South African Class 25NC 4-8-4


The South African Railways Class 25NC 4-8-4 of 1953 was a class of steam locomotives built between 1953 and 1955 for the South African Railways. The Class 25NC was the non-condensing version of the [South African South African Class 25 4-8-4|Class 25 4-8-4|Class 25] condensing locomotive, of which ninety were placed in service at the same time. Between 1973 and 1980, all but three of the condensing locomotives were converted to non-condensing and also designated Class 25NC.

Manufacturers

The Class 25NC non-condensing and Class 25 condensing 4-8-4 Northern type steam locomotives were designed by the South African Railways under the direction of LC Grubb, Chief Mechanical Engineer of the SAR from 1949 to 1954, in conjunction with Henschel & Son of Kassel in Germany who designed the condensing apparatus and the condensing tender of the Class 25 sister locomotive. Between 1953 and 1955,eleven Class 25NC locomotives were built by the North British Locomotive Company and numbered in the range from 3401 to 3411 while 39 locomotives were built by Henschel and numbered in the range from 3412 to 3450.

Characteristics

The Class 25NC was superheated and used piston valves actuated by Walschaerts valve gear. Timken roller bearings were used throughout, including on the three-axle tender bogies, the coupling and connecting rods as well as the crosshead gudgeon pins, while the locomotive's leading bogies and coupled wheels had Cannon-type axle boxes. Compared to earlier SAR practice, a novelty was the adoption of mechanical lubrication. A sixteen-feed lubricator was driven off the expansion link trunnion. The cylinders and frames were cast in one piece by Commonwealth Steel Company in the United States. The steel cylinders and steam chests were fitted with cast iron liners. Being entirely mounted on roller bearings, very little effort was required to move these locomotives.
The Alligator type crossheads were split on the vertical centre line and clamped on to the end of the piston rods, which had three coned rings engaging in grooves in the crossheads. The original coupling rods differed from the usual in being three separate rods, thereby doing away with four knuckle joints and pins.
The multiple-valve superheater header was of the Melesco type. The boiler was fitted with four Ross-pop safety valves, each in diameter, and two Hopkinson boiler blowdown cocks on the firebox wrapper, one on each side. Feedwater was delivered to the boiler by two Friedmann vertical type non-lifting injectors, each with a capacity of per hour.
The locomotive was equipped with a Type EW1 tender which was equipped with a mechanical stoker of which the engine was mounted on the tender. The tank had a water capacity of and the coal bunker a capacity of. The tender frame was also a one-piece steel casting and was a water-bottom frame, with the frame itself forming the bottom of the tank instead of being a separate tank and frame as in previous designs.

Teething troubles

Soon after entering service, problems were experienced with failing connecting rods, big end bearings breaking up as well as cracks developing in the motion girder of the Alligator crossheads. After investigations by SAR engineers with assistance from the South African Council for Scientific and Industrial Research, the crossheads, slide bars and coupling rods were modified. The crossheads were converted to the multiple-bearing type with single guide bars while the three independent coupling rods were replaced with the more conventional single coupling rod with knuckle joints.
When new, the tapered Timken crankpin roller bearings soon became notorious for throwing their lubricant onto the underside of the boiler, from where it ran down to the lowest point and dripped onto the coupled wheel tyres along the way. This manufacturer's fault also applied to the Class 25 and was one of the reasons for the reputation of both classes of being slippery. Timken managed to resolve the problem before all their bearings had been replaced, but by then about two-thirds of the locomotives had already been fitted with redesigned coupling rods with SKF crankpin ball bearings.

Service

The Class 25NC initially served on the unelectrified mainlines from De Aar via Kimberley to Welverdiend. They were pooled from their introduction and were run through from De Aar to Welverdiend and vice versa, recoaling at Warrenton. After electrification was extended from Welverdiend to Klerksdorp, they ran from there to De Aar, still recoaling at Warrenton. Later they also worked from Kimberley via Bloemfontein to Harrismith in the Free State while some joined the Class 25 condensers on the line from De Aar via Beaufort West to Touws River.
When the line south from De Aar was dieselised between 1973 and 1974, the Class 25 condensers working there were moved north to work the section from De Aar to Kimberley, where they replaced twenty-two Class 25NCs which were then relocated to Bethlehem in the Free State. From 1982, Class 25NCs also replaced Class 19Ds and Class GMAM Garratts on the line from Warrenton via Vryburg to Mafeking.

