If you register, you can do a lot more. And become an active part of our growing community. You'll have access to hidden forums, and enjoy the ability of replying and starting conversations.

Bulleid Pacifics - Past or Present

Тема в разделе 'Steam Traction', создана пользователем 34007, 13 май 2008.

  1. Cosmo Bonsor

    Cosmo Bonsor Member

    Дата регистрации:
    10 дек 2014
    Сообщения:
    221
    Симпатии:
    501
    Пол:
    Мужской
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    A couple of points about the engineering if I may.

    The idea of the chains ‘elongating’ rather than stretching is confused by the terminology. It is a particular feature of Morse chain, a type of silent chain. It is correct that wear in the pins and links will cause the pitch, that is the distance between the centres of pins in a link pair to increase. This is true of a roller chain, think bicycles etc. The difference, is that as the chain wears and the links move further apart, they follow the teeth of the gears, so that although there is now a gap at the bottom of the teeth on the gear wheel, the teeth on the inside of the links are still meshing nicely with the gear teeth. The chain meshes with the gear in the way that gears mesh together. Motorcycle engines have a version of these chains, commonly driving the camshaft(s) and sometimes the primary gearbox shaft. A roller chain just gets sloppy and loose when it wears and meshes badly. That’s why a worn bike chain is noisy. Look at a bike with a worn chain if you can, to see what I mean. I can’t find any pics as evidence yet, sorry.

    As for cardan shafts, the drive would have needed two shafts, each with two universal joints, assuming they followed the route of the chains. I can’t see another way of connecting them to the crank and valve gear shaft other than with bevel gears. The arrangement for the crank would be like a live axle on a lorry. The idler shaft would need two sets of bevel gear to go round the corner. Were the bearings in the original design rolling element type or plain? The more expensive and in wartime scarce roller bearings would mean that the lost motion remains constant for a long time and can be allowed for in the design.

    I’d love to see the original layout with shafts, if it exists.

    Lastly, the wheels. They are not a boxpok wheel as is frequently stated. They are a wobbly web wheel, a type of disc wheel. I have seen then called a wavy wheel as well. GIYF here.
     
    Steve, Copper-capped и S.A.C. Martin нравится это.
  2. 5944

    5944 Resident of Nat Pres

    Дата регистрации:
    14 янв 2006
    Сообщения:
    8.862
    Симпатии:
    9.257
    Пол:
    Мужской
    Род занятий:
    Train Maintainer for GTR at Hornsey
    Адрес:
    Letchworth
    Heritage Railway Volunteer:
    No I do not currently volunteer
    Leader or Livery? ;)
     
    35B и Spamcan81 нравится это.
  3. Spamcan81

    Spamcan81 Nat Pres stalwart

    Дата регистрации:
    25 авг 2007
    Сообщения:
    35.831
    Симпатии:
    22.269
    Род занятий:
    Training moles
    Адрес:
    The back of beyond
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Not boxpok as you say. Bulleid Firth Brown (BFB) is the official designation is it not.
     
    S.A.C. Martin, Richard Roper и Big Al нравится это.
  4. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

    Дата регистрации:
    30 май 2009
    Сообщения:
    22.589
    Симпатии:
    22.715
    Адрес:
    1016
    Heritage Railway Volunteer:
    No I do not currently volunteer
    I mean nothing with this comment other than to think creatively about this GSN project.

    There are already examples of Bulleid's original design so actually what is being created is not unique. Whilst, of course, there is no original Merchant Navy, were you to change the number and nameplates on, say 257 Squadron, whilst also adding s few of the cosmetic original differences, you would be hard pushed to spot that it wasn't a MN.

    Given the extent of this rebuild to my mind it would be a missed opportunity not to tweak the work to take account of what may be possible or desirable now compared with 70 years ago.

    Have nothing in mind but when you have purists wanting one thing and engineers wanting something else, I know which way I would lean, shareholders or not.
     
    MellishR и 26D_M нравится это.
  5. 35B

    35B Nat Pres stalwart

    Дата регистрации:
    18 июн 2011
    Сообщения:
    28.731
    Симпатии:
    28.657
    Пол:
    Мужской
    Адрес:
    Grantham
    Heritage Railway Volunteer:
    No I do not currently volunteer
    Both? And I think I got away with a reference to the former…


    Sent from my iPad using Tapatalk
     
  6. Copper-capped

    Copper-capped Part of the furniture

    Дата регистрации:
    19 апр 2017
    Сообщения:
    3.350
    Симпатии:
    4.071
    Пол:
    Мужской
    Адрес:
    Stanthorpe, QLD, Australia
    Heritage Railway Volunteer:
    No I do not currently volunteer
    You make it sound like the Voldemort of locomotives - do not speak its name! For those who have not come across it before, there is a wonderfully readable thread on here dedicated to that particular engine:

    https://national-preservation.com/threads/bulleid-leader.1417852/
     
  7. ghost

    ghost Part of the furniture

    Дата регистрации:
    29 май 2006
    Сообщения:
    4.303
    Симпатии:
    5.727
    Пол:
    Мужской
    Адрес:
    N.Ireland
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    If that is true, then surely changing to cardan shafts or gears would also be unnoticeable while adding great cost in design, manufacture and getting approval for what would be a new design? What would be the point?
     
  8. MellishR

    MellishR Resident of Nat Pres Friend

    Дата регистрации:
    16 апр 2009
    Сообщения:
    8.911
    Симпатии:
    5.847
    The point would be only to produce what Bulleid had wanted to produce. I agree that it would involve more design work, but that is far easier nowadays with CAD than it was in the 1940s. Would manufacture be much more complicated? Getting approval is a complex and demanding process for any loco to be newly introduced on the main line. Would the choice of valve gear make much difference?

