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P2 Locomotive Company and related matters

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

  1. Coldgunner

    Coldgunner New Member

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    Its been a fascinating journey to watch and contribute my few quid each month to. I really should get along to one of the open days before she is rolled out. The whole process has been fascinating. With new drawings and CAD designs, I can see that speeding up the production of spare parts.

    Is there any news on boiler delivery yet?
     
  2. class8mikado

    class8mikado Part of the furniture

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    Given all industry seems to have capacity issues one imagines work on them has stopped in favour of the original Tornado boiler overhaul, post that there is no pressing need for the boiler to be complete before the rest of the loco is ready to receive it, so next year ?
     
  3. 242A1

    242A1 Well-Known Member

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    The cylinder monoblock looks to be coming along well. The three pieces have been placed together for the first time and I now know what a FaroArm is. Have a look at the a1steam/prince-of-wales page. No news on the valve gear development front yet which is probably the last significant technological challenge.
     
  4. Richard Roper

    Richard Roper Well-Known Member

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    Exciting stuff! I wonder if the P2 Group will be going for spring-loaded poppet valves, or if they have considered desmodromic valvegear?

    Richard.
     
  5. guycarr360

    guycarr360 Part of the furniture

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    If they are going to use Desmo valve gear, they are painting it the wrong colour, It needs to be Ducati Red!!!!!
     
  6. class8mikado

    class8mikado Part of the furniture

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    To my knowledge Poppet valves on steam engines are held shut by the steam chest pressure and only need an action to open them...
     
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  7. 242A1

    242A1 Well-Known Member

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    The first B3 4-6-0s, numbers 6166 and 6168, which were converted to poppet valves were fitted with valve springs. These tended to weaken and break because of their exposure to high temperature superheated steam.

    Engines 6164 and 6167 were converted to poppet valves in 1938 following a reappraisal of the gear fitted to the original pair of conversions. A number of improvements were made and these included the elimination of the springs and the use of steam operated valves. There was a period of test running of this pair of engines while working from Woodford where the Shed-master is described as enthusiastic. The results of all this recording have sadly vanished, swept away by the needs of wartime. This pair of engines were well thought of by those who used them, particularly in their early days.

    So some poppet valve fitted engines were fitted with valve springs but steam operated types proved to be superior.
     
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  8. 30854

    30854 Resident of Nat Pres

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    Not an issue I was aware of, so many thanks for highlighting it. Is much more detail known? Were these springs precisely specified or was this an 'early days, off the shelf' feature of the design? Is this an area where today's materials (and computer modelling of the design concept, for that matter) be able to cope?

    I'm reminded of Kevan Ayling's problems with high pressure steam supply to the bogies on his 5in gauge BR(S) Class 36xxx (see what I did there?). Reinforced pipework to withstand pressure wan't an issue, not so handling temperature. The original pipework melted!
     
  9. clinker

    clinker Member

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    I'd be inclined to think that the springs, rather than being 'Valve Springs' in the accepted sense would have been more of an 'Anti Rattle' type of arrangement. If You consider the difference between I.C. inlet poppet valves, opening against 'Suction' and steam inlet poppet valves opening 'against' pressure just imagine if the inlet steam entered 'Under' the valve the size of spring required to hold the valve closed, not to mention closing the valve afterwards, would need to be heavier than a safety valve spring. I have been involved with Sentinels and have run one without valve springs simply to prove the point, if only to Myself.
     
  10. Sheff

    Sheff Resident of Nat Pres

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    AFAIK there are springs involved, unlike British Caprotti, but I can’t swear to it, it’s been a while since I studied the Franklin B gear.


    Sent from my iPad using Tapatalk
     
  11. 242A1

    242A1 Well-Known Member

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    Paxman obtained a licence to use the inventions of Dr. Hugo Lenz probably in 1907 because this is when it started building Paxman-Lentz steam engines and in 1923 Paxman started to promote Lentz valve gear for locomotive use. Quite when Associated Locomotive Equipment came into the equation is rather uncertain. To further confuse matters there exists a reference to The Paxman Loco Valve Gear Company dating to 1924 then the equipment orders are recorded as Lentz Patents Ltd and the last entry in the Paxman order books is dated 21st November 1928 but the LNER continued to fit Lentz valve gear until 1934. Caprotti Valve Gears Ltd had the same address as Associated Locomotive Equipment, 66, Victoria Street, London SW1 and it looks like the Caprotti company acquired the Lentz business. I assume that the valve gear and equipment supplied by Paxman was fully in accordance with the requirements of the licence. There might be more information out there but I have not come across it yet.

    Back to the subject of the monoblock, we can say that we have one since the three sections that make up the assembly have now been tack welded together.
     
  12. 30854

    30854 Resident of Nat Pres

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    According to this .pdf (download), there are. They're what I'd describe as equalising springs, below the camshaft and between cam follower jockey brackets (hope that's what they're called .... see diagram in .pdf)
    https://www.theduke.uk.com/wp-conte...14/09/The-British-Caprotti-Valve-Gear-v02.pdf
     
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  13. Richard Roper

    Richard Roper Well-Known Member

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    I was thinking more on the lines of Norton Racing Silver. Think it was the '62 Manx 30M which had a desmo head. Silver, lined out black and red, would look lovely!

    Richard. :)
     
    Last edited: Jun 23, 2022
  14. guycarr360

    guycarr360 Part of the furniture

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    You would need another tender to carry the required oil, that would leak on a decent run!!!
    Any stop would see the support crew out with hazmat suits, and oil trays to catch the leakage!!!
     
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  15. Richard Roper

    Richard Roper Well-Known Member

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    I managed to sort the chaincase leak on my 650SS ... The engine was lovely and dry too, thanks to Red Hermetite!

    Richard.
     
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  16. ghost

    ghost Part of the furniture

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  17. class8mikado

    class8mikado Part of the furniture

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    Impressive Beard....
     
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