South African Class 26 4-8-4

South African Railways Class 26 "Red Devil"

Company type	Steam locomotive
Industry	Rail transport
Founded	1981 (rebuilt from Class 25NC engine)
Founder	David Wardale
Headquarters	Cape Town , South Africa
Products	Steam locomotive (Class 26)

South African Railways Class 26 4-8-4 Steam Locomotive

The South African Railways Class 26 4-8-4, commonly referred to as the Red Devil, is a steam locomotive that was reconstructed in 1981 from an existing Class 25NC engine. This transformation was carried out by mechanical engineer David Wardale, originally from England, during his tenure with the South African Railways. The comprehensive rebuild was conducted at the Salt River Works located in Cape Town and drew heavily on the advanced engineering concepts pioneered by Argentine mechanical engineer L.D. Porta.

Origin

The locomotive that served as the basis for the Class 26 rebuild was originally introduced in 1953, marking the final unit of the Class 25NC series of 4-8-4 Northern type engines to be constructed. Both the Class 25 condensing and Class 25NC non-condensing models were developed by South African Railways (SAR) under the leadership of L.C. Grubb, who held the position of Chief Mechanical Engineer from 1949 to 1954, in collaboration with Henschel and Son. The initial Class 25 locomotive, numbered 3451, along with most condensing tenders and Class 25NC engines numbered between 3412 and 3450, were produced by Henschel. Meanwhile, Class 25NC locomotives numbered from 3401 to 3411, together with the remaining 89 condensing Class 25 units, were manufactured by the North British Locomotive Company located in Glasgow, Scotland.

Class 19D Trial Rebuild

From the beginning, the rebuilding initiative faced lukewarm backing from SAR management, who had already committed to phasing out steam locomotives in favor of electric and diesel-electric alternatives.

Despite this, Wardale was resolute in proving that steam locomotive efficiency could be substantially enhanced by employing a Gas Producer Combustion System (GPCS), which generates more steam while consuming less fuel. Additionally, he integrated the Lempor exhaust system—developed by Argentine engineer L.D. Porta—to optimize steam utilization.

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Wardale Class 19D no. 2644

For experimental purposes, Wardale undertook extensive modifications on a Krupp-manufactured Class 19D 4-8-2 Mountain type branchline engine, no. 2644. This included fitting a GPCS and tandem dual Lempor exhausts along with supplementary enhancements such as elevated smoke deflectors.

These upgrades enabled the locomotive to deliver notably greater power output while reducing fuel consumption compared to unmodified Class 19Ds. Consequently, Wardale received approval to proceed with constructing a prototype for the Class 26.

Red Devil Rebuild

The transformation of Class 25NC no. 3450 commenced toward the end of 1979. Production of new components and alterations to existing parts were conducted across various SAR workshops situated at Salt River in Cape Town, Bloemfontein, Beaconsfield in Kimberley, Koedoespoort in Pretoria, and Pietermaritzburg. Tasks were assigned according to each workshop’s specialization.

Combustion

The key aims behind these modifications were threefold:

• Enhance combustion efficiency and steaming capacity.
• Minimize the emission of inefficient black smoke.
• Resolve issues related to clinkering within the firebox.

These goals were met through implementing a single-stage gas producer system (GPCS), which operates by gasifying coal on a low-temperature firebed so that combustion occurs above it. This method restricts air flow through the firebed itself; instead, most combustion air is introduced via secondary intakes positioned above the firebed.

In traditional steam locomotives, significant fuel wastage occurs due to unburnt coal particles being carried away by rapid airflow through the grate. The GPCS addresses this by heating coal sufficiently to release volatile gases that combust fully with secondary air above the grate. This process improves overall combustion quality and drastically reduces black smoke emissions—an indicator of incomplete fuel burning caused by uncombusted coal particles escaping through the exhaust.

Engine alterations

In addition to numerous minor refinements, the engine underwent several significant changes, including the following:

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• Extended smokebox designed to fit tandem double Lempor exhausts.
• Dual chimneys positioned off-center.
• Installation of a feedwater heater situated between the chimneys.
• Enhanced lubrication for cylinder and valve liner contact surfaces.
• Addition of a booster to elevate superheating capacity.
• Introduction of new piston valves.
• Implementation of articulated valve spindles.
• Adoption of cooled valve liners.
• Redesigned chromium cast iron rings and valve liners featuring streamlined cylinder ports.
• Replacement cylinder liners.
• Modified valve gear configuration.
• Incorporation of Herdner starting valves.
• Air sanding equipment.
• Redesigned self-cleaning smokebox.
• Enlarged steam chests for improved steam flow.
• Direct steam pipe installation.
• Upgraded pistons.
• Enhanced packing for valves and piston rods.
• Improved variable stroke lubricator drive mechanism.
• Superior insulation materials applied.
• Refined Walschaerts valve gear with dimensions optimized through computer calculations.
• High-mounted Continental European style exhaust deflectors, curved around but not aligned parallel to the smokebox.

