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Boilers & Accidents

Discussion in 'Steam Traction' started by johnofwessex, Sep 3, 2016.

  1. Johnb

    Johnb Nat Pres stalwart

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    I doubt if any engineer would have snowdrifts in mind when they were designing a boiler.
     
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  2. Steve

    Steve Resident of Nat Pres Friend

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    If you run into a snowdrift you may stop relatively quickly but I doubt that the retardation would be that significant. It’s not like hitting a brick wall or the back of another train.
     
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  3. johnofwessex

    johnofwessex Resident of Nat Pres

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    [QUOTE="Ploughman, post: 2582323, member: 2875"...................but the NRM's plough at Shildon is Dumb.[/QUOTE]

    MODS! MODS! He's insulting the NRM's snowplough by saying its Dumb!
     
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  4. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

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    Far more important is what happens to the water as locomotives crest hills and there are still a few of them on the main line and heritage railways. And on loco adhesion, it must surely be a case of "know your loco and know what it can do".

    Back in the time when loco crews were often paired with the same loco, it would seldom have been an issue. This is close to what happens now with crews who come across the same loco often enough to become very knowledgeable about its habits.

    That's good for the crews, good for the loco and reassuring for the loco owners.
     
    Last edited: Jun 16, 2020
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  5. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    Oh absolutely!
     
  6. Steve

    Steve Resident of Nat Pres Friend

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    :):):)
    If you taper the boiler down to a point it would cut through the drift, just like Bryan’s plough. :) Not sure what you’d do with the boiler tubes, though.
     
  7. Allegheny

    Allegheny Member

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    I've just revisited the transcript of the IMech E meeting in 1906 where this was discussed (apologies, I said 1908 earlier)

    To quote from the discussion following the presentation of Churchward's paper
    "There was a Paper read by a member of the Institution in 1887, Mr F.R.F. Brown, the late Superintendant of Motive Power of the Canadian Pacific Railway, on "The Construction of Canadian Locomotives," in which it was stated clearly that the coned barrel was designed originally to prevent the water in the firebox from being shot ahead into the barrel of the boiler when the engine plunged into a snow-drift. By that arrangement the water was kept approximately where it was most wanted, namely over the fire-box"

    So yes, it's protecting the boiler crown rather than anything to do with water-hammer.

    I also seem to remember hearing that there was a similar concern with water movement in the boiler due to the change in gradient on approaching the Severn Tunnel. Could this have made the tapered boiled more attractive to the GWR?
     
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  8. Jimc

    Jimc Part of the furniture

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    I haven't come across that paper. Is it available on line.
     
  9. Wenlock

    Wenlock Well-Known Member Friend

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    More benefit if the plough blade were sprung from the frame, but doubt that is possible.
     
  10. Allegheny

    Allegheny Member

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    It can be downloaded by members of the IMechE, It isn't in the public domain.

    Non-members may be able to purchase a copy
     
  11. Allegheny

    Allegheny Member

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  12. Jimc

    Jimc Part of the furniture

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    Ah thanks, I have a copy of Churchward's paper, which was reprinted in "the Engineer" but not the IMechE discussion. There was no reference to snowdrifts in it. But it seems the actual source is the Brown paper on Canadian Locomotives, it wasn't anything Churchward said.

    It seems to be available here, https://www.canadiana.ca/view/oocihm.61634/5?r=0&s=1 I shall read...

    Aha. The paper lists snowdrift ramming as being only one of a whole collection of subsidiary advantages of the "wagon top" boiler, and states that it "is primarily to obtain by increased height of firebox a sufficient area in the firebox tube plate for inserting such a number of tubes as will give the most efficient proportion of heating surface"

    It would seem that the gentleman who contributed to the IMechE discussion didn't quite correctly remember the content of the paper he was referencing. Just goes to show how important it is to go back to sources! It seems discussion contributors then were no more reliable than forum posters now!
     
    Last edited: Jun 16, 2020
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  13. Allegheny

    Allegheny Member

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    The contributor who mentioned Brown's paper was C.E.Cardew
     
  14. Jimc

    Jimc Part of the furniture

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    A downvote for Mr Cardew then [grin].
     
