This article is about one of two different Natal Government Railways locomotive types to be designated "Class C". For the other, see South African Class H2 4-8-2T.
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]
G.W. Reid
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]
^ abcdClassification 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)
^ abcdefghijEspitalier, 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.
^ abcdefghPaxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 10–11, 31. ISBN0869772112.
^ abcdefghijklmHolland, 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. ISBN978-0-7153-5382-0.