Tender alterations

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The Red Devil's Type EW1 tender featuring raised coal bunker sides

By elevating the sides of the coal bunker, the coal capacity of the Class 25NC’s Type EW1 tender was increased from approximately 18 long tons (18.3 tonnes) to roughly 20 long tons (20.3 tonnes).

Following all modifications, the locomotive’s total operating weight rose from about 231 tonnes (227 long tons) to nearly 236 tonnes (232 long tons).

Reclassification

The scope of these extensive upgrades warranted a new classification, resulting in this locomotive becoming the sole example of Class 26, while retaining its original Class 25NC number, 3450. The original Class 26 number plates, builder’s plate, and Salt River rebuild plate that were affixed to the cab sides have since been replaced by plates marked "Transnet National Collection".

Notably, the Henschel works plates displayed on no. 3450’s cab sides were not original but were sourced from Class GMAM 4-8-2+2-8-4 Garratt number 4068, Henschel works number 28697. This Garratt had been retired and stored at De Aar around the same period when no. 3450 was undergoing its transformation into Class 26. The actual builder’s works number for the Red Devil, 28769, contains the same digits arranged differently.

Test operations

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The locomotive was finished in a striking red paint scheme and officially named L.D. Porta in honor of the Argentine engineer whose concepts influenced many of its modifications. Initial steaming and shunting tests occurred on Thursday, 5 February 1981, followed by its first trial run without load between Salt River and Bellville on the next day. On Monday, 9 February, rebuilt no. 3450 pulled its inaugural three-coach train carrying various railway officials, employees, and members of the press to Dal Josafat, situated approximately 66 kilometres (41 miles) from Cape Town. Subsequent media coverage in Cape Town referred to the locomotive as the Red Devil. This nickname eventually became official and is now displayed on the Class 25NC style exhaust deflectors that replaced the earlier Continental European design.

Performance

When measured against an unaltered Class 25NC, the Red Devil demonstrated a 28% reduction in coal consumption and a 30% reduction in water usage during freight operations, alongside a 43% boost in drawbar power based on its peak recorded output. Its estimated maximum operational range under full freight load on gradients between 1% and 1¼% is approximately 700 kilometres (430 miles) considering coal capacity, and about 230 kilometres (140 miles) based on water reserves.

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The drawbar power values were calculated with considerable conservatism. Utilizing both mechanical and electronic indicators, the Class 26 achieved 4,492 indicated horsepower (3,350 kilowatts) during trials conducted between Pretoria and Witbank, setting a world record for narrow gauge locomotives. According to readings from the dynamometer car, this corresponded to an equivalent drawbar horsepower of 3,787. However, due to the dynamometer car's inconsistent performance and malfunctioning during various tests, the drawbar output measurements were less reliable. These readings showed equivalent drawbar power levels that were unrealistically low compared to indicated power, implying an excessively high locomotive rolling resistance. The peak equivalent drawbar power recorded at 3,787 horsepower (2,824 kilowatts) at 74 kilometres per hour (46 miles per hour) is likely an underestimate of the actual performance; nonetheless, even this conservative figure surpasses the Class 25NC’s maximum by 43%, exceeding the initial estimate of a 35% increase. Projecting from this cautious maximum equivalent drawbar power-speed relationship suggests an output of 3,000 kilowatts (4,000 horsepower) at 100 kilometres per hour (62 miles per hour), which is 52% greater than the highest level attained by the 25NC.

The Red Devil’s rated freight capacities are 700 tonnes (690 long tons) on gradients of 2%, 1,080 tonnes (1,060 long tons) on slopes of 1¼%, and 1,320 tonnes (1,300 long tons) on inclines of 1%. The heaviest freight load officially recorded relative to gradient was 900 tonnes (890 long tons) on a 2% grade. Additionally, it can maintain a steady speed of 100 kilometres per hour (62 miles per hour) while hauling a passenger train weighing 650 tonnes (640 long tons) on a 1% incline.

Drawback

Despite its impressive power output, this strength also revealed a significant limitation. While the Class 25NC already experienced issues with wheel slip, the more powerful Class 26—with largely identical wheel dimensions—was even more prone to this problem. It struggled considerably when starting or moving slowly on steep gradients. During its inaugural journey from Pretoria to Witbank in Transvaal, a signal stop on a 1 in 50 (2%) slope caused considerable difficulty in restarting, resulting in roughly a twenty-minute delay. Neither the Herdner valves nor the air sanding system were effective in resolving these traction challenges.

