South African Class 10B 4-6-2

The South African Railways Class 10B 4-6-2 of 1910 was a steam locomotive from the pre-Union era in the Transvaal.

In March 1910, the Central South African Railways placed ten Class 10-2 steam locomotives with a 4-6-2 Pacific wheel arrangement in service, of which five were built with and five without superheaters. In 1912, when the five superheated locomotives were assimilated into the South African Railways, they were renumbered and designated Class 10B. During 1912, the South African Railways placed five more Class 10B locomotives in service.^{[1][2][3][4][5]}

Manufacturers

G.G. Elliot

Ten heavy 4-6-2 Pacific type passenger locomotives, designed by Central South African Railways (CSAR) Chief Mechanical Engineer G.G. Elliot and based on the Class 10 design of his predecessor, CSAR Chief Locomotive Superintendent P.A. Hyde, were ordered from the North British Locomotive Company and delivered in 1910. They had plate frames, Belpaire fireboxes and Walschaerts valve gear and were delivered in two variants, with five of them using saturated steam while the rest were superheated with Schmidt type superheaters. They were all designated Class 10-2 by the CSAR, numbered in the range from 665 to 674, and entered service in March 1910.^[1][2][4][6]

Characteristics

The Class 10-2 superheated locomotives were similar to the Class 10, except that their boilers were arranged 7 ⁷⁄₈ inches (200 millimetres) further forward and their firebox throats and back plates were sloped instead of being vertical. This modification brought the chimney in line with the cylinders and avoided a "set" in the blastpipe. The cylinders were arranged outside the plate frames. Like the Class 10, the locomotives had 62 inches (1,575 millimetres) diameter coupled wheels, the largest yet used in South Africa at the time.^[1][2]

The Walschaerts valve motion was controlled by a vertical type of steam reversing engine, which was attached to the right-hand side of the boiler, just below the dome. It consisted of a 5 ¹⁄₂ inches (140 millimetres) diameter steam cylinder and a 4 inches (102 millimetres) diameter oil cylinder, fitted with a common piston rod with a crosshead which was machined integral with the piston rod. This crosshead was connected to a lever, fitted to the reversing shaft. After 1912, these reversing engines were replaced with Hendrie steam reversers.^[2]

While the Class 10 had outside admission valves, the Class 10-2 superheated used inside admission piston valves. Two Trevithick exhaust steam feedwater heaters were mounted on the running boards on either side of the smokebox, above the cylinders, and a Weir's feedwater pump was mounted on the left-hand side of the firebox. Each feedwater heater cylinder was 1 foot 2 ¹⁄₂ inches (368 millimetres) external diameter and 5 feet 4 inches (1,626 millimetres) between tube plates, and contained 108 ³⁄₄ inch (19 millimetres) external diameter brass tubes. The feedwater heaters and the feedwater pump were removed after a few years, since the feedwater heater tubes proved to be troublesome to clean.^[1][2][7]

A Wakefield mechanical-feed lubricator was arranged on the right-hand side running board and was operated through a lever and crank, actuated from the crosshead. Mechanical lubricators had the advantage that the rate of oil-feed was always proportional to the speed of the engine. This type of oil-feed was later superseded for the sight-feed lubricator.^[2]

The engines were fitted with the Flaman speed recorder, of which the driving gear was connected to the right trailing crank pin. The records obtained from these indicators were of considerable value when operating fast passenger services. The sand boxes were arranged in front of the leading coupled wheels and fitted with steam sanding gear, which was later found to be an unnecessary refinement for South African conditions.^[2]

Schmidt superheater

The Schmidt type superheater consisted of a series of elements in eighteen 5 ¹⁄₄ inches (133 millimetres) external diameter flue tubes, arranged in three rows. These elements were connected to a superheater header, fitted in the upper portion of the smokebox. The flue tubes were expanded into the firebox and smokebox tube plates in a special manner, which was subsequently found to be unnecessary. Each tube contained a superheater element, consisting of four 1 ¹⁄₄ inches (32 millimetres) diameter steam tubes.^[2]

Schmidt superheater

The construction of the header and its connections to the steam pipe and steam chest were such that steam had to pass through the elements on its way from the boiler to the cylinders. The flow of heat through the large superheater flue tubes was controlled by damper doors (marked "D" in the diagram), hinged or pivoted below the header in the smokebox. The damper doors were actuated by a small automatic steam cylinder and piston, attached to the outer shell of the smokebox. While the regulator was shut, the dampers were kept closed by a counterweight, fitted to a crank. When steam was admitted, the dampers were immediately opened simultaneously. The dampers could also be manually operated from the footplate, independently of the automatic cylinder.^[2]

