Edward Thompson: Wartime C.M.E. Discussion

The issue isn't whether Thompson made the optimal engineering decision it is whether he took a rational decision or acted out of spite, since that is what he has long been accused of. The report lends strong credence to the idea that he made a rational decision based on the facts available at the time and in the conditions of the time (war and then austerity=lower manpower available) and therefore it is less likely there was malice in his motives. As it turns out he could have put his efforts to better use, but that's not germaine

 

A 2-1/2" gauge coal-fired live-steam Pacific built by one L. Lawrence circa 1944. He is/was better known for his writings under the 'nom-de-plume' of LBSC on small scale steam loco building in 'Model Engineer' magazine from 1924 until his death in 1967. I believe the loco still survives in the North London area. Just post-war a fellow in Cheshire built a Southern Rly 'Lord Nelson' loco in 3-1/2" gauge in the late 1940s. Not aware of any standard gauge locos built with the Holcroft gear.

 

Think I've got to challenge that. If, post say 1955, big ends on conjugated gear locomotives were failing at no greater rate than their counterparts with three sets of valve gear, or of inside big ends on 4 cylinder locomotives, then I think you have to say that the big end problem was solved. The task, when designing the big end, is that it should stand up to the loads it will experience in use, sure if those loads are 30% greater than the other cylinders you need a big end to match, but once you have the problem is solved.

Conjugated gear, or not, is another matter, and like all engineering problems there are pros and cons, and different engineering teams will have different priorities. The example of the Pickersgill locomotive with inside stephensons and outside walschaerts gear gives us a graphic demonstration that there were worse solutions than the conjugation gear. At the risk of being flamed from here to the arctic circle, may I suggest that the service record of Bulleid's gear on his pacifics suggests that may not, as implemented, have been a superior solution to the Gresley/Holcroft gear either? I think all we can realistically say about the conjugated gear is that it provided considerable design challenges, and in practice was probably less desirable than 3 sets of gear really well implemented, but certainly better than 3 sets of gear really badly implemented. As for even valve timing. I'm not competent to make any suggestions about how high a priority it should have over other design factors. AIUI from my rather ignorant reading of Ashton and other sources, and please correct me if I'm wrong, the LMS thought their rocker implementation on the Princesses was superior to that of the Kings because they saved a pin joint or two on each side, whilst the GWR thought their implementation was superior because it provided better valve timing. Even valve timing was certainly a particular GWR preoccupation, Cook makes that quite clear in his book, but I'm certainly not competent to tell you whether they were right or wrong, and, frankly, I doubt whether any one else can really provide a full evaluation of all the pros and cons of different lines design priorities including the key financial elements.

 

I was behind 4498 many years ago when she suffered a bent expansion link and she sound awfully off beat but that is part of the outside Walschaerts motion so nowt to do with the derived motion. Did SNG fail on your run, did the middle big end run hot? I've also been behind locos with three independent sets of gear that have sounded lopsided so syncopation is far from a Gresley only problem.

 

Thank you for putting into words what I have been struggling to for some time.

It is the difference between Thompson the irrational, Gresley hating figure as written in railway history by so many, and Thompson the engineer who makes a decision which was rational and justified when made in 1941 on the back of an independent report.

I don't disagree at all - in fact agree on several points - that many things could have been implemented better and differently by Thompson, and yes even by Peppercorn and British Railways thereafter, but the report inherently shows that - at the time of writing - Thompson was justified in his thoughts and justified in making a change on the LNER in relation to locomotive design policy.

 

Yes they did - the redesigned strap of 1947 plus the steel spacers of 1950 plus the change to the bearing shells and lubrication method introduced by Cook cured the problem to all intents and purposes, provided the subsequent maintenance regime was adhered to. I don't know if the whitemetal was changed, but whether it was or not once Cook had changed the shells and oil feed/pads in the eary 50s the big end problem seems to have be effectively cured.

Really? Still? When did you last hear of one failing? I don't recall hearing of any big end failures at all in the preserved fleet of conjugated gear fitted locos. Further Townend states that once the changes were all made the "performance of the various pacific classes was not marred by such serious failures." for the final final years of steam operation. (East Coast Pacifics at Work P131) Since Townend uses the phrase "varous pacific classes" it wasn't just the conjugated gear locos having trouble.

Presumably you are now referring to the conjugated gear itself, not the big end.

