water cap.	6,000 imp gal (27,300 L)
Firebox:
• Type	Round-top
• Grate area	60 sq ft (5.6 m²)
Boiler:
• Pitch	8 ft 6 in (2,591 mm)
• Diameter	6 ft 3+3⁄4 in (1,924 mm)
• Tube plates	20 ft 7 in (6,274 mm)
• Small tubes	160: 2+1⁄4 in (57 mm)
• Large tubes	34: 5+1⁄2 in (140 mm)
Boiler pressure	215 psi (1,480 kPa)
Safety valve	Pop
Heating surface	3,231 sq ft (300.2 m²)
• Tubes	2,945 sq ft (273.6 m²)
• Arch tubes	21 sq ft (2.0 m²)
• Firebox	265 sq ft (24.6 m²)
Superheater:
• Heating area	850 sq ft (79 m²)
Cylinders	Three
Cylinder size	21+1⁄4 in (540 mm) bore 28 in (711 mm) stroke
Valve gear	Outer Walschaerts - Inner Gresley
Valve type	Piston
Couplers	AAR knuckle

Performance figures
Tractive effort	53,650 lbf (239 kN) @ 75%

Career
Operators	South African Railways
Class	Class 18
Number in class	2
Numbers	1360-1361
Nicknames	Henschel Giant
Delivered	1927-1928
First run	1927
Withdrawn	1951

The 3rd & 4th coupled axles had flangeless wheels

The South African Railways Class 18 2-10-2 of 1927 was a steam locomotive.

In December 1927 and January 1928 the South African Railways placed two Class 18 three-cylinder steam locomotives with a 2-10-2 Santa Fe type wheel arrangement in service on the Witbank-Germiston coal line.^[1]^[2]^[3]^[4]

Manufacturer

The Class 18 2-10-2 Santa Fe type steam locomotive was designed by Colonel F.R. Collins DSO, Chief Mechanical Engineer (CME) of the South African Railways (SAR) from 1922 to 1929, and built by Henschel and Son in Germany. Two locomotives were delivered in 1927 and 1928, numbered 1360 and 1361.^[1]^[2]^[5]

Characteristics

They were very powerful three-cylinder locomotives. At the time, three-cylindered locomotives were being built in appreciable numbers in Europe and America. Factors in their favour were their more even turning moment, improved balancing and better distribution of crank-pin thrust. Drawbacks were increased complexity and higher repair cost.^[1]^[2]^[5]^[6]^[7]

When delivered, the third cylinder was clearly visible, but plating was subsequently added beneath the smokebox and hid it from view. These were the most powerful non-articulated steam locomotives to see service on the SAR, with a tractive effort of 53,650 pounds-force (239 kilonewtons) at 75% boiler pressure and capable of hauling loads of 1,800 long tons (1,829 tonnes) over the ruling gradient of 1 in 100 (1%) on the Witbank-Apex section.^[1]^[8]

Contemporary Henschel publicity appropriately referred to them as the "Henschel Giants". They were larger in most respects than Deutsche Reichsbahn's new Standard gauge Class 44 three-cylinder 2-10-0 locomotives. Although their all-up locomotive weight was almost the same, when considering the fact that the SAR's Cape gauge Class 18 had shorter axles and frame stretchers, saving weight that could then be built into other items such as the firebox, the Class 18 was the larger locomotive.^[6]

The Class 18 had a round-topped firebox with a combustion chamber and with arch tubes supporting the brick arch. It was fired by a Duplex D.4 type mechanical stoker, operated by a four-cylinder steam engine on its Type HT tender, which had a coal capacity of 14 long tons (14.2 tonnes), a water capacity of 6,000 imperial gallons (27,300 litres) and a maximum axle load of 19 long tons 8 hundredweight (19,710 kilograms).^[2]^[6]

To allow the locomotive to negotiate curves of 320 feet (98 metres) radius despite its long coupled wheelbase, the third and fourth pairs of driving wheels were flangeless. In addition, the locomotive made use of a Krauss-Helmholtz bogie system, where the leading pair of driving wheels has a limited amount of sideplay with an articulated link to the leading bissel bogie. The bissel bogie was connected to a sleeve around the first driving axle so that any displacement of the bissel bogie in one direction would cause a similar displacement of the leading driving axle in the opposite direction, thereby steering the driving wheels through curves.^[1]^[5]

