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.

P2 Locomotive Company and related matters

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

  1. 242A1

    242A1 Active Member

    Joined:
    Dec 3, 2006
    Messages:
    957
    Likes Received:
    347
    The BC gear on 71000 has issues that are quite peculiar in that no one appears to be sure of quite what is going wrong. Piston valves are cheaper and more robust. It would be foolish to encumber a new build with a known weak link. Given appication of the best modern practice there is little, if anything, to be gained from using the BC gear. It may well hinge on costings. Designing new cylinders and then the associated valve gear, making sure it is not going to perpetuate the D of G tradition will be very expensive relative to the cost of refining and building a PV fitted arrangement.
     
  2. 61624

    61624 Part of the furniture

    Joined:
    Sep 27, 2006
    Messages:
    3,531
    Likes Received:
    1,027
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    I was told by David Elliott that it would be able to run anywhere that Tornado could.
     
  3. 61624

    61624 Part of the furniture

    Joined:
    Sep 27, 2006
    Messages:
    3,531
    Likes Received:
    1,027
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Following that argument.though, you re steering the replica down the A4 front route (no bad thing in my view!) as I don't think the first two locos ever had that front end appearance with Walschaerts valve gear.
     
  4. 242A1

    242A1 Active Member

    Joined:
    Dec 3, 2006
    Messages:
    957
    Likes Received:
    347
    2002 was originally built looking like 2001. The softer blast caused safety issues in that the external casing did not create an airflow that would deflect the exhaust clear of the locomotive. So it was not long before deflector plates were fitted. Then came the Bugatti front end which did everything that could be asked of it. 2002 was rebuilt with it and 2003 - 2006 were out shopped from new. The Lentz gear was persevered with for a while with stepped cams giving a limited range of cut-offs giving a poor comparison with the piston valve fitted engines. The Gresley valve gear was pretty well sorted by this time and the clearance volumes of 2001 in its original form could never match those of its more conventional sisters. So if a P2 for the modern network is wanted how do you want to spend the money? How much would you need for either option and how would the decision impact on the production schedule?
     
  5. Jamessquared

    Jamessquared Resident of Nat Pres

    Joined:
    Mar 8, 2008
    Messages:
    12,567
    Likes Received:
    12,688
    Location:
    21C102
    At what point would you have to decide on valve gear?

    Reading this page (admittedly, a page which largely encapsulates my total knowledge of the class....), it states "five more P2 locomotives were ordered [i.e. 2003 - 2007], but with a choice of valve gear left open." Which sort of imples you could go a long way towards construction without having made a final decision: for example, erect frames, construct wheels, even construct the boiler if you chose to structure the project that way; as well as sundry smaller components, before finalising design of cylinders and valve gear. Or is that misguided?

    Tom
     
  6. m&gn50

    m&gn50 New Member

    Joined:
    Mar 17, 2009
    Messages:
    121
    Likes Received:
    8
    Gents I feel sure the Tornado chaps have looked seriously into all the options, of course it was the LMS that sorted out Gresley's gear! The Caprotti is the finest piece of steam engineering but simply needs replacing when it gets worn out- this should be simpler if all new patterns etc are made and retained and a spare set or 3 made, and no-one had quite sorted out the middle cylinder issues of heat/cooling with it unlike the Gresley middle wicket, but again I am sure this has been looked into well. Would you believe the LMS looked into fitting up a Gresley 3 cylinder job post war, though no loco is mentioned imagine a Gresley Duchess of Doncaster!?
     
  7. Raised on steam

    Raised on steam New Member

    Joined:
    Sep 15, 2013
    Messages:
    12
    Likes Received:
    9
    Gender:
    Male
    Location:
    Tyneside
    Fair comment, with plenty of play in the coupling rods to make allowance for its extra pair of drivers it probably will. It would indeed be able to run on the bigger of the heritage lines too. 9Fs can so therefore so could a P2. If the P2 were completed this year or next it'd be a stunning addition to the stud of main line runners. Another lovely LNER one at that (sorry, had to get that in, I'm an LNER fan as I said :)).
    The question I was asking though is SHOULD we be building giants? We don't know what the future situation will be for large locomotives. The P2 was originally intended for heavy express work. If the build is started soon and the engine is with us in say 5 years, do we know how long after that main line steam with loads to justify a P2 will continue? If someone can produce a hard guarantee that main line steam will be safe for the foreseeable future then no problem. Really I think we're lucky to have as much steam presence as we do. As we have seen (in other forum threads) there were major upsets when the recent steam bans were reintroduced and the fact this emphasises is that main line steam is allowed by the grace of those who run the modern rail network and if they decide they've had enough then that's it. That day will come. It has to.
    Tornado is with us now and is doing a sterling job. How many years might the P2 have to do it's rightful and proper job when it finally turns a wheel?
    Unless there is a real guarantee of a future for main line steam isn't it more sensible to maintain and/or new-build engines suited to lighter main line and smaller heritage routes?
     
