New builds missing a trick?

[S.A.C. Martin]

In short - how much of Tornado's genealogy, applied to a new build P2 (2007 & 2001), is also potentially applicable to a Thompson A2/2?

Further, how much of that needing to be made for a P2 can also be applied to an A2/2?

I'm curious as it strikes me that potentially the A1SLT and DP2LT could help kill three birds with one stone and fill a significant gap in the history of the ECML, if a third group could be found that wanted to build a lone Thompson Pacific; to complete the lineup of the designers and their Pacific wheelbase charges.

The supreme advantage would be ordering in triplicate any components common to all three builds - bringing the price down per item further than simply doubling the order, as has been suggested previously.

Of course the stumbling block would be interest in yet another new build locomotive (and particularly a Thompson machine), and perhaps spreading the money across three locomotive builds, all substantial locomotives and costs probably around, but not limited to, £3 million each; but the possibility of this particular design, derived from the original P2s, of which two replicas in varying forms may or may not be built in the future, being built, intrigues.

It's more a hypothetical "what would be possible" than a call to arms, "let's go build an A2/2", but I wonder if the possibility of filling that final gap (bar the Raven Pacifics, of course) would garner interest.

From what limited information I can garner, and understand, behind the leading set of drivers on a P2, the frames are identical between A2/2 and P2, with the change being the driving wheels, and the front frames ahead (where of course a new set to accommodate a four wheel bogie and divided drive plus three cylinders was welded on). The boiler was a few inches shorter on the A2/2 and also had its pressure reduced to 225lb from 250lb. Everything beyond that point backwards towards the tender remained the same (i.e. the cab and its layout and the cartazzi arrangement).

Of course the possibility of improving the Thompson design, and eradicating the main sources of trouble - the separate cylinder blocks (necessary in wartime conditions) and doing a "Tornado" in terms of roller bearing axleboxes throughout, and various other modern day accoutrements is again, an intriguing thought.

As I say, don't take this as "I want to build an A2/2" more as a hypothetical pondering on a wet Sunday afternoon!

[52D]

I like the cut of your jib Sir, but i must point out that the Raven Pacific was like an evolutionary dead end and a far better scheme would be to recreate an NER Atlantic.

[Atlantic 3279]

Where did Raven come into the discussion

[Solario]

I would far rather see money raised to sort out Green Arrow's cylinder block problem or, maybe even better, a new V2.

I do take the point that there would not be so many components on a V2 that would be interchangeable with a P2 but I guess that the wheel sets would be. Would the cylinder block be interchangeable? I can't remember if the P2s had monoblock castings.

[S.A.C. Martin]

Where did Raven come into the discussion

I was just thinking that myself

[S.A.C. Martin]

I would far rather see money raised to sort out Green Arrow's cylinder block problem or, maybe even better, a new V2.

That wasn't my question

The question was pretty much, what is possible in terms of components being similar, A2/2 to P2, i.e. what is the same and could be used for both?

I do take the point that there would not be so many components on a V2 that would be interchangeable with a P2 but I guess that the wheel sets would be. Would the cylinder block be interchangeable? I can't remember if the P2s had monoblock castings.

I think the P2 did have a monoblock casting, not 100% sure mind.

[Hucknall Central]

I'm a Great Central man myself, but could 52D be confusing his A2s

[Katier]

I'm a Great Central man myself, but could 52D be confusing his A2s

I suspect your right, although as a NER modeller I think the A2 (Raven) would be a lovely loco (cos she looks nice ) to add to the 'new build' collection.. obviously off topic for this discussion though.

[Blink Bonny]

Hmm.

The boiler would be interchangeable between a P2 and A1 plus the tenders and carrying wheels but I'd have thought that that was it as regards major components. After all, the driving wheel diameter, cylinder arrangement and valve gear are all rather different.

Still, provided it has an open front, that'll do me!

[S.A.C. Martin]

I'm not sure anyone has addressed the question I was asking. If they're building two P2s, how much can be used in those builds that would also be applicable to an A2/2...?

I probably should have posted the above instead!

[Steve05]

Hi,

Cock of the North was made with a monobloc casting. I don't know about the others.

Regards


Steve

[Blink Bonny]

I'm not sure anyone has addressed the question I was asking. If they're building two P2s, how much can be used in those builds that would also be applicable to an A2/2...?

I probably should have posted the above instead!

OIC

Again, not much. The driving wheel castings, carrying wheels, tender and boiler but that would be about it. Remember that Thompson like divided drive and equal length connecting rods so much of the valve gear would be of no use, other than the connecting rods and possibly the expansion link brackets.

It's an interesting thought.

[Coboman]

Why anybody would want to even think about building an ungainly, ugly, frame bending, mediocre pacific as an A2/2 is a mystery to me....

[S.A.C. Martin]

Why anybody would want to even think about building an ungainly, ugly, frame bending, mediocre pacific as an A2/2 is a mystery to me....

It was a thought based on the idea that we could fill the final gap, and also show development of a locomotive design through three locomotive designers. Gresley (P2), Thompson (P2 to A2/2), and Peppercorn A1 (used the P2 boiler and divided drive of the A2/2 but with refined cylinder and coupling rod length).

Kill two birds with one stone, if you will.

[Blink Bonny]

Could be a winner, if only to sort out the myths surrounding Thompson's Pacifics.