Class 25 rebuilding

Along with the Class 25NC, ninety Class 25 condensing locomotives were built as part of the same order, one by Henschel and the rest by NBL. The condensing apparatus for these engines and their condensing tenders were designed and patented by Henschel.
Between 1973 and 1980, all but three of the ninety Class 25 condensers were converted to non-condensing locomotives and reclassified to Class 25NC, the exceptions being numbers 3451, 3511 and 3540. The number plates of some were copied and recast with the additional "NC" for "non-condensing" squeezed in next to the existing "25", which resulted in a lopsided class indication on their cabside plates. Locomotives with all four characters neatly in line and centred were therefore usually identifiable as original Class 25NCs.
In the process, their Type CZ condensing tenders were also rebuilt to ordinary coal-and-water Type EW2 tenders by removing the condensing radiators and roof fans and replacing it with a massive water tank. Since the Type CZ tenders were built on single cast steel water-bottom frames it was impractical to attempt to shorten them, which resulted in the rebuilt Type EW2 tenders with their long round-topped water tanks. Locomotives with these rebuilt tenders were soon nicknamed Worshond.

The Class 26 ''Red Devil''

Between 1979 and 1981 no. 3450, the last Class 25NC to be built, was rebuilt to the sole Class 26, the Red Devil, at the SAR workshops at Salt River, Cape Town. The primary objectives of the project were to improve the combustion and steaming rate, to reduce the emission of wasteful black smoke and to overcome the problem of clinkering.
This was achieved by the use of a Gas Producer Combustion System, which relies on the gasification of coal on a low temperature firebed so that the gases are then fully burnt above the firebed. These extensive modifications justified reclassification and the locomotive became the first and only Class 26, although the locomotive's original Class 25NC number was retained.

Project Zimbabwe

During 1988 a severe motive power shortage was experienced by the National Railways of Zimbabwe and discussions with South Africa revealed that numerous class 25NC 4-8-4, had been recently withdrawn from service and were available for either hire or purchase. NRZ decided to investigate the purchase of 20 to 25 of these locomotives for a short-term basis. A team of three were sent down from Bulawayo inspected 50 locomotives at Warrenton and De Aar.
A list of 28 locomotives was submitted from which it would be possible to choose 20 to 25, or any lesser number which might be needed
Category A
3404, 3410, 3422, 3428, 3438, 3442, 3445, 3453, 3457, 3459, 3479, 3504, 3508, 3519
Category B
3412, 3424, 3464, 3473, 3475, 3490, 3498, 3507, 3518, 3520, 3537
Category C
3439, 3446, 3515
The project did not materialise but several did survive into preservation.

Works numbers

The locomotive numbers, builders and works numbers are listed in the table. On the builders' works lists, all the locomotives are shown as having been built in 1953. All tenders bore the same works number as the engines they were built with, except the sixty tenders which were built by Henschel for condensing engines which were built by NBL. These sixty tenders were allocated Henschel works numbers.

