| South African Classes 3B & 3BR 4-8-2 | |
| Hatnote: | ♠ Class 3B as built with a Belpaire firebox Class 3BR rebuilt with a Watson Standard boiler Steel firebox - Copper firebox |
| Powertype: | Steam |
| Designer: | Natal Government Railways (D.A. Hendrie) |
| Builder: | North British Locomotive Company |
| Serialnumber: | 19597-19601, 19688-19692 |
| Buildmodel: | Class 3B |
| Builddate: | 1911-1912 |
| Totalproduction: | 10 |
| Whytetype: | 4-8-2 (Mountain) |
| Uicclass: | 2'D1'h2 |
| Driver: | 2nd coupled axle |
| Leadingdiameter: | NaN0NaN0 |
| Coupleddiameter: | NaN0NaN0 as built 460NaN0 retyred |
| Trailingdiameter: | 300NaN0 |
| Tenderdiameter: | 300NaN0 |
| Wheelbase: | 55feet |
| Engine Total: | 30feet |
| Leading: | 60NaN0 |
| Coupled: | 12feet |
| Tender Total: | 16feet |
| Tenderbogie: | 4feet |
| Over Couplers: | 63feet |
| Height: | ♠ 12feet 12feet |
| Frametype: | Plate |
| Axleload: | ♠ 15lt 15lt |
| Leadingbogie/Pony: | ♠ 14lt 14lt |
| Coupled 1: | ♠ 14lt 14lt |
| Coupled 2: | ♠ 15lt 15lt |
| Coupled 3: | ♠ 15sigfig=4NaNsigfig=4 15lt |
| Coupled 4: | ♠ 15sigfig=4NaNsigfig=4 14lt |
| Trail Bogie/Pony: | ♠ 9lt 10lt |
| Tenderbogieload: | Bogie 1: 21lt Bogie 2: 21lt |
| Tenderaxle: | 10lt |
| Weightondrivers: | ♠ 60lt 59lt |
| Locoweight: | ♠ 83lt 84lt |
| Tenderweight: | 43lt |
| Locotenderweight: | ♠ 127lt 128lt |
| Tendertype: | TM (2-axle bogies) TJ, TL, TM permitted |
| Fueltype: | Coal |
| Fuelcap: | 8lt |
| Watercap: | 4000sigfig=3NaNsigfig=3 |
| Fireboxtype: | ♠ Belpaire - Round-top |
| Firearea: | ♠ 34square feet 37square feet |
| Boiler: | Watson Standard no. 2 |
| Pitch: | ♠ 7feet 7feet |
| Diameterinside: | ♠ 5feet 5feet |
| Lengthinside: | ♠ 18feet 19feet 19feet |
| Smalltubediameter: | ♠ 135: NaN0NaN0 87: NaN0NaN0 |
| Largetubediameter: | ♠ 24: NaN0NaN0 30: NaN0NaN0 |
| Boilerpressure: | ♠ 1850NaN0 1900NaN0 |
| Safetyvalvetype: | ♠ Ramsbottom Pop |
| Totalsurface: | ♠ 2245square feet 2075square feet |
| Tubearea: | ♠ 2110square feet 1933square feet |
| Fireboxarea: | ♠ 135square feet 142square feet |
| Superheaterarea: | ♠ 617square feet 492square feet |
| Cylindercount: | Two |
| Cylindersize: | 220NaN0 bore 240NaN0 stroke |
| Valvegear: | Walschaerts |
| Valvetype: | Piston |
| Coupling: | Johnston link-and-pin AAR knuckle (1930s) |
| Tractiveeffort: | ♠ 35030lbf @ 75% 35980lbf @ 75% |
| Operator: | South African Railways |
| Operatorclass: | Class 3B & 3BR |
| Numinclass: | 10 |
| Fleetnumbers: | 1479-1488 |
| Deliverydate: | 1912 |
| Firstrundate: | 1912 |
| Withdrawndate: | 1976 |
| Notes: | The leading coupled axle had flangeless wheels |
The South African Railways Class 3B 4-8-2 of 1912 was a steam locomotive.