  8. ADB968008

    ADB968008 Resident of Nat Pres Account Suspended

    Joined:
    Dec 3, 2007
    Messages:
    9,265
    Likes Received:
    761
    Occupation:
    Project Management, Software consulting
    Location:
    London
    Isuggest building the wheels, frames and cylinders (ie bottom end), over the next five years, then as tornado goes out for overhaul, use the rest on the P2, giving us 10 years running a P2 and allowing the Tornado lot to earn funds to build another boiler/ tender etc.
     
  9. 5944

    5944 Part of the furniture

    Joined:
    Jan 14, 2006
    Messages:
    4,152
    Likes Received:
    746
    Gender:
    Male
    Occupation:
    Train Maintainer for FCC at Hornsey
    Location:
    Sandy
    What would compatible between the A1 and the P2 though? Tender and boiler, not a lot else I would've thought. The ideal situation would be two locos and three identical boilers, so the locos would be running almost constantly except for routine maintenance and boiler swaps. But a third boiler is gonna cost a few quid!
     
  10. Dan Hill

    Dan Hill Well-Known Member

    Joined:
    Aug 1, 2008
    Messages:
    2,034
    Likes Received:
    114
    Occupation:
    Brick Machine Operator
    Location:
    Haywards Heath
    Supposedly the A1 and the P2 share 70% commonality of parts. Mind you the A1 Trust did have the idea of getting another boiler but can't remember if that was pre or post P2 announcement.
     
  11. 61624

    61624 Part of the furniture

    Joined:
    Sep 27, 2006
    Messages:
    3,531
    Likes Received:
    1,027
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    I'd have thought that the obvious thing to do is make the boiler first so it can be used to keep 60163 running - and earning - whilst the rest of the P2 is built.
     
  12. 242A1

    242A1 Active Member

    Joined:
    Dec 3, 2006
    Messages:
    957
    Likes Received:
    347
    [quote=" The Caprotti is the finest piece of steam engineering but simply needs replacing when it gets worn out- this should be simpler if all new patterns etc are made and retained and a spare set or 3 made, and no-one had quite sorted out the middle cylinder issues of heat/cooling with it unlike the Gresley middle wicket, but again I am sure this has been looked into well.[/quote]


    Really? Spare sets of gear? Not aware of any locomotive fitted with a radial type gear that requires a spare set. You will need some new rings, probably every 50k miles or so based on best current practice and a rebore of the valve liners and a new set of packing elements from time to time.
    If enough money is raised then a poppet valve experiment could be indulged in. How much investment of time and funding would be needed to produce a reliable solution? Piece of string anyone?
    The Trust has gone about things the right way having the behavior of the chassis analysed before trying to take matters further. There are some interesting decisions to be made if this machine is to be built. The cylinder size has gone down and the working pressure up to allow for greater route availability. The P2s had an unusual frame design which could be done away with and made simpler, the originals had mainsprings of the A1/A3 type but 2007 could have the later A4 type. The swing links will be gone but fitting Franklin wedges would be a useful first in the UK.
    But that BC gear. I used to be enthusiastic about it. But we live and learn and so now I woudn't consider it. Not my project though, I've said my bit.
     
    paulhitch likes this.
  13. class8mikado

    class8mikado Well-Known Member

    Joined:
    Jun 1, 2009
    Messages:
    2,099
    Likes Received:
    394
    Occupation:
    Print Estimator/ Font of all knowledge (useful, or
    Location:
    Bingley W.Yorks.
    The LMS sorted out Gresleys gear...come again ? where did you get this nonsense information... Thought about a 'Gresley three cylinder job' is that the monobloc aspect or the conjugated aspect, would that have been under Ivatt ?
    Dont recall any significant alteration being made to the conjugated gear at Doncaster other than Cooks drive in the mid fifties to improve alignment and machining tolerances which improved its performance and longevity a GWR man by the way, under BR auspices.

