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Midland double-framers and the Gronk...

Discussion in 'Steam Traction' started by BrightonBaltic, Dec 10, 2019.

  1. BrightonBaltic

    BrightonBaltic Member

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    I once heard a bit of idle chit-chat suggesting that the early LMS/EE Gronks were based on a steam bottom end, possibly a Kirtley well-tank? Is there any truth or substance to this, or is it so much Scotch Mist?

    I did discover in my searchings earlier that one Johnson Half-Cab was converted into a diesel, unsuccessfully.
     
  2. Richard Roper

    Richard Roper Well-Known Member

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    Interesting - That the early Gronks were built using steam bottom halves is considered antiquated, but the thought of a Kirtley curved double-framed Gronk would have been seen as the ultimate in parsimony! It might have looked nice though!

    Richard.
     
  3. BrightonBaltic

    BrightonBaltic Member

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    So were the early Gronks steam-based then? Or did they just reuse wheelsets at most?
     
  4. jsm8b

    jsm8b Part of the furniture

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    Evolution ?
    I'm sure the tale about steam bottom halves only relates to the earliest experiment.

    12003 (LMS 7080), 12065 and D3791 -- all at Walton Old Jct, Warrington.

    12003 (7080) (sorry Kodak 127 Brownie) was the first of the 30 jackshaft driven shunters & D3791 became 08624 latterly still in action with Freightliner
    Apparently LMS 7069 also survives but never carried a BR number





    Street cred totally gone now :eek:



    32bn60sa010 Shunter 12003 Walton Old Jct 1967.JPG neg 002 12065 Walton Old Junction 1969 ?.jpg 32bn69b2027 D3791 Walton Old Jct 080869.JPG
     
  5. Martin Perry

    Martin Perry Nat Pres stalwart Staff Member Moderator Friend

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    I believe that it had a lot to do with the size of the available traction motors at the time, and their inability to fit between inside frames.
     
  6. LMS2968

    LMS2968 Part of the furniture

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  7. 240P15

    240P15 Well-Known Member

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    Thanks for the link LMS2968.:) That was a relly interesting looking locomotive!

    Knut
     
  8. Cartman

    Cartman Well-Known Member Account Suspended

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    Yes and it kept the same number because it was officially classed as a rebuild, although a bit of a drastic one! The wheelbase of a gronk is much shorter than of a midland 0-6-0 as they all had an 8 foot plus 8 foot 6 coupled wheelbase.
     
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  9. MellishR

    MellishR Resident of Nat Pres Friend

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    That loco looks as if it had a rigid coupling rod between two of the driving wheels with the jackshaft in the middle, but that would surely not be able to accommodate vertical movements of the axles. How did it work?
     
  10. BrightonBaltic

    BrightonBaltic Member

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    I did mention the Johnson half-cab that became a diesel, but I had understood that the 08 frames and wheelsets or designs for same were originally from a steam loco?
     
  11. CymruGarratt

    CymruGarratt New Member

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    I don't know if someone was pulling my leg, but I was told that the frames of the Paxman D95XX diesel hydraulics were modified Dean Goods chassis.
     
  12. Steve

    Steve Resident of Nat Pres Friend

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    I’m fairly certain that the crankshaft drove the rod through a floating bearing that allowed the rod to move vertically with regard to the crank pin.
     
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  13. Fred Kerr

    Fred Kerr Resident of Nat Pres Friend

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    Not quite; I was told by Chris Bailey (involved with D9531 / 37) that he had identified the bottom end as being based on the GWR 94xx chassis.
     
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  14. Fred Kerr

    Fred Kerr Resident of Nat Pres Friend

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    The Class 08 was an amalgam of 2 prototype designs; the Armstrong Whitworth design with Sulzer engines and jackshaft transmissions (7059-68) and the English Electric design with English Electric engines and transmissions (7069-78) which were combined in further LMS orders for 7069-79 based on the Armstrong Whitworth mechanical portion and the English Electric drive train. Despite this development further orders were placed for locomotives fitted with jackshaft drive (7080-7119) but English Electric engines; some subsequently entered wartime service with the War Department and returned to the LMS after the war ended hence the batch of 30 surviving locomotives becoming BR 12003-12032. The English Electric design was perpetuated by the LMS, initially for War service with the Ministry of Supply, and 13 were returned to the LMS to subsequently became 12033 - 12044 whilst the LMS / BR built 12045 - 12102 and Darlington built 12103 - 12138 to the same design for Eastern and North Eastern depots.

    The English Electric design was then modified and the "standard" Class 08 entered service from 1953 although, initially, 3 variants were introduced using (i) standard English Electric engines (ii) D3117-3126 with Crossley engines and Crompton Parkinson traction motors that became the original Class 09 but were withdrawn before receiving the designation (iii) various batches built by Darlington and Doncaster Works with Blackstone engines and GEC traction motors for Eastern Region depots that became Class 10; a small batch (D3152-3166) was fitted with BTH traction motors but these were withdrawn in 1967/68 before the introduction of TOPS.
     
  15. LMS2968

    LMS2968 Part of the furniture

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    Yes, the jackshaft pin works in a vertical slot in the coupling rod to allow for vertical movement. The thrust from the jackshaft is therefore longitudinal only.
     
  16. Steve

    Steve Resident of Nat Pres Friend

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    Do you really believe that? I'd say about the only thing they have in common is that they both have six wheels and plate frames, both totally different in design. They may have been designed to do the same jobs but I'd say that's where the similarity ends.
     
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  17. Martin Perry

    Martin Perry Nat Pres stalwart Staff Member Moderator Friend

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    The Dean Goods/57xx/2251/94xx chassis were all pretty similar anyway?
     
    Last edited: Dec 11, 2019
  18. Jamessquared

    Jamessquared Nat Pres stalwart

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    Without doing a detailed comparison, a 94xx has 4' 7.5" drivers; and a D95xx has 4' 0" drivers. If nothing else, that difference in size would require significant changes to the chassis. And that's before you get to the point that a steam loco has cylinders to brace the front, and a motion bracket half way along its length, whilst a diesel presumably needs completely different arrangement and position of stretchers because the mechanical layout (and how it all fits) will be completely different.

    The 94xx / D95xx chassis "equivalence" seems to be one of those things that has acquired the status of latter-day enthusiast myth, which has become accepted by repetition, without anyone thinking about primary source.

    Tom
     
  19. 5944

    5944 Resident of Nat Pres

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    The overall coupled wheelbase is the same, 15' 6", but that's it. Different wheel spacing, extra cut out for the drive crank, 18" longer frames on a D95xx, completely different size and shape. Wouldn't surprise me if the frames of the diesel were thicker too. Other than being made at Swindon, there's not a lot of similarity.
     
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  20. MellishR

    MellishR Resident of Nat Pres Friend

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    Thank you both. That makes sense and explains the shape of the coupling "rod" with a deep section in the middle. Presumably that seemed better than conventional jointed rods which would have been very short.
     

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