Comparable initiatives

The remarkable achievements of the South African Class 26 can be viewed as the last significant efforts of an era nearing its end. Despite becoming the most powerful and efficient steam locomotive to operate on South African tracks, electric and diesel-electric locomotives had already almost fully supplanted steam power by the early 1980s. Consequently, the program was discontinued after producing only a single prototype.

Class 25NC no. 3454 B.I. Ebing

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The dual Lempor chimneys and extended smoke deflectors of Class 25NC no. 3454

After Wardale left the South African Railways, the Beaconsfield workshops performed a modest upgrade on an ex-Class 25 condenser locomotive, no. 3454, constructed by NBL and converted to a free-exhausting non-condensing Class 25NC known as B.I. Ebing.

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Dual Lempor exhaust fitted to no. 3454, B.I. Ebing

This locomotive's alterations primarily involved fitting it with a dual Lempor exhaust system and lengthening its smoke deflectors to curve upwards around the smokebox. To reduce expenses related to smokebox extension, the chimneys were positioned side by side rather than in tandem as seen on earlier Wardale designs. Besides changes to the blastpipe and chimneys, no further modifications were implemented.

No. 3454 entered service in February 1985. According to reports from engine crews and maintenance personnel, it demonstrated clear reductions in coal and water usage compared to a standard Class 25NC, although these savings were not precisely measured. Additionally, it exhibited greater traction reliability than the Class 26, which frequently experienced wheel slip upon starting.

American Coal Enterprises 3000

Although the Red Devil project showcased that steam locomotives engineered with contemporary principles could substantially outperform older steam technology, it arrived too late to halt South Africa’s transition to diesel power. Comparable ventures such as Ross Rowland's ACE 3000 in the United States during 1985, and later efforts in China, also failed to rekindle official support for steam traction.

ACR Class NG G16A

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ACR Class NG G16A nos. 141 & 155 ascending from Bongwana to Nqabeni, circa 1992

Within South Africa, two narrow gauge Garratt locomotives of the Alfred County Railway's Class NG G16 were rebuilt in 1989 and 1990 employing technology analogous to that used by Wardale for the Red Devil. The reconstruction included installation of a gas producing combustion system (GPCS), Lempor exhausts, enhanced spark arresters, lightweight multi-ring articulated piston valves, refined valve timing, and improved mechanical lubrication.

Mechanical engineer Phil Girdlestone was appointed Chief Mechanical Engineer of the ACR specifically to oversee this rebuilding project at Port Shepstone. The first locomotive treated was Beyer, Peacock-built no. 141 in 1989; it was painted red and soon earned the nickname Red Dragon. The second unit, Hunslet-Taylor-built no. 155, underwent modification in 1990 but retained its original ex-SAR black paint scheme. Both upgraded engines were reclassified as Class NG G16A.

5AT Advanced Technology Steam Locomotive

Wardale's 2001 initiative in the United Kingdom, known as the 5AT Advanced Technology Steam Locomotive, represents the latest attempt at modern steam locomotive development. However, similar challenges that hindered progress in countries such as South Africa, the United States, and China were expected to obstruct the realization of the 5AT project as well.

Modifications

The primary image depicts the Red Devil in Pretoria shortly after its reconstruction was finalized, just over two months later. Following this, numerous alterations were implemented, many of which Wardale believed actually compromised the locomotive’s performance. Over time, caretakers who did not fully endorse the principles behind the recent overhaul made changes that rendered the Red Devil more conventional in design. Several of these adjustments can be observed externally when contrasting the main image with subsequent photographs below.

Preservation

Template:Update section The Red Devil last operated on a steam excursion dated 23 September 2003 before being retired and placed under the stewardship of private enthusiasts representing the Transnet Heritage Foundation (THF) at Monument Station in Cape Town. By November 2015, contractual discussions were underway between the THF and the newly established Ceres Rail Company, which aimed to reactivate the locomotive for weekend excursions running between Cape Town and Robertson on the revived Ceres branch line. On 13 July 2018, it completed its first journey in fifteen years. The agreement with THF restricts its operation exclusively to South Africa’s winter period. Presently, the Red Devil is housed at a maintenance facility belonging to Ceres Rail located in Foreshore, Cape Town.

Illustration

• Class 25NC no. 3450 near Kloofeind, 28 March 1978
  Class 25NC no. 3450 near Kloofeind, 28 March 1978
• At Beaconsfield Depot, Kimberley, Northern Cape, circa April 1985
  At Beaconsfield Depot, Kimberley, Northern Cape, circa April 1985
• In black livery named Soekie at De Aar shed, approximately April 1988
  In black livery named Soekie at De Aar shed, approximately April 1988
• Monument Station, Cape Town, photographed on 8 August 2010
  Monument Station, Cape Town, photographed on 8 August 2010
• Locomotive as seen in September 2023
  Locomotive as seen in September 2023