Loco no		Builder
Works
no		Tender
Builder		Tender
Works no		Rebuilt
Date from class 25 to class 25nc		Date and Place Scrapped
3401NBL272872007 Bethlehem
3402NBL272881986 Bloemfontein Works
3403NBL272892007 Bloemfontein
3404NBL27290
3405NBL27291-
3406NBL272921983 Bloemfontein Works
3407NBL27293-
3408NBL272942007 Bethlehem
3409NBL272952010 Jan Kempdorp
3410NBL27296
3411NBL27311-
3412Henschel287312007 Bloemfontein
3413Henschel287322007 Bethlehem
3414Henschel287332008 Krugerersdorp
3415Henschel287342007 Bethlehem
3416Henschel287351983 Bloemfontein Works
3417Henschel287362016 Worcester
3418Henschel287372007 Bethlehem
3419Henschel287382007 Bethlehem
3420Henschel287392007 Bethlehem
3421Henschel287402007 Bethlehem
3422Henschel28741-
3423Henschel287421993 De Aar
3424Henschel287431993 De Aar
3425Henschel287442007 Kimberley
3426Henschel287452007 Kimberley
3427Henschel287462007 Kimberley
3428Henschel287471993 De Aar
3429Henschel287481993 De Aar
3430Henschel287491993 De Aar
3431Henschel287502007 Bethlehem
3432Henschel28751-
3433Henschel287521985 Bloemfontein Works
3434Henschel287531993 De Aar
3435Henschel287542007 Warrenton
3436Henschel287551993 De Aar
3437Henschel28756-
3438Henschel287572010 Jan Kempdorp
3439Henschel287582007 Warrenton
3440Henschel28759
3441Henschel28760
3442Henschel28761-
3443Henschel287622007 Kimberley
3444Henschel287632007 Kimberley
3445Henschel287642007 Warrenton
3446Henschel287652007 Warrenton
3447Henschel287662007 Kimberley
3448Henschel287672007 Kimberley
3449Henschel287682007 Kimberley
3450Henschel28769Class 26 Red Devil-
3452NBL27312Henschel287801976-091993 De Aar
3453NBL27313Henschel287811977-112010 Jan Kempdorp
3454NBL27314Henschel287821977-06-
3455NBL27315Henschel287831975-091993 De Aar
3456NBL27316Henschel287841976-072007 Kimberley
3457NBL27317Henschel287851978-01-
3458NBL27318Henschel287861975-011993 De Aar
3459NBL27319Henschel28787XX2007 Warrenton
3460NBL27320Henschel28788XX2007 Kimberley
3461NBL27321Henschel287891975-101983 Salt River
3462NBL27322Henschel287901979-122007 Warrenton
3463NBL27323Henschel28791XX1987 Bloemfontein Works
3464NBL27324Henschel287921976-102007 Warrenton
3465NBL27325Henschel287931975-061993 De Aar
3466NBL27326Henschel287941976-042007 Kimberley
3467NBL27327Henschel287951979-07-
3468NBL27328Henschel28796XX1993 De Aar
3469NBL27329Henschel287971979-052007 Kimberley
3470NBL27330Henschel287981975-061993 De Aar
3471NBL27331Henschel287991976-051993 De Aar
3472NBL27332Henschel28800XX-
3473NBL27333Henschel288011976-071993 De Aar
3474NBL27334Henschel288021979-042007 Warrenton
3475NBL27335Henschel288031976-062007 Bloemfontein
3476NBL27336Henschel288041979-06-
3477NBL27337Henschel28805XX2007 Warrenton
3478NBL27338Henschel288061978-082007 Kimberley
3479NBL27339Henschel288071979-052016 Bloemfontein
3480NBL27340Henschel288081975-052014 Capital Park
3481NBL27341Henschel288091975-102008 Dal Josafat
3482NBL27342Henschel288101979-02-
3483NBL27343Henschel288111975-112007 Kimberley
3484NBL27344Henschel288121978-052014 Capital Park
3485NBL27345Henschel288131976-112007 Kimberley
3486NBL27346Henschel288141976-122007 Kimberley
3487NBL27347Henschel288151974-111993 De Aar
3488NBL27348Henschel288161976-08-
3489NBL27349Henschel288171977-032007 Warrenton
3490NBL27350Henschel288181976-052007 Warrenton
3491NBL27351Henschel288191975-022007 Warrenton
3492NBL27352Henschel288201974-111993 De Aar
3493NBL27353Henschel288211975-112007 Kimberley
3494NBL27354Henschel288221975-112010 Jan Kempdorp
3495NBL27355Henschel288231979-122007 Warrenton
3496NBL27356Henschel288241978-08-
3497NBL27357Henschel288251975-021993 De Aar
3498NBL27358Henschel288261977-012010 Jan Kempdorp
3499NBL27359Henschel288271975-062007 Kimberley
3500NBL27360Henschel288281978-022007 Kimberley
3501NBL27361Henschel288291979-08-
3502NBL27362Henschel288301976-022007 Kimberley
3503NBL27363Henschel288311975-052007 Warrenton
3504NBL27364Henschel288321977-092007 Warrenton
3505NBL27365Henschel288331981-102007 Kimberley
3506NBL27366Henschel288341974-121993 De Aar
3507NBL27367Henschel288351976-101993 De Aar
3508NBL27368Henschel288361977-03-
3509NBL27369Henschel288371976-021993 De Aar
3510NBL27370Henschel288381978-041987 Bloemfontein Works
3512NBL273721974-101993 De Aar
3513NBL273731974-072007 Bloemfontein
3514NBL273741976-092007 Kimberley
3515NBL273751975-081993 De Aar
3516NBL273761979-042007 Kimberley
3517NBL273771976-032007 Kimberley
3518NBL273781977-022007 Bloemfontein
3519NBL273791977-022007 Warrenton
3520NBL273801976-032007 Warrenton
3521NBL273811977-042007 Warrenton
3522NBL273821975-121993 De Aar
3523NBL273831975-091993 De Aar
3524NBL273841979-102007 Warrenton
3525NBL273851976-082007 Kimberley
3526NBL273861979-012007 Kimberley
3527NBL273871978-062007 Kimberley
3528NBL273881976-062010 Jan Kempdorp
3529NBL273891976-022007 Kimberley
3530NBL273901975-041993 De Aar
3531NBL273911979-112007 Warrenton
3532NBL273921978-101987 Bloemfontein Works
3533NBL273931978-03-
3534NBL273941976-052007 Kimberley
3535NBL273951979-022007 Kimberley
3536NBL273961978-11
3537NBL273971975-12-
3538NBL273981978-081987 Bloemfontein Works
3539NBL273991979-102007 Warrenton

