Bluebell Motive Power

I'm not sure I really know enough about detailed locomotive design to argue my point firmly. I agree that if you've stuffed up your 2-2-2 design with too much weight on the leading axle than a 4-2-2 conversion is an obvious fix (pace William Dean) and the same is presumably true of 2-4-0s.
But I'm not really thinking of conversions, even paper conversions, but of clean sheet designs.
Going back to the 6 wheel types, the similarity in general layout was such that the GWR could convert redundant 2-2-2s into 0-6-0s by pointing the cylinders at an axle about a foot lower. I submit that the major differences between 2-4-0 and 0-4-2 was that the centre of gravity needed to be a little further forward to get the weight distribution right. Cylinders, motion, valve events, draughting, all these things were fundamentally the same, and that if a locomotive superintendent had said to his staff design an 0-4-2 based on our 2-4-0, both with rigid six wheeled chassis, they wouldn't have found the task very onerous. The reverse is arguably a little more difficult, since there is a certain amount of potential complication with firebox, ashpan and rear axle, but, I submit, not much more challenging.

I suggest that there's no point in building a 4-4-0 (or 2-4-2 or 4-2-2) if a 2-4-0 will do the job, so features like a larger boiler/cylinders which would make a 6-wheeler front heavy must be the reason for the design.

So let's put ourselves in two design offices, one with good 2-4-0s and one with good 0-4-2s (and both with good 0-6-0s). The superintendent comes in and says he wants a 4-4-0. Both teams have to discard the leading axle of their type, and rearrange cylinders and front end frame design, then deal with side control and all the aspects of bogie design. That, I suggest, is the real meat of the job. They can probably retain the same design principles in cylinders, valves, motion etc. The 0-4-2 team have to replace their trailing wheel with a driving axle, but as they are already familiar with such on an 0-6-0 will it really cause any issues for them?

So that while on the one hand, yes, you can successfully argue that the passenger express engine without guiding wheels was a dead end and wasn't going to make the transition to 8 wheeled types (although that doesn't seem to have marred 0-4-4Ts) my suggestion is that in practice the length of the dead end siding was minimal and there were no issues in returning to the main line of steam locomotive development.

 

Here you go Jim. (As I’m sure you are fully aware ):

Joseph Armstrong (Swindon) built the 2-4-0T 445 class "Metro" Tanks and George Armstrong (Wolverhampton) built 2-4-0T 517 class. Both successful designs for similar duties. Unfortunately, I don’t think either brother progressed past six wheel design so I’m at a hypothetical dead end!

 

Sudden vision of an enlarged Gladstone with a wide firebox and trailing bogie...

 

Dean's rather hapless 3521 class 0-4-2Ts ended up as 4-4-0s with an intermediate stage as 0-4-4Ts. There is a prototype for everything! I don't know in how many different places the frames had pieces cut out or welded in, but the dodgiest of cut and shut car hackers would have to stand back in admiration and view their master's work...

 

An Atlantic Gladstone might be a more promising alley, except you run into another Stroudleyism which is the use of inside axle boxes (and frames) on the trailing axle - which restricts the advantages to be had from the wide firebox (and maybe leads to hot axle box problems).

I think in your previous post you underestimate the amount of front-end rearrangement you'd need to change a big three axle 0-4-2 to a 2-4-0 (and thence 4-4-0). Stroudley got big inside cylinders by putting the valves below (rather than between) the cylinders. The connecting rods cleared the front axle by passing over the top; and the valve rods passed underneath. So to change that to a small leading set of carrying wheels (i.e. 0-4-2 --> 2-4-0) almost certainly means an entirely different set of cylinders and valve gear layout.

It seems to me that starting from Stephenson's Planet, you have two lines of development:

Passenger engines: 2-2-0 --> 2-2-2 --> then 2-4-0 --> 4-4-0 --> 4-6-0 or 4-2-2 --> 4-4-2 --> 4-6-2
Mineral / luggage engines: 2-2-0 --> 0-4-0 --> 0-4-2 --> 0-6-0 --> then 0-8-0 or 2-6-0 --> 2-8-0

As the locos get harder, the developments get progressively harder due to packaging concerns, and it is harder to "jump tracks" from one to another.

The LBSCR had 2-4-0 passenger engines under Craven, and Stroudley built a small class of them himself (the Belgravia class, 1872 - 1876), using components ordered but not erected by Craven. They were really the last of the Craven locos, superficially Stroudley-ised but with e.g. outside axle boxes on the leading axle and tenders. His first proper express design was another 2-2-2, (the G class, 1874 - 1882). But then when he needed an enlargement, he went 2-2-2 --> 0-4-2 with the Richmond class (1878 - 1880) and then the Gladstones (1882 - 1891). The result I think was nowhere to go, such that when R.J. Billinton needed an even larger passenger loco, he had to start from scratch with a not conspicuously successful 4-4-0 (the B2 class, 1895 - 1898).

