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The LMS's pre-grouping express 4-6-0s - a question

Discussion in 'Steam Traction' started by John Petley, Mar 20, 2017.

  1. 8126

    8126 Member

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    Can't remember the source right now, but on the Southern I'm sure the lowest maintenance cost per mile of any class was delivered by the four-cylinder Lord Nelsons - noticeably better than the fairly robust two-cylinder King Arthurs.

    There are a few factors that might influence this costing. An express locomotive is obviously going to inherently rack up a lot of miles, which pushes the metric down, but they may well be at speed, which accelerates wear and tear and pushes cost back up. Because there were never enough Lord Nelsons, the top express jobs on the Southern had to be kept within the capability of the King Arthurs (until the Bulleids turned up), so the Nelsons weren't necessarily worked especially hard, whereas the Arthurs filling in were worked to the limit of what they'd do.

    The mechanical design of the Nelsons was also more refined in general. The Arthurs had heavy motion and no axlebox wedges, which accelerated wear; it wouldn't stop them but they could get very rough when they were getting due for overhaul. All this costs money to put right.
     
  2. 35B

    35B Part of the furniture

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    But this begs other questions. Was the more refined design of the Nelsons a function of power, or of their being a later design able to incorporate further improvements? If the Arthurs had had the same power as the Nelsons, and thus not been worked to the limit, would they have racked up the same costs? Or, if there had been enough Nelsons for loads to make them work consistently hard, what would have happened to their maintenance?

    I acknowledge that as counterfactual questions, it is unlikely that anyone could answer any of these with any degree of factual rigour.
     
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  3. huochemi

    huochemi Active Member Friend

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    Were adjustable wedges common on locos in this country?
     
  4. Jamessquared

    Jamessquared Resident of Nat Pres

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    Bradley gives the following comparative repair costs, in pence per mile, for various classes in the mid 1950s (at which point, the Nelsons were 30 years old, but the Standard 5s were brand new...). I've highlighted the 4-6-0s for comparison.

    LMS Black 5 - 3.34
    BR Std 4 2-6-0 - 3.43
    GWR Hall - 3.45
    BR Std 5 - 3.50
    BR Std 4 4-6-0 - 3.57
    GWR Castle - 4.05

    SR Schools - 4.13
    SR Lord Nelson - 4.54
    SR U - 4.57
    SR U1 - 4.60
    LMS Royal Scot - 4.67
    SR King Arthur - 5.01

    SR West Country - 5.14

    I think the big caveat on these figures is that comparing, say, a Black 5 repaired at Crewe with a Lord Nelson repaired at Eastleigh is not comparing equivalent works organisation. So I think you can probably make the point (as you have done above) between, say, the Lord Nelson and King Arthur to consider the advantages or otherwise of 2 vs 4 cylinders; but I'd be more wary at comparing, say, Black 5 and King Arthur: I think the difference could be as much to do with the relative works efficiency as anything inherent in the design. Or at the very least, disentangling how much of the difference was down to the design and how much to the works would be very difficult.

    A second point is that in the detailed breakdown (not given above but in Bradley), there is a big variation in boiler repair costs as a part of the overall. For example, the West Country is the most expensive of the lot overall, but has the cheapest per mile boiler repair costs, by a massive margin. (West Country: 0.18 pence per mile; Hall: 0.97 pence per mile - more than five times the cost). Taken as a whole, the LMS engines seem to do particularly well on boiler repair costs and the GWR locos rather badly. To compare similar locos of similar vintage, the Royal Scots had average boiler repair costs of 0.54; Lord Nelson 0.71 and Castle 0.89.

    Tom
     
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  5. 8126

    8126 Member

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    Common enough without being universal. If you go through South Western loco history, for instance...

    All the Adams classes had them. The Drummond classes appear not to have and Urie was opposed because of the risk of a badly adjusted wedge binding the axlebox and leading to a derailment. Maunsell classes I believe generally had them; certainly the Nelsons and Schools. Bulleid Pacifics didn't have them. Seems to have been a case of designer's preference, and probably drawing office practice.

