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Bulleid 'Leader'

Discussion in 'Steam Traction' started by Eightpot, Mar 23, 2020.

  1. Monkey Magic

    Monkey Magic Part of the furniture

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    Given the poor history of tank engines on Southern metals, how did the BR standard tanks do? Relative both to earlier Southern experiences, but also compared to their experiences on other regions.

    I seem to recall from the tests after Sevenoaks that the Rivers ran ok on the LNER.
     
  2. RLinkinS

    RLinkinS Member

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    The realisation that improvements to bogie side control were needed came a little earlier than this. E S Cox discusses it in one of his books. There were problems with a class of pacifics in India. This was investigated and eventually it was realised that stronger side control was needed. As ESC admits nobody really understood the problem before. I think the LNER V2s were fitted with improved pony trucks to improve their riding. I suspect that a slide control system that relies on slides or links will have a variable effect depending on friction which may well change. Side control by sprins is much more predictable. The bogies on Stanier locks certainly have side control springs which are pre-loaded





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    Last edited: Mar 27, 2020
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  3. 30854

    30854 Part of the furniture

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    Interesting question, which raises another. The aversion clearly didn't extend to passenger tank classes with 4w leading bogies (I1x, I3, J, 0415) on passenger services, but where there ever any restrictions placed on bunker-first (passenger) working of these, or the D1s or the numerous 0-6-2T classes (i.e. running with 2 wheels leading)?
     
  4. Cartman

    Cartman Member

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    Part of the problem on the South Eastern section was the track. As has been said, a River class was tried out on the LNER after the accident at Sevenoaks, but before rebuilding and it ran OK. The same thing was done with the Hastings DEMUs after the Hither Green accident in 1967 and the same result, they also ran OK on the east coast route but were rough at speed on the Southern
     
  5. ragl

    ragl Member

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    Interesting that you mention the V2s in relation to improved pony-trucks being fitted, this only happened after Doncaster had constructed LMS 8Fs during the war and borrowed that locomotive's design to be fitted to the V2s.

    Cheerz,

    Alan
     
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  6. City of truro fan

    City of truro fan New Member

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    It was probably just because the track was in poorer condition and had not been looked after as good so it bounced a lot more
     
  7. 8126

    8126 Member

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    I assume they were essentially grandfathered in, as long as they were known to be no trouble. If their duties were to be changed, they could be put through trials. Since they already existed, it's not as though any effort had been wasted.

    Although in advance of Sevenoaks, Urie was asked to put an H16 through trials on semi-fasts in 1922. Bradley records that only one trial run was made with it running bunker first, and extrapolates (on no particular evidence that he mentions) that the inspector must have deemed its riding at speed in this direction unacceptable, though probably not dangerous. There were various restrictions on them later; I believe on ECS duties they were restricted to chimney first if going to the buffers at Waterloo, after one of them struck a platform edge.

    The Civil Engineer wasn't totally inflexible, he offered to allow Bulleid to build a couple of prototype 2-8-2s for trials. If all that work of design and prototype construction is undertaken, only to find that the new design can't be deployed on the desired duties, that's a lot of time and effort wasted. The SR had put a lot of work into improving the track in the interim, but that was still the position.

    The key to the LMS design of side control is the step in forces around the straight ahead position. The springs are preloaded considerably, but also constrained so they can't act beyond the centreline. That way, you require a large force to overcome the spring compression in either direction, you don't get the opposite spring helping you. There was nothing new about that, if you look at the Adams bogie under an O2 (for instance) you'll see exactly the same principle, just with leaf springs. That step in force helps break up any oscillations that might be set up at speed, whereas a simple mass-spring or swing link system will happily act as an oscillator. There is some use of friction damping as well, but the main finding of the work done in connection with the Indian Pacific issues @RLinkinS mentions was the realisation that the initial control forces needed to be much stronger.
     
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  8. Jamessquared

    Jamessquared Nat Pres stalwart

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    It wasn't only the River tanks that had a problem - after the first LBSCR L class 4-6-4T entered service, it was found to have similar instability, to the extent that the side tanks were cut down functionally (but not cosmetically) and an additional well tank added between the frames to replace the lost water capacity. The well tank was a source of perennial maintenance problems on shed with leakage being difficult to rectify due to its location.

    Tom
     
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  9. RLinkinS

    RLinkinS Member

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    The South Eastern Railway used Dungeness shingle as ballast. The rounded profile meant that the stones did not lock together and the track could move out of alignment. There was also the problem of clay pumping up into the ballast. I think 1927 was a wer year making the problem worse. After 1927 the Southern Railway carried out a lot of reballasting using stone from Meldon.

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  10. 30854

    30854 Part of the furniture

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    That may explain Sevenoaks in 1927, but surely can't be blamed for the quite appalling riding 'qualities' (in the 70s and 80s) of either the 4CEPs (even those latterly fitted with 'commonwealth' bogies), or the 2/4EPBs (Southern or BR flavours, especially in their dotage). From a standing start at Lewisham, and not yet moving at more than a few mph, they rocked and rolled quite alarmingly by the time they left the Loughborough Jnc line to head up past St.Johns on the through line. It couldn't all be down to knackered stock, as the incoming 'Networker' relacements didn't behave much better.
     