    N.B. I accept that it won't happen, but this forum is full of WIBN ideas.
     
    srapley нравится это.
  9. Jamessquared

    Jamessquared Nat Pres stalwart

    Дата регистрации:
    8 мар 2008
    Сообщения:
    27.790
    Симпатии:
    64.454
    Адрес:
    LBSC 215
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    The one thing we really know Bulleid wanted to produce was a 2-8-2. That might require even more fundamental re-working of 35011!

    Tom
     
    Chris86, srapley, MellishR и ещё 1-му нравится это.
  10. 30854

    30854 Resident of Nat Pres

    Дата регистрации:
    8 мар 2017
    Сообщения:
    12.172
    Симпатии:
    11.496
    Пол:
    Мужской
    Род занятий:
    Retired
    Адрес:
    Brighton&Hove
    Heritage Railway Volunteer:
    No I do not currently volunteer
    I'm curious ..... Does that translate as we won't be building a pacific, or we won't be building the 2-8-2 originally posited OVSB? :)
     
  11. S.A.C. Martin

    S.A.C. Martin Part of the furniture

    Дата регистрации:
    31 авг 2010
    Сообщения:
    5.615
    Симпатии:
    9.418
    Пол:
    Мужской
    Род занятий:
    Asset Engineer (Signalling), MNLPS Treasurer
    Адрес:
    London
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    He did build a 2-8-2 though, just for another railway company...
     
  12. twr12

    twr12 Well-Known Member

    Дата регистрации:
    2 сен 2007
    Сообщения:
    1.658
    Симпатии:
    820
    Considering that there is 45 gallons of gear oil flying about in a Bulleid Pacific “oil bath”, there is very good or excellent lubrication to everything; including the 2 Morse chains.
    Any wear to the valve gear chains would have been at a very slow rate, and the chains can be adjusted by the movable intermediate gear anyway.
     
  13. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

    Дата регистрации:
    30 май 2009
    Сообщения:
    22.589
    Симпатии:
    22.715
    Адрес:
    1016
    Heritage Railway Volunteer:
    No I do not currently volunteer
    Yes, and all that oil soaked the cladding and started fires (other than in the firebox). But, of course, for a heritage loco the meticulous maintenance should remove that particular concern.
     
  14. twr12

    twr12 Well-Known Member

    Дата регистрации:
    2 сен 2007
    Сообщения:
    1.658
    Симпатии:
    820
    A few Bulleid’s in preservation have lightweight steel sheeting on the underside of the boiler barrel to stop oil getting to the insulation.

    Besides, any oil being thrown around by the BFB wheels, isn’t from the oil bath anyway. It’s axlebox oil from the top feed axlebox lubrication running down the inside of the wheels and collecting in the pockets.
    Obviously with spoked wheels, overflowed axlebox oil just runs down the spokes.
     
  15. 30854

    30854 Resident of Nat Pres

    Дата регистрации:
    8 мар 2017
    Сообщения:
    12.172
    Симпатии:
    11.496
    Пол:
    Мужской
    Род занятий:
    Retired
    Адрес:
    Brighton&Hove
    Heritage Railway Volunteer:
    No I do not currently volunteer
    Can I assume you mean in the same way that F.V. Russell built the GER S69? :)
     
  16. MellishR

    MellishR Resident of Nat Pres Friend

    Дата регистрации:
    16 апр 2009
    Сообщения:
    8.911
    Симпатии:
    5.847
    You'll be building what you intend to build, which is your privilege. A MN more or less the same as first built by the SR, with a few tweaks.
     
  17. Dave Williams

    Dave Williams New Member

    Дата регистрации:
    29 мар 2021
    Сообщения:
    23
    Симпатии:
    26
    Пол:
    Мужской
    Адрес:
    Devon
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Just for info this general arrangement drawing is of the first batch of ten MN valve gear. It was used in all subsequent publicity.
     
  18. srapley

    srapley New Member

    Дата регистрации:
    27 июл 2008
    Сообщения:
    78
    Симпатии:
    103
    Род занятий:
    Aerodynamicist (by day)/CME 35011 (spare time)
    Адрес:
    Burton-on-Trent
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    The oil fires were predominantly due to two things that weren't the oil bath: the oil from the lubrication of the axle boxes pooling in the BFB pockets when stationary and then being flung up onto the underside of the boiler & it's lagging, and then when the loco was braking, sparks from the brake blocks igniting it. The former is something that is a still present risk, the latter was mitigated by BR in the 1950s by a change of brake block material that created less sparks under braking. More cleaning under heritage conditions should also help as you say
     
  19. Allegheny

    Allegheny Member

    Дата регистрации:
    8 май 2015
    Сообщения:
    637
    Симпатии:
    311
    Пол:
    Мужской
    Heritage Railway Volunteer:
    No I do not currently volunteer
    Although a worn chain will still clearly provide drive to the valvegear, it will also introduce a timing error to the valve operation. I think this was the main point of concern.
     
  20. S.A.C. Martin

    S.A.C. Martin Part of the furniture

    Дата регистрации:
    31 авг 2010
    Сообщения:
    5.615
    Симпатии:
    9.418
    Пол:
    Мужской
    Род занятий:
    Asset Engineer (Signalling), MNLPS Treasurer
    Адрес:
    London
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    No idea to be frank! Bulleid was a prominent member of Gresley's team that built Cock O' The North, the Gresley P2 2-8-2 prototype, and even travelled with the locomotive to France for its testing there. It is notable in the primary evidence that Bulleid deputised for Gresley quite often when reporting back on this prototype.
     

Поделиться этой страницей