South African Class H 4-10-2T

25+3⁄4 in (654 mm)Coupled dia.45 in (1,143 mm)Trailing dia.25+3⁄4 in (654 mm)Minimum curve300 ft (91 m)Wheelbase30 ft 6 in (9,296 mm) ​ • Leading5 ft 4 in (1,626 mm) • Coupled16 ft 8 in (5,080 mm)Length:
​ • Over couplers37 ft 6 in (11,430 mm)Height12 ft 6 in (3,810 mm)Frame typePlateAxle load12 LT 5 cwt (12,450 kg) ​ • Leading9 LT 17 cwt (10,010 kg) • 1st coupled10 LT 18 cwt (11,070 kg) • 2nd coupled12 LT 5 cwt (12,450 kg) • 3rd coupled10 LT 13 cwt (10,820 kg) • 4th coupled10 LT 10 cwt (10,670 kg) • 5th coupled10 LT 10 cwt (10,670 kg) • Trailing4 LT 4 cwt (4,267 kg)Adhesive weight54 LT 16 cwt (55,680 kg)Loco weight68 LT 17 cwt (69,950 kg)Fuel typeCoalFuel capacity4 LT (4.1 t)Water cap.1,880 imp gal (8,550 L)Firebox:​ • TypeRound-top • Grate area21.15 sq ft (1.965 m²)Boiler:
​ • Pitch6 ft 10 in (2,083 mm) • Diameter4 ft 7+7⁄8 in (1,419 mm) • Tube plates10 ft 4 in (3,150 mm) • Small tubes287: 1+3⁄4 in (44 mm)Boiler pressure175 psi (1,207 kPa)Safety valveSalter & RamsbottomHeating surface:​ • Firebox134.79 sq ft (12.522 m²) • Tubes1,358.71 sq ft (126.228 m²) • Total surface1,493.50 sq ft (138.751 m²)CylindersTwoCylinder size19 in (483 mm) bore
27 in (686 mm) strokeValve gearAllanValve typeRichardson balanced slideCouplersJohnston link-and-pin

Performance figures
Tractive effort	28,440 lbf (126.5 kN) @ 75%

Career
Operators	Natal Government Railways South African Railways Witbank Collieries
Class	NGR Class C SAR Class H
Number in class	NGR 101, SAR 93
Numbers	NGR 149-249, SAR 232-324
Official name	Reid Tenwheeler
Nicknames	Walloper
Delivered	1899-1903
First run	1899
Withdrawn	1977

The leading and trailing coupled axles had flangeless wheels

The South African Railways Class H 4-10-2T, introduced in 1899, was a steam locomotive from the pre-Union era in the Colony of Natal.

Between 1899 and 1903, the Natal Government Railways placed 101 tank steam locomotives with a 4-10-2 wheel arrangement in service. In 1912, after the establishment of the South African Railways, 93 of these Class C Reid Tenwheelers survived unmodified and were designated Class H.^[1][2][3]

Design

By 1898, increasing traffic on the new Natal Government Railways (NGR) mainline into the interior, with its sharp curves and severe 1 in 30 (3⅓%) gradients, necessitated double-heading of the NGR's Dübs A 4-8-2T locomotives on the heavier section of the Natal mainline between Estcourt and Mooirivier as a means to run longer trains to reduce occupation of the line. The requirement therefore arose for a tank locomotive which could haul at least one-and-a-half times as much as a Dübs A locomotive.^[2][3][4]

The limitations within which G.W. Reid, Locomotive Superintendent of the NGR at the time, had to meet this requirement were rather severe. The maximum axle load was not to exceed 14 long tons (14,220 kilograms) within the construction loading gauge of 13 feet (3,962 millimetres) high by 9 feet (2,743 millimetres) wide, while the locomotive had to be able to negotiate gradients of 1 in 30 (3⅓%), compensated for curves of 300 feet (91 metres) radius. The result was Reid's design of a 4-10-2 tank engine, the first locomotive in the world to use this wheel arrangement.^[2][3][4]

Manufacturers

Since there was no precedent for such an enormous Cape gauge tank locomotive, the design was the subject of some severe criticism and various objections were put forward against its introduction. It was therefore decided to order only one experimental locomotive from Dübs and Company. It was delivered in 1899 and numbered 149.^[4]

In 1900, the General Manager of the NGR reported that the trials of the 4-10-2T Reid locomo­tive had proven successful beyond anticipation and that the engine could haul a gross load of 200 long tons (203.2 tonnes) over the worst section of line with ease, 50% in excess of that taken by a Dübs A locomotive. As a result, orders were placed for another 100 of these locomo­tives between 1901 and 1903. The first 95 of these locomotives were built in four batches by Dübs and were numbered in the range from 150 to 244.^[2][4]

Since Dübs and a number of other Scottish locomotive builders were merged to form the North British Locomotive Company (NBL) while the locomotives were being built, the last five engines were delivered as having been built by the newly established NBL, numbered in the range from 245 to 249.^[4][5][6]