  11. Dunfanaghy Road

    Dunfanaghy Road Member

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    Who was the CCE in Bulleid's time? George Ellson was the CCE at the time of Sevenoaks and, I believe, suffered a nervous breakdown as a result. I have read that, subsequently, any mention of 2-6-4 tanks on passenger work gave him the heebie-jeebies.
    As far as BR era track is concerned there was a resource problem. Over and above the difficulty of recruiting in the London area, BR allocated OTM on the basis of track classification. No SR track was 100 mph plus, so the other regions had more machines (or less miles per machine, if you prefer), this in spite of the density of traffic and axle hung traction motors. (I remember being told this by Peter Pescod, DCE Wimbledon, after he retired and joined the Mid Hants as Hon. Consultant CE.)
    Pat
     
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  12. RLinkinS

    RLinkinS Member

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    I think the nose suspended traction motors were pretty hard on the track and tended to "knock it about". The stock was certainly rough riding, the ride down from Sevenoaks tunnel to Tonbridge was exhilarating.

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  13. johnofwessex

    johnofwessex Part of the furniture

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    I remember trying to do what you should not do when the train was in the station on a boat train coming back from Dover.

    I suggest that the Ladies probably found the process much simpler....................
     
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  14. cav1975

    cav1975 Member

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    Having had a career in product development (in I C Engines) I sort of understand how this might have happened. Boards and management teams rarely understand the technical details but are usually well aware of the shortcomings of existing products. So when a technical director or chief engineer comes along and (with conviction) tells them that his new wiz bang idea will fix everything they might well agree and provide initial funding.

    In the development teams we had to iron out the bugs left in by both the concept designers and the detail designers and try to make the stupid things work to specification. Sometimes the concept was too revolutionary and could never be made to work efficiently or reliably due to having too many novel features in one product. The most successful products that I worked on were all evolutionary rather than revolutionary or were a new mixture of existing proven concepts.
     
  15. huochemi

    huochemi Well-Known Member Friend

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    When you say "the opposite spring", I am not sure I understand that in terms of the LMS bogie, as the side control springs are parallel fore and aft of the pivot block. The SR arrangement had springs either side of the central pivot block.
     
  16. 8126

    8126 Member

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    You're quite right, that'll serve me right for not thinking about the detail of the design, I'd forgotten how neat it is. They're preloaded between two end stops and then pushed inwards off alternate end stops when the pivot block translates in each direction, correct? It still has the desired effect of a large restoring force that has a step change from +F to -F when you pass the centreline, rather than a linear reduction to zero and corresponding linear increase in the opposite direction.
     
  17. LMS2968

    LMS2968 Part of the furniture

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    A bit difficult to see but . . .
     

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  18. huochemi

    huochemi Well-Known Member Friend

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    Thanks. It's a neat little design. Interesting that Stanier specified this design when the Horwich Crabs and the earlier "Fowler" 2-6-4Ts had swing links, and the Great Western generally preferred inclined planes on its trucks. Side control springs seem to be in the minority internationally. Swing links remained popular, certainly for non-high speed locos, presumably because springs were prone to breakage e.g. the WD 2-8-0s had swing link trucks. The US moved on to variations of gravity control - rockers and "geared centering devices".
     
  19. Cosmo Bonsor

    Cosmo Bonsor New Member

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    I wonder why we didn’t use Garratt loco’s more in the UK and think they could have been a better solution than the Leader.

    In my mind’s eye Bulleid could have used his existing designs of boilers MN, WC and Q1 or any other SR designs. The SR had experience in building and maintaining the boilers in use already and it would have saved on tooling costs.

    As for the whirly bits, 2x2 outside cylinders of a size to suit the boiler and a well designed gear which the drawing offices were easily capable of.
    Add a wheel arrangement of your choice, I’m guessing 2-6-0+0-6-2 although it seems the SR designs of pony trucks were poor. Choose the size of wheel for intended speed range and put it all together on nice fabricated, electrically welded frames. A loco that can run uphill and down dale at a near constant speed would be good for the train planners and the timetable. It might have been that a lower top speed, say 60 mph was useful.

    Use as many maintenance and labour saving features as you can and play about with the variables according to axle weight and loading gauge.

    I think Garratts were either seen as coal draggers or just ‘Not what a passenger loco looks like’ for their wider use in this country.

    It would have been interesting to see.

    Back to the dusting...
     
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  20. johnofwessex

    johnofwessex Part of the furniture

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    Looking at the only surviving Standard Gauge Garratt in the UK, William Francis, they dont have to be very big either, but plenty of room for the grate & ashpan. No reason I suppose why it cant be a 2-4-0?
     

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