66xx no.6695

Isn't it very rare that we get to hear what the designers were thinking? What we do know is, like a number of other designs, the 56 was very much an update of an existing design rather than a clean sheet of paper. It was based around Rhymney Railway 0-6-2Ts, but updated with GWR boiler and fitting, piston valves and an all new valve gear design and GWR standard wheels etc. There was a glitch in the early days though. The RR locomotives had a longer wheelbase (7'3" + 8'0") than most other Welsh 0-6-2T classes and as a result they were given a generous amount of side play in the wheels. Enough, in fact, that some even had a vertical joint in the coupling rods. The first 56s, however, it seems were turned out with standard GWR clearances, and the result, we are told, was a rash of axlebox trouble.

 

How can you argue that it was based on a Rhymney Railway loco when it had a different boiler, fittings, cylinders , motion, axleboxes and wheels and, by inference, different frames. About the only similarity was that it was an 0-6-2 and used coal as a fuel.

 

Oh I think perhaps a little more similarity than that. Here is the R Class post WW1, the R class as reboilered by GWR, and the 56xx. I don't find it hard to see a family resemblance. In particular the wheelbase was identical, and quite different to other Welsh 0-6-sTs like the Barry Class B which is the 4th image.

 

The second and third pictures make an especially interesting comparison, the Swindon boiler on the Rhymney loco having a significantly shorter smokebox than the one on the 5600.

 

Obviously had grandfather rights for non-compliance with GWR ergonomic standards.

 

I am always careful when commenting on GWR locos having not been issued with
the requisite rose coloured spectacles

My understanding is the 56xx were designed in a hurry to meet an urgent need;
200 built within 2 years. No more, often attributed to the success of the 57xx 0-6-0 PTs
which could navigate tighter curves than the 56xx. ( which if true rather negates the
requirement for a more powerful loco design )

The 56xx design was essentially a Rhymney Railway Class A and R with a standard
GWR No.2 boiler. Although the intent I believe was for all the more modern Rhymney
0-6-2s to be given the No.2 boiler when replacement due, in practice only three were so
treated. Despite that one Rhymney loco had had an extensive rebuild at Swindon.
Twenty six Rhymney locos were subsequently rebuilt with the Standard No.10 which
had a barrel length of 10’3” and firebox length of 6’ 0”compared with No. 2, 11’ 0” and 7’0”

(The respective grate and heating surface areas reflected the smaller boiler, Also as a note
Taff Vale 0-6-2 tanks were rebuilt with Standard No.3, which had a 10’3”” long barrel aligned
with a 7’0”” long firebox. )

The 56xx had a poor reputation wrt rough riding and were hard on the track. I doubt the
difficulty of removing ash from the firebox was of major concern in 1926. The weight
distribution was poor ( if memory correct ) and very high on the rear coupled wheels, they
were red route restricted.

With hindsight it seems Swindon was in too much of a hurry to withdraw and replace many former
South Wales Railway Companies’ locos. More time in the design office might have produced a better
piece of kit. But the 56xx had a long and useful life.

Regarding why not a 2-6-2 ? The 0-6-2 configuration had evolved, was considered good and
appropriate to ‘Valleys’ operations on the curves and heavy gradients.

Michael Rowe

 

Well, I've studied your drawings and I'm still inclined to the view that a Rhymney class R and a 56XX are hardly similar, except in wheel arrangement and wheelbase. in fact, apart from the wheels and, I assume cylinders and valve gear, I can't see much in common between the Rhymney loco and its rebuilt and reboilered version. Not even sure if the frameplates were retained.

 

I don't think the Std No 10 boiler was introduced until 1930, for the 2251 class 0-6-0. But the Std No 3 already existed in 1924 (introduced by Churchward for the 36XX 2-4-2T) and would seem to have been an option for Collett when the 56XX was designed. The 9-inch shorter barrel could have slightly eased the 56XX smokebox cleaning issue and reduced weight at the front end, although possibly not by enough to avoid the Red route restriction.

