Building the new Gresley Class P2 No. 2007 Prince of Wales

The Gresley class P2 2-8-2 ‘Mikados’ were the most powerful express passenger locomotives to operate in the UK. They were designed by Sir Nigel Gresley to haul 600 ton trains on the arduous Edinburgh to Aberdeen route. Sadly, the design was never fully developed and they were rebuilt by his successor Edward Thompson into ungainly 4-6-2s in 1943/4, and scrapped by 1961.

As the builders of new main line steam locomotive No. 60163 Tornado, The A1 Steam Locomotive Trust has therefore decided to set itself a new challenge: to develop, build and operate an improved Gresley class P2 Mikado steam locomotive for main line and preserved railway use.

We will use the latest computer aided design and modelling techniques to realise the potential of the original design and estimate that No. 2007 Prince of Wales will cost around £5m to build over a 7-10 year period. The fundraising for the project got off to a racing start with the launch of The Founders Club in September 2013, beating its target by over 350% by the time it closed in July 2014. As with Tornado, funds will be raised for Prince of Wales through regular ‘a P2 for the price of a pint of beer a week’ donations from as little as £2.50 per week. In addition, specific workstreams for the new locomotive will be financed through The Boiler Club (to fund the construction of the boiler), The Mikado Motion (to fund forging and machining of the heavy motion) Club, The Cylinder Tender Club (recently launched to fund the construction the tender), Dedicated Donations (to fund specific components) and commercial sponsorship. The Founders Club (to get the project to the point of assembling the frames), The Mikado Club (to wheel the locomotive) and The Cylinder Club (to fund the design and manufacture the cylinder block) have all now closed having reached or exceeded their targets.

– Frames: engine’s frames erected; all frame stays, brackets, horn blocks, axle boxes & buffers cast and fitted; cab erected and cab side & spectacle window frames fitted; footplating & splasher kits fitted to frames
– Cylinders & valves: design studies into cylinder block manufacture and selection of valve gear complete; 3D CAD design of the cylinder block and valve gear substantially complete; weld details and assembly order being finalised.
– Smoke box & fittings: smokebox assembled and trial fitted to the frames; chimney fitted.
– Boiler: boiler design study completed; forged foundation ring corners manufactured & machined; regulator castings delivered; superheater header cast & machined; boiler cladding manufactured, trial fitted to frames and now in storage; boiler order placed with DB Meiningen for delivery in July 2021; foundation ring forgings and regulator castings despatched to Meiningen; the minor re-design of the banjo dome to suit the P2 cladding by has been completed by DB Meiningen; first firebox flange plates manufactured.
– Fittings: many non-ferrous fittings are being cast and machined.
– Brakes: work well advanced on manufacture of brake rigging.
– Spring gear well underway; spring hanger brackets complete; coupled spring links bolts and spring cups manufactured, procurement of springs underway.
– Wheelsets: study into ride & suspension completed using Vampireâ software; crank axle re-designed to comply with modern standards, approved and manufactured; all engine wheelsets complete and fitted to engine; balance weights being fitted.
– Motion: all heavy motion ordered from order with Stephenson Engineering Ltd of Atherton, Manchester; first 2 forgings completed – more underway.
– Valve gear: updated poppet valve gear design almost complete; components in manufacture.
– Pipework: design well advanced and installation under way.
– Electricals: significant progress on design and manufacture of electrical system; overall system architecture signed off; layout of electrical trunking almost complete; battery boxes approaching completion, belt driven tender alternator nearing completion; turbine wheel for steam turbo alternator manufactured.
– Tender: axlebox and other tender castings produced by William Cook Cast Products; frames being assembled by ID Howitt at Crofton; tank construction under way by North View Engineering Solutions in Darlington; wheelsets delivered to South Devon Railway Engineering for assembly and substantially complete.
– Finishing: nameplates and chime whistle delivered.
– Over £2.1m spent, £2.7m raised and £3.4m pledged of the required £5m.

Over the next 12 months, the Darlington based team aims to:
Complete the pony truck.
Make substantial progress on the tender tank and frames.
Finish the detailed design of the electrical system.
Manufacture and take delivery of most of the coupling and connecting rods.
Complete the cylinder block design with construction nearing completion.
Start manufacture of the valve gear.

History of the P2
Sir Nigel Gresley’s P2s were conceived to haul heavy trains over the Edinburgh to Aberdeen road. The original scheme combined the 2-8-2 wheel arrangement with an A3 boiler but this was subsequently worked up into a design with a longer firebox and double chimney. The 2-8-2s were the most powerful express passenger locomotives to run in Great Britain and their mechanical innovations were matched by their bold outward appearance. The doyen of the class, No. 2001 Cock o’ the North, was radically equipped with Lenz rotary valve gear, an ACFI feed water heater in place of injectors, a 50 sq. ft. fire-grate and streamlined steam passages to three cylinders which exhausted via a double Kylchap chimney. Gresley was greatly influenced by the work of the French engineer Andre Chapelon who had pioneered the use of these features and was determined to incorporate them in the P2s. Externally the design hid the tapered boiler in a parallel, elliptical cladding running from a V-fronted cab to a muscular, streamlined smoke-box (which incorporated integrated smoke deflectors), the whole affair sitting on a high running board which exposed the 6’2″ drivers entirely. The 220lb/sq in boiler fed three 21″ x 26″ cylinders and the locomotive developed a nominal tractive effort of 43,460lb. As a final touch Cock o’ the North was the first L.N.E.R. loco to carry a chime whistle.
The second member of the class, No. 2002 Earl Marischal, was fitted with Walschaerts valve gear and was equipped with additional smoke deflectors to compensate for the softer exhaust which resulted from its use. The final four members of this small class, No. 2003 Lord President, No. 2004 Mons Meg, No. 2005 Thane of Fife and No. 2006 Wolf of Badenoch, all appeared with an A4 front end coupled with the elliptical boiler cladding of the first two. Only No. 2001 was equipped with the feed water heater and this was removed when Nos. 2001 and 2002 were later rebuilt with the A4 nose.

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