  15. Allegheny

    Allegheny Member

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    Thanks for sending the link.
    It sounds like "snow bucking" was done deliberately when required, and could have been something important for the Canadian Pacific at the time.
     
  16. Cosmo Bonsor

    Cosmo Bonsor Member

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    We seem to have moved on to boiler water levels.

    I’m sure the Severn Tunnel was not a consideration in boiler design other than overall power maybe.

    The gradient change at Imberhorne for example is from 1 in 55 to 1 in 60 much worse than going to or from Wales under water. There are countless examples of sharp summits on railways.

    As for braking or slamming into a snowdrift, even if the water does go out of sight briefly the tide will come back in soon enough. Bulleids do indeed have the quality of a small change in water level when going over a summit, the regulator doesn’t alter it much either.

    There’s sometimes a bit of undue concern in some quarters about the water dipping out of sight. It’s something the crew has to manage and comes with experience. I often wonder what the gauge glasses were showing when stopping from 90 mph +. I bet the water was gone for quite a while. The crown sheet doesn’t instantly melt!

    I often brake to the water level, that is going chimney first you can keep the level safe by varying the brake force.
    I think the front taper was a good thing on high speed engines for this reason as well as the weight mentioned by others in this thread.

    Clive Groome’s observations are interesting, sadly I never fired to him that often, although I learnt a lot when I did and he wasn’t given to idle chat during a turn.
     
  17. torgormaig

    torgormaig Part of the furniture Friend

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    You mention stopping from 90 mph - this is one of the concerns you have if you miss an AWS/TPWS warning, or are too slow in acknowledgeing it. The brake goes in and the driver has no control over the situation whatsoever. At high speed, and 75 mph is quite fast enough to my mind, your water goes to the front and stays there a long long time. Not long enough for the crown sheet to melt but you keep fingers and everything else crossed that the fusible plugs are ok. There is the world of difference between a controlled stop and an uncontrolled one.

    Peter
     
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  18. Apollo12

    Apollo12 New Member

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    I wish all drivers did that :Bored:
     
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  19. Jamessquared

    Jamessquared Nat Pres stalwart

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    I'm certainly not advocating it as something to be relied on, nor to do an experiment to find out, but reading some of the accident reports from when crown sheets collapsed often seems to suggest a period of running of quite a long time with low water. There are sometimes comments that the plug may have been dropped for five minutes or more before the crown collapses. Fortunately I have never been on a footplate when a plug has been dropped, but I do wonder how easy it would be to detect on a loco that was working very hard - which seems to be a common feature of such accidents. Not something that can be simulated in training either.

    Tom
     
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  20. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

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    This thread started as a discussion about how slippery a Bulleid really is and turned into a wider debate about the importance of drivers knowing their locomotives and their individual characteristics. It has now slowly morphed into a focus on what the person on the other side of the footplate is doing. Over time, as an amateur observer I have come to recognise that the skills of a fireman are arguably at least as important, if not more than those of a driver.

    I recall one instance of a charter climbing out of Weymouth with a diesel on the rear when on the platform it was decided that the diesel would not assist unless called for. That was the challenge. All was good through Upwey and everything was set, until the loco primed. That put an end to the unassisted climb as the loss of speed while the loco was sorted out made all the difference. The fireman at the time said afterwards that he had put too much water in the boiler and that had been the tipping point. By contrast, on another occasion with the same circumstances, the loco started out of Poole and climbed up to Parkstone unassisted. The fireman was the crucial factor.

    I have in mind two main line drivers/firemen who are highly competent in what they do and importantly have a precise understanding of the Bulleid that they crew several times. There is no doubt in my mind that both are masters of what they do on either side of the footplate and the nature of the way they work is such that they have to do both. But in conversation with them it comes over that one seems to prefer to drive and the other fire. For the one who prefers to fire, he enjoys the skill of the control needed to have available what is needed when it is needed. This is especially true on start/start/looped charters where fire and water management are key.

    On the regulator, the same person says that it can sometimes be rather routine and also a little frustrating as signallers control what you do. It seems that in this context, whether a loco might pick up its wheels on starting could be one of the few times you get to demonstrate your competence on the big railway!
     
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