Current and Proposed New-Builds

Similar but not the same...

The barrel is almost the same size at 14ft 10ins long with an extra 3 inches on the max diameter for the 47 (6ft vs 5ft 9). The tube layout is different as well. According to the RCTS the firebox was the same at 10ft.

The end result is a grate of effectively the same size at 30 and a bit square ft with the total heating area at 2556 square feet on the 47 and 2312 for the castle.

The no7 boiler was always held in high regard by the crews and at least one Old Oak fireman that I spoke to maintained that the 47 would do anything a castle could and burn less coal in the process. He was in a position to know but I guess time will tell.

The newsletter announcing the change in cylinder plans implies that the new boiler will be mounted 2 inches lower so as to comply with the current NR limits. This allows for correct size boiler mountings. The new cylinder blocks have therefore been designed to suit.

 

It would still require the chimney and safety valve to be cut down, plus a bit trimming off the cab roof. I must say that I'm a bit confused as to the motive, as the GWS have widely announced that they have finished with mainline running, and any issues with getting it in and out of Didcot would apply equally to 6023.

Dropping a boiler down a couple of inches may seem inconsequential, but it can create all sorts of unforeseen problems.

 

I suspect that the decision to abandon any plans for mainline running was made after the cylinder block design had been completed.

 

That wouldn't suggest the greatest level of joined-up thinking, as the decision on whether to continue with mainline running had been under discussion by the GWS board, senior management team and locomotive committee for some time. Maybe I'm reading between the lines too much, but I get the impression from the group's website that the plan is still to run it on the mainline. It would just be nice to have some clarification.

The section of the cylinder block which has been reduced is probably the most 'simple' part of the casting. Even if it required redoing the finite element analysis, adjusting the CAD drawing or polystyrene pattern would be a small price to pay for avoiding the countless issues which could otherwise occur. Hopefully Bob Meanley will be providing the guiding hand of experience, as I believe he has some involvement.

 

I'm suddenly tempted to paint a 4MT tank in blue... A 00 gauge one, anyway, so that there's fewer people after my head!

 

Don't they need to get it across now-electrified NR lines to get to/from didcot? height is going to be pretty key under those circumstances, even if it's not going to run on the mainline. Also, it's a pretty big casting, so if you can make it NR-compliant, it avoids shutting doors on what is a very rarely-replaced component.

 

THey should think about doing a new city of Truro so we can still see one running. I’m surprised no one builds old style locos as well as modern ones

 

Well, there's a dozen or so replicas of very early (pre 1840s ish) locos; there's the NER G5 (to a design dating from 1894); the Saint (first one built 1902); the LBSCR H2 (first built 1910). Even the loco in question (47xx) is over 100 years old in design.

Tom

 

I was thinking like the dean single one that Hornsby do and is at windsor

 

4709: l just think spending an extra £500,000? , substantially delaying completion of the project and minimising the Swindon content is a wrong turn.
:

 

I'd far rather have a Dean Single instead of a County, Grange and 47xx, all of which are extremely similar to existing locos not really filling any major gaps in locomotive development. There's not many places where a big single driver locomotive is very practical though, although Didcot could probably have been one. The fact is though, the people who actually go out and do all the hard work rather than pontificate on the internet chose those designs, and are getting on with them, and there's only so much that can be done. If it were my decision, I'd have built something different, but it wasn't so I'm not.

 

The thing is that these new-build projects, regardless of the age of the original incarnation of the locomotive, is something that has some use to the heritage railway industry - with enough tractive effort to haul trains that could be expected for its size. A larger locomotive is likely to be more costly to build and maintain, but by hauling more it could theoretically bring in more income to fund said maintenance.

A small G5 won't be expected to haul too much, but has comparible tractive effort to a 2MT and should be quite capable of most loads demanded of it. Something larger, like the 47xx, could haul particularly heavy trains on more demanding lines.

A Dean Single, however, does not have a lot of tractive effort for its size.

 

Yes it will need to fit under the wires, the question is whether you permanently cut it down for the sake of an occasional ten minute trip behind a 66, or just accept the faff of taking the full size fittings off every now and then. These same issues are going to affect 4079 and 6023. Regarding the cylinders, yes I get where you're coming from, but I think sometimes you just need to accept that a door has permanently closed, and move on. Believe me, there has been more than enough straw-clutching at Didcot with regards to mainline running!

 

It's a valid argument - and one reason for the original plan to make use of the available no1 boiler. But for the reasons already explained the decision has been taken to 'go the whole hog' and build a no 7.

To my mind a 47 with a no1 boiler is not a real 47 so it's a decision I personally applaud. Yes, I know the prototype ran in that condition briefly but the class established its reputation as GJC's masterpiece in the no7 form and that is the way 4709 should be.

Stand by for the heated and well worn debate on that masterpiece statement!!

M

 

I too would love to see a Dean Single. Perhaps on the Worth Valley. Or Foxfield,

 

Why not the SMR? I gather they are quite keen on new-build

 

Erm, a big single driver locomotive does actually exist and it's at Didcot..........

Here seen on demo in Londinium.....




Cheerz,

Alan

 

Another one on the way at Tyseley if they ever get it finished - that one has the advantage of not being saddled with "Gas Works" parentage - tin hat fixed, now running for cover!


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The GW mafia will be after you now. Watch your back after the lockdown is over...they have long memories!

 

No worries they've been doing that for years with some of my favorite railway jokes usually heading in that GW direction, although my favorite was coined by a fellow former band member and long running editor of one of the railway mags:

"If they'd looked after their staff they could of (have) had a Duchess!"


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