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South African Class 25NC 4-8-4

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South African Railways Class 25NC
Company typeSteam locomotive class
IndustryRail transport
Founded1953
FounderL.C. Grubb (Chief Mechanical Engineer)
Headquarters
South Africa
,
South Africa
Area served
South African Railways network
Products4-8-4 steam locomotives

South African Railways Class 25NC 4-8-4 Steam Locomotive (1953)

The Class 25NC 4-8-4 steam locomotive was produced for the South African Railways (SAR) between 1953 and 1955. This series represented the non-condensing counterpart to the Class 25 condensing locomotives, with ninety units entering service concurrently. From 1973 to 1980, nearly all condensing locomotives—except for three—were converted into non-condensing types and subsequently reclassified as Class 25NC.

Manufacturers

File:L.C. Grubb.jpg
L.C. Grubb
File:25NC 3405 Builders Plate.jpg
25NC 3405 Builders Plate
File:25Nc 3437 Builders Plate.jpg
25Nc 3437 Builders Plate

The Class 25NC non-condensing and Class 25 condensing 4-8-4 Northern type steam engines were developed by the South African Railways (SAR) under the leadership of LC Grubb, who served as Chief Mechanical Engineer from 1949 to 1954. This design process was carried out in collaboration with Henschel & Son of Kassel, Germany, who were responsible for the condensing system and tender on the Class 25 condensing variant.[1] Between 1953 and 1955, eleven Class 25NC units were constructed by the North British Locomotive Company (NBL), assigned numbers from 3401 to 3411, while Henschel produced 39 locomotives numbered from 3412 to 3450.[2][3][4]

Characteristics

The Class 25NC was equipped with superheating and utilized piston valves controlled by Walschaerts valve gear. Roller bearings manufactured by Timken were employed extensively, including on the tender’s three-axle bogies, coupling rods, connecting rods, and crosshead gudgeon pins. The locomotive’s leading bogies and driving wheels featured Cannon-type axle boxes. A notable innovation compared to prior SAR models was the introduction of mechanical lubrication, driven by a sixteen-feed lubricator attached to the expansion link trunnion. The cylinders and frames were cast as a single unit by the Commonwealth Steel Company in the United States, with steel cylinders and steam chests lined internally with cast iron. Due to the comprehensive use of roller bearings, these locomotives required minimal effort to move.[5][6][7][8][9]

The Alligator type crossheads were vertically split at the centerline and secured onto the piston rod ends, which featured three coned rings that engaged with grooves in the crossheads. Unlike conventional designs, the original coupling rods consisted of three separate rods instead of one piece, thereby eliminating four knuckle joints and their associated pins.[5]

The boiler incorporated a Melesco multiple-valve superheater header and was fitted with four 2+1⁄2 inches (64 millimetres) diameter Ross-pop safety valves. Additionally, two Hopkinson boiler blowdown cocks were installed on either side of the firebox wrapper. Boiler feedwater was supplied by two Friedmann vertical non-lifting injectors, each capable of delivering 5,200 imperial gallons (23,600 litres; 6,240 US gallons) per hour.[6]

This locomotive was paired with a Type EW1 tender, which housed a mechanical stoker powered by an engine mounted directly on the tender frame. The tender's water tank held 10,500 imperial gallons (47,700 litres; 12,600 US gallons) of water while its coal bunker could accommodate 18 long tons (18.3 tonnes; 20.2 short tons) of coal. The tender frame was crafted as a single-piece steel casting featuring a water-bottom design where the frame itself formed the tank’s base, differing from earlier models that had separate tank and frame components.[5][10]

Initial Challenges

Shortly after their deployment, the locomotives encountered issues such as connecting rod failures, disintegration of big end bearings, and the emergence of cracks in the motion girders of the Alligator crossheads. Following thorough examinations conducted by SAR engineers, aided by the South African Council for Scientific and Industrial Research, adjustments were made to the crossheads, slide bars, and coupling rods. The original crossheads were redesigned into a multiple-bearing style featuring single guide bars, while the three separate coupling rods were substituted with a more traditional single coupling rod equipped with knuckle joints.[5][11][9]

