The South African Railways Class 7D 4-8-0 of 1915 was a steam locomotive.

Between 1899 and 1903, the Rhodesia Railways placed 52 Cape 7th Class 4-8-0 Mastodon steam locomotives in service. During the Second Boer War, one more was obtained from the Imperial Military Railways in March 1901, as replacement for a locomotive which was damaged beyond local repair capabilities as a result of hostilities during delivery.

In May 1915, five of these locomotives were sold to the South African Railways, where they were renumbered and reclassified, four of them to Class 7D and the remaining one erroneously to Class 7B. At the same time, the ex Imperial Military Railways locomotive was also sold back to South Africa and was, also erroneously, designated Class 7D.

Rhodesian 7th Class The original Cape 7th Class locomotive had been designed in 1892 by H.M. Beatty, at the time the Cape Government Railways Western System Locomotive Superintendent.Espitalier, T.J.; Day, W.A.J. (1944). The Locomotive in South Africa – A Brief History of Railway Development. Chapter II – The Cape Government Railways (Continued). South African Railways and Harbours Magazine, January 1944. pp. 9–10.

Between 1899 and 1903, 52 such Cape 7th Class 4-8-0 steam locomotives were built for the Beira and Mashonaland and Rhodesia Railways (BMR), later the Rhodesia Railways (RR). These locomotives were acquired by Southern Rhodesia at the time when railways were still expanding from South Africa via the Bechuanaland Protectorate into Southern Rhodesia in the southwest, and from Beira in Mozambique to Umtali in the east, and while the Second Boer War was in progress. At the time, the system was composed of several smaller railways, still largely under construction, which were eventually all linked up in 1902. These were:

The fledgling Bechuanaland Railways (BR), which was still being operated by the Cape Government Railways (CGR), from Vryburg via Mafeking in the Cape Colony to Bulawayo in Southern Rhodesia. The Mashonaland Railways (MR), which operated in Southern Rhodesia from Bulawayo to Umtali in the east. The Rhodesia Railways Northern Extensions (RRM), which operated north and east of Bulawayo, towards Northern Rhodesia. The Beira and Mashonaland and Rhodesia Railways (BMR), which operated between Umtali in Southern Rhodesia and Beira in Mozambique.

Manufacturers The 52 locomotives were ordered in five batches from three British manufacturers.Neilson, Reid works list, compiled by Austrian locomotive historian Bernhard SchmeiserNorth British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser

Twelve were delivered by Neilson, Reid and Company between August and October 1899. They were virtually identical to the SAR Class 7A. Two of them were numbered BR7 and BR8 for the BMR, for service at the Beira end, while the rest were numbered in the range from RR1 to RR10.

In 1901, eleven of them were renumbered in the range from MR8 to MR18, MR20 and MR21, not in order, for the BMR. The exception was no. RR8, which was delivered damaged beyond local repair abilities, apparently as a result of hostilities, while in transit through the area under control of the British Military near Mafeking. A Neilson, Reid-built 7th Class locomotive of the Imperial Military Railways (IMR), no. IMR 110, was subsequently transferred to the BMR at Umtali in March 1901 as replacement for the damaged no. RR8. It was renumbered to MR19, the number which would have been allocated to no. RR8. The renumberings are tabled below.

A second batch of twelve were delivered by Neilson, Reid in August 1900 and numbered in the range from RR11 to RR22. They were placed in service on the line from Vryburg to Bulawayo and shedded at Mafeking. In 1901, four of them, no. RR11, RR12, RR17 and RR20, were relocated to the BMR and renumbered in the range from MR20 to MR23, in order. Many of the Neilson, Reid-built locomotives from both batches were renumbered a second time in 1906, as shown in the table. A third batch of eight locomotives was delivered from Kitson and Company between 1901 and 1903, numbered in the range from RR23 to RR30. These were built with Belpaire fireboxes instead of the usual round-topped fireboxes with which all earlier 7th Class locomotives of the CGR, the IMR and the RR were delivered. They were also placed in service at Mafeking. The fourth batch of ten locomotives, again with Belpaire fireboxes, was delivered from North British Locomotive Company (NBL) in October and November 1903. They were numbered in the range from RR31 to RR40. Of these, numbers RR31 to RR38 were allocated to the Mashonaland Railways-Kalomo-Broken Hill (MR-KB) section. They retained their RR numbers, but had brass plates with the letters "KB" affixed above their number plates on their cab sides, to indicate their ownership. The other two were also placed in service at Mafeking. The fifth and final batch of ten Rhodesian 7th Class locomotives was also built by NBL and delivered in November and December 1903, numbered in the range from RR41 to RR50. They were also placed in service at Mafeking.

South African Railways In May 1915, six of the Neilson, Reid-built 7th Class locomotives were purchased by the South African Railways (SAR) to augment its locomotive stock, which was being taxed severely due to war conditions at the time. These six locomotives included the war-damaged no. RR8 which had still not been repaired and consequently never ran a mile in revenue service in Rhodesia, as well as the ex IMR locomotive which had been transferred to Rhodesia as compensation for the damaged no. RR8.

These locomotives were initially referred to as Class RR, until they were later designated SAR Class 7D. Five of them were renumbered in the range from 1351 to 1355 on the SAR roster. The sixth, SAR no. 949, was erroneously designated Class 7B.Espitalier, T.J.; Day, W.A.J. (1947). The Locomotive in South Africa – A Brief History of Railway Development. Chapter VII – South African Railways (Continued). South African Railways and Harbours Magazine, December 1947. p. 1033.