The primary reason for dampers was to prevent the elements from possible overheating and damage while the regulator was closed. Once experience showed these precautions to be unnecessary, all such dampers were discarded.^[2]

In service, it was found that the superheated locomotives could handle almost 25% more load than their saturated steam sister engines, so much so that double-heading of passenger trains in the Orange Free State became unnecessary with the Class 10-2 superheated locomotive.^[1][2]

South African Railways

When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (Cape Government Railways, Natal Government Railways and CSAR) 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 required careful planning and was only implemented with effect from 1 January 1912.^[3][8]

When they were assimilated into the South African Railways (SAR) in 1912, the five saturated steam locomotives were designated Class 10A, while the five superheated steam locomotives, numbered in the range from 670 to 674, were designated Class 10B and renumbered in the range from 752 to 756.^[1][3]

During 1911, the CSAR had ordered a further five superheated Class 10B locomotives from Beyer, Peacock and Company. These were delivered to the SAR in January 1912 and numbered in the range from 757 to 761, with their engine numbers out of sequence with their builder's works numbers.^{[3][4][9][10]}

Unlike the earlier engines, these locomotives were built without feedwater heaters. Their Pyle National Turbo-generators were arranged on top of the last boiler barrel course, instead of in front of the chimney and behind the headlight.^[9]

Watson standard boilers

During the 1930s, many serving locomotives were reboilered with a standard round-topped boiler type, designed by then Chief Mechanical Engineer A.G. Watson as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification letter.^[4][11]

Five of the Class 10B locomotives were eventually reboilered with Watson Standard no. 1 boilers and reclassified to Class 10BR. In the process, their boiler pitch was raised by 8 inches (203 millimetres). Fitting them with the new boilers required minimal modifications, such as fitting a new cab front. At the same time, the steps leading to the cab were removed from the tender and attached to the engine.^[4][9][11]

Their original Belpaire boilers were fitted with Ramsbottom safety valves, while the Watson Standard boiler was fitted with Pop safety valves. An obvious difference between an original and a Watson Standard reboilered locomotive is usually a rectangular regulator cover, just to the rear of the chimney on the reboilered locomotive. In the case of the Class 10BR locomotives, an even more obvious difference was the absence of the Belpaire firebox hump between the cab and boiler on the reboilered locomotives.^[11]

The table lists the locomotive builders, works numbers, CSAR to SAR renumbering and the Watson Standard boiler reclassification for the Class 10B and 10BR locomotives.^[1][3]

Service

The Class 10B was placed in service to haul passenger trains out of Johannesburg. On the fast trains running between Pretoria and Johannesburg, the scheduled time of 1 hour 15 minutes was maintained daily and the 36 miles 28 chains (58.5 kilometres) between Pretoria and Germiston were covered at an average speed of 37.3 miles per hour (60 kilometres per hour) in both directions.^[9]

Most of their working lives were, however, spent on the Cape Midland system, where they were used on the mainline out of Port Elizabeth. Two of them worked as station pilots at Kimberley until 1960, when they joined the rest of the Class, which were by then working the suburban between Port Elizabeth and Uitenhage.^[4]

In later years, they also served on the Reef's suburban routes, while a few were used in the same service around Cape Town, until they were eventually relegated to shunting work. They were scrapped in 1974.^[4]

Illustration

The main picture shows a CSAR Class 10-2, later SAR Class 10B, as delivered with feedwater heaters on the running boards, while the 1930s picture below shows one with the feedwater heaters removed.

• 
  Belpaire firebox Class 10B on a passenger train, c. 1930
• 
  Class 10BR no. 758 at the Old Uitenhage Station Museum

References

Wikimedia Commons has media related to South African Class 10B (4-6-2).

