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BR Standard class 6 No. 72010 'Hengist' and Clan Discussion Thread

Discussion in 'Steam Traction' started by Bulleid Pacific, Nov 23, 2009.

  1. ianh1

    ianh1 New Member

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    OK here's a different subject. Yesterday we had a design review meeting on the bogie. We've encountered an issue and would welcome any guidance you can provide

    An issue has been identified with bogie bolster lubrication. E.S.Cox comments in his autobiography (locomotive Panorama Vol 2) about the Indian Pacific Locomotive Committee that "only a combination of stronger side control springs plus appropriate damping could give the desired result". Therefore lateral control springing should be accompanied by some form of damping system.

    The bogie bolster system carries the weight of the front of the locomotive but also allows for movement in a horizontal plane to cater for the rotation of the bogie plus the sideways movement of the centre slide engaged in the bogie pivot. The side control springs must resist the sideways movement but, following Cox's explanation, we would expect a damping system.


    From top to bottom the bogie bolster system comprises of the following


    · 2 bogie bolster domes (SL/DE/19621) bolted to the outside of the main locomotive frames with the domes pointing downwards.

    · 2 bogie bolster cups (SL/DE/19697), cup upwards. These engage in the bogie bolster domes.

    · 2 circular Ferobestos pads, 5/16" thick secured to the underneath of the bolster cups with 4 countersunk set screws. There is 1/8" clearance between the top of the set screw and the surface of the pad to allow for wear. A modern Tufcot material has been substituted for the Ferobestos material with similar friction characteristics.

    · 2 circular YM3 alloy pads, 3/8" thick secured to the top of the bogie stretcher casting with countersunk holes for 4 set screws. Grooves are machined into the upper surface of the pad and a 5th hole is aligned with the grooves and with a lubrication hole on the stretcher.

    · Grease lines feed the top of the bolster dome and the underneath of the bogie stretcher


    The upper grease feed is logical. The bolster dome/cup interface is a metal to metal contact and the grease lubricates this interface.


    The lower grease feed to the stretcher poses the problem. The Ferobestos pads are fixed to the bolster cups. They cannot move and there is no reason for lubrication. The stretcher grease feed hole is aligned with a hole in the YM3 alloy pad. As the pad is fixed to the stretcher, there is no need for lubrication at this interface. The hole in the YM3 alloy pad feeds the grooves in the pad suggesting that the grooves are grease lubrication grooves. The only interface that can move is the interface between the Ferobestos pad and the YM3 alloy pad. This interface will be lubricated by the greasing system. Yet Ferobestos is a friction material. If damping of the lateral control system is required, as indicated by Cox, surely the point of the Ferobestos pad is to damp any movement?If this interface is greased, why use a friction material as a pad as it's friction properties will be destroyed by the grease?

    Any help apreciated!
     
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  2. class8mikado

    class8mikado Member

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    Perhaps the ungreased ferrobestos provides too much friction and lightly greased provides enough ?
    Any ideas from 71000 / 70000/70013 ? 73XXXX ?
     
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  3. huochemi

    huochemi Member Friend

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    The bogie which Nock termed the "De Glehn bogie" (side control springs rather than swing links, and weight transfer by side bearers into "spittoons" sliding on flat surfaces) started with the Stars and was ultimately used by all the Big Four (e.g. Tornado has one), and the Standard bogie was basically LMS, so the technology should be well known and advice readily obtainable. Prima facie it is surprising that they wanted to create friction as one would have thought that that would inhibit the functioning of the bogie and cause rapid wear to the flat surfaces. There is however a passage in the first chapter (by Langridge) in The LMS Duchesses edited by Doherty, p26, which says "The LMS practice was also to fit Ferobestos liners under the "spittoons" to stop bogie hunting." Perhaps that was the original idea but it was later used just for its composite qualities and lubricated?

    I attach an image of the Britannia bogie which may be helpful to those trying to understand the arrangements (copyright notice on the image). The bearing surfaces (your YM3 pad) are covered in grease.
     

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  4. std tank

    std tank Member

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    Nail on the head, sir. 473 Standard locos were so fitted. I think that the Derby design office knew what they were doing.
     
  5. ianh1

    ianh1 New Member

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    Note the passage from Cox's book "appropriate damping" - you'll find more of the context here https://www.theclanproject.org/build/Clan_BuildBogie.php.

    Cox indicates that the lessons from the Indian Pacific Locomotive Committee were applied to LMS types and the Standards.