Tom

 

You're probably right, and as I used to say to executives, its the detail where you fail. But Dean/Churchward used the Stroudley arrangement of valves under the cylinders on various types, including the Aberdare 2-6-0s, and on the Aberdares its arranged so that both sets of rods passed over the leading driving wheel axle. I don't have an appropriate 4-4-0 drawing available, but I believe the arrangement was the same, both over the bogie. You could go and look at one [grin].

 

Ref the above discussion about 2-4-0 vs 0-4-2, note that Patrick Stirling built both types in parallel over many years - 139 2-4-0s and 154 0-4-2s for the GNR between 1867 & 1895. Major components seem to have been common to both types. The 2-4-0s had 6ft 7in drivers for passenger work while the 0-4-2s had 5ft 7in drivers for mixed traffic, so essentially a variation on the practice of some other engineers in building large-wheeled and small-wheeled versions of 2-4-0s or 4-4-0s.

A few NER 0-6-0s of Classes 59 (LNER J22) and 398 had similar size wheels. Fletcher-era NER engines were notable for lack of standardization, with major variations within a single "class". The Class 398 had several different wheel diameters between 4ft 6in and 5ft 8in.

Ivatt appears to have a built the large-wheeled (LNER Class) J1/J2 0-6-0s as an interim solution to supersede the Stirling 0-4-2s on mixed-traffic duties. The long-term solution was the mixed-traffic 2-6-0, introduced by Gresley in 1912 and developed through his K2 & K3, eventually evolving into the V2 2-6-2. So Ivatt and Gresley could be seen as having found a path forward from the mixed-traffic 0-4-2, but it was a path unique to the GNR.

 

I think valves under the cylinders were certainly common enough on 4-4-0s, the aforementioned Clauds and T19 Rebuilds both had that configuration. The Clauds kept valves underneath through all their variants until some D16/3 rebuilds got piston valves with the valves above the cylinders, driven through rockers from the original valve gear, much like the S69/B12 and Maunsell's D1 and E1 rebuilds.

A couple of posts seem to have implied "Why build an 0-4-2 when it could be an 0-6-0?" The question does have some legs, I've looked at the drawings for an Adams Jubilee, and it does indeed look like you could have fitted a third coupled axle in the same longitudinal position as the trailing axle, although the rear tyre would have been pretty close to the drag beam. But the Jubilee had 6'0" coupled wheels; I doubt it needed the extra coupled axle for adhesion purposes, and will have been rather freer running without it. The T1 0-4-4T with exactly the same cylinders coped fine with 5'7" drivers and I certainly can't think of any 6'0" driver 0-6-0 classes. Eventually the Jubilees were replaced from both directions, by later 2-6-0s and 0-6-0s. The Jubilees and T1s are interesting for other reasons, having been built originally with valves below and later with valves between. Returning slightly to the original point, they (with the O2s and G6s) were a completely separate evolutionary breed to Adams' 4-4-0s, although I'll admit that the outside cylinders on those do muddy the waters.

In general though, I'd argue that the 2-4-0 to 4-4-0 still represents the smallest evolutionary leap, as shown with the GER classes. Most 2-4-0 classes could basically have been converted by adding a bogie stretcher and pivot under the cylinders, removing any now-extraneous outside-framing for the leading axle (I know this sounds drastic, but on a T19 or T26/E4 the outside framing is practically vestigial past the coupled wheels, only taking on any significant depth at the front), and fitting an Adams bogie, which takes care of all the side control entirely within the bogie itself. Some extension of the leading frames and the job is mostly done.

Looking at the bigger picture, it's often said that Stroudley went down the 0-4-2 line to maximise the power for the length of the locomotive, being constrained by servicing facilities and space at the major LBSCR depots. Given that (as we've discussed), there really can't have been much headroom for more power in an 0-4-2, it would be interesting to know whether the railway recognised this at the time, and was putting in place the necessary investment to accommodate a longer class when the need arose.

 

Here's a little tale of why steam locomotives are so bl**dy labour intensive!

The Q class has been having a fairly extensive piston and valve overhaul over the winter (including new piston heads and bored our cylinders, but that's another story). Today's task was to reassemble the crossheads.



The first photo shows the main bits. The crosshead is at the back. The piston rod (held in by a cotter pin) fits in the hole at the front; the little end of the connecting rod goes between the two sides.