 

Agreed, hence my comments “ more time in the design office “. The No.3 is in effect I think a No.2 with
a shorter barrel but incorporating the No.2 firebox. ( both 36xx and some 33xx )

Michael Rowe.

 

I have read somewhere, unfortunately I can't find the reference, that after the grouping Swindon sent it's inspectors to survey the loco stock of the Welsh railways and there were adverse reports about the condition , particularly of the boilers. Some rapid action was required and it made more sense to built something that sort of fitted into the GWR standard range of locos rather than spend a lot of time and money overhauling a range of designs that were for practical purposes worn out. Given some of the features of the 56xx class it looks to me as if the Swindon design office held some sort of a grudge against the Welsh enginemen and fitters!

 

My understanding is that the Rhymney was an exception when it came to Swindon's opinion of Welsh maintenance. The RR's works at Caerphilly were expanded and became one of the major factories.

The later RR locomotive designs were a distinct family, with about 9 classes (roughly speaking - there was overlap and some conversions from one class to another) that can be divided into four groups, all with the same wheelbases:
0-6-0Ts with 4'4.5 in wheels
0-6-2Ts with 4'4.5 in driving wheels and smaller size boiler
0-6-2Ts with 5'0 driving wheels and smaller size boiler
0-6-2Ts with 4'6 wheels and larger size boiler.

When given GWR boilers the larger boiler types got Std 2s and the rest Std 10s. The Std 10 boiler was developed for absorbed classes, along with the Std 9 and Std 11. They were all variations on existing Std boilers, with longer or shorter barrels and/or fireboxes. The RR had had quite a bit of trouble with boiler design before WW1, and many of their boilers were relatively new at the grouping , so my assumption is that they were able to keep enough boilers in good condition cheaply enough that there was no need to convert the whole fleet. I don't know what operational requirements brought a need for both 4.'4.5 wheels and smaller boiler 0-6-2Ts versus 4'6 wheels and larger boilered ones.

 

At the risk of being a pedant.

The Nos 9 & 11 were standard domed ( not taper) boilers, with a 4 ft 5 inch diameter barrel, grate area 19.7sq.ft
I think solely as replacements in South Wales and unique.

Michael Rowe

 

And then No 12 was for the King Class and No 14 for the Manor Class.

But what was Std No 13? Something designed but never used?

 

I'm not aware of a Standard 13. Standard 21, which came before the Standard 14, was a version of the Standard 11 with a drum head smokebox. The Standard 11 was a T class with a longer firebox, the T, AKA Metro, having been used on some 0-6-0T as well as the 2-4-0T Metros. The Standard 21 was the boiler for 54/64/74 classes.

Std 15 was the 8F based boiler used on the 4-6-0 Counties, and Standard 16 was the small boiler used on the 16xx.

There's some more data on the boilers on my GW boilers page https://www.devboats.co.uk/gwdrawings/gwrstandardboilers.php , including a list of those of the prefixes (sub classes) that survived into the 40s.

 

Low p.288 lists
Nos 8, 10, 12, 14 & 15 as standard taper boilers.

Nos 9, 16 & 21 as standard domed boilers.

He lists the 60xx boiler with 4. row superheater between 12 and 14 but without a number ?

Answers on a postcard ?

Michael Rowe,

 

I've recently seen an original WR document that classified the 4 row King boiler as Std 12, prefix WB.

Jim C

 

Never had a problem oiling one or cleaning the smokebox.
Mind you I have not hit middle age yet.........................

 

This Easter Bank Holiday saw a huge push on 6695's progres at the S&CR with most of the Loco cladding fitted, the next few weeks will see this finished up and painted in undercoat ready for the eventual move to the paint shop at the loco shed in Hayes Knoll.

Pictures below:

 

Looking nice. I'll be the one to ask - which livery is she going to be painted in this time around?

 

I don't know off the top of my head but it'll be GWR this time and not BR as far as I recall.