The Iarnród Éireann (IÉ) / Northern Ireland Railways 201 Class locomotives are the newest and most powerful diesel locomotives operating in Ireland and were built between 1994 and 1995 by General Motors Diesel. They are model type JT42HCW, fitted with an EMD 12-710G3B engine of , weigh and have a maximum speed of . A freight version, the EMD Series 66, with the same engine, is used on privately operated European mainline freight duties. History By the early 1990s, the locomotives operating passenger services in Ireland were becoming increasingly obsolete, with the newest type in service being the 071 Class introduced in 1976. The economic boom in Ireland in the mid-1990s allowed Iarnród Éireann to begin significant investment in the infrastructure of the railways, which began with an order for 32 brand new express locomotives from GM-EMD. Northern Ireland Railways also purchased 2. The first were delivered in 1994, with deliveries continuing until 1995. To allow clearance tests and driver training to commence in advance of the delivery of the main order of 201s, it was decided to transport the first locomotive, number 201, to Dublin by air. An Antonov An-124 was used to transport the locomotive from London, Ontario to Dublin Airport, arriving on Thursday 9 June 1994. The first light-engine test run operated from Inchicore works to Kildare on the Tuesday 14. Unfortunately, the locomotives have had a chequered service history. The authors of Jane's Train Recognition Guide noted that IÉ had had problems with engine fires and bogie cracks. Technical details Main Generator Assembly: AR8PHEH/CA6 Head End Alternator (HEP): Dayton-Phoenix, model E7145, 438 kVA, 220/380VAC, 3-phase, 50 Hz Standby HEP: 220 kVA from AR8, available only when stationary Auxiliary Generator: 5A-8147, Air Compressor/Exhauster: Gardner Denver, model WLPA9B Multiple Working: All IÉ & NIR EMD locos Push Pull Working: Locos 206-209 & 215-234 Curve Negotiation Capability: Yard: Running line: Coupled to train: Equipment new to IÉ locos Air Dryer Teloc 2200 Event Recorder Electrically heated windscreens Active noise control in both cabs Enclosed body style, last seen on 1950s Metro-Vic A and C Classes Head End Power (HEP) This system supplied AC power to the train for heating, battery charging, etc. and was intended to replace the Mark 2 & Mark 3 Generator Vans used at the time. In the event HEP was only used on the Enterprise cross-border De Dietrich service. HEP is no longer used due