If you register, you can do a lot more. And become an active part of our growing community. You'll have access to hidden forums, and enjoy the ability of replying and starting conversations.

Edward Thompson: Wartime C.M.E. Discussion

Discussion in 'Steam Traction' started by S.A.C. Martin, May 2, 2012.

  1. MrDibbs

    MrDibbs New Member

    Joined:
    Jan 24, 2019
    Messages:
    132
    Likes Received:
    101
    Location:
    York
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    I would have thought that the key advantage is you're not trying to put all your power through a single axle, especially as metallurgy was not to current standards. (Look at the P2 Project which has beefed up it's crank axle given the class' issues in service, and the bullied pacifics which were temporarily withdrawn from service following the incident with 35020)
     
    S.A.C. Martin likes this.
  2. 8126

    8126 Member

    Joined:
    Mar 17, 2014
    Messages:
    823
    Likes Received:
    962
    Gender:
    Male
    I think the divided/unified drive debate tends to ignore the reality that all design is a compromise, and sometimes different compromises are chosen. You can find successful examples of just about every variation on the theme in both three and four cylinders, especially if the view is broadened to the continent, but to take (mostly) British examples:

    4-cylinder divided, equal rods: GWR 4-cyl classes
    4-cylinder divided, unequal rods: Lord Nelson, Duchess
    4-cylinder unified: Bavarian S3/6 (and a compound to boot!)
    3-cylinder unified: Gresley and Bulleid Pacifics
    3-cylinder divided: Royal Scots, post-Gresley Pacifics, Duke of Gloucester.

    In theory, you should be able to do a better job of the balancing with divided drive, since it allows for a horizontal inside cylinder, but I've occasionally wondered if the general reputation of 3-cylinder divided drive classes for rough riding has something to do with them being two differently-unbalanced axles tied together. If it was nose heaviness, you'd expect the Duchesses and Nelsons to also have a poor reputation, but AFAIK they don't. With a powerful 4-6-0 there isn't really much choice, the crank axle would otherwise be occupying firebox space, like on a 4-4-0. If you're building both 4-6-0s and 4-6-2s there could be an argument for commonality, but the only person who built both types in large numbers with the same number of cylinders (more than two) was Gresley and the Pacifics came first. On the whole, classes with unequal rods seem to have had less trouble with frames than those with equal rods, but I'm aware there's a Castle-sized counterpoint to this...

    Unified drive allows for a more compact design lengthwise. Look at the Bulleids in particular; their coupled wheelbase is stretched out to spread the weight and meet route availability requirements, and yet they're still short and compact compared to a divided drive engine, which helps keep weight down (this is one of my hobby horses, a lot of the more cosmetically noticeable stuff obscures just what a clever piece of packaging those Pacifics are, before and after rebuilding). On the other hand, there's always going to be a bigger vertical component from the inside cylinder, and forcing it upwards reduces the available space. The Gresleys get around that with the steamchest beside the cylinder, the Bulleids with that unusual boiler. I will argue that the Bulleid crank axle problems were a detail issue rather than conceptual, again partly due to chasing reduced weight.

    It's all a matter of making choices that work. Sometimes the unified/divided choice mattered a lot. A lot of the time it probably didn't, although very different engines would have resulted.
     
  3. S.A.C. Martin

    S.A.C. Martin Part of the furniture

    Joined:
    Aug 31, 2010
    Messages:
    5,591
    Likes Received:
    9,325
    Gender:
    Male
    Occupation:
    Asset Engineer (Signalling), MNLPS Treasurer
    Location:
    London
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    I think there’s a bit of confusion as to - why - Thompson chose divided drive and I think there is also some confusion as to how it was applied to the Thompson A2 sub classes fitted with it.

    Firstly, please have a look at the drawings below:

    Thompson A2-2_outline drawing.png
    Thompson A2-2_general arrangement drawing.png

    We have to remember the following:

    In 1941 the Gresley P2s had:

    • Broken several crank axles (all at low speed)
    • Instances of overheating axleboxes
    • High fuel consumption
    • Frame cracking at the joint between first and second coupled driving wheels
    • Poor overall availability of under 50%.
    All this in addition to a poor reputation for track spreading (which to date I cannot find any actual hard evidence of, just hearsay from writers of the time. Certainly no official reports).

    The whys of the above have been debated at length. Nevertheless, Edward Thompson inherited six non identical mikados and was tasked with improving them.

    He had a number of things he could and couldn't do, due to the restrictions placed on him by the Wartime Executive and the LNER Emergency Board.

