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P2 Locomotive Company and related matters

Discussion in 'Steam Traction' started by class8mikado, Sep 13, 2013.

  1. 46118

    46118 Part of the furniture

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    I cannot find any contemporary evidence that the "LMS sorted Gresley's gear", maybe there is unintended confusion in that Stanier was consulted about bogies, and supplied engineering details of the LMS bogies used under their pacifics. Doncaster adopted the LMS design of side checks on their bogies to give a steadier ride on the LNER engines at speed.
    The only attempt I can see noted to deal with the weakness of the Gresley conjugated gear ( before Cook and his postwar involvement to improve engineering tolerances) was that there was a realisation that at speeds over 75 mph the middle cylinder was developing nearly half the horsepower instead of one third, due to cumulative clearances and whip on the two-to-one levers. The remedy from Doncaster was to increase the middle valve lap by one-sixteenth of an inch to reduce the middle cylinder port opening to steam, thereby trying to equalise the power output of all three cylinders.
     
  2. class8mikado

    class8mikado Well-Known Member

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    Well i thought i'd read pretty much everything that Mr Cox had to offer and missed that snippet, so please advise us all where this is from Mr m&amp. Gresley and Stanier we're known to correspond on a number of ideas both personally and through the 'Institute'. Suggestion of using a more durable material may well have improved matters or may have been considered unwise as harder materials also tend to be more brittle. If the recomendation was never taken up ( any record of this ?) then this hardly constitutes the LMS sorting things out...

    On the matter of Valve gear this would have to be decided at the cylinder casting stage, ie the middle cylinder would be needed to complete the frame assembly so fairly early on. Swallowing the 'normal valve gear' pill may well be something that the P2 people have to do as the pro Walshaerts comments are entirely reasonable. It would open the possibility of a more accurate 'Bolt on' wedge front and possibly an extra livery option ( always handy from the marketing perspective).
    I have every confidence that whatever there is to know about the potential shortcomings of 71000's gear, the A1slt's engineers will be in on it, have considered its merits and what improvements can and therefore should be made
    Perhaps someone at the LMS should suggest using harder materials, that should sort it out !
     
  3. Spamcan81

    Spamcan81 Nat Pres stalwart

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    Of all the books I've read on Gresley and his locos, the only mention I've seen regarding LMS involvement in the derived motion is after Gresley had died, the LNER (at the instigation of Thomson?) sought advice from Stanier. All Stanier was prepared to say was that it was not a design he would use himself but otherwise implied no criticism of the gear.
     
  4. 242A1

    242A1 Active Member

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    I am not anti poppet valve gear per se, but taking on board the latest thinking on the matter of valves and valve gear if there is no discernsble improvement to be gained from the application of a more expensive and less robust system then why on earth think of applying it? YTM.
     
  5. class8mikado

    class8mikado Well-Known Member

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    Well in this case it would a compromise between historical perogative and best available 'equivalent'. Its accepted that BR Caprotti was as good performance and efficiency wise as valve gear got for UK FGS and is a world away from the original Lentz
    Its since been shown that pushing the envelope with Walshaerts/ Piston valves can give equivalent results with less complexity, its even possible to have the Variable inlet outlet control that is the holy grail of valve design which is the strength. in theory of Poppet valve systems but again at the expense of simplicity.
    At the end of the day its not for us to decide, and hopefully it will be cleverer people than I who make the decision;) but if BR Caprotti is not used the big decision is whether to design a seperate set of inside motion , like Thompson/ Peppercorn locos or use the derived Gresley/Holcroft Conjugated like the original (2002 onwards)
     
  6. daveannjon

    daveannjon Active Member

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    Thought I'd read something about this, from Master Builders of Steam by Oliver Bulleid's son H.A.V. (Anthony) Bulleid (p159):

    "...He (Stanier) was called upon for a report on the conjugate valve gear soon after Sir Nigel Gresley's death in April 1941. He had the linkage set out, estimated likely wear at relevant points, and showed the consequent extent of lost motion, thus voting against this arrangement and supporting E. Thompson's case for spending money on the third set of gear." We can probably assume that Thompson commissioned the report.

    In the chapter on Gresley, Bulleid wrote that Gresley had been "enraptured with his conjugated valve gear, and too lightly dismissed the snags." And "if he (Gresley) had been brought in as a consultant to weigh the evidence, he would certainly have voted for a third set of valve gear."

    Master Builders of Steam should be required reading for all steam enthusiasts, Anthony Bulleid had the great advantage of being related to a lot of CMEs so knew the inside track. This is an interesting obit of him from 2009
    http://www.independent.co.uk/news/o...d-the-work-of-amateur-filmmakers-1773181.html

    Dave
     
  7. 242A1

    242A1 Active Member

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    The conjugated valve gear has been contentious for years. True it could give some problems in the early days but mathematically it worked fine. More important it removed the inside cylinder valve gears from between the frames. It also eliminated the eccentric that drove the same. This was felt to be very important since the securing of the eccentric to the axle was a source of stress concentration. And cranked axles could give enough trouble (particularly on the design under discussion but the more so on some earlier types)
    The conjugated gear was fitted with roller/ball bearings. During WW2 these were replaced by plain bearings down to costs and availability.
    Well the gear was grease lubricated, and this part of locomotive preparation was frequently forgotten, it probably didn't need greasing every trip, (though they didn't use Menno cups but Tecalmit) so people being what they are and the times being what they were, you can guess the rest. You try not lubricating a mechanism and see what happens (clocks etc. using lignum vitae are out).
    So, when it came to the inspection and report what exactly was Stanier given to look at? Maybe ET would have been better advised to make sure that the preparation was carried out correctly as opposed to making cheap, self aggrandising capital so soon after HNGs death.
     