In 1912, the South African Railways took delivery of ten Class 3B steam locomotives with a 4-8-2 Mountain type wheel arrangement which had been ordered by the Natal Government Railways the year before.[1] [2]
With the experience gained from the sole experimental Class B American D locomotive, Natal Government Railways (NGR) Locomotive Superintendent D.A. Hendrie redesigned his Class Hendrie D and placed orders for ten locomotives with the North British Locomotive Company on 29 March 1911. These locomotives, which would have become the NGR's Class Superheated Hendrie D, were built in two batches of five and were all delivered in 1912 after the renumbering and reclassification of the locomotives of the constituent former Colonial railways into the South African Railways (SAR). Upon delivery, they were therefore taken directly onto the SAR roster, numbered in the range from 1479 to 1488 and designated Class 3B. The first of these engines entered service in February 1912.[1] [2] [3]
Like the NGR Class Hendrie D which it was based on and which was later designated the SAR Class 3, the Class 3B had plate frames, Walschaerts valve gear and Belpaire fireboxes. They were the first of Hendrie's designs to have superheaters and, as a result, piston valves instead of slide valves. They also sported a new design of leading bogie with cast-steel framing and three-point suspension links.[1]
To accommodate the redesigned cylinders and the necessary alteration to the Walschaerts valve gear, the running boards had to be raised to clear the steam chests and motion. This resulted in the gentle sweeps at either end where the running boards dropped down to the buffer beam and below the cab. These curves became a Hendrie hallmark and enhanced the appearance of the locomotive. In other respects, however, they were practically identical to the Class 3.[1]
The locomotives were delivered with Type TM tenders with an 8lt coal capacity and a 4000sigfig=3NaNsigfig=3 water capacity. When the coupled wheels were retyred, their diameter on tread was increased from NaNto. This reduced their tractive effort to 35030lbf at 75% of boiler pressure, which was set at 1850NaN0. The engines, as built, had flangeless wheels on the leading coupled axle, but these were subsequently also flanged as shown in official SAR dimensional locomotive drawings.[1] [4] [5]
The superheated Class 3B 4-8-2 Mountain type became the forerunner of the most numerous basic type of steam locomotive to be used in South Africa.
In the 1930s, many serving locomotives were reboilered with a standard boiler type designed by then Chief Mechanical Engineer (CME) A.G. Watson as part of his standardisation policy. Such Watson Standard reboilered locomotives were reclassified by adding an "R" suffix to their classification.[4] [5]
When all ten Class 3B locomotives were eventually reboilered with Watson Standard no. 2 boilers, they were therefore reclassified to . Reboilering raised their boiler pitch by 10NaN0, while the boiler pressure was set at 1900NaN0. Their original Belpaire boilers were fitted with Ramsbottom safety valves, while the Watson Standard boiler was fitted with Pop safety valves. Probably at the same time, their Type TM tenders were rebuilt to the more attractive smooth-sided Type TL tenders. The most obvious visual 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 3BR locomotive, an even more obvious visual distinction is the absence of the Belpaire firebox hump between the cab and the boiler.[1] [4] [5]
The Class 3B was placed in service on the upper section of the Natal mainline. They were later also used in the Eastern Transvaal and the Eastern Cape. Towards the end of their service lives, they ended up in Cape Town, where they were used as shunting engines until the last ones were withdrawn from SAR service by 1976.
Most of them ended up in service on South Africa's coal and gold mines. Only one of them had been withdrawn by April 1973. At the time when the other nine began to be withdrawn from railway service, the world oil crisis of the mid-1970s had erupted and all nine were virtually snapped up by industrial users responding to the South African Government's call to save oil by using alternative sources of energy. Ironically, at the same time, the State-owned SAR was replacing steam with diesel-electric locomotives.
The ten individual locomotives were disposed of as follows:
Two 3B class survive.
| Number | Works nmr | THF / Private | Leaselend / Owner | Current Location | Outside South Africa | ? | |
|---|---|---|---|---|---|---|---|
| 1486 | NBL / 19690 | Private | Umgeni Steam Railway | Kloof (Station) | |||
| 1488 | NBL / 19692 | Private | Oscar Sabitini | Krugersdorp Locomotive Depot |
The main picture shows Umgeni Steam Railway's Class 3BR no. 1486 Maureen at Kloof station on 6 June 2010, while the following show the Class in its original as-delivered SAR livery and in two of the mining liveries which were applied to it while in industrial service.