Classification

On the NGR, the locomotive type became known as the Reid Tenwheeler. When a locomotive classification system was introduced on the NGR, they were designated Class C.^[4][5][7]

Characteristics

To negotiate sharp curves, both the first and fifth pairs of coupled wheels were flangeless. The cylinders were arranged outside the plate frame, while the Richardson balanced type slide valves were placed between the frames. The locomotive used saturated steam and was equipped with Allan straight link valve gear, which was reversed by hand-wheel and quick screw gear. Allan valve gear was chosen chiefly because it required less space than the more usual Stephenson lifting link gear and was simpler in construction. The trailing Bissel truck was of the Cartazzi type which allowed the axle some lateral movement.^[2][3][4]

The leading bogie was controlled by two side-check springs and had 4 inches (102 millimetres) of side-play in each direction. This arrangement was later modified on some locomotives by substituting it with swing links. The portion of the driving crankpins for the connecting rod big-ends was turned 1+1⁄2 inches (38 millimetres) eccentric to that of the coupling rods to obtain the longest possible piston stroke which the wheel diameter would permit, while keeping the throw of the coupling rod to a reasonable amount. Since the piston rod and crosshead was forged in one piece, the connecting rod small-end had to be forked.^[2][4]

The firebox, at 8 feet 11+5⁄8 inches (2,734 millimetres) long and 2 feet 4+1⁄2 inches (724 millimetres) wide inside and arranged between the frames, was the longest ever used in South Africa.^[2]

Modifications

The main shortcoming of the Reid Tenwheeler was a tendency to derail while reversing, particularly over points, since the trailing coupled wheels were flangeless and tended to drop off the rails in the 1 in 7 turnouts which were in use at the time. This was overcome by increasing the tyre width from 6 inches (152 millimetres) to 7 inches (178 millimetres), after which the locomotives proved successful in service.^[2][4]

When some were withdrawn from mainline service and placed in branch line and shunting service where smaller radius curves were encountered, they were modified to 4-8-2T locomotives by removing the fifth pair of coupled wheels.^[3][4]

South African Railways

When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (Cape Government Railways, NGR and Central South African Railways) 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.^[1][8]

In 1912, the 93 as yet unmodified Class C Reid Tenwheelers were designated Class H on the South African Railways (SAR) and renumbered in the range from 232 to 324. The modified 4-8-2T engines, also designated NGR Class C, were designated Class H2 on the SAR and renumbered in the range from 227 to 231. Three locomotives, NGR numbers 194, 195 and 214, had been scrapped prior to 1912 and did not come under the renumbering scheme.^[1][3][4]

The SAR Class H locomotives were gradually also modified to a 4-8-2T wheel arrangement. The first three of these, SAR numbers 240, 294 and 305, were renumbered again to 329, 330 and 331 respectively, but the rest retained their Class H engine numbers after modification. Their builders, works numbers and renumbering are listed in the table.^[1][4][6]