  8. LMS2968

    LMS2968 Well-Known Member

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    In one of the books I have (I thought it was Eric Langridge's 'Under Ten CMEs' but can't find it there), Stanier's report (which he delefgated to either Stuart Cox or Roland Bond) was commissioned by Edward Thompson to provide evidence to justify his removal of the conjugated gear and replacement by an independent inside gear. The report examines valve events at various speeds and states of wear and, suffice to say, provided Thompson with the evidence he wanted.
     
  9. class8mikado

    class8mikado Well-Known Member

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    One wonders if the Gresley conjugated gear has been run through 'the geometry software' to see how good it actually is and whether there is scope for a tweak....
     
  10. 61624

    61624 Part of the furniture

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    I seem to remember reading in Roland Bond's book that although the LMS officials prepared the report for Thompson, they had a great deal of respect for Gresley and did so very reluctantly. Unfortunately the book is packed away somewhere so I can't find it to check what he wrote, but I'm sure that's the gist of it.
     
  11. 73129

    73129 Part of the furniture

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    I visited my local model shop a few weeks ago and was told they wouldn't see the P2 until next year now.
     
  12. Jimc

    Jimc Well-Known Member

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    Rather easier said than done under wartime conditions I suspect, even if he actually had the authority over the footplate staff.
     
  13. Spamcan81

    Spamcan81 Nat Pres stalwart

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    Since Gresley's Pacifics outlasted Thompson's, one assumes BR had no undue problems with it. In fact Top Shed used the A4s on top link work right up to the end of steam out of Kings Cross.
     
  14. Foxhunter

    Foxhunter Member

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    With P2 No. 2007 officially launched this morning the P2SLC has launched a new website and FB page:

    http://www.p2steam.com/

    Foxy
     
  15. Brunswick Green 2

    Brunswick Green 2 New Member

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    In my humble opinion the trust would be far better building a second boiler for Tornado than this P2 fantasy. If it ever gets built (allowing for a similar building schedule to Tornado) what are the chances of steam still being allowed to run on the national network? How many heritage lines could accommodate such a loco? Really think this is a step to far as regards new builds.
     
  16. MarkinDurham

    MarkinDurham Well-Known Member

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    As I understand it the boiler will be pretty much identical to the one fitted to Tornado, so there will be the possibility of swaps there. Also, the figure of 70% commonality of parts with 60163 has been mentioned, so many patterns & drawings should already be to hand, saving a lot of time. Differences? Frames - technically straightforward. Wheels? Again, now a straightforward task. Pony truck? Already looked at, I believe, as this was one of the potential 'banana skins' that needed the all clear from the VAB/NR. Valve gear? That one is still the subject of much discussion, but if the safer option of Walschaerts is taken rather than Lenz or British Caprotti then again it's known technology.

    The A1 Trust won't have proposed this without doing some serious investigation into its viability. Good luck to them & their newbuild, 2007.
     
  17. Spamcan81

    Spamcan81 Nat Pres stalwart

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    No offence but I look forward to seeing you proved wrong.
     
  18. m0rris

    m0rris New Member

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    I suspec in terms of 0 to finished, the P2 will be much much quicker than the A1 and other projects. Whilst we've seen a lot of the projects to date come very close to completion, only the A1 guys have a proven track record and the publicity, the rest are getting there but don't have the A1 trust's exposure.

    They have a lot of the patterns, a high profile and popular prototype and a proven track record... Good luck to them, I'll be sending them some of my hard earned IDC.
     
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  19. Jamessquared

    Jamessquared Resident of Nat Pres

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    Quoting http://www.p2steam.com/index.php/2013-09-19-15-12-10/design :

    "The decision to closely follow the pattern set by Cock o' the North means that the locomotive will have the original semi-streamlining and rotary cam valve gear and will look, to all intents and purposes, like No. 2001. " (my emphasis).

    So looks like it's not going to be Walschaerts...

    Given my known predilection for all things small, ancient and Southern, ;-) this is nonetheless one big, modern, Northern engine that I would really love to see in the flesh - especially in semi-streamlined form.

    Edit: though later on the same page, they are a bit more equivocal - that page has the feel of having been mashed together from several articles written at slightly different stages in the thought process...

    Tom
     
  20. MarkinDurham

    MarkinDurham Well-Known Member

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    Yes, there's still a little 'vagueness' about final details of things like the valve gear, hence my own thoughts :) . A final decision on the gear by the Group would seem to be required fairly early on though, looking at the website.
     

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