The outside cylinders drove the third pair of driving wheels while the inside cylinder drove the second pair through a cranked axle, with the cylinder mounted in an inclined position. The three cranks were arranged at an angle of 120 degrees to each other, allowing for the inclination of the inner cylinder.^[1]^[2]^[3]^[4]

Service

The Class 18 was introduced in an attempt to ease problems which were being experienced with increasingly heavy coal trains on the line between Witbank and Germiston, where the Class MF Mallets were considered as being too sluggish and the hauling capacity of the non-articulated fleet was being stretched to the limit.^[1]^[5]

In service, the locomotives disappointed. In spite of the two sets of flangeless coupled wheels and the Krauss-Helmholtz system, the Class 18 experienced excessive flange and tyre wear while the Chief Civil Engineer claimed increased rail wear. The cylinder design was outdated and along with the lightweight motion and rods, contributed to them being uneconomical high-maintenance machines. The complicated valve gear was not robust enough and frequently gave trouble owing to wear and breakage. The result was that the locomotives had to be shopped at under 40,000 miles (64,374 kilometres).^[1]^[5]^[9]

Both Class 18 locomotives were withdrawn by 1951. After their locomotives were withdrawn from service, the two Type HT tenders had their mechanical stokers removed and their drawgear modified for use with Class 15CA locomotives. They were then redesignated Type KT.^[1]^[5]^[10]

Knuckle couplers

In 1927, the SAR began to convert the couplers of its Cape Gauge rolling stock from the Johnston link-and-pin coupling system which had been in use since the establishment of the Cape Government Railways in 1873, to AAR knuckle couplers. Judging from contemporary photographs as well as the official SAR Locomotive Diagram Book and the dimensional locomotive drawings as published by Holland, which were for the most part based on the original as-delivered and unmodified locomotives, the Class 18 locomotives were delivered new with knuckle couplers fitted, as were the Classes GCA, GF, HF and U which also entered service in 1927.^[1]^[3]^[4]

Conversion of all rolling stock would take several years and both coupler types could still be seen on rolling stock into the late 1950s. During the transition period, knuckle couplers on locomotives had a horizontal gap and a vertical hole in the knuckle itself to accommodate a link and a pin respectively. This enabled them to couple to vehicles which were still equipped with the older Johnston couplers.^[1]^[3]^[4]

Knuckle couplers had first been used in South Africa more than two decades earlier. The Central South African Railways (CSAR) introduced Gould knuckle couplers on the rolling stock of its Limited Express and Imperial Mail passenger trains in 1904. The Limited Express operated between Pretoria and Johannesburg while the Imperial Mail operated between Pretoria and Cape Town. These knuckle-couplers also had split knuckles to accommodate coupling to the old Johnston couplers with a link and pin, since the CSAR retained the old couplers on all their locomotives to keep them compatible with their own goods and older passenger rolling stock as well as with that from the other railways it connected with.^[11]

Illustration

Class 18 with the third cylinder visible, as delivered, c. 1930
Class 18 with plating beneath the smokebox hiding the third cylinder
Cutaway diagram of a Class 18 2-10-2 locomotive
Ex Type HT tender, modified and redesignated Type KT, c. 1970

References

Wikimedia Commons has media related to South African Class 18 2-10-2.

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Holland, D. F. (1972). Steam Locomotives of the South African Railways. Vol. 2: 1910-1955 (1st ed.). Newton Abbott, England: David & Charles. pp. 51–52. ISBN 978-0-7153-5427-8.
^ ^a ^b ^c ^d ^e Espitalier, T.J.; Day, W.A.J. (1946). The Locomotive in South Africa - A Brief History of Railway Development. Chapter VII - South African Railways (Continued). South African Railways and Harbours Magazine, Jun 1946. pp. 453-455.
^ ^a ^b ^c ^d 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. 25.
^ ^a ^b ^c ^d 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, 25.
^ ^a ^b ^c ^d ^e ^f Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 10–11, 69. ISBN 0869772112.
^ ^a ^b ^c Durrant, AE (1989). Twilight of South African Steam (1st ed.). Newton Abbott: David & Charles. pp. 27–30. ISBN 0715386387.
^ Henschel-Lieferliste (Henschel & Son works list), compiled by Dietmar Stresow
^ South African Railways & Harbours Photo Journal, Vol. 1, no 8, pp1-3, by Les Pivnic
^ Soul of A Railway, System 7, Western Transvaal, based in Johannesburg, Part 21: Witbank Line by Les Pivnic, Eugene Armer, Peter Stow and Peter Micenko. Captions 6, 7. (Accessed on 4 May 2017)
^ Soul of A Railway, System 8, Part 2: Pretoria: including local services, workshops and running sheds, Part 2. Caption 43. (Accessed on 18 March 2017)
^ Soul of A Railway, System 8, Part 1: Pretoria: including local services, workshops and running sheds, Part 1. Captions 8, 13. (Accessed on 15 March 2017)

