New IRM DL Class Hunslet diesel locomotives revealed

Following on from the success of its Mark 2 Enterprise coaches, the Accurascale IRM team started looking at what would pull them and felt that the Hunslets would make for an ideal model albeit there were only three of these locomotives and they are a little bit niche.

The sole survivor was scanned at the Ulster Folk and Transport Museum in Cultra, Co. Down, and research progressed at a rapid rate. With such swift progress made, the Accurascale IRM team has been able to get the Hunslets designed and tooled in record time and the first samples have been under test for several months.

With just a trio of locomotives and a small pool to choose from for variations, Accurascale IRM has decided to cover all major liveries for everyone in this first (and possibly only) production run.

Specification

• Die-cast metal chassis, with ABS plastic body. Weight (without decoder) 406g.
• Centrally mounted, twin flywheel 5-pole motor, driving both sets of axles, with all-wheel pickup
• Helical gearbox for maximum performance and slow-speed running
• Gearing arranged so locomotive can achieve a scale maximum top speed of 80 mph (128.75 km/h), with a load of 1.1kg
• Supplied as DCC Sound Ready, or DCC Sound fitted
• Scale length of 180.71mm over buffers
• Bogie wheelbase of 30.71mm (93.781mm between bogie centres), allowing operation over a minimum radius of 438mm (2nd radius set-track)
• Single style of 13.33mm solid locomotive wheel, correctly profiled both on the inside and outside to RP25-110 standard, set in blackened brass bearings or contact strips and chemically blackened, and conforming to Accurascale standards of 14.4mm back-to-back on 2mm diameter axles, over 28mm pinpoints (to allow for potential re-gauging to 21mm finescale standards).
• Brake blocks fitted and aligned with wheel centres for 00 gauge
• Fully detailed die-cast underframe with all cylinders, battery boxes, cabinets and piping applied separately
• NEM pockets at both ends, fitted via full kinetic couplings
• Eroded metal, plastic and wire detail parts, including (but not limited to) roof details, handrails, door handles, kick plates, lamp brackets, nameplates, brake gear, brake discs, draw gear, bogie chains, vents and louvres.
• Prism-free flush glazing.
• Easily removable roof section, to allow access to PCB for speaker and decoder fitting.
• Fitted stay-alive arrangement.
• Designed to work with the ESU LOKSOUND V5 21-PIN Decoder with easy access via removable roof panel. Blanking plate to carry switches for limited DC lighting options.
• Fully directional lighting, with full range of light options for day/night running and shunting/yard configurations
• Separate cab lighting configurations.
• Working DCC-operated roof fans (single fixed speed on DC)
• Supplied DCC Sound Ready, with fitted ESU 22mm x 42mm x 8.0mm rectangular 4Ω speaker and Passive Radiator.

Available to pre-order now via the IRM or Accurascale websites  and expected to arrive at the end of 2025, prices are £219.99 DC/DCC Ready and £319.99 DCC sound fitted.

About the prototype

Having undertaken a programme of station refurbishment, improved its ticketing arrangements and introduced new on-track plant and shunting locomotives, in 1969 the still embryonic Northern Ireland Railways set out to improve the Dublin-Belfast ‘Enterprise’ service, by replacing the existing diesel railcar sets with a locomotive hauled service. Intended to reduce the time for the 180 km journey to just two hours, the NIR Class 101 (DL) locomotives were designed to run in a push/pull configuration, with a 270-ton 8-car set of BR Mk.2b stock, at a maximum speed of 80mph.

When Mrs Joan Humphreys, wife of Northern Ireland Railways’ chairman Myles Humphreys, unveiled the nameplate of 101 Eagle on May 8, 1970, it was an astounding triumph for the Hunslet Engine Company of Leeds; having beaten off stern competition from the likes of General Motors in the United States for the contract, with the event marking the remarkable culmination of a ten-month delivery programme.

The pace of the delivery programme was dictated by NIR’s lack of diesel-electric stock to haul the Enterprise to the new timings; the British United Traction 700/900 Class and UTA Class 70 railcars not being up to the task in hand and while Hunslet had secured the order, the company’s workshops were already full, being committed to other orders. For Hunslet, the answer was to sub-contract out the manufacturing work, so having designed the superstructure and bogies, fabrication of the superstructure, along with the final assembly, testing and painting were contracted out to British Rail Engineering Limited at their Doncaster site.

Traction was trusted to English Electric/AEI Traction, who designed the English Electric 8CSVT Mk II design prime mover for the project, which essentially was an updated version of the Class 20's prime mover, fitted with an additional intercooler. Linked to a Bo-Bo bogie arrangement, this unit provided 1,350 hp (1,010 kW), of which 350hp was required for the Mk2’s heating system!

Completed on schedule, 101 Eagle was handed over to NIR on May 8, 1970, with 102 Falcon following on May 22 and 103 Merlin on June 8 and all three locomotives (on temporary bogies) were subsequently shipped to Belfast on the Ferry from Preston (probably on the MV Ionic Ferry) and on arrival were moved to Queens Road for the fitting of the 5’ 3" gauge wheelsets.

The Press Launch/Test Train took place on July 3, 1970, with 102 Falcon leading out to Dublin from Belfast’s Great Victoria station and 101 Eagle trailing, and aside from a few comments regarding ‘hunting’ due to the push locomotive, all went well.

The three locomotives alternated on the Enterprise and continued to do so until they were succeeded by the General Motors’ NIR Class 111 fleet in 1983. When not required for Enterprise services, the 101s would run as single engines on locomotive-hauled services such as the Saturday Excursion traffic to Portrush. This period also coincided with NIR being awarded the contract for the haulage of spoil from Magheramorne, to the Oil Terminal construction site at Cloghan Point (near Kilroot Power Station).

Between October 7, 1974, and August 22, 1975 these spoil trains were generally headed by one of the NIR 101 fleet, hauling the Cravens-built wagons from the steam-hauled spoil contract of the late 1960s.

Their ability to haul significant loads led to each locomotive being fitted with Multiple Unit cabling for Push/Pull working and after their replacement on the Enterprise, the three locomotives were moved to secondary services, such as to Derry and between Bangor and Portadown, along with working diagrams that included haulage of the CIÉ weed control train, freight turns with 42’ Fertiliser Flats and 40T Ballast Hoppers, as well as general shunting duties in Adelaide Yard.

All three locomotives were gradually withdrawn from service as mechanical woes set in, with 103 Merlin being first in 1989 and 102 Falcon last in 1998, although after having spent four years out of service Falcon was briefly re-instated as a working locomotive in 2002, before being placed back into storage at Whitehead. 103 Merlin was scrapped in 1997, but 101 Eagle and 102 Falcon remained at Whitehead for some time until being offered by Translink for sale.

Both locomotives were purchased by the Railway Preservation Society of Ireland (RPSI) in 2005, with Falcon being selected for full restoration, utilising parts from Eagle where possible. Unfortunately, despite getting tantalisingly close to restoration back into working order, the task proved too much, and 102 Falcon was sold to the Ulster Folk & Transport Museum at Cultra in 2011, where it now resides. 101 Eagle had become no more than a bare shell, as parts had been stripped from it and when no buyer for it could be found the remains succumbed to the cutter’s torch the previous year, in January 2010.

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