Class H 4-10-2T
Builders, works numbers and renumbering

Year	Builder	Works no.	NGR no.	Class H no.	Class H2 no.
1899	Dübs	3835	149	232
1901	Dübs	4040	150	233
1901	Dübs	4041	151	234
1901	Dübs	4042	152	235
1901	Dübs	4043	153	236
1901	Dübs	4044	154	237
1901	Dübs	4045	155	238
1901	Dübs	4046	156	239
1901	Dübs	4047	157	240	329
1901	Dübs	4048	158	241
1901	Dübs	4049	159	242
1901	Dübs	4050	160	243
1901	Dübs	4051	161	244
1901	Dübs	4052	162	245
1901	Dübs	4053	163	246
1901	Dübs	4054	164	247
1901	Dübs	4055	165	248
1901	Dübs	4056	166	249
1901	Dübs	4057	167	250
1901	Dübs	4058	168	251
1901	Dübs	4059	169	252
1901	Dübs	4060	170		227
1901	Dübs	4061	171	253
1901	Dübs	4062	172	254
1901	Dübs	4063	173		228
1901	Dübs	4064	174	255
1902	Dübs	4117	175		229
1902	Dübs	4118	176	256
1902	Dübs	4119	177	257
1902	Dübs	4120	178	258
1902	Dübs	4121	179	259
1902	Dübs	4122	180	260
1902	Dübs	4123	181	261
1902	Dübs	4124	182	262
1902	Dübs	4125	183	263
1902	Dübs	4126	184	324
1902	Dübs	4127	185	264
1902	Dübs	4128	186	265
1902	Dübs	4129	187	266
1902	Dübs	4130	188	267
1902	Dübs	4131	189	268
1902	Dübs	4132	190	269
1902	Dübs	4133	191	270
1902	Dübs	4134	192	271
1902	Dübs	4135	193	272
1902	Dübs	4136	194	Scrapped
1902	Dübs	4137	195	Scrapped
1902	Dübs	4138	196	273
1902	Dübs	4139	197	274
1902	Dübs	4140	198	275
1902	Dübs	4141	199	276
1902	Dübs	4254	200	277
1902	Dübs	4255	201	278
1902	Dübs	4256	202	279
1902	Dübs	4257	203	280
1902	Dübs	4258	204	281
1902	Dübs	4259	205	282
1902	Dübs	4260	206	283
1902	Dübs	4261	207	284
1902	Dübs	4262	208	285
1902	Dübs	4263	209	286
1902	Dübs	4264	210	287
1902	Dübs	4265	211	288
1902	Dübs	4266	212	289
1902	Dübs	4267	213	290
1902	Dübs	4268	214	Scrapped
1902	Dübs	4269	215	291
1902	Dübs	4270	216	292
1902	Dübs	4271	217		230
1902	Dübs	4272	218	293
1902	Dübs	4273	219	294	330
1902	Dübs	4274	220	295
1902	Dübs	4275	221	296
1902	Dübs	4276	222	297
1902	Dübs	4277	223	298
1902	Dübs	4278	224	299
1903	Dübs	4310	225	300
1903	Dübs	4311	226	301
1903	Dübs	4312	227	302
1903	Dübs	4313	228	303
1903	Dübs	4314	229	304
1903	Dübs	4315	230	305	331
1903	Dübs	4316	231	306
1903	Dübs	4317	232	307
1903	Dübs	4318	233	308
1903	Dübs	4319	234	309
1903	Dübs	4320	235	310
1903	Dübs	4321	236	311
1903	Dübs	4322	237	312
1903	Dübs	4323	238	313
1903	Dübs	4324	239	314
1903	Dübs	4323	240		231
1903	Dübs	4326	241	315
1903	Dübs	4327	242	316
1903	Dübs	4328	243	317
1903	Dübs	4329	244	318
1903	NBL	15723	245	319
1903	NBL	15724	246	320
1903	NBL	15725	247	321
1903	NBL	15726	248	322
1903	NBL	15727	249	323

Service

The Reid Tenwheelers were initially employed on the lower section of the Natal mainline and worked both passenger and goods trains. Most of them continued to work there even after more powerful locomotives were placed in service. When the Corridor Train was introduced between Durban and Johannesburg in 1903, the Reid Tenwheelers worked the trains between Durban and Volksrust, but their limited coal and water capacity necessitated en route engine changes at Inchanga, Pietermaritzburg, Mooirivier, Ladysmith and Hattingspruit.^[2]

In the SAR era, some were relocated to De Doorns in the Cape Province for banking service up the Hex River Railpass. They had a long service life and some, modified to the 4-8-2T Mountain type, remained in service until 1977.^[3]

Other operators

Imperial Military Railways

In 1902 during the Second Boer War, the Imperial Military Railways (IMR) placed orders with Dübs and Company and Neilson, Reid and Company for altogether 35 locomotives of the Reid Tenwheeler type. In SAR service, these locomotives were designated Class H1 in 1912.^[2][3][4]

Industry

A final order for one new Reid Tenwheeler locomotive was placed by Witbank Collieries as late as 1927. The 137 locomotives built to this design was about double the number of all other 4-10-2 locomotives in use elsewhere in the world, all of which were tender locomotives which served mainly in the United States of America and Brazil.^[5]

Illustration

• 
  NGR Class C no. 149, SAR Class H no. 232, c. 1900

References

1. ^ ^{a b c d} Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer's Office, Pretoria, January 1912, pp. 7, 11, 13, 23-25 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
2. ^ ^{a b c d e f g h i j} Espitalier, T.J.; Day, W.A.J. (1944). The Locomotive in South Africa - A Brief History of Railway Development. Chapter III - Natal Government Railways. (Continued). South African Railways and Harbours Magazine, June 1944. pp. 422-424.
3. ^ ^{a b c d e f g h} Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 10–11, 31. ISBN 0869772112.
4. ^ ^{a b c d e f g h i j k l m} Holland, D.F. (1971). Steam Locomotives of the South African Railways. Vol. 1: 1859–1910 (1st ed.). Newton Abbott, England: David & Charles. pp. 92–95, 123–124. ISBN 978-0-7153-5382-0.
5. ^ ^{a b c} Durrant, AE (1989). Twilight of South African Steam (1st ed.). Newton Abbott: David & Charles. p. 15. ISBN 0715386387.
6. ^ ^{a b} North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
7. ^ The Railway Report for year ending 31 Dec. 1908, Natal Government Railways, p. 39, par 14.
8. ^ The South African Railways - Historical Survey. Editor George Hart, Publisher Bill Hart, Sponsored by Dorbyl Ltd., Published c. 1978, p. 25.

4' 8½" gauge3' 6" gauge2' gauge