Locomotives of South Africa

Steam

7' ¼" gauge	East London 0-4-0VB Table Bay 0-4-0ST Table Bay 0-4-0T Table Bay 0-4-0WT
Standard gauge	Cape 0-4-0T Blackie Cape 0-4-2 Cape 2-4-0T CGR 0-4-0ST Aid Natal 0-4-0ST Durban Natal 0-4-0WT Natal Natal 4-4-0T Perseverance
Cape gauge Tank engines	CGR 0-4-0ST 1873 CGR 0-4-0ST 1874 CGR 0-4-0ST 1881 CGR 0-4-0ST 1881 Coffee Pot CGR 0-6-0ST CGR 0-6-0T CGR 2-6-0ST 1900 CGR 2-6-0ST 1902 CGR 1st Class 0-4-0ST 1875 CGR 1st Class 0-4-0ST 1876 CGR 1st Class 2-6-0ST CGR 1st Class 4-4-0T CGR 2nd Class 4-4-0T CGR 3rd Class 2-6-0T CGR Railmotor CSAR Class C CSAR Class E CSAR Rack 4-6-4RT CSAR Railmotor Durban's Congella Durban's Edward Innes Durban's John Milne Durban's Sir Albert Port Elizabeth 0-4-0ST Kowie Railway 0-6-0T Kowie Railway 4-4-0T Metropolitan & Suburban 4-6-2T NGR 2-6-0T Durban & Pietermaritzburg NGR Class I 2-6-2T NGR Class K 0-4-0ST NGR Class K 0-6-0ST NGR Class K 2-6-0T NZASM 10 Tonner NZASM 13 Tonner NZASM 14 Tonner NZASM 18 Tonner NZASM 19 Tonner NZASM 32 Tonner NZASM 40 Tonner PPR 26 Tonner PPR 35 Tonner Portuguese SAR Class A SAR Class B SAR Class C SAR Class C1 SAR Class C2 SAR Class D SAR Class E SAR Class F SAR Class G SAR Class H SAR Class H1 SAR Class H2 SAR Class J SAR Class K SAR Railmotor SAR Dock 0-4-0ST SAR Dock 0-4-0T SWA 2-8-0T
Cape gauge Tender engines	CGR 1st Class 2-6-0 1876 BP CGR 1st Class 2-6-0 1876 Kitson CGR 1st Class 2-6-0 1879 CGR 1st Class 2-6-0 1891 CGR 1st Class 4-4-0 CGR 1st Class 4-4-0TT CGR 2nd Class 2-6-2TT CGR 3rd Class 4-4-0 1883 CGR 3rd Class 4-4-0 1884 CGR 3rd Class 4-4-0 1889 CGR 3rd Class 4-4-0 1898 CGR 3rd Class 4-4-0 1901 CGR 3rd Class 4-4-0 1903 CGR 4th Class 4-4-2 CGR 4th Class 4-6-0TT 1880 CGR 4th Class 4-6-0TT 1882 CGR 4th Class 4-6-0TT 1882 Joy CGR 4th Class 4-6-0TT 1884 CGR 5th Class 4-6-0 1890 CGR 5th Class 4-6-0 1891 NGR Havelock NGR Class I SAR Class Exp 1 SAR Class Exp 2 SAR Class Exp 3 SAR Class Exp 4 SAR Class Exp 5 SAR Class Exp 6 SAR Class S SAR Class S1 SAR Class S2 SAR Class 1 SAR Class 1A SAR Class 1B SAR Class 2 SAR Class 2C SAR Class 3 SAR Class 3A SAR Class 3B SAR Class 4 SAR Class 4A SAR Class 5 SAR Class 5A SAR Class 5B SAR Class 6 SAR Class 6A SAR Class 6B SAR Class 6C SAR Class 6D SAR Class 6E SAR Class 6F SAR Class 6G SAR Class 6H SAR Class 6J SAR Class 6K SAR Class 6L SAR Class 6Y SAR Class 6Z SAR Class 7 SAR Class 7A SAR Class 7B SAR Class 7C SAR Class 7D SAR Class 7E SAR Class 7F SAR Class 8 SAR Class 8A SAR Class 8B SAR Class 8C SAR Class 8D SAR Class 8E SAR Class 8F SAR Class 8R SAR Class 8X SAR Class 8Y SAR Class 8Z SAR Class 9 SAR Class 10 SAR Class 10A SAR