South African Class 25NC 4-8-4


The South African Railways Class 25NC 4-8-4 of 1953 was a steam locomotive.
Between 1953 and 1955, the South African Railways placed fifty Class 25NC steam locomotives with a 4-8-4 Northern type wheel arrangement in service. The Class 25NC was the non-condensing version of the 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.

Preservation

The following is a list of 25NC and 26 class that have survived into preservation.
Most are still owned by the Transnet Heritage Foundation. None except the class 25Nc 3437 & 25Nc 3482 are mainline certified as of January 1st 2019.
Number Works numberTransnet Heritage Foundation / PrivateLeaselend / OwnerCurrent LocationNotes
3404NBL 27290Transnet Heritage FoundationPhilipp MaurerGermiston 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 FoundationCape Town station
3432Hensc 28751PrivateMainline Steam Heritage TrustAuckland, New ZealandExported 1996
3437*Hensc 28752PrivateOscar SabitiniKimberley Locomotive DepotOperational
3440Hensc 28759PrivateRovos RailCapital Park Locomotive DepotScrapped?
3441*Hensc 28760Transnet Heritage FoundationSteamnet 2000Kimberley Locomotive Depot
3442*Hensc 28761PrivateRovos RailCapital Park Locomotive Depot
3454*NBL 27314Transnet Heritage FoundationMainline SteamBloemfontein Locomotive Depot
3457*NBL 27317Transnet Heritage FoundationSteamnet 2000Kimberley Locomotive Depot
3467NBL 27327Transnet Heritage FoundationSteamnet 2000Kimberley Locomotive Depot
3472NBL 27331Transnet Heritage FoundationReefsteamersGermiston Locomotive Depot
3476NBL 27336Transnet Heritage FoundationMainline SteamWaterval Boven
3480NBL 27340PrivateRovos RailCapital Park Locomotive DepotScrapped?
3482NBL 27342Transnet Heritage FoundationSteamnet 2000Kimberley Locomotive DepotPassed boiler test 1 February 2020
3488*NBL 27348PrivateSandstone EstatesGermiston Locomotive Depot
3496NBL 27356Transnet Heritage FoundationSandstone EstatesSandstone Estate
3501*NBL 2731Transnet Heritage FoundationKimberley Locomotive Depot
3508NBL 27368PrivateMainline Steam Heritage TrustAuckland, New ZealandExported 1996
3533*NBL 27393PrivateRovos RailCapital Park Locomotive Depot
3536NBL 27396Transnet Heritage FoundationSandstone EstatesSandstone Estate
3537NBL 27397PrivateKimberley Locomotive Depot
3450Hensc 28397Transnet Heritage FoundationCeres Railway CompanyRoyal Cape Yacht ClubOperational