Preservation

The following is a list of 25NC and 26 class that have survived. AUGUST 2025.
Most are still owned by the Transnet Heritage Foundation. None except the class 25Nc 3437 & 25Nc 3482 are mainline certified as of 1 January 2019.
Number Works numberTransnet Heritage Foundation / PrivateLeaselend / OwnerCurrent LocationNotes
3404NBL 27290Transnet Heritage FoundationGermiston Locomotive Depot
3405NBL 27291PrivateQuainton Railway SocietyBuckinghamshire Railway Centre, EnglandRepatriated 1991
3407*NBL 27293PrivateGreg McLennanWorcester Locomotive Depot
3410NBL 27296Transnet Heritage FoundationTransnet Heritage FoundationBloemfontein Locomotive DepotSelected as Transnet Heritage Foundation representative of the class
3411NBL 27311Transnet Heritage FoundationMuseumKimberley station
3422Hensc 28741Transnet Heritage Foundation Cape Town stationOilburner
3432Hensc 28751PrivateMainline Steam Heritage TrustAuckland, New ZealandExported 1996
3437*Hensc 28752PrivateOscar SabitiniKimberley Locomotive Depot
Passed boiler test July 2024
Operational
3440Hensc 28759PrivateRovos RailCapital Park Locomotive DepotScrapped 3440 or 3480
3441*Hensc 28760Transnet Heritage FoundationSteamnet 2000Kimberley Locomotive Depot
3442*Hensc 28761PrivateRovos RailCapital Park Locomotive DepotNamed Anthea
3454*NBL 27314Transnet Heritage FoundationBloemfontein Locomotive Depot
3457*NBL 27317Transnet Heritage FoundationSteamnet 2000Kimberley Locomotive Depot
3467NBL 27327Transnet Heritage FoundationSteamnet 2000Kimberley Locomotive Depot
3472NBL 27331Transnet Heritage FoundationGermiston Locomotive Depot
3476NBL 27336Transnet Heritage FoundationWaterval Boven
3480NBL 27340PrivateRovos RailCapital Park Locomotive DepotScrapped 3440 or 3480
3482NBL 27342Transnet Heritage FoundationSteamnet 2000Kimberley Locomotive DepotPassed boiler test June 2023
Operational
3488*NBL 27348PrivateSandstone EstatesSandstone Estate, Ficksburg
3496NBL 27356Transnet Heritage FoundationSandstone EstatesSandstone EstatePartly converted to oilburner
3501*NBL 2731Transnet Heritage FoundationKimberley Locomotive DepotOil Burner
3508NBL 27368PrivateMainline Steam Heritage TrustAuckland, New ZealandExported 1996
3533*NBL 27393PrivateRovos RailCapital Park Locomotive DepotNamed King Zog
3536NBL 27396Transnet Heritage FoundationSandstone EstatesSandstone Estate
3537NBL 27397PrivateHenry PosnerKimberley Locomotive Depot
3450Hensc 28397Transnet Heritage FoundationCeres Railway CompanyRoyal Cape Yacht Club