    He could not:
    • build all new experimental locomotive designs
    He had to:
    • fulfill any orders for locomotives and rolling stock for the War Department
    • improve overall locomotive availability on the LNER (which had plummeted)
    • organize the major LNER works to continue their railway output whilst increasing their supply of munitions, vehicles and aircraft for the war department
    At a very high level, Edward Thompson (and before him, Gresley too) were responsible for some very big decision making, most of which was about fulfilling the needs of the war effort whilst also keeping the railway going. A very difficult balancing act.

    Where the P2s were concerned:
    • They were a small class
    • The A4s and rebuilt W1 were proving capable of doing the P2s work without drama
    • No other region wanted them
    This I think is something that many people miss when they clamour for "the P2s should have been sent south to help with XYZ". All well and good - but by 1941 the P2s were performing the worst of all of Gresley's biggest locomotives.

    If you're a shedmaster in England, already suffering from locomotives whose reliability is falling, are you going to take on the P2s with the reputation they'd built up to this point? Their problems were not new in 1941, they didn't suddenly become unreliable the moment Edward Thompson took office as CME.

    The records show they had poor reliability for at least five years prior, in particular the single chimney P2 Thane of Fife. (I say that because I have now dissected and put together from their engine cards the data required to match to the availability statistics for the years prior to 1941).

    So, on Thompson's start as CME, we have the big locomotive availability problem. This is not up for dispute: it was real, it was not something Thompson concocted - the LNER, more than any of the other railways, was suffering with poor locomotive availability. (I have spoken before, both in my lectures, and here, on the make up of the railway's fleet including around 6500 pre grouping designs, whose ages were all 25 years or older, and of an average age mostly over 50).

    So, in order to persuade the board of the need to change the design ethos going forward, Thompson asks Sir William Stanier to do a report on the availability of locomotives. E.S. Cox acts as his deputy. The materials are collated, the evidence gathered, and the two LMS men spend the best part of a year investigating the conjugated valve gear locomotives in particular - as they are proving to have the biggest issues on a day to day basis.

    After the report is presented to the board, Thompson has permission to rebuild ONE P2.

    The locomotive chosen is Thane of Fife, the single chimney black sheep.

    Thompson and his design team - including Robert Thom - examine the P2 design.

    They know that the P2 design has split frames between the front and second set of driving wheels. This has proven to be a weakness in the P2s, where the axlebox overheating failures are found, together with some minor cracking and flexing at the front end. Coincidentally, this is where the crank axle is, all three cylinders driven onto the second axle.

    Now - this the next bit is hazy. Some sources report that Robert Thom suggested equal length connecting rods and divided drive. One writer suggested that Thompson selected it himself - because of his fondness for all things Great Western (? - always wondered about this as other sources state the GER was Thompson's railway love - which makes sense given his association with Stratford Works, the locomotives he worked on, and Great Northern's unique GER themed livery).

    Whoever chose it, the design was signed off with the drawings confirming that all three cylinders would be set at the same height, with cranks set at 120 degrees to each other, and with equal length connecting rods.

    This setup, with the centre cylinder driving the front axle and the outside pair driving the second (if you're keeping up, these were the second and third axles on the P2s originally!) gave equal valve events in theory, as well as distributing the drive between two axles instead of onto a single axle.

    Thane of Fife is rebuilt incredibly quickly at the back end of 1942 and is put to work in 1943. its final availability as a P2 is around 46%.

    As a prototype A2 Pacific, it achieves 76% in its first year, 65% in its second, 78% in its third and in 1946 - Thompson's last year as CME - it achieves 93% availability and is the best locomotive of its size for that year.

    Its total engine mileage varies from around 60,000 to 85,000 miles for those four years - up from a class average of 34,000 miles in 1942.

    Now - we could argue the toss about many things. We could argue about their maintainability, their appearance, we could argue about performance in later life after Thompson's departure (not as bad as has been painted, by far, as it happens) - but there is one indisputable fact.

    The P2s - which had suffered crank axle failure - when rebuilt as A2/2s, never did so again, and their immediate availability for work improved significantly.

    If you're in charge of the figures at the LNER, which is better? A locomotive of high performance that is unreliable and costly - or a locomotive of more medium performance that is more easily fixed and more reliable in service?

    It's what I would call a "no brainer". Thane of Fife was the only Thompson A2 for around a year - the reports to the LNER Emergency Board were very positive - and the rest were ordered to be rebuilt.

    The cost of converting a P2 to an A2 was far cheaper than building a new V2, incidentally - and reusing as much of the original locomotives as possible saved on what would have been crucial manufacturing time and effort that likely went into the war effort in other ways.

