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9F why does not having a flange on the centre wheels stop it being mainlined

Discussion in 'Steam Traction' started by thequantocks, Jul 28, 2014.

  1. class8mikado

    class8mikado Part of the furniture

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    Is the track over there generally more or less crap than it is over here...?
     
  2. Eightpot

    Eightpot Resident of Nat Pres Friend

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    I'm not sure that fitting a Krauss-Helmholz pony truck (which in effect turns the pony truck and leading coupled axle into a bogie) would have any benefit due to the lack of side play on the latter that can be built into the design due to our restricted load gauge. A 9F is only 8' - 10-1/8" (26956 mm) wide over the cylinders, while a 52 is 10' - 0-7/8" (3070 mm) at its widest point. This extra width gives the scope for working in side play on the 1st and 5th coupled axles, in the case of the 52 it is 25 mm either side of centre, i.e. 50 mm (1.97") in total. This plus thinned flanges on the driving axle wheel sets means that they can negotiate curves quite freely.

    It must be remembered that by continental load gauge standards a 52 is a relatively small locomotive in profile (height over chimney 4400 mm - 14' - 1-1/4") as it was intended to run anywhere in Europe. In contrast the German 01 Pacific is 3150 mm (10' - 4-1/2") over cylinders and 4550 mm (14' - 11-1/8") over the chimney. This gives the scope for flexibility in chassis design.

    As this country was the inventor/pioneer in railways this also means that in hindsight we made the mistakes which others benefitted from. As a complete aside, am I correct in thinking that George Stephenson's 'Rocket' as originally built, the chimney height exceeded the current 13'-odd height limit by a considerable margin?
     
  3. Jimc

    Jimc Part of the furniture

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    Whatever you may think about the track gauge, there's surely no doubt he was bang on the money about the loading gauge.
     
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  4. Eightpot

    Eightpot Resident of Nat Pres Friend

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    I think the answer here is both 'Yes' and 'No'. Fine if you think in terms of inside cylinders and (mostly) outside frames with small locomotives. Essentially the Broad Gauge reached the end of its development with the then locos. Yes, that the GWR may have had a more generous load gauge profile than most other railways is not denied.

    However, can you imagine a 'King', Castle' or whatever to run on Broad Gauge? It would have to be (7' - o-1/4" minus 4' - 8-1/2") which would end up being 27-3/4" wider than the Standard Gauge version. Not compatible with even the generous GWR load gauge, I fear!
     
  5. Jamessquared

    Jamessquared Nat Pres stalwart

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    Collett would probably have relished the opportunity it afforded him to stick all four cylinders and associated motion inside the frames...

    Tom
     
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  6. Jimc

    Jimc Part of the furniture

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    You're still thinking about track gauge as part of it. My point is that the *loading gauge* on GBR railways is just too small for the job, and Brunel was quite right to think that much larger locomotives and stock would be required.
    I think its a mistake to think much about the GWRs narrow gauge loading gauge. The loading gauge on the broad gauge was actually very different. A very substantial part of the GWR - could it be half? - wasn't built to the broad gauge. It must be a myth to suggest that the GWRs slightly larger loading gauge had much to do with the broad gauge. And didn't some of the Scottish lines have a substantially bigger loading gauge too?

    The broad gauge loading gauge was not very different from current Continental GB and GB1 loading gauges, a little wider, a fair bit taller in the middle (but a fair bit shorter than GC which has a *lot* more width at height) , but without the extra "corners" the modern gauges have, so it wouldn't be as advantageous as you'd hope for container traffic.

    I don't see any value in trying to translate a King or whatever to run on broad gauge. If you were designing for the broad gauge you'd design entirely different locomotives. That was where we started...

    There's a lot of rather over simple thinking about that subject. Perhaps for a separate topic. But the Kings and Castles could *not* have had outside valve gear without either a complete end to end re design, or else valve timing problems. There was a wheel where Stanier put the rocking lever to the inside gear on the Duchesses, and of course it would be quite pointless to have 4 sets of valve gear. The Churchward/Pearce layout is actually a very elegant and compact solution to the problem.
     
