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The 10A Allocation

Discussion in 'Steam Traction' started by GWR4707, Apr 8, 2019.

  1. huochemi

    huochemi Member Friend

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    According to the RAIB report, the original design of gudgeon pin and those manufactured on restoration were both 3" diameter by 8 tpi. I think the reference to the coarse thread is because of the decision to use a castellated nut which was highly likely to mean that the (rather massive) preload on the gudgeon pin nut could not be accurately applied, as the final position was dictated by the castellations (one suspects that even with a 10 or 12 tpi thread, the same issue could have occurred). The SR design used a plain nut. The report mentions that castellated nuts were used on BR and LMS locos but the design of the little end was different and with a smaller diameter thread on the pin. The report suggests that the restorers may not have had access to original drawings (at least of this component) when rebuilding the loco (I take that to mean they did not have the drawings) which was presumably a learning point. (the work was not done at Carnforth)
     
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  2. jnc

    jnc Member

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    And no doubt there are many (perhaps even more) women who know men like that...

    Noel
     
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  3. std tank

    std tank Member

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    2-1/2" dia x 6TPI on Standard locos.
     
  4. huochemi

    huochemi Member Friend

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    Thanks, so even coarser surprisingly. There must have been some other feature to ensure that the taper was fully drawn into the bore in the crosshead. I guess you could machine the nut (or washer if there is one) until it fits exactly.
     
  5. Richard Roper

    Richard Roper Member

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    And probably not a few men who know women like that! I know of a few but am thankfully not associated with them!

    But back to Tangmere...

    Richard.
     
  6. Big Al

    Big Al Resident of Nat Pres Staff Member Moderator

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    That point about access to original drawings in restoration is a really important one. Without detailed engineering expertise I won't go into specifics. But I do know via second hand information that the starting point has to be the original pattern. Just because an alternative 'fix' is chosen that appears to work (maybe from a different design or as a generic solution) doesn't mean that this is appropriate for a particular locomotive.

    Of course, over time, design solutions develop and these may be better options but the original design/pattern was there for a reason and you deviate at your peril.
     
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  7. std tank

    std tank Member

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    Your last sentence sums the situation up.
     
  8. Spamcan81

    Spamcan81 Resident of Nat Pres

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    Indeed. Damned autocorrect.
     
  9. mike1522

    mike1522 New Member

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    An update on Galatea would be appreciated. Glad Leander was out yesterday. Thanks
     
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  10. Johnb

    Johnb Resident of Nat Pres

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    If you look at Tangmere’s overall record it was pretty good
     
  11. Fred Kerr

    Fred Kerr Part of the furniture

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    A feature not confined to steam traction. As a typical example the preserved Class 14 fleet is increasingly becoming less standard as owners make modifications to their locomotives to meet their operating needs but - as not all operating conditions are identical - the solutions have tended to move away from any "standard" designs; add in the (usual) lack of drawings or technical documentation and the possibilities of (expensive) damage becomes a greater possibility.

    In terms of steam locomotives I am reminded of the recent problems of metal specifications where IIRC the certified metal quality disagreed with the actual quality leading to locomotive failures - proving that maintenance repair and overhaul of steam traction is a responsibility not to be taken lightly.
     
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  12. jnc

    jnc Member

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    Did someone in the supply chain make a mistake, or was there skulduggery? (Fraudulent materials/marking has become quite a problem in the aircraft world.)

    Noel
     
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  13. std tank

    std tank Member

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    Is this about the copper that was used for stays, but was later found to have no arsenic in it?
     
  14. Richard Roper

    Richard Roper Member

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    I remember from earlier discussions on Nat Pres - The quality of some metals being imported is suspect, because the material is being falsely certified, ie. falsified documentation is being produced and sent out from the Far East with steel shipments. If I remember correctly, material has been bought legitimately, but has been found to be of a specification other than that which it should be according to the paperwork.

    Just found the link -
    https://www.national-preservation.c...tion-falsified-in-japan.1022062/#post-1952203

    Richard.
     
    Last edited: Apr 15, 2019
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