Edward Thompson: Wartime C.M.E. Discussion

Whats radical about the Modified Hall?

 

Nothing. It’s a GW and they’re all the same.

 

They used names from outside of the GWR area.

...coat

 

They had full length frames and bolted on cylinders rather than the combined cylinder/half saddle casting and extension frames of the Churchward standards. It seems to be considered a big deal in some quarters, but as all the four cylinder classes had full length frames and bolted on outside cylinders it's not entirely clear to me why.

 

Wasn't the change to full length frames and bolted on cylinders just taking the GWR back into line with pretty well all other British railways?

 

That sounds pretty radical.

 

a radical and revolutionary thing to do in GWR eyes

But this is my point - just like abandoning the Gresley valve gear, it seems like a perfectly rational thing to do, and not a gratuitous act of iconoclasm.

No one (I dunno maybe they do in GWR circles) accuses Hawksworth of being anti-Churchwood in the way in which Thompson is accused of being anti-Gresley.

 

Although Churchward had been dead a bit longer, and (given few saw dieselisation coming fast) there was less debate about the need for some new thinking - especially given Collett had basically been a steady evolutionary hand on the tiller with nothing much to rock the boat. Note I didn't say *no* debate... There is a school of GW fandom that rails against the counties for having straight splashers, and looks askance at 94xx and 15xxs....

Though such latter flights of fancy could be excused by those who knew that Hawksworth had proved himself by basically designing the Kings...

 

Is that a compliment? (Massively overweight design with heavily restricted route availability that didn't seem much operational advance on a Castle ...) Not Swindon's finest hour, I'd suggest.

Tom (Running for cover)

 

But they had an inside-outside bogie, which filled the key GW design brief of being different to everyone else...

Seriously it's interesting how GW-specific, GW designs, and the King specific to a specific bit of the GW, were.

 

Ah, but if you're a GW fan*, they're the apex of British locomotive design.... so within the context of the 'if it's not Swindon I'm not interested' fraternity designing the King is worth at least 5 house points.

*by which I mean the cheerleadery fan in the street, rather than the thinking one!

 

..... and further south, finally unmasks the real reason Mr Maunsell was instructed to curtail construction of his celebrated Class V 4-4-0s.

 

I used to work with an ex Swindon apprentice, He considered abandoning 7' gauge was radical.

 

don't know about radical - I think it's probably still too early to say if it is a good idea or not.

 

Route availability is interesting... The GWR red route limit of 19.5 tons per axle, which the Castle met, prohibited, among a good many others, most LNER Pacifics, the Merchant Navies and the Stanier Pacifics.

Whatever you may think about the track gauge, I challenge anyone to deny that Brunel was right that the loading gauge was too small.

 

Simon - Your fresh research has unearthed information from the archives that was probably unknown to previous writers on the Thompson era of LNER locomotive history. I refer in particular to the statistics on mileage and availability. During the War, that was classified information to be communicated only on a "need to know" basis, and certainly not shared with the likes of CJ Allen & OS Nock.

A number of points emerge from these statistics. It was perhaps expected that passenger engines typically did higher annual mileages than freight engines and that the Pacifics, working long-distance trains, did the highest annual mileages of all. But other information was a surprise, certainly to me. Older Pre-Grouping designs often seemed to be more reliable than the modern LNER standard types. For example, Gresley's own GN-era J6 0-6-0 and K2 2-6-0 had similar annual mileages and higher availability than the later J39 and K3. But perhaps the stand-out data was the poor availability of the P2s.

The P2 had been Britain's most powerful express engine type, capable of prodigious feats of haulage and attracting much admiration. So when they were rebuilt to the apparently less powerful A2/2s (also seen by some as ugly), many would have been shocked and perplexed. That rebuilding may have been justified by much improved availability, but that explanation was unknown to most. So the explanation that "Thompson was trying to change everything that Gresley did" would have seemed a logical explanation for the P2 rebuild to the majority who were not "in the know".

Previous authors have noted that there were problems in wartime with the maintenance of conjugated gear, for example the FAS Brown biography of Gresley (1961). The RCTS LNER Loco History Pt 6B (1983) deals extensively with the P2 problems, including the whole series of crank-axle failures. But do any other publications mention those crank-axle failures? And even the RCTS failed to pick-up that the P2 mileage and availability in wartime had fallen well below the levels of the Gresley Pacifics.

I think that anti-Thompson feeling would have been boosted by bafflement at the P2 rebuild, along with other factors of course. There can be no definitive answer over whether the A2/2 was the right or wrong answer to the P2 problems, but you have done a most valuable service in showing how Thompson's actions can be logically explained by the genuine difficulties that he was facing and the constraints on his options for resolving those problems.

 

I disagree with this. The Pacific design that emerged, worked well out of the box and improved the status quo by way of mileages and availability. We have the stats to back up that fact.

Therefore it is one of the potential "right" answers, if the question being posed is "how can we improve these locomotives availability and mileages" and not "can we preserve the Gresley P2s".

The rebuilds worked successfully and improved the status quo. By definition, the rebuilds are a right answer.

Thank you.

 

Thompson did ugly things to some other three-cylindered locomotives and I have played a little with numbers.

P2-simple by Hermod posted May 18, 2021 at 5:18 PM

Picture left side shows P2 as was from Gresley in loading gauge with three 21 times 26 inch cylinders and rigth side is a possible two cylinders 24 times 30 making same tractive effort
It would need eigth Hall GWR wheels and axles ,two new rather long connecting rods unto third driver set and a new cylinder pattern.By lifting cylinders somewhat up we avoid collision between front driver coupling pin and crosshead.Front driver set can then displace plus minus an inch and we can have KH or Zara truck.
USA made 1340 141R locomotives for France that was very usefull and longlived of almost same layout.

 

Well, we get into semantics don't we. The stats say pretty unequivocally that the Thompson rebuilds were a considerable improvement on what went before, therefore a good answer. But *the* right answer? That's arguably very hard. Don't you have to start with the traffic need the P2s were meant to fulfil, and then consider how that need might have changed by the time Thompson was looking at the situation?

 

The prototype A2, Thane of Fife, did the exact same traffic as the existing P2s for over a year, with double the mileage and availability. That year-long comparison of work done is at the heart of the decision to then rebuild the entire class.

If that's not a "right answer", then what is?