South African Railways Class 19D 2-8-4 No 2644 was Wardale's first locomotive modification incorporating a limited number of "Porta features". It became a test-bed for trying out ideas that would later be incorporated into Class 26 4-8-4 No 3450 The Red Devil.
The redesign and modification work was undertaken in 1979 at the unofficial request of a district engineer who wanted to see what could be done to improve the unreliable steaming of the 19D 4-8-2s that operated out of Mafeking in the far north of the country, the work to be paid for out of the Beaconsfield locomotive depot's maintenance budget.
Given the limited budget and limited facilities at the depot workshops, modifications were limited to the following:
- Gas Producer Combustion System including modified grate and clinker-prevention steam to the ash-pan;
- Twin Lempor Exhaust System without Kordina;
- Lengthened smokebox housing an enlarged and improved spark arrestor;
- Superheater booster in the form of a hinged baffle plate in the smokebox covering the lower tubes which was lifted by the smokebox vacuum at high power outputs;
- Piston valves and liners fitted with additional valve rings ; "ring control" of admission and cut-off; streamlining of port and valve edges; 5mm exhaust lap was later added to reduce firebed disturbance;
- Valve and cylinder lubrication improvements through the application of lubricants directly onto the rubbing surfaces (between the rings, in the case of the valves);
- Snifting, drifting and bypass valves removed and instructions issued to drivers to drift in mid-gear;
- Adhesion improved through the application of sand under the rear bogie wheels and intermediate coupled wheels (in addition to the the leading coupled wheels) and pedal-control of sanding;
- Steam rail washer fitted ahead of the trailing wheels to remove sand from the rails (thereby reducing the rolling resistance of the train);
- Exhaust deflectors fitted to lift the low velocity exhaust clear of the cab.
Despite the limited nature of the alterations, the modified locomotive was a remarkable success once teething difficulties, principally with firebed instability, had been resolved. Originally chosen because it was the "black sheep" of the Beaconsfield fleet and a notoriously bad steamer, it became a star performer, capable of hauling 20 to 30% greater loads than its unmodified sisters, with consumption of coal and water reduced by 20% or more - improvements that were regarded by SAR officialdom (which had never officially sanctioned the changes) as "marginal" and therefore not worthy of attention, let alone replication.
Some of its crews could not accustom themselves to the operating methods that the locomotive required - in particular, maintaining a deep firebed, keeping the firedoor open at all times, and drifting in mid gear (with the throttle cracked open). However, those who were willing to adapt were unstinting in their praise - one writing to tell Wardale that "most agreed she was exceptionally strong and all agreed that she was exceptionally fast".
It is worth noting too that at 2644's first M-repair in May 1980 after it had covered 21,000 km, "there was no wear on the valve heads and rings and no carbon deposits on the port edges and very little carbon on the valve heads; the right hand piston showed no signs of wear and the left hand piston was 2mm, attributed to running with a faulty lubricator during early tests; wear and carbon formation on loco 2644 are absolutely minimal" [extract from The Red Devil and Other Tales from the Age of Steam page 127.]
Wardale largely lost touch with 2644 at the end of 1979 when approval came through for the modification of a 25NC to assess the improvements in performance and economy that might be achieved. The heavy workload involved in the redesign and overseeing the alterations to 25NC No 3450 (later to emerge as The Red Devil) meant that Wardale was unable to implement further improvements that might have made 2644 an even better machine.
2644 ended its working career at Mafeking in 1988 when it was purchased by the Railway Society of Southern Africa and moved to the South African National Railway and Steam Museum where photos of it were taken by Derek Walker in 2011 - see http://allatsea.co.za/blog/wardale.
It had been hoped that it would have been secure from the illegal cutting up of locomotives under SANRASM's care. Some reassurance on this was given by in a letter written by Mike Dyke, Chairman of the Executive Committee of South African National Railway and Steam Museum, saying that: “Our intention is to devote whatever (funds) remain available to the restoration of some of our more significant items – probably Wardale 2644 would be the first”. Sadly however, Mr Dyke's expectations were not to be realised: in April 2014 news has been circulated that thieves had cut her frames to steal her axleboxes and rendered the locomotive irreparable.