What Ifs, and Locos that never were.

It's also highlighted to me that the handrail stops halfway down - clearly the regulator linkage was deemed adequate!

 

I like the look of that!

Always thought the running plates on the Ivatt looked as if they were raised as a last minute change.

 

Fixed the handrail height and extended it to the cab

 

I quite like the Pigs as they are but have to say that's a rather nice looking machine @Corbs nice one mate.

 

To revert to debate about the Leader for a mo, I've been thinking that we are missing a main part of the picture.

We really don't know what Bullied's true motivation was. Obviously he seized on the M7 issue as an opportunity, but an opportunity to do / prove what? Let us remember he was also an enthusiast for dieselisation, both on the Southern and in Ireland.

The Leader as built came very near to working, within a certain limited definition of 'working' and yet much of its design was clearly flawed. What could he have achieved if he had used better engineering judgement? The offset boiler was really impossible and he should have spotted that before any metal was tortured, as was the fireman's location.

One also wonders what the board thought when they saw the behemoth they had funded.

 

I fancied doing a what if, and thought, supposing the GWR had needed a more powerful Auto tank than the 48/1400s, but which was more flexible and kinder on track than the 0-6-0s. So, I made a 2-4-0 version of the 5400 pannier tank.



I moved the leading wheels forward slightly so that there would be a bit more weight on the drivers and a bit less on the leading wheels. Even so it was so comically quick and easy that it rather defeated the object of a bit of fun. Also the weight on the leading wheels worried me a bit.

So, what about a side tank version. This pulls the weight back a bit, so is probably better balanced.



It is, I suppose, really as much an updated version of the Metro as the 48 is an updated version of the 517. Funny how the logic repeats.

Might have been good for the Wenford Bridge line...

 

Mmmm ..... not too sure about the pannier, but the side tank has possibilities alright. Lose the Belpaire firebox and safety valve bonnet, shave 3ins off the chimney, slap on a westinghouse pump and you're half way to an updated version of the IWR locos. Probs not too heavy ..... at any rate, not after the Southern had upgraded the PW to take O2's!

 

Well the board which sanctioned it certainly wouldn't have been unduly concerned, having long ceased to exist when 36001 steamed for the first time and the BR board had what's now known as 'plausible deniability'.

 

Should be a tad under 16 tons on the driving wheels, at a very uneducated guess under 45 tons altogether. They'd be BR class 1P TE ~15K unless you put a 7400 boiler in (180psi not 165psi) which would put the TE just over 16K and probably BR power class 2P.

 

With the longer wheelbase might it actually be less kind on the track than the 0-6-0. The advantage of the four coupled tanks was presumably that they were freer running. In Dean's time 0-6-0 saddle tanks did very occasionally have the rear wheels uncoupled for passenger work.


Approaching it from the other end replacing the trailing wheels on your 5400 would produce a modern version of the larger 3571 class suburban 0-4-2T.

 

I was envisaging a degree of controlled side play in the leading wheels which would be less practical in the 0-6-0. An 0-4-2 would be a bigger redesign, because the 54s were slightly lighter on the leading wheels than the other two pairs. Besides, less fun in drawing a slightly different 4800. Here's a go though, but I don't think it works.

The problem is that the 54s as built were heavier on driving wheels and trailing wheels than the leading wheels. So, admittedly with a gross shortage of design ability, aptitude and experience, my ill informed guess is that the side tanks would put more weight at the back, although there would also be a saving from the wheels and lack of rods. If you try moving the boiler forward on the chassis then all the relationships with everything mess up...

Its interesting though, its the first time I've really contemplated the 16/48/54/64/74 group from a kit of parts point of view, and there are certainly more permutations in there...

 

The 4800s did have more weight on the trailing axle than the leading coupled axle, the 3571s which had longer fireboxes had over 1.5 tons extra weight on the trailing carrying axle. By comparison the 5400, with pannier tanks set further forward had less than 1/4 ton extra weight on the trailing axle.

I don't think there would be anywhere on the GWR passenger network that would require sideplay to the carrying axles on locos of this size, particularly if designed for lines with yellow weight restriction.

 

That's getting close to suggesting that Bulleid's aim was to demonstrate the unsuitability of steam for a reversible locomotive.

 

Probably why they didn't build any then [grin]

 

Speaking of the Leader, I was thinking about it the other day. If Bulleid was after a modern-looking, labour saving loco which could be driven from either end, underneath that body shell, between two cabs and mounted on those power bogies, he could have built it something along these lines:


Flip the boiler 180 degrees (removing the need for that dangerous fireman cab and saving the forward cab from being right next to the smokebox), sod the offset boiler (and save a lot of weight from the counterbalancing), use the space around the boiler to put the water tanks (saving on the overall length and thus weight), oil fire it (maybe not best practical in post-war Britain) and then put another cab on the other end - hey pesto!

Thought I'd put that out there before James^2 comes along with his M7 post

 

It always seems to me he was trying to do with coal and steam what Ivatt was doing with diesel and electricity with 10000/100001 - provide a full adhesion locomotive with a "generation unit" mounted on power bogies. He will have been involved with the introduction of the Sentinel railcars with what were in effect boilers on power bogies, and maybe hoped to expand on their relative success to provide much more power. That said, his decisions regarding the boiler design and the use of double acting sleeve valve pistons instead of the single acting poppet valve pistons of the later sentinel engines tend to mystify me. The idea of using a lot more, smaller, pistons in a sealed engine crankcase like an IC engine seems sensible in terms of lubrication and cleanliness, but choosing double acting pistons involves extra seals and sleeve valves were never a robust idea, even in automotive and avaiation applications. The could be powerful for sure, but they needed exceptional care in operation.

 

What sort of loco though could/should Bullied have built as a M7 replacement?

What about using the dimensions of a 45xx with outside walschaerts valve gear, BFB wheels & all mod cons?

The loco the operators wanted to replace the M7's and all the other superannuated pre WW1 machines.

 

Except that 4500s were generally smaller in most leading dimensions.

 

I like the cab-forward concept. Bulleid should've considered a cab-forward instead of the Leaders. Southern Pacific did really well with their AC Subclasses.

 

They always fascinated me too. IIRC, weren't the number of tunnels on the SP route the primary reason for adopting this layout? Of course, US loading gauges gave designers a fair bit of leeway which British and Irish CME's could only dream of!

Of course, we had that concept here ...... more or less!
(Photo credit clwydfhs.co.uk):

What do you mean .... "not quite as impressive"? .... the damn cab's at the front, isn't it?!