South African Class H 4-10-2T


The South African Railways Class H , 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 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.

Design

By 1898, increasing traffic on the new Natal Government Railways mainline into the interior, with its sharp curves and severe 1 in 30 gradients, necessitated double-heading of the NGR's Dübs A 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 locomotive.
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 within the construction loading gauge of high by wide, while the locomotive had to be able to negotiate gradients of 1 in 30, compensated for curves of radius. The result was Reid's design of a tank engine, the first locomotive in the world to use this wheel arrangement.

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.
In 1900, the General Manager of the NGR reported that the trials of the Reid locomo­tive had proven successful beyond anticipation and that the engine could haul a gross load of over the worst section of line with ease, 50% in excess of that taken by 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.
Since Dübs and a number of other Scottish locomotive builders were merged to form the North British Locomotive Company 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.

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.

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.
The leading bogie was controlled by two side-check springs and had 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 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.
The firebox, at long and wide inside and arranged between the frames, was the longest ever used in South Africa.

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 to, after which the locomotives proved successful in service.
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 locomotives by removing the fifth pair of coupled wheels.

South African Railways

When the Union of South Africa was established on 31 May 1910, the three Colonial government 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.
In 1912, the 93 as yet unmodified Class C Reid Tenwheelers were designated on the South African Railways and renumbered in the range from 232 to 324. The modified 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.
The SAR Class H locomotives were gradually also modified to a 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.

Year		Builder
Works
no.		NGR
no.		Class H
no.		Class H2
no.
1899Dübs3835149232
1901Dübs4040150233
1901Dübs4041151234
1901Dübs4042152235
1901Dübs4043153236
1901Dübs4044154237
1901Dübs4045155238
1901Dübs4046156239
1901Dübs4047157240329
1901Dübs4048158241
1901Dübs4049159242
1901Dübs4050160243
1901Dübs4051161244
1901Dübs4052162245
1901Dübs4053163246
1901Dübs4054164247
1901Dübs4055165248
1901Dübs4056166249
1901Dübs4057167250
1901Dübs4058168251
1901Dübs4059169252
1901Dübs4060170227
1901Dübs4061171253
1901Dübs4062172254
1901Dübs4063173228
1901Dübs4064174255
1902Dübs4117175229
1902Dübs4118176256
1902Dübs4119177257
1902Dübs4120178258
1902Dübs4121179259
1902Dübs4122180260
1902Dübs4123181261
1902Dübs4124182262
1902Dübs4125183263
1902Dübs4126184324
1902Dübs4127185264
1902Dübs4128186265
1902Dübs4129187266
1902Dübs4130188267
1902Dübs4131189268
1902Dübs4132190269
1902Dübs4133191270
1902Dübs4134192271
1902Dübs4135193272
1902Dübs4136194Scrapped
1902Dübs4137195Scrapped
1902Dübs4138196273
1902Dübs4139197274
1902Dübs4140198275
1902Dübs4141199276
1902Dübs4254200277
1902Dübs4255201278
1902Dübs4256202279
1902Dübs4257203280
1902Dübs4258204281
1902Dübs4259205282
1902Dübs4260206283
1902Dübs4261207284
1902Dübs4262208285
1902Dübs4263209286
1902Dübs4264210287
1902Dübs4265211288
1902Dübs4266212289
1902Dübs4267213290
1902Dübs4268214Scrapped
1902Dübs4269215291
1902Dübs4270216292
1902Dübs4271217230
1902Dübs4272218293
1902Dübs4273219294330
1902Dübs4274220295
1902Dübs4275221296
1902Dübs4276222297
1902Dübs4277223298
1902Dübs4278224299
1903Dübs4310225300
1903Dübs4311226301
1903Dübs4312227302
1903Dübs4313228303
1903Dübs4314229304
1903Dübs4315230305331
1903Dübs4316231306
1903Dübs4317232307
1903Dübs4318233308
1903Dübs4319234309
1903Dübs4320235310
1903Dübs4321236311
1903Dübs4322237312
1903Dübs4323238313
1903Dübs4324239314
1903Dübs4323240231
1903Dübs4326241315
1903Dübs4327242316
1903Dübs4328243317
1903Dübs4329244318
1903NBL15723245319
1903NBL15724246320
1903NBL15725247321
1903NBL15726248322
1903NBL15727249323

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.
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 Mountain type, remained in service until 1977.

Other operators

Imperial Military Railways

In 1902, during the Second Boer War, the Imperial Military Railways 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 South African Class H1 4-8-2T| in 1912.

Industry

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

Illustration