At introduction, the tapered Timken crankpin roller bearings developed a reputation for expelling lubricant onto the underside of the boiler. This oil would then flow down to the lowest points and drip onto the coupled wheel tyres, causing slippage issues. This defect was also present in the Class 25 locomotives and contributed to both classes being known for their slippery nature. Although Timken rectified this problem before all bearings were replaced, approximately two-thirds of the fleet had already been fitted with redesigned coupling rods featuring SKF crankpin ball bearings.[9]

Operational Deployment

File:SAR Class 25NC 3442 (4-8-4) ID.JPG

The Class 25NC locomotives initially operated on the non-electrified mainlines running from De Aar through Kimberley to Welverdiend. From their introduction, they were pooled and operated continuously between De Aar and Welverdiend in both directions, stopping for refuelling at Warrenton. Following electrification extending from Welverdiend to Klerksdorp, their service route shifted to running between Klerksdorp and De Aar, maintaining refuelling stops at Warrenton. Subsequently, some units also served routes from Kimberley via Bloemfontein to Harrismith in the Free State province, while others worked alongside Class 25 condensers on the stretch from De Aar through Beaufort West to Touws River.[2][12]

When diesel locomotives replaced steam south of De Aar between 1973 and 1974, Class 25 condensers operating there were reassigned northward to cover the De Aar to Kimberley section. This relocation allowed them to substitute twenty-two Class 25NCs that were subsequently transferred to Bethlehem in the Free State region. From 1982 onwards, Class 25NCs also took over duties from Class 19Ds and Class GMAM Garratts along the route from Warrenton via Vryburg to Mafeking.[13]

Rebuilding of Class 25

File:SAR Class 25NC 3467 (4-8-4) ID.JPG

Ninety Class 25 condensing locomotives were produced alongside the Class 25NC under the same procurement, with Henschel manufacturing one unit and North British Locomotive Company constructing the remainder. The condensing systems for these engines, including their tenders, were engineered and patented by Henschel.[5]

From 1973 until 1980, all but three of these ninety Class 25 condensers were transformed into non-condensing versions and redesignated as Class 25NC. The exceptions to this conversion were locomotives numbered 3451, 3511, and 3540. Some units had their number plates duplicated and modified by adding "NC"—standing for "non-condensing"—adjacent to the original "25," which created an uneven appearance on their cabside class markings. Therefore, locomotives displaying all four characters aligned and centered were typically recognized as original Class 25NC models.[14][15]

During this conversion, their Type CZ condensing tenders were also rebuilt into standard coal-and-water Type EW2 tenders by removing the condensing radiators and roof fans and substituting them with a large water tank. Since the Type CZ tenders featured single cast steel water-bottom frames, shortening them was not feasible. This resulted in the rebuilt Type EW2 tenders retaining long, rounded water tanks. Locomotives equipped with these modified tenders earned the nickname Worshond (meaning Sausage dog or Dachshund).[13]

The Class 26 Red Devil

Between 1979 and 1981, locomotive no. 3450—the final Class 25NC constructed—underwent a transformation at the SAR workshops in Salt River, Cape Town to become the unique Class 26, known as the Red Devil. The key aims of this overhaul were to enhance combustion efficiency and steaming capacity, reduce excessive black smoke emissions, and resolve issues related to clinker formation.[16][17][18][19]

This was accomplished through implementing a Gas Producer Combustion System that promotes coal gasification on a low-temperature firebed, allowing gases to combust fully above the firebed. Due to these significant modifications, the locomotive was reclassified as Class 26 while retaining its original Class 25NC number.[16][17]

Project Zimbabwe

In 1988, the National Railways of Zimbabwe encountered a critical shortage of motive power. Following consultations with South African counterparts, it was revealed that numerous Class 25NC 4-8-4 locomotives had recently been retired and were available for lease or purchase. Consequently, NRZ considered acquiring between twenty and twenty-five of these units on a short-term basis. A delegation of three personnel from Bulawayo conducted inspections of fifty locomotives at Warrenton and De Aar.

