Edward Thompson: Wartime C.M.E. Discussion

I was trying to make the point that he designed a loco that was a radical departure from Southern practice , got approval from the board and past the government objections and into service in pretty short order . he would have done it faster if the war had not intervened. it was not a comment on how effective they were.

the man who really showed the wtg was Urie ,with his S15 & N15. they were not perfect when they entered service ,but the concept of a 2 cyl loco with nowt between the frames was 15 years ahead of its time .

 

Well, Urie and Maunsell - the N Class predated the S15/N15 by a few years and was arguably even closer to the later BR standard template.

Tom

 

Yes steve you are correct but I was thinking of a class 7 mixed traffic engine that was simpler to build and maintain than the Green Arrows. I was also wondering if there was any evidence that Thompson had considered the idea.

Cerainly a class 8P needs 3 or more cylinders, there just is not space in the British loading gauge to fit large enough outside cylinders.

 

Weight is the big consideration we have not talked about. It bedevilled designs. A lot of excellent locomotives gave trouble overtly originally or implicitly later in their careers because the chassis was not strong enough: lightening holes that were progressively reduced on the big LNER engines and how rough many engines of class 5 turned with
mileage. We were not interested in frame stiffness as the French were - it was one of Chapelons concerns - which must have arisen early there from the inherent
difficulty of rigidity between the outside cylinders across the connecting rods from the inside ones with the de Glehn layout. Nor did we use bar frames despite
their being standard in Germany and a great success in New Zealand locomotives.

It is interesting that that Churchward, Robinson and Urie all simply used thick heavy frames and their locomotives were appreciated by their successors, developed,
rebuilt, improved and indeed built new over periods like twenty to fifty years. The plates and cross stays would take it over time. The LNER 04 was very comparable to what was done on the Urie 4-6-0s: somebody later taking a sturdy chassis, fitting it with modern cylinders and valve events - the result with a good new boiler showed up well in the 1948 trials and continuing the rebuilding of the classic Robinson 2-8-0 ought to have been considered with some priority.

Getting agreement within a railway. There was an extraordinary contrast on the Southern between Clayton's care over how heavy individual components would be - when a new design was being built, each new piece whose weight was not on file was weighed when it was machined ready to be erected and the figure reported to the drawing office to be compared to the estimated weight so an eye could be kept on how the overall weight was developing compared to the weight budget - with the Merchant Navies there was no such thing and smoothed over with Bulleids charm - the weight in working order included a specially selected light driver "with a very small pair of boots" -
there was actually quite a to do over how it came out heavy.
(Though apertures appeared in the frames I don't think they gave trouble and needed to be replaced or welded up like the Standard 5s were around the driving axle boxes.
However given the welding you need to do on a Bullied Light Pacific firebox because of the want of rigidity in the fabricated foundation ring I stand to be corrected on this.)
It seems that the various internal negotiations, renegotiations with more or less of a redesign each time - it was to have been originally a 2-8-2 with a Zara truck and rotary valve gear etc. which all went out the window between the Civil Engineer and a purchasing department rule of not paying royalties - left no time for tabs to be effectively kept on how the weight was developing.

 

Brittania had two 20*28 cylinders 6 feet 8 apart.
Put connecting rods inside coupling rods on front driving wheels .
In this case two 22*30 outside cylinders can be slimmer than three 18*28 on the Duke.
Complete cylinder volume is bigger fot the two big than the three small.
And more efficient as well

 

Yes Hermod, perhaps it could be changed to a 4 - 6 - 0 as well.
Think Thompson was wise not follow through with two cylinders on anything much bigger than a B1.... don't think the Brit is sufficiently robust for its cylinders and should have been more so /or a three cylinder/ or had smaller cylinders.

 

How do you get that figure? Two-thirds of the P2's cylinders and everything else the same would give two-thirds of the P2's TE. Raising the boiler pressure from 225 psi to 250 psi still comes to just under 30000 lb TE.

 

I have always found it extraordinary that a fairly conservatively designed 6ft 2in Pacific on one railway, which ran to the end of the steam, was pretty reliable, not outstanding, but was never rebuilt, gets so much flack compared to a radically designed 6ft 2in Pacific for which a number of teething troubles were found, materials technology was not up to scratch with the experimental components, and all were rebuilt within a decade to a form in essence and layout very similar to the first design.

I speak of course about the A2/3 and the Merchant Navy.

It is truely bizarre that we praise the rebuilt Merchant Navy locomotives to high heaven but ignore that Thompson had already done this.

But maybe that’s for another thread...

 

P2 tractive effort is 43462 lb (fromthe weight diagram). Reducing this to 2/3 to allow for only 2 cylinders and then increasing it by a ratio of 250/220beacause of the higher pressure

 

Frame stiffness can be a double edged sword. I have experience of some large vibrating coal screens (not unlike a set of loco frames in size) that started to crack up after three weeks of use. When replacement frameplates were fitted the manufacturers (GEC) decided they were too stiff and all intermediate stiffeners were removed. AFAIK, thee was no further experience of frame cracking. How you build in stiffness can be critical and pin jointed struts are at an obvious advantage over moment jointed cross bracing. You need to avoid cyclic bending moments as much as possible.

 

Indeed. See Cox's paper to the ILocoE (extract attached).

 

I stand corrected. I mistakenly started with the TE of the A2/2s, overlooking their reduced cylinder size.

 

But that's surely because stiffness and resistance to cracking are really two different design problems.

 

Agreed.