    I still find it astonishing that Doncaster Works drawing office, and Doncaster Works engineering staff, put together a workable design and built a prototype within six months. That the locomotive then went on to improve its lot by way of availability - even more impressive.

    Far from the A2/2 being a Thompson failure, it's an absolute success story for the workers of Doncaster - under incredibly difficult wartime conditions, they designed a new Pacific by reusing what they could of another class, put it into work, and when called upon, did it all over again for the rest in short time too.

    The rebuild was well thought out, well organised, and did the job asked of it. They created a mixed traffic Pacific from a Mikado.

    Okay, so a Mikado has many advantages - and as a founder member of Prince of Wales, I am thrilled we will finally get to see one.

    But there is a part of me that looks at the Thompson A2/2 story and thinks - wow. What an achievement by a department under incredible strain. Not least given the wartime context.
     
    Last edited: Feb 1, 2020
    ross, ragl, pete2hogs and 14 others like this.
  4. Hermod

    Hermod Member

    Joined:
    May 6, 2017
    Messages:
    985
    Likes Received:
    283
    Gender:
    Male
    Location:
    Klitmoeller,Denmark
    Heritage Railway Volunteer:
    No I do not currently volunteer
    Was the A2/2 cylinders taken from shelves or new constructions?
     
  5. RalphW

    RalphW Nat Pres stalwart Staff Member Administrator Friend

    Joined:
    Sep 11, 2005
    Messages:
    35,445
    Likes Received:
    9,143
    Gender:
    Male
    Occupation:
    Retired-ish, Part time rail tour steward.
    Location:
    Northwich
    Heritage Railway Volunteer:
    No I do not currently volunteer
    @S.A.C. Martin. Simon most if not all that long post above has been said before more than once, do you really have to regurgitate it once again?
     
    Victor likes this.
  6. johnofwessex

    johnofwessex Resident of Nat Pres

    Joined:
    Apr 6, 2015
    Messages:
    9,185
    Likes Received:
    7,226
    Gender:
    Male
    Occupation:
    Thorn in my managers side
    Location:
    72
    Heritage Railway Volunteer:
    No I do not currently volunteer
    I think that it summarises the situation excellently, makes a few new (to me) points and reminds some of the 'Anti Thompson' camp of the reality of the situation he was in
     
    ragl, pete2hogs, 60525 and 6 others like this.
  7. S.A.C. Martin

    S.A.C. Martin Part of the furniture

    Joined:
    Aug 31, 2010
    Messages:
    5,591
    Likes Received:
    9,325
    Gender:
    Male
    Occupation:
    Asset Engineer (Signalling), MNLPS Treasurer
    Location:
    London
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Is it a problem that I have in response to a question?
     
  8. flying scotsman123

    flying scotsman123 Resident of Nat Pres

    Joined:
    Sep 9, 2013
    Messages:
    10,438
    Likes Received:
    17,937
    Gender:
    Male
    Location:
    Cheltenham
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Just because you're bored, doesn't mean the rest of us are. If you've got nothing nice to say...
     
    ross, Romsey, 60525 and 8 others like this.
  9. Miff

    Miff Part of the furniture Friend

    Joined:
    Jun 17, 2008
    Messages:
    2,857
    Likes Received:
    2,793
    I think Simon’s post was well written and argued. I enjoyed reading it. No doubt many of these points have been made before but perhaps not in a way that draws them together so effectively. Maybe this is a benefit of the scrutiny Simon’s views have received (peer review, if you like) over several years in this discussion forum.

    If anyone wants to refute Simon’s case why not try writing something as good? No doubt I’ll enjoy it too.
     
    Last edited: Feb 1, 2020
    pete2hogs, MellishR, 60525 and 7 others like this.
  10. Spamcan81

    Spamcan81 Nat Pres stalwart

    Joined:
    Aug 25, 2007
    Messages:
    35,121
    Likes Received:
    20,771
    Occupation:
    Training moles
    Location:
    The back of beyond
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Look on the bright side Ralph, a trawl through this thread will save you the need of buying the book - if it's ever published. :)
     
    Victor likes this.
  11. S.A.C. Martin

    S.A.C. Martin Part of the furniture

    Joined:
    Aug 31, 2010
    Messages:
    5,591
    Likes Received:
    9,325
    Gender:
    Male
    Occupation:
    Asset Engineer (Signalling), MNLPS Treasurer
    Location:
    London
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Given I have often offered Nat Pres members the book entirely free of charge when complete, this seems a little mean.

    You are more than welcome to have a read of the current (and likely final) draft if you so wish. I am happy to share.
     