A list comprising twenty-eight locomotives was compiled from which NRZ could select twenty to twenty-five units or fewer if required:

Category A (locomotives with over five years before major overhaul): 3404, 3410, 3422, 3428, 3438, 3442, 3445, 3453, 3457, 3459, 3479, 3504, 3508, 3519

Category B (requiring heavy repairs by 1993–1994): 3412, 3424, 3464, 3473, 3475, 3490, 3498, 3507, 3518, 3520, 3537

Category C (requiring heavy repairs by 1992): 3439, 3446, 3515

Although the project did not proceed as planned, several locomotives from this group have been preserved.

Works numbers

The table below details the locomotive numbers, their manufacturers, and corresponding works numbers. According to the builders' records, all locomotives were constructed in 1953. Each tender carried the identical works number as the locomotive it was paired with, with the exception of sixty tenders produced by Henschel for condensing locomotives built by NBL. These particular tenders were assigned unique Henschel works numbers.

3433 Henschel 28752 1985 Bloemfontein Works 3434 Henschel 28753 1993 De Aar 3435 Henschel 28754 2007 Warrenton 3436 Henschel 28755 1993 De Aar 3437 Henschel 28756 - 3438 Henschel 28757 2010 Jan Kempdorp 3439 Henschel 28758 2007 Warrenton 3440 Henschel 28759 - 3441 Henschel 28760 - 3442 Henschel 28761 - 3443 Henschel 28762 2007 Kimberley 3444 Henschel 28763 2007 Kimberley 3445 Henschel 28764 2007 Warrenton 3446 Henschel 28765 2007 Warrenton 3447 Henschel 28766 2007 Kimberley 3448 Henschel 28767 2007 Kimberley 3449 Henschel 28768 2007 Kimberley 3450 Henschel 28769 Class 26 Red Devil 3452 NBL 27312 Henschel 28780 1976-09 1993 De Aar 3453 NBL 27313 Henschel 28781 1977-11 2010 Jan Kempdorp 3454 NBL 27314 Henschel 28782 1977-06 3455 NBL 27315 Henschel 28783 1975-09 1993 De Aar 3456 NBL 27316 Henschel 28784 1976-07 2007 Kimberley 3457 NBL 27317 Henschel 28785 1978-01 3458 NBL 27318 Henschel 28786 1975-01 1993 De Aar 3459 NBL 27319 Henschel 28787 XX 2007 Warrenton 3460 NBL 27320 Henschel 28788 XX 2007 Kimberley 3461 NBL 27321 Henschel 28789 1975-10 1983 Salt River 3462 NBL 27322 Henschel 28790 1979-12 2007 Warrenton 3463 NBL 27323 Henschel 28791 XX 1987 Bloemfontein Works 3464 NBL 27324 Henschel 28792 1976-10 2007 Warrenton 3465 NBL 27325 Henschel 28793 1975-06 1993 De Aar 3466 NBL 27326 Henschel 28794 1976-04 2007 Kimberley 3467 NBL 27327 Henschel 28795 1979-07 3468 NBL 27328 Henschel 28796 XX 1993 De Aar 3469 NBL 27329 Henschel 28797 1979-05 2007 Kimberley 3470 NBL 27330 Henschel 28798 1975-06 1993 De Aar 3471 NBL 27331 Henschel 28799 1976-05 1993 De Aar 3472 NBL 27332 Henschel 28800 XX 3473 NBL 27333 Henschel 28801 1976-07 1993 De Aar 3474 NBL 27334 Henschel 28802 1979-04 2007 Warrenton 3475 NBL 27335 Henschel 28803 1976-06 2007 Bloemfontein 3476 NBL 27336 Henschel 28804 1979-06 3477 NBL 27337 Henschel 28805 XX 2007 Warrenton 3478 NBL 27338 Henschel 28806 1978-08 2007 Kimberley 3479 NBL 27339 Henschel 28807 1979-05 2016 Bloemfontein 3480 NBL 27340 Henschel 28808 1975-05 2014 Capital Park (Rovos Rail) 3481 NBL 27341 Henschel 28809 1975-10 2008 Dal Josafat 3482 NBL 27342 Henschel 28810 1979-02 3483 NBL 27343 Henschel 28811 1975-11 2007 Kimberley 3484 NBL 27344 Henschel 28812 1978-05 2014 Capital Park (Rovos Rail) 3485 NBL 27345 Henschel 28813 1976-11 2007 Kimberley 3486 NBL 27346 Henschel 28814 1976-12 2007 Kimberley 3487 NBL 27347 Henschel 28815 1974-11 1993 De Aar 3488 NBL 27348 Henschel 28816 1976-08 3489 NBL 27349 Henschel 28817 1977-03 2007 Warrenton 3490 NBL 27350 Henschel 28818 1976-05 2007 Warrenton 3491 NBL 27351 Henschel 28819 1975-02 2007 Warrenton 3492 NBL 27352 Henschel 28820 1974-11 1993 De Aar 3493 NBL 27353 Henschel 28821 1975-11 2007 Kimberley 3494 NBL 27354 Henschel 28822 1975-11 2010 Jan Kempdorp 3495 NBL 27355 Henschel 28823 1979-12 2007 Warrenton 3496 NBL 27356 Henschel 28824 1978-08 3497 NBL 27357 Henschel 28825 1975-02 1993 De Aar 3498 NBL 27358 Henshel 28826 1977-01 2010 Jan Kempdorp 3499 NBL 27359 Henschel 28827 1975‑06 Kimberley 3500 NBL 27360 Henschel 28828 1978‑02 Kimberley 3501 NLB 23761 Henschel 28829 179‑08 3502 NLB 23762 Henschel 28830 176‑02 3503 NLB 23763 Henschel 28831 175‑05 3504 NLB 23764 Henschel 28832 177‑09 3505 NLB 23765 Henschel 28833 181‑10 3506 NLB 23766 Henschel 28834 174‑12 1993 De Aar 3507 NLB 23767 Henschel 28835 176‑10 1993 De Aar 3508 NLB 23768 Henschel 28836 177‑03 - 3509 NLB 23769 Henschel 28837 176‑02 1993 De Aar 3510 NLB 23770 Henschel 28838 178‑04 1987 Bloemfontein Works 3512 NLB - 3513 NLB - 3514 NLB - 3515 NLB - 3516 NLB - 3517 NLB - 3518 NLB - 3519 NLB