Locomotives of the Central South African Railways
3' 6" gauge	CSAR 0-6-0ST 1896 CSAR 4-6-0T 1887 CSAR Class 6-L1 CSAR Class 6-L2 CSAR Class 6-L3 CSAR Class 7 CSAR Class 8-L1 CSAR Class 8-L2 CSAR Class 8-L3 CSAR Class 9 CSAR Class 10 1904 CSAR Class 10 1910 CSAR Class 10-2 Saturated CSAR Class 10-2 Superheated CSAR Class 10-C CSAR Class 11 CSAR Class B 0-6-4T CSAR Class C 2-8-4T CSAR Class D CSAR Class E 4-8-0TT CSAR Class E 4-8-2T CSAR Class E 4-10-2T CSAR Class F CSAR Class M CSAR Mallet Saturated CSAR Mallet Stoker CSAR Mallet Superheated CSAR Rack 4-6-4RT CSAR Railmotor IMR 0-6-0ST 1896 IMR 4-6-0T 1887 IMR 46 Tonner 0-6-4T IMR 55 Tonner 2-6-4T IMR 7th Class 4-8-0 IMR 8th Class 4-8-0 IMR Reid Tenwheeler 4-10-2T IMR Western Australian 2-8-4T NZASM 10 Tonner NZASM 13 Tonner NZASM 14 Tonner NZASM 18 Tonner NZASM 19 Tonner NZASM 32 Tonner NZASM 40 Tonner NZASM 46 Tonner OVGS 1st Class 4-4-0TT OVGS 2nd Class 2-6-0 OVGS 2nd Class 2-6-0ST OVGS 3rd Class 4-4-0 OVGS 4th Class G 4-6-0 OVGS 5th Class K 4-6-0 1890 OVGS 5th Class K 4-6-0 1891 OVGS 6th Class L 4-6-0 OVGS 6th Class L2 4-6-0 OVGS 6th Class L3 4-6-0 PPR 0-4-0ST Natal PPR 26 Tonner PPR 35 Tonner Portuguese PPR 55 Tonner
2' gauge	CSAR Pankop
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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 4' 8½" 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 3' 6" 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 3' 6" 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 3' 6" 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 SAR Class ES SAR Class ES1 SAR Class Exp-AC SAR Class 1E SAR Class 2E SAR Class 3E SAR Class 4E SAR Class 5E s1 SAR Class 5E s2 SAR Class 5E s3 SAR Class 5E1 s1 SAR Class 5E1 s2 SAR Class 5E1 s3 SAR Class 5E1 s4 SAR Class 5E1 s5 SAR Class 6E SAR Class 6E1 s1 SAR Class 6E1 s2 SAR Class 6E1 s3 SAR Class 6E1 s4 SAR Class 6E1 s5 SAR Class 6E1 s6 SAR Class 6E1 s7 SAR Class 6E1 s8 SAR Class 6E1 s9 SAR Class 6E1 s10 SAR Class 6E1 s11 SAR Class 7E SAR Class 7E1 SAR Class 7E2 s1 SAR Class 7E2 s2 SAR Class 7E3 s1 SAR Class 7E3 s2 Spoornet Class 7E4 SAR Class 8E SAR Class 9E s1 SAR Class 9E s2 SAR Class 10E SAR Class 10E1 s1 Spoornet Class 10E1 s2 SAR Class 10E2 SAR Class 11E SAR Class 12E Spoornet Class 14E Spoornet Class 14E1 TFR Class 15E Spoornet Class 16E Spoornet Class 17E Spoornet Class 18E s1 TFR Class 18E s2 TFR Class 19E TFR Class 20E TFR Class 21E TFR Class 22E
Gas-electric	SAR Gas-electric
Diesel	3' 6" 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 2' gauge Diesel-electric SAR Class 91-000 3' 6" gauge Diesel-hydraulic SAR Class 61-000 3' 6" gauge Electro-diesel Spoornet Class 38-000
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South African steam locomotive tenders
Cape gauge	Type CL Type CZ Type ET Type ET1 Type EW Type EW1 Type EW2 Type FT Type GT Type HT Type JT Type JT1 Type JV Type KT Type LP Type MP Type MP1 Type MR Type MS Type MT Type MT1 Type MT2 Type MX Type MY Type MY1 Type SH Type SK Type TJ Type TL Type TM Type WE Type WG Type X-17 Type X-20 Type XC Type XC1 Type XD Type XE Type XE1 Type XF Type XF1 Type XF2 Type XJ Type XM Type XM1 Type XM2 Type XM3 Type XM4 Type XP1 Type XS Type YB Type YC Type YE Type YE1 Type ZA Type ZB Type ZC Type ZE
List of South African locomotive classes South African locomotive history