    Last edited: Sep 15, 2016
  7. Eightpot

    Eightpot Resident of Nat Pres Friend

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    Bulleid fitted three cylinders between the frames on his 'Leader' design - 36001 broke a crank axle after only 6000 miles! How long would an unsupported 4-throw crank axle last?
     
  8. Jamessquared

    Jamessquared Nat Pres stalwart

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    I think you are treating my bit of whimsy with more analytical seriousness than it warranted <insert smiley here />

    Tom
     
  9. pete2hogs

    pete2hogs Member

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    I would suspect such a design it would have a supplementary centre frame and bearing. A three main bearing four throw crankshaft is perfectly feasible.
     
  10. Eightpot

    Eightpot Resident of Nat Pres Friend

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    Sprung? Unless it's like a separately mounted countershaft driving the wheels by gears.
     
  11. class8mikado

    class8mikado Part of the furniture

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    well the outer bearings are 'sprung' so the centre bearing would obviously have to be likewise
     
  12. LMS2968

    LMS2968 Part of the furniture

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    Now that's a crank axle I'd like to see!
     
  13. LMS2968

    LMS2968 Part of the furniture

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    No. The LNWR used a centre bearing on their later locos. It was unsprung and entirely free to move in the vertical direction. Then someone at Derby said 'unnecessary maintenance' and ordered its removal, followed by a spate of frame crack around the driving horn gap.
     
  14. 8126

    8126 Member

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    I was about to wonder what it was doing if it wasn't taking any vertical load. Then I remembered that for a crank axle the piston thrusts are much more significant - about 25 tons per piston for an LNWR G2, for instance.
     
  15. class8mikado

    class8mikado Part of the furniture

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    Stand corrected, and 8126 has identified its utility, but I would have thought it advantageous to have it sprung even if only to take the weight of the additional axlebox .
    We are now a mile away from Flangeless drivers, perhaps we could get back there VIA compensated springing.....
     
  16. LMS2968

    LMS2968 Part of the furniture

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    It wouldn't though, would it? The axleboxes are an unsprung weight anyway. However, back to the flangeless coupled wheels debate!
     
  17. Smokestack Lightning

    Smokestack Lightning Member

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    Out of interest, is that a universal dimension or just specific to the 9Fs or Standards?

    Dave
     
  18. RAB3L

    RAB3L Member

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    On a related issue, does anybody know whether the Iron Duke replica has flanges on its drivers? The class was built without flanges but I don't remember Iron Duke not having flanges. The Lord of the Isles drivers at Swindon certainly don't have flanges. It might explain its tendency to derail itself. I was fireman on it once when it derailed. For information, the carrying wheels are mounted in the same rigid frame as the drivers.
     
  19. Mr Valentine

    Mr Valentine Member

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    The drivers do have flanges, the engine also has a fixed wheelbase not far off a 42xx, which might explain a few things. This was all before my time, but I seem to remember hearing that some 'emergency' side play was introduced while at Didcot?

    To be fair when Fire Fly started running it also had issues, but this was put down to a dodgy bit of track, which was sorted out. It may have been responsible for some of the antics with Iron Duke. I believe the original Fire Flies also had flangeless drivers.
     
  20. MellishR

    MellishR Resident of Nat Pres Friend

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    Seeing as this thread has been revived, I'd like to raise something that has never made sense to me. I don't think it has been covered before in this thread. The function of a check rail is to catch the inside edge of a wheel if the flange of the wheel on the outside of the curve is in danger of riding up onto the running rail. That might not work with a flangeless wheel, but if the check rail is raised that should give it a better chance of catching the flangeless wheel. So raised check rails should reduce the risk of a 9F derailing.

    Where is the flaw in that argument?
     

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