    Mr 242A1 is as we all know anti Caprotti - comparison with any old poppet Valve gear which Chapeleon couldnt get to work with Second generation walshaerts is not a fair one.
    Whilst 71000 has problems until we know the whys and wherefores i find the ' it must be the Gear ' finger pointing a bit shallow, there is an issue here but if the response to every issue of this nature was lets go back to Plain Vanilla then Porta/ Wardale etc would never have done all the things they have. No disrespect to the 71000 restoration but 73129 with its original gear has had no issues that i can recall ( but it doesnt get quite as thrashed as DoG has and hasnt had its cylinder lubrication, and timing settings 'Improved',
    Walshaerts gear and piston valves to a run of mill FGS spec cannot achieve what BR Caprotti can, so it becomes a question of changing Steam chest, lap, travel and gear geometry to get there and whilst im all for that too be aware there are just as many uncertainties and potential banana skins here...
     
  14. JMJR1000

    JMJR1000 Member

    Joined:
    Jul 27, 2009
    Messages:
    471
    Likes Received:
    204
    Gender:
    Male
    Location:
    Cleethorpes
    You make a fair comment there when it comes to the question of the practicality of building such a sizable locomotive, but then again, could the same not be said Didcot's own large new build, 4709? In fact, you could argue that the question of if we SHOULD be building these giants should also include the existing giants we are/have yet to restore (the Merchant Navy Class being a prime example.)

    And that is before we consider that it could also be argued that the question should perhaps include fully restored/ complete steam losomotives too; Do we really need two working Kings, multiple Merchant Navies, and a handfull of Castles and A4s? One could argue they're not very pacticle either, yet here we we, with them puffing they're way down express network and sleepy heritage lines alike.

    The point I'm trying to make here is that, if there's one thing I've learned about the steam heritage movement, we are not the most sensible and practical of people, yet we love it with a passion, and be damned if we're told otherwise when it comes to practicality. Not that we're people with no common sense mind you, but this is a lifetime hobby for many, and we do so love to indulge in such projects as these, big and small.

    Another fair comment and I can see your point of view, but the question of how long steam locomotive hauled railtours/excursions will last would seem to have gone on for decades now, with no real clear sign yet that such a doomsday is coming.

    Of course circumstances can soon change, but there are also some things that don't change; for example, though trains have been getting faster over the last few decades, they are still operating on what is effectively victorian era engineering, meaning that there are limitations to how fast they can ultimately go even with whatever upgrades they'd have in mind, though how fast they'll be able to go in the end remains to be seen.

    Then of course, there is the matter that some mainline routes will still be open to steam for a good long time yet, the Settle–Carlisle Line being a prime example. Don't get me wrong, I don't dismiss the idea that steam activity on the network could eventually decrease, but I do not believe that it will disappear all together.

    My belief is that it will become a more exclusive affair, for the motive power to be precise, with stricter rules and less tolerance for elderly steam engines suffering failures and unable to keep to precise timetable requiring continued high speeds running, (the highest speeds possible for that particular engine.) Naturally then, new builds like Tornado would be well suited to this possible, more stricter future working environment, though there is another side to this possible future.

    The other side to this possible future is that, as there would be fewer steam excursions occurring, demand for these excursions will be ever higher. And as a result of this, as well as speed you'd need pulling power, having to work on possibly longer, heavier than normal trains, and also pulling these said trains up varying and challenging gradients while keeping up your speed to stick to the stricter timetables. Now this too is where new builds like Tornado could do fairly well, but locomotives like the P2 (or even 4709) would be perfectly suited to such a task. So in theory then, we could possibly have a future where steam still trundles the network rails (albeit less frequently), yet ironically is only able to do so with the use of these giants of steam, like the P2.

    Again, I can see where your coming from and I do agree with you, more new builds are needed for specifically heritage railways in mind. Inevitably though, the bigger more glamorous projects do attract the most attention though, and therefore the most money, so despite the questions of practicality and viable usage in the future, projects like the P2 are unlikely to die out anytime soon.
     