Preservation

As of August 2025, the following locomotives from the 25NC and 26 classes remain extant.

The majority continue to be under the ownership of the Transnet Heritage Foundation. With the exception of class 25Nc units 3437 and 3482—which are only certified for mainline operation during the winter months—none have mainline certification as of 1 January 2019.

Number (*EW2 tenders) Works number Ownership (Transnet Heritage Foundation / Private) Lessee / Owner Current Location Remarks
3404 NBL 27290 Transnet Heritage Foundation Germiston Locomotive Depot
3405 NBL 27291 Private Quainton Railway Society Buckinghamshire Railway Centre, England Returned to England in 1991
3407* NBL 27293 Private Greg McLennan Worcester Locomotive Depot
3410 NBL 27296 Transnet Heritage Foundation Transnet Heritage Foundation Bloemfontein Locomotive Depot Designated as the Transnet Heritage Foundation’s class representative (National Collection)
3411 NBL 27311 Transnet Heritage Foundation Museum Kimberley station
3422 Hensc 28741 Transnet Heritage Foundation Cape Town station Converted to oil burner
3432 Hensc 28751 Private Mainline Steam Heritage Trust Auckland, New Zealand Exported in 1996
3437* Hensc 28752 Private Oscar Sabitini Kimberley Locomotive Depot