The primary aim of the investigation was to assess the gear and it's influence on the "mechanical trouble in question" - which seems to be more the bearing failures than the premature wear. As part of his investigation Cox (who says he made the inspection and wrote the report) calculated that the gear was unlikely to "contribute other than in a minor way to the (big end) overheating which has been experienced." Whilst he made two comment on the gear compared to one on the bearing, the fact that the gear wear would not significantly affect the big end failure rate means that the gear had become a secondary conclusion within the report, despite being the primary reason for the investigation. One might ask if Stanier/Cox would have been approached at all if the big end failures had occurred on locos with three sets of gear, which they later did.

The language of the report was certainly damning, it's a shame the scope of the investigation and the logic applied was insufficient to allow such language, as i have comment earlier in the thread.

Gresley died on 5th April 1941. The inspection was carried out in 1942, though I can't seem to find when in 1942. The failure comparison was for "last year", which I take to be 1941, so for 3/4 of that time, either Thompson, or even no-one, was in charge at Doncaster. The locos were certainly Gresley's but he was no longer in any position to try to solve the problem, being dead and all that. nitpicking? possibly, but one should try to be as precise as possible when making such statements.


One point I didn't mention previously when commenting on the Stanier report was the seeming lack of any attempt to improve the design or maintenance of the gear other than to point out the different bearing sizes. It took until the end of the war for Bill Harvey to go round the sheds trying to find the problems (I found where Townend relates Bill Harvey told him the inspection was post war - East Coast Pacifics at Work P 129) and his recommendation for the conjugated gear was to use oil lubrication, and for heavens sake stop shovelling smokebox ash all over the centre bearing of the gear. I quote again from steamindex.com http://www.steamindex.com/locotype/grespac.htm

"Collaboration with Bert Spencer to examine design weaknesses, especially those emphasised by wartime working: "A start was made with those common to all areas, the Pacific and V2 classes. All the principal depots on the East Coast main line between King's Cross and Edinburgh (Haymarket) were visited in turn and the views and suggestions of the maintenance staff canvassed. All complained of the deterioration in performance of the middle big-end and its tendency to run hot when subjected to additional loading caused by wear in the pins of the 2-1 gear due to ingress into their bearings of smokebox ash. The 2-1 gear was a simple and ingenious arrangement of two levers connecting the right- and left-hand valve gears in such a way that their combined motion gave a correct steam distribution to the middle valve, thus dispensing with the need for a separate inside valve gear. All advantages have corresponding disadvantages – any lost motion caused by wear in either of the outside gears was also imparted to the middle valve thereby increasing its port opening to steam and consequently the loading on the middle big-end. Over-running of the middle valve occurred at high speed due to whip in the two primary valve motions when these were subjected to heavy inertia forces. In peacetime with good maintenance and regular and thorough greasing, wear was easily contained within acceptable limits. The principal causes of excessive wear under war conditions were the ingress of fine smokebox ash into the bearings and over-long intervals between greasing. We recommended as a temporary expedient until pre-war standards of maintenance could be assured that an oil lubricated plain bearing of the largest possible diameter (which could be given attention by the driver) be substituted for the existing grease-lubricated main fulcrum roller bearing, also that special attention be given to making the footplating and inspection door above the 2-1 gear ash proof."

Note that he continued to think that the gear wear was responsible for the big end running hot, despite the Cox/Stanier report concluding that the wear would have little effect, meaning that Thompson had not disabused his staff of the incorrect belief that the valve gear was overheating the bearings.

I have to ask why such an assessment wasn't carried out by Thompson, or even Cox. Didn't they want to fix the problem?

 

I'll respond in full later when I am back with my books later this evening, but I must emphasise again that we are not just talking about the Pacific classes - Cox's report covers the whole of Gresley's designs with conjugated valve gear which covers Pacifics, tank engines, mineral engines and many more besides (around 600 in total). Simply picking on the A4 Pacifics or A3s and saying in effect that there's no real issue doesn't take into account the full story which covers an entire locomotive fleet.

I will need to check the dates but I was taken to believe that the report was made in 1941, not 1942. But you are correct that we should be accurate about these things, and if I have been incorrect I will correct myself accordingly.

 

Indeed; Do you have breakdowns for big end failures by class?

Loco Panorama Vol 1 P 140 - Cox definitely says 1942 - still, he may have misremembered.

 

Not by class but I am working on it.

Interesting - I have that book on order so will check that out. Thank you for the page number, most useful.