Class 10B SAR Class 10C SAR Class 10D SAR Class 11 SAR Class 12 SAR Class 12A SAR Class 12B SAR Class 13 SAR Class 14 SAR Class 14A SAR Class 14B SAR Class 14C 1st SAR Class 14C 2nd SAR Class 14C 3rd SAR Class 14C 4th SAR Class 15 SAR Class 15A SAR Class 15B SAR Class 15C SAR Class 15CA SAR Class 15E SAR Class 15F SAR Class 16 SAR Class 16A SAR Class 16B SAR Class 16C SAR Class 16D SAR Class 16DA 1928 SAR Class 16DA 1930 SAR Class 16E SAR Class 17 SAR Class 18 SAR Class 19 SAR Class 19A SAR Class 19B SAR Class 19C SAR Class 19D SAR Class 20 SAR Class 21 SAR Class 23 SAR Class 24 SAR Class 25 SAR Class 25NC SAR Class 26 SAR Katanga SWA 2-8-0
Cape gauge Articulated engines	CGR Fairlie CGR Kitson-Meyer SAR Class FC SAR Class FD SAR Class GA SAR Class GB SAR Class GC SAR Class GCA SAR Class GD SAR Class GDA SAR Class GE SAR Class GEA SAR Class GF SAR Class GG SAR Class GH SAR Class GK SAR Class GL SAR Class GM SAR Class GMA SAR Class GO SAR Class HF SAR Class KM SAR Class MA SAR Class MB SAR Class MC SAR Class MC1 SAR Class MD SAR Class ME SAR Class MF SAR Class MG SAR Class MH SAR Class MJ SAR Class MJ1 SAR Class U
2' 6" gauge	Cape Copper John King & Miner Cape Copper Britannia Cape Copper Caledonia Cape Copper Clara Cape Copper Condenser Cape Copper Scotia Namaqua Copper Pioneer Walvis Bay 2-4-2T Hope
2' & 600mm gauges	ACR Class NG-G16A CGR NG 0-4-0T CGR NG 0-6-0T CGR NG 4-6-2T CGR Type A 2-6-4T CGR Type C 0-4-0T NGR Class N 4-6-2T SAR Dutton SAR NG 0-4-0T SAR Class NG1 SAR Class NG2 SAR Class NG3 SAR Class NG4 SAR Class NG5 SAR Class NG6 SAR Class NG7 SAR Class NG8 SAR Class NG9 SAR Class NG10 SAR Class NG-G11 SAR Class NG-G12 SAR Class NG-G13 SAR Class NG-G14 SAR Class NG15 SAR Class NG-G16 SWA Class Ha SWA Class Hb SWA Class Hc SWA Class Hd SWA Jung SWA Zwillinge

Electric

Amcoal Class E38

Gas-electric

SAR Gas-electric

Diesel

Cape gauge Diesel-electric	PRASA Class Afro 4000 SAR Class DS SAR Class DS1 SAR Class 31-000 SAR Class 32-000 SAR Class 32-200 SAR Class 33-000 SAR Class 33-200 SAR Class 33-400 SAR Class 34-000 SAR Class 34-200 SAR Class 34-400 SAR Class 34-500 SAR Class 34-600 SAR Class 34-800 SAR Class 34-900 SAR Class 35-000 SAR Class 35-200 SAR Class 35-400 SAR Class 35-600 TFR Class 35-800 SAR Class 36-000 SAR Class 36-200 SAR Class 37-000 Spoornet Class 39-000 TFR Class 39-200 TFR Class 43-000 TFR Class 44-000 TFR Class 45-000
2' gauge Diesel-electric	SAR Class 91-000
Cape gauge Diesel-hydraulic	SAR Class 61-000
Cape gauge Electro-diesel	Spoornet Class 38-000

South African steam locomotive tenders

Cape gauge

Type FT

Type GT

Type HT

Type KT

Type LP