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P2 Locomotive Company and related matters

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

  1. JMJR1000

    JMJR1000 Member

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    From what I've gathered on the well reported weaknesses of the class, the frames (along with the leading pony truck) were the most notable flaws in the P2's design, so it doesn't surprise me that the frames have had to be given possibly the biggest changes to the design.

    It's a fact like this that reminds me just how interesting a project like this is, where the design of locomotive their building, unlike say the A1s, was notably flawed yet had great potential if corrected to be a highly successful one. We've seen a situation like this before with Duke of Gloucester and a similar process is happening with the new build Clan class, Hengist, but the new build P2 has to be the boldest undertaking down this particular path we've seen yet, if ever.
     
  2. Pesmo

    Pesmo Member

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  3. Foxhunter

    Foxhunter Member

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    The update has been revised to read 2013! That's more likely.... the CAD drawings are hot off the press and show how much work David Elliott is putting in to sorting out the known flaws in the design:

    [​IMG]

    The grey parts are almost identical to the original design being principally the main frame plates. The only significant change to them is the plate thickness, eg 30mm today instead of 1 1/8" in the originals.
    The green parts are where A1 Tornado design will be incorporated and includes, roller bearing cannon/axle boxes and hornblocks with manganese steel liners. The whole of the rear frame area under the cab and firebox where the original design has a dished section in the inner frames to clear the bosses of the Cartazzi wheelsets (in common with Gresley A1/A3 classes). For the later Thompson and Peppercorn Pacifics, the dragbox was made narrower and the set in the frames moved forwards to avoid the need for the dished frames.
    The profile of the rear inner and outer frames are modified to make extra space to take the A1 style hopper ashpan.
    The yellow components are original P2 design which requires minor modification, for example spring hangers which all alteration to clear the longer roller bearing hornblocks.
    The red components are original P2 design which requires significant modification, for example large frame stays which were designed to support vacuum brake cylinders which will need redesign for air brakes, and the front boiler support which will need altering to accommodate the shorter A1 boiler.

    Foxy
     
  4. philw2

    philw2 Member

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    It seems to me that the long wheelbase of the P2 will cause the basic frame to deflect on plan to an extent where metal fatigue through stress is a possibility. Can modern design introduce connections which accept a degree of movement so that these deflection forces are neutralised? The frames would need some sort of telescopic joint with compensation in the motion..
     
  5. 10640

    10640 New Member

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    Adopting the P2/4 designation would also clarify which P2 project was which.

    David
     
  6. MarkinDurham

    MarkinDurham Well-Known Member

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    Agreed.
    But it might confuse the 'normals'?

    Mark
     
  7. class8mikado

    class8mikado Part of the furniture

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    Slightly surprised to see the frames in Grey as i'd heard that ideally they would be cut as one piece, not two, and its likely that they will be cut from the nearest metric equivalent thickness. Perhaps having none of the frames represented 'as original' doesnt present the right picture .... ?
     
  8. Foxhunter

    Foxhunter Member

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    I think you may be right! The angle of the illustration hides the fact that there is no joint between the green and grey sections and I suspect they will be rolled and cut as one as were the frames of 'Tornado'. To colour the frames green might have worried some folk! However, aft of the last driving wheelset the geometry of the frames will follow that of No. 60163 and thus has to be shown as 'new' design. Fascinating stuff.

    Foxy
     
  9. Steamage

    Steamage Part of the furniture

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    Anyone sufficiently interested in supporting this project will either already know about LNER class designations or will be interested to know how they work. All it needs is a small side-bar or pop-up labelled "Design improvements" or "P2/4 - What does /4 mean?" It would also be good to describe how the other 3 sub-class differed, to make the evolution clear.
     
  10. 21B

    21B Part of the furniture

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    Forgive me if I have misunderstood you, but I think the connections which accept a degree of movement are commonly known as springs?
     
  11. class8mikado

    class8mikado Part of the furniture

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    I think it was movement in another plane that was being hinted at...
     
  12. Pesmo

    Pesmo Member

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    If they are building a loco for what is the digital age why not describe it as a P2.1 ? :D

    Okay, okay I will get my coat........
     
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  13. Foxhunter

    Foxhunter Member

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    P2.1! I love it! :rolleyes: A further CAD rendering has been added to the P2SLC site:

    [​IMG]
    This illustrates the fabricated cylinder block (blue) and the V2 pony truck arrangement (purple) - for those of you reading in black and white the purple piece is attached to the red stretcher.....

    Foxy
     
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  14. 242A1

    242A1 Well-Known Member

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    The rear framing takes the form introduced on the A4s, it is well established. The front section of framing is set to the standard width you would expect to find on a Pacific and this overlaps the frame for the driven wheel sets. I was concerned that the Trust would not maintain this feature since the extra lateral clearance it provides could be very useful as an aid for solving the chassis development issue. I wonder if the 1st and 3rd axle will be fitted with a lateral control mechanism?
     
  15. philw2

    philw2 Member

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    I have been giving some thought to the problem of a rigid long-wheelbase loco and have come up with the following:

    Reduce the width over the frames (by joggling) at the position of the rear drivers to allow a degree of sideplay with angled hornguides to give a degree of 'steering' to the rear axle, introduce an automotive type propshaft with univeral joints and differential gearboxes between the third and rear axles and make the rear coupling rods cosmetic only with telescopic joints. Simples.

    I have decided not to patent this idea and offer it to the P2 trust gratis..
     
  16. 10640

    10640 New Member

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    I am confident that the P2 Steam Locomotive Company will achieve engineering solutions to the challenges presented by the coupled wheelbase, but one option not so far posted would be the Kraus-Hemholtz truck, as used on the Ravenglass and Eskdale Railway's River Esk and WHR (ex SAR) NG15s. I'm not sure how this would translate into P2 terms, but the original six locos worked out their time as 2-8-2s on the line for which they were designed, curvature notwithstanding. Given the opportunity to design out problems inherent in the original design, 2007 should do its job, 'straight out of the box', if 60163's 'track record' is anything to go by.

    What could Gresley's design team have done with CAD, computer modelling etc?

    David
     
  17. Sheff

    Sheff Resident of Nat Pres

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    I'm not clear what problems are being alluded to above? The new P2's chassis design has been modelled using state of the art industry standard software and the result accepted by their VAB, so there aren't any problems left to solve?
     
  18. 10640

    10640 New Member

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    I am not saying that there will be problems; perhaps I wasn't clear enough, but I agree with what you say Sheff; others (earlier) seem to have doubts.

    David
     
  19. louis.pole

    louis.pole New Member

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    60163's 'track record' you must be joking! the kettle initially proved to be a real nightmare; seemingly now corrected. Accepted that the chassis of the much simpler A1 has been relatively trouble free but a P2 provides the complexity and hence a perfect opportunity for a multiplicity of problems; not all of which will be solved on the drawing board. In wishing them well I would suggest caution that the chassis will be right first time. I'm confident such technical problems will be overcome but haven't really come to terms with what routes it will work profitably. (A bit like the Night Owl in a way i.e. where's the business case?).
     
  20. osprey

    osprey Resident of Nat Pres

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    I would have thought with today's finite element analysis software and their experience with Tornado, which I assume has been used, a lot of potential problems will have come to light.
     

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