GNRI Class V

Great Northern Railway (Ireland) class V
85 Merlin approaches Peter's Bridge, Co. Down on 18 June 2004
Type and origin Power type Steam Designer George T Glover Builder Beyer, Peacock & Co. Order number 1524 Serial number 6731–6735 Build date 1932 Total produced 5
Specifications Configuration: ​  • Whyte 4-4-0  • UIC 2′B h3v Gauge 5 ft 3 in (1,600 mm) Driver dia. 6 ft 7 in (2.007 m) Total weight 103 long tons 11 cwt (232,000 lb or 105.2 t) Boiler pressure 250 psi (1.72 MPa), later 215 psi (1.48 MPa) Cylinders Three – 1 HP (inside) and 2 LP (outside) High-pressure cylinder 17 1⁄4 in × 26 in (438 mm × 660 mm) Low-pressure cylinder 19 in × 26 in (483 mm × 660 mm) Valve gear Stephenson
Performance figures Tractive effort 23,762 lbf (105.70 kN),br.later 20,435 lbf (90.90 kN)
Career Operators Great Northern Railway (Ireland) Ulster Transport Authority CIÉ Class V Numbers 83–87 Nicknames Pounders; Compounds Preserved No. 85 Merlin Disposition One preserved, four scrapped.

The Great Northern Railway (Ireland) V class steam locomotives were 4-4-0 three-cylinder compound locomotives built in 1932 by Beyer, Peacock and Company.

The V class was intended for the GNR's most important passenger service, the Dublin – Belfast expresses. The 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 T Glover designed the resultant ‘V’ class with on-site experience learnt from the design teams for the British LMS compounds.

The locomotives were ordered from Beyer, Peacock and delivered in 1932. They cost £5,847 (about £2million in 2011 ), 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 lb_f/in², reducing tractive effort by 20%.

No. 87 Kestrel was the first to be rebuilt in 1946 and was the first GNR loco to receive a Harland and Wolff-built square topped Belpaire firebox. Merlin had one fitted in 1950 with its old boiler rebuilt as a spare.