Classification errors During this SAR classification and renumbering process, two of these locomotives were incorrectly classified, possibly as a result of their records getting exchanged in an apparent administrative error.

Ex IMR no. 110, which had replaced the damaged no. RR8, would have become Central South African Railways (CSAR) no. 380 in 1902 and, with the rest of the ex IMR locomotives, would have been designated SAR Class 7B in 1912, but this never happened since the engine had already been transferred to the BMR at Umtali in March 1901. When it was taken onto the SAR roster from Rhodesia in 1915, it was incorrectly designated as Class 7D instead of Class 7B and renumbered SAR no. 1355. Ex no. RR1, later no. MR8 and then no. RRM63, was incorrectly designated as Class 7B instead of ex IMR no. 110 and was renumbered SAR no. 949.

Class 7 sub-classes Other 7th Class locomotives which came onto the SAR roster from the other Colonial railways in the region in 1912, namely the CGR, CSAR, the Natal Government Railways (NGR) and, in 1925, from the New Cape Central Railways (NCCR), were grouped into six different sub-classes by the SAR, becoming SAR Classes 7, 7A to 7C, 7E and 7F.

Modifications During the 1930s, many of the Class 7 family of locomotives were equipped with superheating and piston valves. On the Class 7B and Class 7C, this conversion was sometimes indicated with an "S" suffix to the class letter on the locomotive number plates, but on the rest of the Class 7 family this distinction was not applied consistently. The superheated versions could be identified by the position of the chimney on the smokebox, the chimney having been displaced forward to provide space behind it in the smokebox for the superheater header.South African Railways and Harbours Locomotive Diagram Book, 2'0" & 3'6" Gauge Steam Locomotives, 15 August 1941, as amended

Service

South Africa In SAR service, the Class 7 series worked on every system in the country. They remained in branch line service until they were finally withdrawn in 1972.

South West Africa In 1915, shortly after the outbreak of the First World War, the German South West Africa colony was occupied by the Union Defence Forces. Since a large part of the territory's railway infrastructure and rolling stock was destroyed or damaged by retreating German forces, an urgent need arose for locomotives for use on the Cape gauge lines in that territory. In 1917, numbers 1351 to 1353 were transferred to the Defence Department for service in South West Africa.

These three locomotives remained in South West Africa after the war. The Class 7s proved to be so successful in that territory that more were gradually transferred there in later years. By the time the Class 24 locomotives arrived in SWA in 1949, 53 locomotives of the Class 7 family were still in use there. Most remained there and were only transferred back to South Africa when the Class 32-000 diesel-electric locomotives replaced them in 1961.

Works numbers Their builders, works numbers and renumbering are listed in the table.Pattison, R.G. (2005). Thundering Smoke, (1st ed.). Ilminster, Somerset: Sable Publishing House. pp. 42–48. .Durrant, A.E. (1997). The Smoke that Thunders, (1st ed.). Harare: African Publishing Group. . +Rhodesia Railways 7th Class, SAR Class 7DBuilders, works numbers and renumbering Builder WorksNo. Year RRNo. 1901No. 1906No. SARNo.Neilson, Reid5675 1899 BR 7MR 14MR 8Neilson, Reid5676 1899 BR 8MR 15MR 9Neilson, Reid5677 1899 RR 1MR 8RRM 63Class 7B 949Neilson, Reid5678 1899 RR 2MR 9To ShireNeilson, Reid5679 1899 RR 3MR 10MR 10Neilson, Reid5680 1899 RR 4MR 11MR 11Neilson, Reid5681 1899 RR 5MR 12MR 12Neilson, Reid5682 1899 RR 6MR 13RRM 641352 Neilson, Reid5683 1899 MR 11MR 18RRM 671353 Neilson, Reid5684 1899 RR 81354 Neilson, Reid5685 1899 RR 9MR 16RRM 651351 Neilson, Reid5686 1899 RR 10MR 17RRM 66Neilson, Reid5791 1900 RR 11MR 20RRM 69Neilson, Reid5792 1900 RR 12MR 21RRM 70Neilson, Reid5793 1900 RR 13Neilson, Reid5794 1900 RR 14Neilson, Reid5795 1900 RR 15Neilson, Reid5796 1900 RR 16Neilson, Reid5797 1900 RR 17MR 22RRM 71Neilson, Reid5798 1900 RR 18Neilson, Reid5799 1900 RR 19Neilson, Reid5800 1900 RR 20MR 23RRM 72Neilson, Reid5801 1900 RR 21Neilson, Reid5802 1900 RR 22Neilson, Reid5817 1900 IMR 110MR 19RRM 681355 Kitson40621901RR 23Kitson40631901RR 24Kitson40641901RR 25Kitson40651901RR 26Kitson40661901RR 27Kitson40671901RR 28Kitson40681901RR 29Kitson40691901RR 30NBL16085 1903 RR 31NBL16086 1903 RR 32NBL16087 1903 RR 33NBL16088 1903 RR 34NBL16089 1903 RR 35NBL16090 1903 RR 36NBL16091 1903 RR 37NBL16092 1903 RR 38NBL16093 1903 RR 39NBL16094 1903 RR 40NBL16171 1903 RR 41NBL16172 1903 RR 42NBL16173 1903 RR 43NBL16174 1903 RR 44NBL16175 1903 RR 45NBL16176 1903 RR 46NBL16177 1903 RR 47NBL16178 1903 RR 48NBL16179 1903 RR 49NBL16180 1903 RR 50

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