  12. Spamcan81

    Spamcan81 Nat Pres stalwart

    Joined:
    Aug 25, 2007
    Messages:
    35,121
    Likes Received:
    20,771
    Occupation:
    Training moles
    Location:
    The back of beyond
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Simon,
    Look at the smiley - it was a joke.
     
    jnc, S.A.C. Martin and 35B like this.
  13. S.A.C. Martin

    S.A.C. Martin Part of the furniture

    Joined:
    Aug 31, 2010
    Messages:
    5,591
    Likes Received:
    9,325
    Gender:
    Male
    Occupation:
    Asset Engineer (Signalling), MNLPS Treasurer
    Location:
    London
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Apologies! I can’t see the smiley on this computer. I will take your word for it :)
     
  14. RalphW

    RalphW Nat Pres stalwart Staff Member Administrator Friend

    Joined:
    Sep 11, 2005
    Messages:
    35,445
    Likes Received:
    9,143
    Gender:
    Male
    Occupation:
    Retired-ish, Part time rail tour steward.
    Location:
    Northwich
    Heritage Railway Volunteer:
    No I do not currently volunteer
    OK so a few of you may read every word Simon posts and are no doubt eagerly awaiting the book, but there will be countless few members who are thoroughly brassed off with the never ending stream of minutia concerning Thompson and his acolytes. All we ask is you give it a rest.
     
    Victor likes this.
  15. Jamessquared

    Jamessquared Nat Pres stalwart

    Joined:
    Mar 8, 2008
    Messages:
    26,099
    Likes Received:
    57,414
    Location:
    LBSC 215
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Who’s the “we” in that sentence? You could apply the same logic to endless descriptions of some repeat rail tour - when we’ve read one report, who needs another a week later?

    It’s a discussion forum: no-one is forcing you to read any particular part of it. If you are bored, don’t read this thread, but there’s no reason to thereby imply no-one else should either.

    Tom
     
    ross, pete2hogs, MellishR and 9 others like this.
  16. paullad1984

    paullad1984 Member

    Joined:
    Oct 16, 2007
    Messages:
    918
    Likes Received:
    428
    I for one enjoy this thread, Simon's posts are informative and insightful.
     
    pete2hogs, MellishR, Romsey and 4 others like this.
  17. 2392

    2392 Well-Known Member

    Joined:
    Jun 7, 2010
    Messages:
    1,902
    Likes Received:
    1,148
    Gender:
    Male
    Location:
    Felling on Tyne
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Indeed the same remark could/should be levelled at many more responders on this thread no matter how long or short their reply is........
     
    MarkinDurham, jnc and Kylchap like this.
  18. S.A.C. Martin

    S.A.C. Martin Part of the furniture

    Joined:
    Aug 31, 2010
    Messages:
    5,591
    Likes Received:
    9,325
    Gender:
    Male
    Occupation:
    Asset Engineer (Signalling), MNLPS Treasurer
    Location:
    London
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    I find it really sad that you feel that way Ralph.

    I would like to think I have added value to Nat Pres, in as much the good people who have engaged with this thread have helped me (and are thanked in my book accordingly).

    This thread has been brilliant for finding new sources of information, talking out ideas, even finding out new things about the wider railway in general.

    Off the back of this thread I’ve done three lectures, a podcast, articles are being written by others based on my research, we even have the frankly amazing sight of new Hornby Thompson Pacifics to enjoy in future.

    I’m proud of what we’ve achieved in this thread, collectively, over the years. We understand Thompson and Gresley, and the LNER in wartime, far better than before.

    When alls said and done, how can that be a bad thing?
     
    ragl, pete2hogs, MellishR and 8 others like this.
  19. johnofwessex

    johnofwessex Resident of Nat Pres

    Joined:
    Apr 6, 2015
    Messages:
    9,185
    Likes Received:
    7,226
    Gender:
    Male
    Occupation:
    Thorn in my managers side
    Location:
    72
    Heritage Railway Volunteer:
    No I do not currently volunteer
    I have no particular view on Thompson, and matters LNER are, by and large a mystery to me. None the less I find the discussion on the subject fascinating, because of the light it shines on railways in general and the situation in the Second World War.
     
    pete2hogs, Bluenosejohn, jnc and 2 others like this.
  20. S.A.C. Martin

    S.A.C. Martin Part of the furniture

    Joined:
    Aug 31, 2010
    Messages:
    5,591
    Likes Received:
    9,325
    Gender:
    Male
    Occupation:
    Asset Engineer (Signalling), MNLPS Treasurer
    Location:
    London
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    I will find out for you.
     

Share This Page