Editing GNRI Class V (section)

==Design==
[[File:GNRI 85 Merlin (2).jpg|thumb|''Merlin'' at [[Inchicore Railway Works]]]]
The V class was intended for the GNR's most important passenger service, the [[Dublin]] – [[Belfast]] expresses. The [[GNRI Class S|S and S2 Classes]] that had previously served the route were giving trouble as boiler pressure had been raised to increase power and performance. This increased maintenance (particularly with broken crank axles) and as a result the boiler pressure was brought back down. This obliged the GNR to develop a more powerful engine.

George Glover designed the resultant 'V' class with on-site experience learnt from the design teams for the British [[LMS Compound 4-4-0]] compound locomotives.

[[File:GNRI 85 Merlin (Fabrikschild).jpg|thumb|''Merlin's'' [[builder's plate]]]]
The locomotives were ordered from [[Beyer, Peacock & Company]] and delivered in 1932. They cost £5,847, which was £3,000 less than the SG3 Class 0-6-0s built ten years before. Beyer, Peacock built only the locomotives; the GNR itself built the tenders at its works in [[Dundalk]].

The GNR named the locomotives after birds of prey: 83 ''Eagle'', 84 ''Falcon'', 85 ''Merlin'', 86 ''Peregrine'', and 87 ''Kestrel''. The V class were the first three-cylinder compound locomotives in Ireland. They had a round-topped firebox and [[Stephenson valve gear]] and weighed 103 tons 11 cwt including tender. The result was an engine that looked dramatically larger than their predecessor the S Class. This led to the unfounded rumour among railway workers that they had been designed for use in the USSR. As the GNR's only compound locomotives they were often called simply "The Compounds".

They were introduced for the accelerated Dublin – Belfast schedule, on which they reduced running times by up to 22 minutes. However, as for the S Class before them, the demanding timetable resulted in severe maintenance problems: hot axle boxes, connecting rod problems and boiler re-tubes. As a result, the boiler pressure was reduced by 50 [[Pounds per square inch|lb<sub>f</sub>/in<sup>2</sup>]],<ref name=Kelly/> reducing tractive effort by 20%.