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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. osprey

    osprey Resident of Nat Pres

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    My life as been spent in the Machine Tool Industry where working to .0005 (@12microns) was common place. To build a steam locomotive using those parameters..it would, I feel,... "lock solid"...
     
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  2. osprey

    osprey Resident of Nat Pres

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    Interesting..is there a transcript of that somewhere?
     
  3. class8mikado

    class8mikado Part of the furniture

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    At the end of the day if it takes a couple of hours to hand scrape a component so it fits true, and there are people on hand willing to chase that thou for the sake of a job done as well as is humanly possible - then that is what goes. Like most projects of this type the limiting factor is funds not time or labour or skill.
     
    Last edited: Mar 8, 2023
  4. 242A1

    242A1 Well-Known Member

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    Correct, but there again I would not number you amongst the mutterers and suspect that you are not hazarding a guess but are rather giving others a nudge.

    The Kent and East Sussex Railway has a Virtual Mutual improvement Classroom with a wide range of Downloads available. Hope some are interested enough to benefit from this facility.
     
  5. Tobbes

    Tobbes Member

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    Where what happened?
     
  6. std tank

    std tank Part of the furniture

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    Swindon tolerances?
     
  7. Jamessquared

    Jamessquared Nat Pres stalwart

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  8. osprey

    osprey Resident of Nat Pres

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  9. osprey

    osprey Resident of Nat Pres

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    Just had a quick look...super stuff...
     
  10. LMS2968

    LMS2968 Part of the furniture

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    The GWR famously changed components when wear had brought them to the same tolerances which the other railways used for new construction.

    Had I been a GWR shareholder, I'd have had a few questions about that!
     
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  11. talyllyn1

    talyllyn1 Member

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    Churchward's comment to the board about Swindon construction costs being twice that of the LNWR comes to mind - "Because one of mine can pull two of their bl**dy things backwards! " ;)
     
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  12. Jamessquared

    Jamessquared Nat Pres stalwart

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    Reminds me of a (possibly apocryphal) story about the Rolls Royce Merlin. During the war, a group of Rolls Royce engineers went to the USA with blue prints, with the intention of allowing US companies to manufacture the engine under licence.

    Said representative of US company looked at the blue prints and declared "we couldn't possibly build an engine to those tolerances".

    Rolls Royce engineer, with slightly smug feeling: "What's wrong? Are they too fine for you?"

    US engineer: "Oh no, quite the contrary. We don't know how we could build anything so crude".

    On GWR tolerances: I think the GWR, as outlined by Cook (*) were on to something really quite modern in engineering terms, well in advance of the other companies. Not so much in the tolerances or optical methods for frame alignment, but in setting mileage as the ultimate arbiter of when something needed repairing. In the modern world - who drives a car listening for every knock and clonk, periodically stripping bits down and measuring, and then taking it for service when certain patterns of wear are met? The vast majority of people simply follow the mileage-based service schedule: if it has done 12,000 miles, you take it for a service.

    That method of working seems to have been novel for the time - certainly the SR didn't do likewise - but has a very profound advantage in that it is relatively easy to plan your required workshop capacity. If the shopping intervals are based on mileage, then the capacity you need (and when you need it) is closely tied to the annual service plan. That in turn reduces two alternate sources of waste. If you shop locos when they break, then you really only have two alternatives (which probably both occur at different times). You either have too much workshop capacity, with men and machines standing around idle. Or else you have too little capacity which means you need to store broken or worn locomotives out of traffic but not in the works, which in turn means your overall fleet (and capital tied up in locomotives) is bigger than it otherwise might need to be. Either way, it is a cost to the company and the return on capital employed.

    Cook describes an ideal in his book, and I don't know how close the GWR got to it. But it would be really interesting to know, across different company fleets:
    • What was the average mileage between overhauls
    • What was the variability in mileage between overhauls (i.e. if on average you run 80k miles per overhaul; with two locos you could achieve that if both ran 80k; or if one ran 10k and the other ran 150k. But the former situation is much preferable; so the key numbers are not only the average, but also the variation, for example "our average is 80k and 90% of all locos get shopped within 5% +/- of that figure")
    • How many loco failures per mile run did each company get
    My hunch is that the GWR were onto something in optimising those figures.

    (*) And allowing that in his book, he could have been being slightly self serving in presenting a best case of what was achieved in the inter-war years

    Tom
     
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  13. LMS2968

    LMS2968 Part of the furniture

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    A Swindon engine could pull two LNWR engines backwards? It didn't work out in practice when the new owners of the former LNWR lines in South Wales decided to use a Hall instead of the usual LNWR engine for the train for sweet shop owners to go to the annual big get-together at Bourneville. They always went by road after that. (Working with LMS Steam - H.C.H. Burgess).

    Tighter tolerances? Horwich went that way under George Hughes. After they combined in 1922, Crewe was asking what these new-fangled 'thous' were.

    The LMS did base repairs on mileage, which was why the Pacifics', Scots', etc. overhauls were about two to three years apart and 8Fs and similar about five. It didn't always work. A shed would propose an engine for repair on the grounds that it was kn@ckered, only to have the proposal rejected with the instruction to re-propose in 6,000 miles. Many an engine sat at the stop blocks while another engine had to do its work, that mileage being credited to the stopped engine. Of course, it was only a matter of time before the active engine reached a similar state of decrepitude while still below its shopping mileage . . .
     