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
from or to
3401NBL27287
3402NBL27288
3403NBL27289
3404NBL27290
3405NBL27291
3406NBL27292
3407NBL27293
3408NBL27294
3409NBL27295
3410NBL27296
3411NBL27311
3412Henschel28731
3413Henschel28732
3414Henschel28733
3415Henschel28734
3416Henschel28735
3417Henschel28736
3418Henschel28737
3419Henschel28738
3420Henschel28739
3421Henschel28740
3422Henschel28741
3423Henschel28742
3424Henschel28743
3425Henschel28744
3426Henschel28745
3427Henschel28746
3428Henschel28747
3429Henschel28748
3430Henschel28749
3431Henschel28750
3432Henschel28751
3433Henschel28752
3434Henschel28753
3435Henschel28754
3436Henschel28755
3437Henschel28756
3438Henschel28757
3439Henschel28758
3440Henschel28759
3441Henschel28760
3442Henschel28761
3443Henschel28762
3444Henschel28763
3445Henschel28764
3446Henschel28765
3447Henschel28766
3448Henschel28767
3449Henschel28768
3450Henschel28769Class 26 Red Devil
3452NBL27312Henschel28780Class 25 Condenser
3453NBL27313Henschel28781Class 25 Condenser
3454NBL27314Henschel28782Class 25 Condenser
3455NBL27315Henschel28783Class 25 Condenser
3456NBL27316Henschel28784Class 25 Condenser
3457NBL27317Henschel28785Class 25 Condenser
3458NBL27318Henschel28786Class 25 Condenser
3459NBL27319Henschel28787Class 25 Condenser
3460NBL27320Henschel28788Class 25 Condenser
3461NBL27321Henschel28789Class 25 Condenser
3462NBL27322Henschel28790Class 25 Condenser
3463NBL27323Henschel28791Class 25 Condenser
3464NBL27324Henschel28792Class 25 Condenser
3465NBL27325Henschel28793Class 25 Condenser
3466NBL27326Henschel28794Class 25 Condenser
3467NBL27327Henschel28795Class 25 Condenser
3468NBL27328Henschel28796Class 25 Condenser
3469NBL27329Henschel28797Class 25 Condenser
3470NBL27330Henschel28798Class 25 Condenser
3471NBL27331Henschel28799Class 25 Condenser
3472NBL27332Henschel28800Class 25 Condenser
3473NBL27333Henschel28801Class 25 Condenser
3474NBL27334Henschel28802Class 25 Condenser
3475NBL27335Henschel28803Class 25 Condenser
3476NBL27336Henschel28804Class 25 Condenser
3477NBL27337Henschel28805Class 25 Condenser
3478NBL27338Henschel28806Class 25 Condenser
3479NBL27339Henschel28807Class 25 Condenser
3480NBL27340Henschel28808Class 25 Condenser
3481NBL27341Henschel28809Class 25 Condenser
3482NBL27342Henschel28810Class 25 Condenser
3483NBL27343Henschel28811Class 25 Condenser
3484NBL27344Henschel28812Class 25 Condenser
3485NBL27345Henschel28813Class 25 Condenser
3486NBL27346Henschel28814Class 25 Condenser
3487NBL27347Henschel28815Class 25 Condenser
3488NBL27348Henschel28816Class 25 Condenser
3489NBL27349Henschel28817Class 25 Condenser
3490NBL27350Henschel28818Class 25 Condenser
3491NBL27351Henschel28819Class 25 Condenser
3492NBL27352Henschel28820Class 25 Condenser
3493NBL27353Henschel28821Class 25 Condenser
3494NBL27354Henschel28822Class 25 Condenser
3495NBL27355Henschel28823Class 25 Condenser
3496NBL27356Henschel28824Class 25 Condenser
3497NBL27357Henschel28825Class 25 Condenser
3498NBL27358Henschel28826Class 25 Condenser
3499NBL27359Henschel28827Class 25 Condenser
3500NBL27360Henschel28828Class 25 Condenser
3501NBL27361Henschel28829Class 25 Condenser
3502NBL27362Henschel28830Class 25 Condenser
3503NBL27363Henschel28831Class 25 Condenser
3504NBL27364Henschel28832Class 25 Condenser
3505NBL27365Henschel28833Class 25 Condenser
3506NBL27366Henschel28834Class 25 Condenser
3507NBL27367Henschel28835Class 25 Condenser
3508NBL27368Henschel28836Class 25 Condenser
3509NBL27369Henschel28837Class 25 Condenser
3510NBL27370Henschel28838Class 25 Condenser
3512NBL27372Class 25 Condenser
3513NBL27373Class 25 Condenser
3514NBL27374Class 25 Condenser
3515NBL27375Class 25 Condenser
3516NBL27376Class 25 Condenser
3517NBL27377Class 25 Condenser
3518NBL27378Class 25 Condenser
3519NBL27379Class 25 Condenser
3520NBL27380Class 25 Condenser
3521NBL27381Class 25 Condenser
3522NBL27382Class 25 Condenser
3523NBL27383Class 25 Condenser
3524NBL27384Class 25 Condenser
3525NBL27385Class 25 Condenser
3526NBL27386Class 25 Condenser
3527NBL27387Class 25 Condenser
3528NBL27388Class 25 Condenser
3529NBL27389Class 25 Condenser
3530NBL27390Class 25 Condenser
3531NBL27391Class 25 Condenser
3532NBL27392Class 25 Condenser
3533NBL27393Class 25 Condenser
3534NBL27394Class 25 Condenser
3535NBL27395Class 25 Condenser
3536NBL27396Class 25 Condenser
3537NBL27397Class 25 Condenser
3538NBL27398Class 25 Condenser
3539NBL27399Class 25 Condenser