V2 4771 green arrow to return?

I was fortunate enough to see her running in both BR green and LNER green and I think I prefer the BR livery. I might try and find photos later.

 

Is there not an element of confusion about the word 'fabricate' entering the discussion here? As I understand it, BR started replacing the monobloc castings on V2s with 3 separate cylinder castings which were then bolted together, and not, as I suspect some have concluded, by attempting to weld together large lumps of metal to form (fabricate) the cylinder assembly. (See the previous post about 76079). The stumbling block (no pun intended) to a swift overhaul of 4771/60800 after her last time in service was that it was believed that the monobloc was in need of replacement, and following BR practice & producing a replacement in 3 castings as opposed to one would not be acceptable to the Science Museum Group for reasons of originality, was it not?

 

Although on a much smaller scale than a V2 or P2, the L&B's 'Lyn' has fabricated cylinders.


Keith

 

As does “Beachy Head”, though it hasn’t run yet.

Tom

 

Thanks Tom - I knew there was a full size new build loco with fabricated cylinders, but somehow Beachy Head slipped my mind!

Keith

 

I may be wrong, but my understanding is that the intention with the P2 is to fabricate the entire monobloc of casting, comprising three
cylinders and valve chests in one lump. I do not believe that the intention is to build it up from castings, but rather to weld together steel components. The argument for not using separate castings, as performed by BR, is that presumably some frame aqnd somebox alterations would be needed and the appearance of the loco would be changed.

Beachy Head and Lyn, are not really relevant examples, they effectively have two separate outside cylinders so are not directly comparable. It will be interesting to see whether the A2's cylinders can be successfully fabricated, and equally whether the V2's cylinders could be repaired.

 

They were made 2008 - 2010. It’s an interesting thought, but conceivably if they were being done now, the poly pattern casting route would look attractive, but at the time plans were being worked out in 2006-7 ish, that was a much less obvious route and traditional wooden patterns looked very expensive. The Patriot I think was instrumental in demonstrating a really serious set of cylinders made by that pattern-making process, but that was after the cylinders for Beachy Head had been fabricated.

Obviously, whichever route is chosen, as standalone cylinders and separate valve chest, they are simpler than any potential route to the three cylinders with integral valve chests of a V2.

Some pictures here:
https://www.bluebell-railway.co.uk/bluebell/locos/atlantic/latest_08.html

https://www.bluebell-railway.co.uk/bluebell/locos/atlantic/latest_10.html


Tom

 

What's particularly good about this forum is people ready to pour scorn on a discussion, where, the points can be joined, and case made to restore the loco.

I personally find it incredible that many bodies do not use the historic factor to bid for money, and not the standard lottery stuff.

A huge fund that HAS to be spent before we leave Europe, is undersubscribed massively, that money will be given back.

heritage, restoration, tourists based operations, could have benefitted, but I doubt many have applied, looking at the applicants recently.

I am positive that on the back of job creation, heritage attraction, plenty of ££££ is still available for 4771 to be restored, people just need to look out of the box, on this one.

This is probably why I sit in my armchair, regarding steam, but raise the funds for another area.....

A £5m project we have on going, is going to be part funded through a series of connections, and funders, that the heritage movement could tap into.

 

Yes, but the solution to that has been mentioned more than once: make new cylinders (by whatever method seems best) and display the original monoblock.

 

Ahem.

 

Totally agree - but as I recall that wasn't acceptable to the SMG at the time.

 

SMG ? small minded gets ?.... oh of course Science Museums Group

 

Still only a single cylinder and valve chest, though, isn't it?

 

Announcement ref new V4 - she will have a fabricated 3 cyl monobloc with piston valves and conjugated gear - sound familiar ? https://www.a1steam.com/category/news/

 

A1st already partner Gresley Society so why not with the NRM V2 support group who could raise the required funding ?

 

One thing I found interesting and somewhat surprising, is that the N2 1744 has the same size driving wheels [5'8"] as 3403. With both the Gresley Society and A1SLT, I take it, splitting the costs of having a pattern and new wheels produced.

 

Welded cylinders been recently produced for the new build Baldwin for the Lynton & Barnstable.

To get the new build to haul half as much again and making it within the original outline meant quite a number of enhancements:
gas producer firebox, superheater, much higher boiler pressure, piston valves, internal streamlining, and an improved exhaust.
To realise the passages in welded cylinders took a lot of intricate work - little fillets welded in to mitigate what otherwise be right angled corners in the steam passages to the cylinder ends - both in terms of careful thought that it could be welded together and a great deal of really skilled work to ensure it actually was. The extensive series of drawings to prove the sequence of what the pieces were to weld and tactfully provide a step by step guide to the assembly is one of the remarkable things I have seen in years. When it was all welded up it was heat treated to let any welding stresses out and seems to have run fine. It may be too early for it to have done a lot of running and it could probably benefit form some tuning up yet but there is no reason to doubt that welded cylinders ore seviceable - they have been extensively used abroad.

It does however make me wonder about the relative costs of cast and welded cylinders. I suspect that that to compare identical cylinder designs made
in the two different ways might not be straight forward, as to get the best result you would i end up with two different layouts - one to suit casting and one to suit welding, each would have its different strengths. My first thought would be that casting should give you smoother curves and better steam flow.

 

This is the kind of thing that would be perfect for SLM 3D printing. I doubt anyone has made a printer that big yet tho.

As for fabricated cylinders, a post weld heat treat would be wise. 600c or so for 5/6 hours should be sufficient. Exact values depend on the filler and base metal used.

Heat blankets or the use of a foundry's oven are two options.

They will move and distort by the nature of the manufacturing process, so those residual stresses will be looking for a way out.

 

In former East Germany many locomotives were overhauled and in some cases replaced by newbuilds using all welded cylinders. E.g. metre gauge Harz 2-10-2 and 900 mm Molli in Bad Doberan 2-8-2.
But in the latest new build for the Molli line 99-2324 ten years ago, I think Meiningen still just used old DR drawings and the outcome was very far from streamlined. The picture below is from the indicator runs for the loco. You may see the welds for the steam channels between the valves and cylinder running straight down from the indicator connections and then horizontally to the cylinder ends. Not "modern steam" directly...

 

They kept this quiet......

https://www.world-of-railways.co.uk/news/green-arrow-latest-locomotive-at-new-doncaster-gallery/

So not the expected "other" exhibit after all..........