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Sir Nigel Gresley - The L.N.E.R.’s First C.M.E.

Discussion in 'Steam Traction' started by S.A.C. Martin, Dec 3, 2021.

  1. Eightpot

    Eightpot Resident of Nat Pres Friend

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    'The issue was never the rigid wheelbase,' - I beg to differ. You cannot run a long rigid wheelbase through sharp curves without something eventually giving way.

    'It was always the pony truck.' - The swing link pony truck was used on the GNR and LNER for 45 years before giving trouble. First used here on the Baldwin built 2-6-0s of 1899 as supplied to the GNR (and the GCR and Midland Railways as well) followed by the Gresley 2-6-0s from 1913 (LNER K1, to K4), the o1 and o2 2-8-0s, and V1 to V4 2-6-2s. Yes, there may have been shortcomings in the pony truck design, but how was it that it took 45 years to discover that they could be prone to derailment? Answer - track condition not maintained due to an accumulation of wartime shortages of material and maintenance availability resulting in derailments at Thirsk, Newark, Hatfield and Marshmoor in the 1944 to 1946 period..

    (As an aside I can recall my Grandmother [who lived in Hatfield] taking me to see the Hatfield derailment just south of the station, access to the site being via an over bridge for a pathway underneath which has long since been filled in and the bridge girders removed.)

    If some flexibility was built into the chassis a Krauss-Helmholz truck could be used which would be pivoted on the leading coupled axle, essentially turning these into a bogie. As far as side play was concerned this would be the equivalent of turning a 2-8-2 into a 4-6-2.
     
    Last edited: Apr 12, 2023
  2. 8126

    8126 Member

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    I'm not convinced it's as as simple as saying that the long rigid wheelbase presents an insoluble problem to ride and track forces with a large-wheeled 2-8-2. Sure, it's easy to be seduced by French mixed traffic Mikados with Italian Zara trucks, or American 4-8-4s with spring controlled sideplay on the first three coupled axles, and they do probably represent a technically superior solution. But equally, there were quite a lot of large wheeled 4-8-2s (in France, for example) with large coupled wheel diameters and no sideplay in the coupled wheelsets at all. Now you might say that of course these have leading bogies, which are superior to pony trucks, and this is also true. But equally, there were quite a lot of large-wheeled 2-8-4s built, particularly in Eastern Europe following the Austrian 214 design, and most of them did not had Zara trucks, Krauss-Helmholtz leading axles or equivalent, while being allowed a maximum speed of 120 kph. So, provided the penalty in curve radius could be accommodated, a rigid wheelbase, large-ish diameter 8-coupled design with a pony truck was definitely shown to work.

    Even in Britain, I'd argue that there are other examples of side-control provision being thought to be adequate up until either the design got heavier or the track got worse. Look at the River tanks; fine on the ECML but not on the Southern, and yet they had exactly the same wheelbase and pony trucks as the U-class into which they were rebuilt. Side control was fairly poorly understood in Britain for a lot of the steam era, arguably up until various LMS personnel were involved in the investigation into the riding qualities of Indian Pacifics which had been derailing with alarming frequency. The Rivers would probably have been fine with a better pony truck, and I am confident that the P2 can also be made to behave. Swing link trucks are mechanically quite elegant in some ways, but the inherent requirement for them to lift the front end does put some additional demands on the springing of the coupled wheelbase. Without full compensation, they do add a potential issue, no matter how many smaller and less demanding designs coped.

    As a side note, I will mischievously argue that the A1s were probably on the edge of the envelope for the bogie which served the Gresley Pacifics very well. It seems to be fairly well established that, for all their many virtues, the Peppercorn Pacifics were not in the first rank of British Pacifics when it came to ride quality, even when in good condition. It was said of them in BR service and when Tornado did its 100mph run the crew even said to camera that it was a bit lively, or words to that effect, somewhat unlike KentYeti's description of 35003 at over 100mph in this post. So at least, having thoroughly instrumented Tornado at speed rather than a nice smooth A4 like Bittern on its 90mph runs, the P2 Trust are setting a more attainable comparison for 2007.
     