Successfully passed boiler inspection in July 2024 Currently operational

3440 Hensc 28759 Private Rovos Rail Capital Park Locomotive Depot Either no. 3440 or 3480 was scrapped
3441* Hensc 28760 Transnet Heritage Foundation Steamnet 2000 Kimberley Locomotive Depot
3442* Hensc 28761 Private Rovos Rail Capital Park Locomotive Depot Known as Anthea
3454* NBL 27314 Transnet Heritage Foundation Bloemfontein Locomotive Depot
3457* NBL 27317 Transnet Heritage Foundation Steamnet 2000 Kimberley Locomotive Depot
3467 NBL 27327 Transnet Heritage Foundation Steamnet 2000 Kimberley Locomotive Depot
3472 NBL 27331 Transnet Heritage Foundation Germiston Locomotive Depot
3476 NBL 27336 Transnet Heritage Foundation Waterval Boven
3480 NBL 27340 Private Rovos Rail Capital Park Locomotive Depot Either no.3440 or no.3480 was dismantled
3482 NBL 27342 Transnet Heritage Foundation Steamnet 2000 Kimberley Locomotive Depot

Successfully passed boiler test June 2023 In operational condition

3488* NBL 27348 Private Sandstone Estates Sandstone Estate, Ficksburg
3496 NBL 27356 Transnet Heritage Foundation Sandstone Estates Sandstone Estate

Partially converted to oil burner

3501* NBL 2731 Transnet Heritage Foundation Kimberley Locomotive Depot

Equipped with oil burner

3508 NBL 27368 Private Mainline Steam Heritage Trust Auckland, New Zealand

Exported in the year 1996

3533* NBL 27393 Private Rovos Rail Capital Park Locomotive Depot

Known as King Zog

3536 NBL 27396 Transnet Heritage Foundation Sandstone Estates Sandstone Estate
3537 NBL 27397 Private Henry Posner Kimberley Locomotive Depot
3450 Hensc 28397 Transnet Heritage Foundation Ceres Railway Company Royal Cape Yacht Club


Illustration

References

  1. ↑ £27 Million Motive Power Order for South African Railways Railway Transportation March 1952 page 43
  2. ↑ 2.0 2.1 Template:Paxton-Bourne
  3. ↑ North British Locomotive Company works list, compiled by Austrian locomotive historian Bernhard Schmeiser
  4. ↑ Henschel-Lieferliste (Henschel & Son works list), compiled by Dietmar Stresow
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Cite error: Invalid <ref> tag; no text was provided for refs named Holland 2
  6. ↑ 6.0 6.1 South African Railways 25NC Class Locomotives Railway Gazette 15 May 1953 pages 568/569
  7. ↑ Condensing Locomotives for South Africa Railway Gazette 26 February 1954 pages 237-240
  8. ↑ Pivnic, Les (1970). S.A.R. Class 25NC 4-8-4. South African Transport, October 1970. pp. 548-550.
  9. ↑ 9.0 9.1 9.2 Soul of A Railway, System 1, Part 4: Touws River to Beaufort West. Introduction par 4, Caption 3. (Accessed on 27 November 2016)
  10. ↑ South African Railways & Harbours/Suid Afrikaanse Spoorweë en Hawens (15 August 1941). Locomotive Diagram Book/Lokomotiefdiagramboek, 2'0" & 3'6" Gauge/Spoorwydte, Steam Locomotives/Stoomlokomotiewe. SAR/SAS Mechanical Department/Werktuigkundige Dept. Drawing Office/Tekenkantoor, Pretoria. pp. VIII, 6a-7a, 20-21, 28-28A.
  11. ↑ Information supplied by R.S. Loubser, son of M.M. Loubser
  12. ↑ Soul of A Railway, System 7, Western Transvaal, based in Johannesburg, Part 26: Braamfontein West to Klerksdorp (home signal) by Les Pivnic, Part 1. Caption 36. (Accessed on 6 May 2017)
  13. ↑ 13.0 13.1 Template:Durrant-Twilight
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named diagram-book
  15. ↑ Frieda steam forward alone Diamond Fields Advertiser 27 March 1986
  16. ↑ 16.0 16.1 Gas Producer Combustion System (GPCS)
  17. ↑ 17.0 17.1 The Ultimate Steam Page
  18. ↑ South Africa's Red Devil The Railway Magazine issue 963 July 1981 pages 317/318
  19. ↑ Steam Locomotive Development in South Africa Continental Railway Journal issue 64 December 1985 pages 39-43

External links

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