7027 Thornbury Castle

And a new superheater header, which is a complicated casting.

Reslistically, it would be feasible if all those items needed replacement anyway, but very expensive otherwise. (Or more correctly - very expensive regardless, but at least if all three were worn out you wouldn’t be introducing u necessary expense).

Tom

 

Are they putting longer elements in? Swindon had a habit of reducing the length of the elements over the years. They also played about with the number of tubes in the elements (or are they called 'fingers', or some such?). I don't have the figures to hand, but if I'm not mistaken, the superheater area of an early two-row Saint wasn't far off that of a three-row Modified Hall. It would be interesting to compare an original 1923 Castle boiler with a 1950's one.

 

Yeah, but with a bag check on the way in, and on the way out...

 

Too much superheat can carbonise the cylinder oil, leading to greater cylinder/piston wear. Churchward was conservative with superheat because the cylinder oil at the time was of poorer quality. As the quality of cylinder oil improved as a result of improved refining, the degree of superheat could be increased by increasing the number of flue tubes. Shortening the elements was a way of moderating the degree of superheat - a four row superheater with shorter elements would not have had twice the superheat of a two row but it would have had more. Superheating would also have been increased to compensate for inferior fuel after WW2.

 

NOT an area of any particular expertise on my part, but ..... are we speaking here of an inherent limitation of mineral oils generally? Synthesised hydrocarbon lubricants have been on the market for half a century, to my certain knowledge. The advantage of these (rather more expensive) options is that their properties are designed to remain consistent over their operating range. Is this a quality which would negate (at least the bulk of) carbonised deposits?

I suppose it's only just over an Etruscan century since superheating came in. Can't expect things to change overnight, eh?

 

Any cylinder oil, synthesised or not, would have a temperature limit. While this limit has increased with time, going above that limit would lead to more cylinder/piston wear. Carbonised oil does not lubricate.

 

Accept that, though the properties of (certainly Mobil's) synthesised offering retained it's properties over a far wider temperature range (especially the upper limit). This was a product originally developed for performance vehicles to overcome issues inherent to mineral oils.

As to steam locos spefifically, does any of the work from L.D.Porta, Phil Girdlestone or Martyn Bane address this issue?

 

In fairness, half a century ago takes us back to the early 1970s - just a tad too late for BR steam!

 

Porta started work on advanced cylinder tribology in 1957. The rubbing surface temperature rather than the steam temperature was the most important factor with oil being admitted directly to the liner surface or surfaces.

With a superheated steam temperature of 450 degrees celsius liners cooled to 325 degrees celsius in the cooled zone gave satisfactory results (D. W.)

So work has been going on for quite a long time.

 

Here are two statements from a letter from Richard Croucher. They are interesting and seem significant, but beyond that I pass them on without further comment.
(Building a new No. 7 boiler from scratch) "is feasible although it will have to be scaled down to the No. 8 boiler dimensions to fit within the current loading gauge".
"We have discussed at length our proposal with the vendor and despite the emotional reaction in some quarters they wish the No. 8 boiler from 7027 to be used for 4709 although we have agreed to take a pause in the transaction for six months."

 

Interesting comments. I assume 'current loading gauge' is a reference to NR? I wasn't aware mainlining was an option. Re: No.7 boiler specifically, was this loading gauge issue already known to be the case?

 

The vendor wants the boiler to be used for 4709. What?

The amount of nonsense around the Thornbury Castle saga continues apace in Steam Railway I see today, where every letter printed is one carefully selected to condemn the loco out of hand. I even read one which states, and I quote:

When was this "open bidding" process? Where was 7027 advertised for sale? What magazine, what website, where?

Is there any evidence that this actually happened? Because from where I am sitting, there was - absolutely - no bidding process whatsoever, no advertisement that the locomotive was for sale, just a single cryptic message on Rail Advent and then a report it was not for sale, and then suddenly it had been sold.

I am all for publishing letters but there is no correction in Steam Railway Magazine to indicate that this isn't true. Unless we were all under a rock and we had a group hallucination/coma/whatever, there was no open bidding process for Thornbury Castle at all. I object to that disingenuous suggestion that it was.

 

There was articles in some of the railway magazines saying that they were reviewing the collection etc and it was potentially up for grabs.

No doubt the purchaser saw that and moved in swiftly with an offer. It is unlikely in these situations that there will ever be a formal advert. What did you expect that it would be announced on the 6pm news that it was for sale ?

Likewise potentially it is now available again for 6 months but you need to follow the grapevine not wait until some official advert.

 

I would hope that the GWS, will be putting out a correction, explaining that Mr, Croucher's statement does not in any way reflect the situation as the committee of the GWS sees it, that as far as they are concerned, the entire engine is for sale, and that any statement put out by Mr Croucher, is his, and not that of the GWS.

 

It's unclear to me who the "vendor" mentioned in the letter from Mr Croucher is. GWS, 4709 group, Mr Croucher or Mr Gregory? If it's Mike Gregory that would suggest that the original sale hasn't been completed yet, and stipulating how the boiler is used would be a very strange condition to impose?
The whole thing appears to be an utter mess, and nobody emerges with any credit.

 

Its odd, because I am not aware of any dimension of a 47 boiler that is larger than that of a King boiler, so its not immediately apparent to me why the Std 7 presents a greater gauging problem than the King. I haven't seen all the drawings of course, so its entirely possible there's a factor I'm unaware of.

 

As the boiler itself comes nowhere near the loading gauge envelope that statement is open to being challenged.

Wasn't the centre line of the boiler lowered by a couple of inches when the proposal was to build a new No 7 boiler in order to overcome this?

The chimney, safety valve & cab as per the GW design may well be foul of the loading gauge for NR. But as this loco, under the aegis of the GWS, is hardly likely to ever operate on NR surely this is academic. That is of course unless it is to be bastardised simply to traverse the few hundred yards between the road loading point & Didcot Railway Centre. The logic looks flimsy.

 

They're trying to justify the use of Thornbury's boiler, by constructing a narrative that they can't use a No.7. What that statement is really saying, is 'why build a brand-new no.8 boiler, when we can just use Thornbury's?'

It has nothing to do with the loading gauge. The real reason they want to use Thornbury's No.8 boiler, is because there isn't enough interest to finance a No.7 in a reasonable timescale.

This kind of manipulation has been going on for years. I'm reminded of the time one of Mr C's cronies stood up at an AGM, and stated that the drive for using the Barry 10 to rebuild extinct classes, came from Vale of Glamorgan Council. Not from a group of GWS members, oh no. It was Vale of Glamorgan Council who wanted them to be used this way. The way it was presented was almost as if the GWS were doing the council a favour.

 

So what you end up with is the equivalent of a reengined heritage diesel.

It might look like a............

But how it sounds/performs etc isnt what it should be

 

To be fair there is an awful lot more to modern gauging than the simple cross section profile. But having said that I would like to hear why the Std 7 is a greater challenge than a King boiler, and indeed why the relatively minor differences between Std 7 and Std 8 - basically just the barrel - make a difference.