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  3. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Whilst that is true, the Vampire analysis from Delta Rail for the P2 Trust indicated that the change of pony truck would improve the running significantly. Having a longer coupled wheelbase actually improves the ride quality on straight track, and if properly transitioned through curves, you don't get issues such as extra wear and tear and potential for damaging crank axles/axle boxes and middle big ends, let alone the track.

    It had been recognised as a problem for around twenty years, actually. The issues were at their greatest at high speeds (above 60mph), something that was rarer for the medium sized and smaller locomotives fitted with it. With the V2s, they did more regular turns at high speed (as did the P2s) and both classes had issues arising from the pony truck design. The Stanier/Thompson derivative was introduced after derailments had occurred as a result of the pony truck for the first time. One of those occasions where I feel the L.N.E.R. should have done something much earlier.

    The problem with that analysis (my apologies) is that Tornado (and the original A1s in fact) are/were fitted with the Thompson/Peppercorn bogie, which is in fact a different design to the Gresley bogie.
     
  4. MellishR

    MellishR Resident of Nat Pres Friend

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    Anyone able to answer my questions?
     
  5. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Yes, I am writing a response. Sorry it's been a bit manic this week.
     
  6. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    So this may or may not be lost to the annals of history, but many secondary sources actually put the emphasis for an eight coupled locomotive at the door of Oliver Bulleid, who was working directly for Gresley at that time and was overseeing a number of projects, including the P2 and W1. The traffic department in Scotland requested a locomotive capable of taking a 550 ton trains.

    Unsurprising (to me at least), the Pacifics had always been capable of pulling up to 600 ton trains from their earliest incarnation, but the older types were pushed harder until converted to A3s or replaced by A4s. The simple answer is: the drivers adapted and the requirement for a P2 to do the work disappeared.

    I am aware of the argument that some of the issues of the P2s was the change of engine midway, which I understand but remain sceptical on. The Pacifics were able to run on unhindered without change. That suggests the P2s were being deliberately limited in mileages - why? Did the traffic department recognise a propensity for failure earlier than intended? Who knows. Either way, Pacifics and six coupled locomotives took over their duties post war and no one clamoured for an eight coupled locomotive again.
     
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  7. MellishR

    MellishR Resident of Nat Pres Friend

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    Many thanks for that.
    What it seems to boil down to is that the P2s seemed a good idea at the time but were found in practice to have some issues, and that the job didn't actually need 8-coupled locos anyway. So Thompson certainly made a right decision, though there could perhaps have been alternative right decisions.
    In the light of your researches, is it becoming any clearer which of the issues supposedly afflicting the P2s were real and which were not?
    Given that Pacifics turned out to be able to do the job that the P2s had been built for, and even to do it better, may I ask your personal motivation for supporting the building of a new (improved) one? (I think mine is primarily aesthetic.)
     
  8. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    The only issue that has turned out to be light on evidence is the claim of “spreading the track” by way of the long fixed wheelbase. Everything else has either been confirmed or turns out to be worse than reported in LNER secondary sources.

    I’ve always been fascinated by the originals and my late grandfather would have loved to have seen one. Just because I am critical of the originals does not mean I can’t see the potential they had. Nor does it mean I don’t have faith in David Elliotts work.
     
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  9. huochemi

    huochemi Part of the furniture

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    Thompson introduced the so-called de Glehn bogie on his Pacifics/B1, which brought the LNER into line with the LMS/SR/GWR, and Peppercorn continued the design on his A1/A2. The distinguishing feature of the De Glehn is the weight transfer by side bearers ("spittoons"), whereas on Gresley's designs the weight transfer was through the bearing around the central pin. The Gresley bogie had to be modified on the A4s to prevent rolling - see Part 2A p.102-3.
     
  10. Hermod

    Hermod Member

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    I wonder is why P2 wheels were designed so big?
    The Pebbercorn A2 with 6feet 2 drivers did (according to audial analysis) eqvivalent to 160mph before disintegrating.
    I have also seen mentioned that MN/BB with 6feet 2 wheels (and three cylinders) often did plus 100mph .
    My second most beatifull railway trip was 1982 going from Edingbourgh to Aberdeen.
    Has there ever on said line been a regular schedule for locomotive (be they diesel or steam)- hauled trains demanding more than 75mph?
     