Either side of the the crosshead are two slipper blocks which slide in the slide bars (four for each crosshead on the Q, upper and lower on each side - i.e. eight in total). The slipper blocks are themselves made up of the block itself, which slides in the slide bars, with a cheek plate on the side, which is bolted to it with two bolts, visible on the rear one.

Finally there is the gudgeon pin. This has to fit through the slipper block, through the cheek plate, into the crosshead, through the little end of the connecting rod, through the other side of the crosshead (to which it is held by a key), through the other cheek plate and slipper block.

The gudgeon pin is machined in a series of gradually reducing diameters, so it can push through each component but be a snug fit in the next.



Here's the cross head, with the key visible. I don't know how much it weighs, maybe about 40 pounds or so. You can lift it, but equally you wouldn't walk off with it accidentally in your pocket ... The gudgeon pin is also heavy - a two hand job to handle safely.



And, about five hours work later, the crosshead part-assembled as a dry run, with the gudgeon pin a snug fit and the key in place. Not just me: someone else was fettling the cheek plates to fit. Five hours of trial fit, remove, gentle scraping, then another trial fit, and so on and so on. We were only getting on to checking the fit of the gudgeon pins (which are new) in the connecting rod at the end of the day. The space between the frames to reassemble everything is tight, so the idea was to dry run everything first to make sure everything fitted first.

OK, I'm certainly not remotely a skilled fitter, and I suspect others could have got it done quicker. But that's just one small task in putting a loco back together. And all a bit unpredictable: the right-hand crosshead almost fell back together; the left-hand one took all day. Actually getting them all back together in situ is another task; then the piston rods have to be fitted into the crosshead; the piston heads put on the piston rods (pushed against a tapered rod, with a heavy nut to hold in place and cotter pin to hold the nut on the Q); piston rings fitted; then somewhat similar work for piston valves ... Whenever you think of rolling your eyes at a "it'll be ready when it is ready", there's your answer. Plug 'n' play it certainly isn't!

Tom

 

A couple of updates:

Fenchurch - boiler work:

https://www.bluebell-railway.co.uk/bluebell/loco_news/oh_72_fenchurch.html

I have some photos of the frames (being restored off site at Statfold Engineering) which will be in the forthcoming issue of The Bluebell Times.

Secondly, the April newsletter from the Standard 2 group: https://www.bluebell-railway.com/brps/2mt-project/#latest

Tom

 

Just been reading the latest issue of Trackside Magazine, and it would appear the team building Beachy Head are reconsidering their options of what to do next now. Though previously they stated intent on building a replica SECR E Class, it seems their giving serious consideration instead to overhauling the Adams Radial Tank.

Certainly I for one would be very eager to see them pursue such an approach, as it was clear such a project to restore the engine could not ideally be done by the railway itself, being far too busy with restoring other more capable locomotives for their day to day services. The Radial Tank is a vital part of the Bluebell's history and identity though, and it be a tragedy to never see it steam again. I know too that many have said that the Atlantic House was ideal a facility for the more specialized, extensive projects such as the Adams tank and indeed perhaps Stepney someday.

So while it would be fascinating to see a new E Class, I can't deny their proposal to look at restoring the Radial Tank instead has me very excited and hopeful that's the favored approach.

 

Ooh yes please! I’d quite happily chuck a few quid towards that! And on the proviso it’s in LNWR Blackberry Black (just to get the livery debate started!)

 

Surely that depends on which variety of chimney is fitted .....

 

Do you perhaps mean LSWR? You could try painting the Adams in LNWR Black but I suspect there would be quite an uproar about it!

 

A very belated comment on a previous post: the Midland built three 0-6-0s with 6 foot wheels "for fish traffic". They did not last very long, I think only just into LMS days.

 

LNWR Black with a ‘ferret and dartboard’ the livery it carries currently

 

Oooh I bet that will generate some discussion. For what it's worth, I'd rather see the E Class. We have the Radial, and its going nowhere, and it will, eventually steam again I'm sure. But the E class represents the opportunity to recreate a lost class of locomotive whilst at the same time bolstering the active steam fleet in UK heritage with another brand new loco. Seems like a win-win to me!

 

Some of us were only kids when the Radial Tank last steamed, we’re now worrying about things like grey and thinning hair as we approach middle age! If there’s a chance to see 488 back in action I’d like it to be taken please!

 

We do have a D Class too, safely ensconced in the NRM. It's in need of a new crank axle (almost certainly amongst many other things), but is jolly well near identical to the E, so while this will likely get up Tom's nose (sorry!), TBH I'd have preferred the E1 (Maunsell rebuild), but then again, I'm not the one building it!

Still very happy at the thought I may yet live to see the Radial back in harness.

 

Radial would get my attention. Beautiful loco.