    The problem is that as soon as you introduce a bit of contamination to a friction material, those friction properties go out of the window - as I found out with a tiny leak from the brake caliper on my bike!

    huochemi - thanks for the photo - very useful
     
  6. ianh1

    ianh1 New Member

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    On the photo you can clearly see that the grooves on the pad are full of grease
     
  7. class8mikado

    class8mikado Member

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    Toying with the idea that perhaps you could use the Wheel centres pattern of county of Glamorgan ( subject to permission) for this project ?

    Not withstanding that is 1 inch too big - ( that inch could im sure be mitigated by either thinner tyres or adjusting the springs to sit the axleboxes half an inch further up and noting the change in axle centre datum) one feels that the relocation of the crank pin and machining the bosses to suit would certainly be do able and hardly anyone would actually notice a difference

    This would however deny the Standards community as a whole a Pattern that would benefit the other 6ft 2 inch driver loco's ( certainly the wheels on the Brits have had a bit of patching up already)
     
  8. Jamessquared

    Jamessquared Nat Pres stalwart

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    Not sure I see what would be gained by such a course of action. You end up with something less than optimal and not "true" to the original design for the sake of the cost saving of one pattern. My understanding is that provided you have someone capable of providing the necessary CAD drawing (and the Clan project appear to have that capability), then the poly-patterns approach has dramatically cut the cost of pattern making relative to traditional wooden patterns. The casting itself would still be expensive, but that is the same however you produce them. So I can't see the benefit of using the County wheelset pattern and then having to apply a bunch or modifications.

    Tom
     
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  9. ianh1

    ianh1 New Member

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    I don't think we'd want to go with that one - lots of problems quickly come to thought! jamessquared is right. We've already had a discussion with our pattern maker. He says that making the wheel centre is fairly straightforward as a wooden pattern but the spoke pattern would be made using moulded resin. The master would be modifed to cater for the different spokes. The rim would be a number of equal sections in resin.
     
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  10. class8mikado

    class8mikado Member

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    Hoping to have have any problems i hadnt seen pointed out
    Think for this one a trad wooden pattern is the way to go, its good to give something back into BRSLOG.
    - apparently there are two different patterns needed ( coupled and connected wheels) so the Modular approch mentioned by Ian comes into its own.
     
  11. ianh1

    ianh1 New Member

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    Well, the biggest problem would be that we were diverging from the drawings in a key area. The regulatory bodies are very keen that we "follow the BR drawings". As soon as we start to diverge we have to justify that change and that can get complicated. Also, thinner tyres would limit how much life we get out of them. We read reports in the railway press that so and so loco has used up its tyre life. We want to keep HENGIST on the track as much as possible.
     
  12. std tank

    std tank Member

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    Yet, you have just been questioning the fact that BR drawings show grease lubrication to the friction pads.
     
  13. ianh1

    ianh1 New Member

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    Yes, it's not an easy life is it?
     
  14. northernsteam

    northernsteam New Member

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    .. and don't 'Clan' know it! But we learn all the time. I did wonder if the 'friction pads' were, to some extent, sacrificial, as in easier and cheaper to replace than the pad? Even with full lubrication design and regular maintenance we cannot be 100% sure that metal faces will not come into contact and wear when we don't want them to, so a 'disposable' interface would be useful in difficult situations. I'm probably completely wide of the mark but never mind.
     
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  15. class8mikado

    class8mikado Member

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    Makes perfect sense to me... so your suggestion is clearly wrong :Wacky: !
     
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  16. Jimc

    Jimc Well-Known Member

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    They won't be destroyed though surely, they'll simply be modified. A lubricated friction material will surely have greater friction than lubricated mirror finish metal surfaces.
     
  17. Sheff

    Sheff Well-Known Member

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    That is exactly my thinking. A sacrificial wear surface which is relatively easy to replace. But as we have already have several of these bogies in service on the mainline, surely the answer is already out there (assuming the Brits and Duke also have 'friction' pads) ?
     
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  18. ianh1

    ianh1 New Member

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    The BR drawing shows applicability to Class 7, 6, 5, 4 (4-6-0 and 2-6-4) and Class 8
     
  19. class8mikado

    class8mikado Member

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  20. daveannjon

    daveannjon Member

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    Now I'm not one to start a livery discussion (ahem) but I recently saw a photo in BackTrack of a Clan with green cylinder cladding - could be a big decision to be made there ;).

    Dave
     

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