  14. 8126

    8126 Member

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    It's not apocryphal, or if it was Stanley Hooker made it up for his book (Not Much of an Engineer), which we'll go with as unlikely, especially as he was apparently the smug Rolls engineer. It was actually a representative of Ford UK, explaining that they couldn't mass produce on a production line scale to such wide tolerances as Rolls permitted. But then Rolls were used to having skilled fitters make the wide tolerances work, whereas as Hooker graciously said, Trafford Park eventually produced Merlins like shelling peas out of a pod. I'm not sure how they got round the reticence of the American parent company towards getting involved; I seem to recall they were sounded out quite early in the war but Henry Ford wouldn't have it, so Packard got involved instead and did an excellent job of US production.
     
  15. huochemi

    huochemi Part of the furniture

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    https://www.national-preservation.com/posts/1911226/
     
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  16. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    I have the 1937 copy of the LNER’s annual revision of shopping for locomotive classes (I included it as an appendix in my Thompson book). That was in use from the formation of the LNER as a required standard by Gresley.

    The document is a guide to shopping, and pre Second World War it’s likely was adhered to more strictly. During WW2, the LNER suffered availability issues and it’s a matter of record that most of its classes did not achieve their shopping mileages by significant amounts.

    Basically Tom, you’re describing the LNER’s Use of Engine Power document and we have that information over on the Thompson thread and included in the appendices of my book on Thompson (and the Gresley equivalent is coming soon), albeit only for 1942-1946 currently, which I accept is a small snippet of the overall working life of LNER locomotives (but I am doing my best to transcribe the rest).

    There is a frustrating trend in LNER writing to emphasise the high mileages between shopping for heavy generals to make some locomotive classes sound better. Almost pride in working as many miles between fixing things when the locomotive could likely be very worn down. The only real exception in LNER terms is the Peppercorn A1 with roller bearings, where you could do more additional mileage between overhauls. I think it is likely though that wear and tear on the whole locomotive would leave it running at not exactly optimum performance for services.

    The true measure, as I’ve been saying for years, is annual mileage in year and then overall availability in year for work. A much better measure.

    In one LNER book from the 1960s (that only went out of print recently) a certain writer declared that a certain LNER class achieved 120,000 miles or thereabouts between general overhauls in the late 1930s. What he didn’t tell the reader was that this mileage between overhauls for the class was achieved over a three and a half year period when the locomotive had been expected to be doing in excess of 50,000 miles a year. It was therefore well below the expected annual mileages and its availability was poor.

    That class had performed poorly pre war and when reviewing the data for the Thompson book it explained a lot of things.

    It also, to the shock of several LNER enthusiast friends - but not me - showed that the overall known story to date about “Thompson locos requiring more shopping” was not looking at the whole story. They were indeed shopped more. They also achieved better mileages and availability than most of the rest of the LNER fleet, in year, every year. They didn’t get so run down between shopping and were basically the example of preventative maintenance against run to failure, which is a point we need to keep stressing.

    It is bad for locomotive fleet availability to run to failure. You want to shop regularly to keep them working at optimal levels.

    But - true story - I didn’t see things that way until you pointed that out on the Thompson thread Tom. So thank you, sincerely, for enlightening me on that point.
     
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  17. osprey

    osprey Resident of Nat Pres

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    This is an very interesting discussion. Regarding the GWR, my humble view is that in the final days of steam...it was still the GWR. It did not, at grouping, inherit other company, "big" locomotives, as say the LMS & LNER did, creating problems of maintenance and inherit rivalry. It also had to drop the wide gauge problem, very, very early, and did so, dramatically, and learnt from that? Surely this led to their standardisation, thereby creating planned maintenance based on standard components and economies of scale. Of course when BR came along with the standard designs, they benefitted from past experience. This is not modern practice in industry...the Romans practiced it..standardisation .
    I hope you get my gist of things...
     
  18. Pesmo

    Pesmo Member

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    I got an emailed open invitation to the Clan Open day at CTL seal on Sat 15th April this morning. What a brilliant idea to share the event with the Spirit of Sandringham group and to include a few other loco and heritage groups (Including the new build Single Fairlie Gowrie group and Bridge the Gap). I very much hope to come along as tours of the wider CTL Seal works are planned as they engineer some large & interesting stuff. Admission is only £3 to non members and free to members or the two projects.
     
  19. northernsteam

    northernsteam Member

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    I am gutted that I cannot attend this event due to a clash with holiday travel. There will be a lot to see this year, I am sure, with both loco groups in action and both with progress to show. Seeing the 'News' today it must be great to do a days work and come away knowing that you have managed to get the smokebox door back on!
    Yes, I know they achieve great steps regularly, and small ones every week, and the team must be applauded for their work. At a cost of £3 it is a cheap trip to visit them. By the way, that is a typo by Pesmo, I hope, members of the projects get in free, doesn't matter which one!, not both.
     
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  20. ianh1

    ianh1 Member

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    The frames have been moved in the assembly shop today. Anyone know the last time that a set of Pacific locomotive frames were moved by 2 overhead cranes? See the news section and this video



    The bogie wheelsets should be back from South Devon Engineering in time for the Open Day
     

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