 

There are some indicator diagrams in Nock's book but they are for 2631 which appears to have had independent cut-off on the HP and LP cylinders. The final form of the locos appears to have had linked cut-off arrangements with, rather counter-intuitively (to me at least), a shorter cut-off on the LP than the HP. If one has to have a shorter cut-off on the LP to equalise power output, on the face of it that could be achieved by having a larger HP cylinder (or smaller LP cylinders). It would have been useful if Riemsdijk had included the cut-off arrangements in his tables of loco types e.g whether independent valve gear / fixed ratio if linked, rather than simply the cylinder sizes, as there seems to be limited info in general on this aspect of compound locos.

 

You're correct - the original Midland Compounds did have separate HP and LP controls when first built, but it was subsequently found to be an unnecessary complication

 

I am happy to stand corrected but I thought the first installment of Bittern's preservation mainline career (York depot based) was in the early 1970s (after 60532 was bought) when she ran as LNER No.19, before it was decided that the cracking had become too great (I think remember reading somewhere that the late Kim Maylon was involved in the 1970s and then later had a role in bringing her back decades later).

I believe Corbs is right, but it was not quite how Wikipedia presented it.

 

Yes.

On the general issue, I think the central point is that, regardless of the Cox report, the conjugated valve gear locos worked away quite happily until the end of their natural lives under successive CME's. So if Thompson (and Cox) were convinced that the conjugated gear alone was the cause of the problem (and in my opinion that is not what Cox says) then they were wrong.

The simple fact is that the LMS at that time had a better design (or implementation) of the centre big end than the LNER.

Did Thompson resent Gresley's intervention on one or two managerial decisions? Yes, he clearly did. Did he resent Gresley as a person? Probably not. Did he resent the board preventing him from doing what he wanted to do after he became CME? Yes, most certainly. Especially when there was resistance from drawing office staff as well. Is any of this unusual in anyone other than a saint? No.

If he'd have been Dugald Drummond or Patrick Stirling no-one would have dared to voice an objection. I would suggest he was actually a perfectly reasonable man somewhat frustrated in his career and meeting with stubborn objections when he tried to make what he thought were important improvements. Whether those improvements were actually effective is secondary when studying the problems he was facing as a leader - certainly they weren't abject failures in the way that, say, Drummond's 4cyl 4-6-0's were.

My view is that having HNG dangled in front of him as someone whose work could not be improved upon by the board kicked off a certain "well, I'll show them, the b***s" reaction, which, bearing in mind what Thompson knew about failures and costs, is probably what I would have done as well. And after all, what did he actually do? Rebuilt a handful of engines that in the majority of cases were not improved by the experience. But on the other hand his rebuilds did give us the thoroughly useful and practical K1 and O1.

It also should be remembered that his original proposals for some of the designs were distinctly more Gresley-like than was eventually carried out, so the reaction clearly increased after he became CME, hence my pinpointing of the board's words as the trigger point

I still don't know why, if 1470/4470 was considered too expensive to restore to GN state for preservation but important enough to carry out the exercise of costing it, 1471 wasn't chosen by the BRB instead. It was built at the same time and was equally historic.

 

hi pete,

re Great Northern v Flying Scotsman, Flying Scotsman wasnt on BTC/BRB's list for preservation and so was saved privately by alan pegler. the reason why Flying Scotsman was preserved is a bit off topic, but was in most people's eyes the most famous LNER loco due to its being specially named after the train service carrying that title, and being given a special finish for the Wembley exhibition, and used on LNER publicity material for many years, plus the little matter of the 100mph run. it was also an early film star! Great Northern might have been the first A1 but it wasnt nearly so famous or renowned as the third member of the class! the same could be said of 'Sir Frederick Bansbury' the second loco of the class.

cheers,
julian

 

As I understand it, because Mallard had been nominated for preservation, another Gresley Pacific was regarded as 'duplication', even though 4472/60103 was the first officially recorded 100mph locomotive...

 

...But wasn't King George V on the list whilst Caerphilly Castle was already preserved? GWR bias!

 

Hard to look at a list that contained 10 GWR and consituents locomotives out of 71, (http://www.didcotrailwaycentre.org.uk/visitor_information/otheritems/GWShist_01.html) including just one of the classic standard 2 cylinder locos (and that already preserved) and concluded it indicated a pro GWR bias. But yes, very odd to preserve all three classes of 4 cylinder 4-6-0s and no 2 cylinder ones.

 

jimc,
lets not get too off topic!
im still waiting for simon's response to Lplus's excellent resume and response to simon's comment on my own replies!
perhaps simon has torn up half or more of his book manuscript by now!
cheers,
julian