  15. m&gn50

    m&gn50 New Member

    Joined:
    Mar 17, 2009
    Messages:
    121
    Likes Received:
    8
     
  16. threelinkdave

    threelinkdave Well-Known Member Friend

    Joined:
    Aug 1, 2013
    Messages:
    1,780
    Likes Received:
    870
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Stratford-upon-Avon or in a brake KD to BH
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Pertinent to this discussion are the SECR based design 3 cylinder U1 & N1 classes. This also used derived centre valve events but as designed by Holcroft. I Blaged the following from wickapedia

    Holcroft valve gear[edit source | editbeta]

    The valve gear assembly originally designed by Holcroft for use on the N1 class regulated the timing of the valve events that admitted steam into the cylinder, increasing efficiency whilst reducing mechanical wear and the effects of hammerblow on the track.[8] Holcroft incorporated a new method of driving the middle cylinder from the right-hand set of the two outside Walschaerts valve gear without the need to use a separate set of valve gear between the frames, saving overall weight.[9] This was achieved by using the combination lever assembly that controlled the fore and aft movement of the valve spindle, which admitted "live" steam into the cylinder and ejected "spent" steam through the ports.[8]
    Holcroft’s process of driving the middle cylinder directly from the combination lever contrasted to the approach taken by Sir Nigel Gresley, who used an extension of the valve spindles on the outside valve gear to operate the middle cylinders of his locomotives.[9] This variant therefore held an advantage over Gresley’s design, as the Holcroft valve gear would be immune to variations in valve events brought about by heat expansion of the valve spindles and flexing of the conjugation levers when in heavy use.[9]
     
  17. Jamessquared

    Jamessquared Resident of Nat Pres

    Joined:
    Mar 8, 2008
    Messages:
    12,567
    Likes Received:
    12,688
    Location:
    21C102
    Picture here, clearly showing the linkage for the conjugated gear:

    http://en.wikipedia.org/wiki/File:SECR_N1_class.jpg

    I guess one knock-on effect of the Holcroft gear is that, in order to stay within gauge, the conjugating lever had to slope across the top of the cylinder, which explains the slightly odd cylinder design, with the valve chest sloping inwards rather than directly above the cylinder. I'm not sure whether that had any practical effect, but it is certainly visually distinctive. The W class trip-freight locos and Z class shunters shared the cylinder design, even though they were simple two-cylinder designs, so I guess it can't have been too compromised! (http://en.wikipedia.org/wiki/File:C...2-6-4T_geograph-2665159-by-Ben-Brooksbank.jpg)

    Subsequent multi-cylinder Maunsell designs ditched the conjugated gear in favour of multiple sets of valve gear (three in the case of the Schools; four in the case of the Lord Nelsons).

    Tom
     
  18. Spamcan81

    Spamcan81 Nat Pres stalwart

    Joined:
    Aug 25, 2007
    Messages:
    25,518
    Likes Received:
    8,453
    Occupation:
    Training moles
    Location:
    The back of beyond
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    Source please as I'd like to know more.
     
  19. paulhitch

    paulhitch Part of the furniture

    Joined:
    Oct 12, 2008
    Messages:
    3,885
    Likes Received:
    1,712
    Gender:
    Male
    Location:
    Hayling Island
    Heritage Railway Volunteer:
    Yes I am an active volunteer
    A mere typo I suspect, for both of these were definitely three cylinder. Part of the raison d'etre for the "Z" having three cylinders was reduction in exhaust noise to lessen disturbance caused by heavy shunting in urban goods yards at night. It shared the same boiler with the Brighton C2X but whilst both types would be more suitable for 25m.p.h tourist railway use than most new build projects, one hopes that people will not get too excited!
    Paul H.
     
  20. Jamessquared

    Jamessquared Resident of Nat Pres

    Joined:
    Mar 8, 2008
    Messages:
    12,567
    Likes Received:
    12,688
    Location:
    21C102
    Ah yes, brain fade. Note to self - don't make factual assertions after putting the children to bed...

    I guess what is interesting is that they didn't have the conjugated valve gear, and, after a period, the N1 locos were also converted to have three independent sets of valve gear, though they kept the sloping cylinders. So I guess whatever advantages conjugation had, ultimately those advantages weren't sufficient to keep the locos from being rebuilt. Evidently Gresley's experience led to a different conclusion.

    Tom
     

Share This Page