 

You also have to bear in mind that the LNER was the poorest of the Big 4, especially after 1929. and Gresley was in no way encouraged to go in for wholesale replacement of existing classes, it is also important to remember that the LNER regions were much more autonomous than on the other lines. Thompson was able to ignore that in a war situation.

It is also arguable that, ignoring the GWR which was something of a special case, Gresley inherited the strongest selection of locos from his constituent companies, especially in freight haulers. There really was no pressing case to replace the NBR 0-6-0's, the Robinson 2-8-0's, the NER 0-6-0's and 0-8-0's, or the GER 0-6-0's. All of which were working reasonably economically until the 1960's.

 

Are you saying there does not exist a responsibility for the CME to provide adequate traction for the present and future needs of the railway?

That the CME should not adapt to the changing needs of the railway and should therefore not be proactive in changing things?

Gresley and the LNER inherited the bulk of its locos in 1923. In 1941 this was nearly twenty years later. Are we saying over two decades all of the pre grouping loco fleet was still acceptable and economically viable?

Could you explain the relevance here please? The regions of the LNER have never had full autonomy - always required the office of the CME to sign off rebuilding etc. So how is that relevant?

While that might have been true in 1923, by 1941 all of the above were around 20-25 years old (or more in fact).

In any event, you are ignoring of course the real issues which were numerous and elderly 2-4-0s, 2-4-2s, 4-4-0s, 4-4-2s, a range of inadequate small 4-6-0 classes and genuine maintenance issues in the conjugated valve gear fleet.

 

Whilst there is concern that Gresley did not produce a 4-6-0 design in his lifetime could that be because, based on his experience of 3-cylinders and the successful operation of his V1 / V2 / V3 designs, the V4 concept was his equivalent. IIRC his calculation that the 2-6-2 wheel arrangement plus 3 cylinders gave more power than a 2 cylinder 4-6-0 whilst giving lower hammer blow was the rationale behind his decision and the two locomotives that were built were actually prototypes to test boiler options. In fact Gresley's design was meant as a standard locomotive to replace the mix of pre-Grouping locomotives used on secondary passenger services but his early death gave Thompson the opportunity to introduce the simpler 2-cylinder B1 4-6-0 design. A question for Martin to consider was how far was the B1 concept forced by its introduction during wartime shortages rather than any antipathy towards Gresley - given that Gresley had not indicated placing orders for the V4 design during its test period; in fact how long was Gresley allowing for the V4s to be tested ?

 

I think objectively the V4 is a brilliant design, with a very obvious number of flaws for its time.

Use of expensive materials that were not available in the quantities required, and producing a locomotive that used some standard parts but introduced another boiler type.

It was an expensive design and I question Gresleys thinking, a little, in the height of WW2 and particularly when the Cox report later revealed the extent of the LNERs maintenance woes.

If it was intended to do that, it wouldn’t have been able to do so quickly enough post war, given materials shortages. There would have had to have been (as we see in Thompson’s B1 and L1 classes) compromises.

It was almost entirely driven by wartime shortages, as the rest of his standardisation plans were.

Gresley had in fact signed off a batch of 10 V4s.

Cancelled by Thompson once the prototype B1 had been tested for around six months. The difference in cost of a B1 to a V4 and the fact they could do virtually the same jobs sealed the V4s fate.

 

the one 4-6-0 that was introduced under Gresleys' auspices was the B17.

this was one of history's near misses . some crews got good work from them ,but they became extinct earlier than might have been expected .
my understanding is that NBL were given a brief they were not entirely happy with - including 3 cyls , of course .
they were also pretty heavy at 77 tons for a TE of 22000lb . -3 tons short of a Jubilee , and 5 more than a B1. but with a performance that matched neither

as has been said before , if NBL had simply been asked for a 5MT , the LNER would probably have got a B1 type ,in 1927 . it was a lost opportunity.
mind you , it was a fine looking engine , but handsome is .........

Equally , by 1930, It was obvious that a Scot was capable of taking 500 tons out of Kings X on an express schedule at a first cost considerably less than a A1/10/3. and with 3 cyls.
So it is hard to avoid asking why it was not done . Vanity?/dogma? who can tell, but a 4-6-0 with a GWR King firebox and a shortened V2 boiler and 6'2" drivers with Scot cylinders could have been quite something .

While the WCML is my home line , I hope not to be unduly partisan . the LMS has long been criticised for its small engine policy , but from an accountants point of view were not 48 Pacifics and a stud of 1000 modern 4-6-0 exactly what was needed for both companies ?

the LNER had 312 4-6-2 & 2-6-2 and a ragbag of pre grouping 4-6-0s plus 73 B17 that were not as good as they should have been. if you look at the coal consumption of the older 4-6-0/Atlantics (50 lb per mile -and then some) that alone would have suggested a modern new build . a saving of 20lbs per train mile is not summat to sneeze at . it might even have paid for 500 or so B1 over say , a 10 year period

I wonder what the build cost of an A3 v/s B1 was , at say 1930 values

 

1. I had assumed (wrongly ?) that Gresley was looking to the post-war period I suspect when he calculated that the cost of repairing locos would be greater than building new; I would point to the EWS order for 250 Class 66s as a modern example of similar thinking when the latter company analysed its fleet and came to the same conclusion re new v repair. This might also be a factor over-looked by Cox when reporting on the LNER maintenance woes given that the report would have been written after Gresley's death hence he would be unaware of Gresley's thinking and future plans.

2. Whilst first cost considerations made the B1 a cheaper option what is known about the respective running costs including hammer blow affecting track wear & tear.