  11. Spamcan81

    Spamcan81 Nat Pres stalwart

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    The P2 also had 6 feet 2 drivers. According to books I've read, they were not built to speed up the Aberdeen trains but as an attempt to eliminate double heading
     
  12. Hermod

    Hermod Member

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    My question put otherwise:

    Why use 6 feet two inches drivers on an eigth-coupled, three-cylindered locomotive that will never be going faster than 75 mph in revenu service?
    As I remember route was neither flat or straight?
    Five feet drivers would have saved 4 tons unsprung and that is very good for track and four tons more steam making steel is not bad either.
     
  13. 8126

    8126 Member

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    Ah, now you both mention it that does jog my memory somewhat, they basically added limiters to the A4 bogie to stop it rolling too far on the centre bearer? I will stand by the suggestion that the A1 probably provides a less exacting benchmark for the P2 than an the A4 would in terms of ride and dynamic track loading, should there be any issues gaining acceptance.

    The de Glehn bogie wasn't exactly adopted in a universal format elsewhere; the SR version dispensed with the equalised suspension of the GWR/LMS edition and had four individual wheel springs, which I suppose is similar to the arrangement on the Kings, just without the unusual axlebox arrangements. Of course, the vast majority of Southern 4-6-0s still had Adams bogies with equalisers and load transfer through the central bearing. But you're quite correct to say that the side bearers were near universal on later bogie designs.
     
  14. huochemi

    huochemi Part of the furniture

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    The "de Glehn" bogie did not have equalising beams - look at the images of GWR 102-104, they have individual leaf springs and plate frames, similar to the LNER style. The only distinctive de Glehn feature is the weight transfer method. Churchward imported bar frames and equalising beams with a single inverted leaf spring from the practice in the USA.
     
  15. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    This afternoon I submitted my first round editing copy to my publisher and a few of my editors. If there's anyone on the forum who'd like to read it and provide feedback ahead of printing, please drop me a line - as with the Thompson book, we'll add your name to the special thanks page.
     
  16. Jimc

    Jimc Part of the furniture

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    Holcroft refers to side bearing bogie or french type rather than de Glehn type and is clear the design developed by adapting the older GWR design from swing links to the spring control. Cook doesn't use the name de Glehn either, not sure where that came from.
     
  17. huochemi

    huochemi Part of the furniture

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    I think Ossie Nock is the culprit - see e.g. Stars Castles and Kings - see Chapter 4 on the Stars where a drawing is labelled "The De Glehn-Swindon bogie". The bearers for the weight transfer arrangement used on the De Glehn compounds were more inboard than the GWR arrangement. I do not know whether coil spring side control springs had been used previously anywhere, but the GWR arrangement was a bit more elegant with springs tucked discreetly in front of and behind the sliding central block. Bulleid reverted to the "De Glehn" arrangement (where the spring housing looks like it could give you a nasty bash on the ankle) which may have been copied from the Lord Nelson bogie.
     
  18. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Question for the floor.

    Is it Cartazzi or Cortazzi?

    One of my editors has stated it should be the latter. I can see that F.J. Cortazzi was the designer of the Cartazzi/Cortazzi arrangement, but literally every single secondary source (including a book by that editor) states "Cartazzi" in preference of "Cortazzi". It's even "Cartazzi" on LNER drawings.

    I realise this is a minor thing in the overall scheme of things but I really want to get things right.
     
  19. Fred Kerr

    Fred Kerr Resident of Nat Pres Friend

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    Looking at discussions on the speed / track profile of the Edinburgh - Aberdeen route with regard to the P2 I wonder what consideration - if any - was given to the track especially between Edinburgh and Dundee where the many coal mines of the area would be passing below the main line hence adding instability to the infrastructure. Whilst not causing any track spread the axle weight would be a critical parameter of any performance hence my curiosity asto how much allowance was made for this factor in any locomotive designs for traversing the 60 miles between Edinburgh and Dindee - perhaps even explaining a need for locomotive changes at Dundee ?
     
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  20. MellishR

    MellishR Resident of Nat Pres Friend

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    This page https://www.steamindex.com/people/engrs.htm#surca sheds a small glimmer of light.
     
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