Important cylinder and bearing refurbishment work on Britain's most treasured steam locomotive, 'Flying Scotsman', was completed recently with help from a UK-based engineering company, itself steeped in tradition. Corus Process Engineering (CPE), part of Corus Group, carried out critical precision machining work on engine cylinders and axle box bearings for The National Railway Museum (NRM), owners of the famous steam locomotive since 2004. 'Flying Scotsman' is currently in the National Railway Museum workshops at York undergoing important refurbishment work as part of its seven-year overhaul.
The locomotive has been withdrawn from service, as the current period of certification, which legally allows it to run on the main line, has expired.
It is now being completely dismantled and overhauled in order to re-certify it for the next 10 years.
By late 2007, this process should be completed.
Although much of the refurbishment work is taking place at York, various components need to be sent to specialist engineering companies all over the UK.
'Flying Scotsman' is a three-cylinder steam locomotive.
The machining work undertaken by CNES involved precision machining the face of the right hand outside cylinder, which weighs around 1.5 tonnes, with a cylinder bore diameter of 19in and a piston stroke of 26in.
Rod Lytton, chief engineer at the National Railway Museum commented: 'Since December 31st 2006, the locomotive has been out of service.
We've been stripping it down since then and refurbishing parts as required.
Whilst dismantling the engine, it was confirmed to us that the right hand side outside cylinder had a crack from end-to-end.
We had a spare cylinder, but the large face, which bolts onto the main frame of the engine, was pitted with rust, as it had been 40 years since the spare cylinder was removed from a locomotive.
So we looked for an engineering company who had the capability to precision machine the cylinder face.
A minimum amount of metal was to be machined away, 2mm as it turned out, so that a standard size of steel shim could be manufactured to maintain the centre distance from the cylinder to the engine frame.
Corus [CPE] at Workington had the necessary machining facilities to undertake the work and made life easier for us by ensuring that all we had to do was get a standard size steel shim manufactured,' added Lytton.
More refurbishment work was required on 'Flying Scotsman's' bogie frame, situated at the front end of the locomotive.
The four small bogie wheels are located in front of the main driving wheels and their purpose is to guide and take the weight of the train while pulling it around curves in the track.
There are eight 'horn faces' in total, four per axle on the bogie, each made from steel, and all lying parallel to each other.
These faces guide four plain bearing axle boxes, which should all be correctly aligned.
However, as Lytton explained: 'By manually inspecting the dismantled bogie frame, we discovered some discrepancies with the alignment of the axle box bearings'.
'You could actually see the misalignment with the naked eye.
One of these bearings, which are made from bronze lined with white metal, had been running hot during trips we made from York to Scarborough whilst the train was still in service, so we suspected there was some misalignment there.' The bearing faces were precision machined at CPE's Workington site.
All eight bearing faces, the axle centre lines are eight feet apart, had to be machined on the same machine setting to restore the alignment.
Marketing manager at CPE David Scatchard said: 'We were fortunate that we had just the machine to help with the project.
The one we used was a planer that was large enough to take the whole frame and with a small enough universal milling head to get between the axle box faces.
The cylinder block was machined on the same machine, but we were able to use a much larger cutter.' He concluded: 'Everyone in the organisation can relate to such a prestigious project and it is great to be able to keep part of our national heritage in full working order.
We look forward to seeing 'Flying Scotsman' back in steam.' * Editor's note - the' Flying Scotsman' express passenger locomotive, built for the London and North Eastern Railway in 1923 from a design by the late Sir Nigel Gresley, once was a member of a series of 78 similar, coal-fired steam locomotives.
The first two were built in 1922 under the then Great Northern Railway, and all were rebuilt from 1927 onwards with higher pressure boilers.
'Flying Scotsman was recorded officially as the UK's first steam locomotive to pass the 100 miles/h 'barrier' in the early 1930s.
A fellow member of the series, 'Papyrus', reached 108 miles/h.
Named mostly after English horserace winners, they had the 4-6-2 (or 231 or 2C1) wheel arrangement and an indicated horsepower output of around 2000HP.
'Flying Scotsman' was sold out of service in 1963 by British Railways, which retired the last member of the series - based in Edinburgh - around 1966 or so.