    Powerful two-cylinder 4-6-0s tended to suffer from axlebox wear, some of the (low) mileage stats between works visits for Scottish Black Fives before the introduction of manganese steel liners are eye-opening. The Arthurs never got manganese liners.

    I agree completely, even comparing given a variety of duties is difficult, let alone the works. Really, Maunsell should have taken a brand new King Arthur and LN, put them on identical duties in the same link, worked turn and about by the same crews, when the works had an identical amount of experience in maintaining both classes ... and then I might think we'd had an adequately controlled experiment. Most inconsiderate of him :(.

    I was only really trying to make the point that multi-cylinder classes are not necessarily expensive to run as an inherent feature, although I'm sure the Southern shedmasters and preparation crews didn't care how cheap to run the Nelsons were as they scrabbled to get them ready in time. Certainly the U and King Arthur are hardly flying the flag of simple two-cylinder classes when it comes to repair costs. Looking at your numbers, I suspect economies of scale come into it as well, the LMS would certainly have had a powerful incentive to get Black 5 repair costs down, given how many they had. Enough spares to maintain overhaul throughput for a class of 800 is not going to be fifty times the stock required for a class of 16.

    Regarding the boiler repair stats, I know Crewe had a good reputation for its boiler work, but regional water quality may also have been an influence? The LMS would have used a fair bit of soft Scottish water. Perversely, the steel fireboxes of the Bulleids necessitating water treatment may have helped their low (boiler) repair costs.
     
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  6. Jamessquared

    Jamessquared Resident of Nat Pres

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    From the point of view of a controlled experiment, probably the best comparison in those data is between U and U1 - which interestingly show an essentially negligible difference in per mile repair costs.

    Tom
     
  7. LesterBrown

    LesterBrown Member

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    The Saints and Stars were directly comparable 2 and 4 cylinder types.

    Holcroft, who was transferred to the Swindon drawing office at the time North Star was being developed, said that the Stars were intended for heavy non stop trains running at high speed and that the higher first cost was anticipated to be compensated for by running a greater mileage between general repairs.

    He noted that the opinion of the locomotive footplate inspectors was that the 4 cylinder locos were "a coach better" with train loads of 12 to 14 or more at 60 mph and over while the 2 cylinder locos had the advantage in acceleration at lower speeds with parity in the region of 40 mph. Holcroft attributed the difference to the varying characteristics of Stephenson and Walschaert valve gears.

    He also says that it was after tests had shown the greatly reduced hammer blow of 4 cylinder locos that the SR Chief Engineer permitted a relaxation in the axle loading for multi cylinder designs, allowing the Lord Nelsons to be designed. I seem to recall that Bowen Cooke had previously failed to so persuade the LNWR Chief Engineer when designing the Claughtons with almost negligible hammer blow, however that was prior to the setting up of the Bridge Stress Committee in 1923 and the testing of locos from several companies over selected bridges fitted with deflection recorders.
     
    Last edited: Mar 30, 2017
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  8. huochemi

    huochemi Active Member Friend

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    Thanks, I am not very familiar with Southern locos.
     
  9. andrewshimmin

    andrewshimmin Active Member

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    The LMS spent a lot of time and money in the late 1920s on improving running and repair costs. That was part of the reason for standardisation, and for scrapping and replacing. They spent tens of thousands on sheds and works to get loco turnarounds down, shop time down, repair mileage up, repair time and coat down. And it worked: they saved an equivalent of 2500 locos from the mid-1920s to the mid-1930s (I.e. the needed that many fewer locos, because the ones they had were in service and working more). As an example, 7 Duchesses could do the work of 8 A4s, because they spent more time on service. Similar comparisons could be made for other comparable classes.
     
  10. Jimc

    Jimc Well-Known Member

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    The reduction of doubleheading as a result of abandoning the midlands small engine policy must surely have had a role to play there too though.
     
  11. John Stewart

    John Stewart Part of the furniture

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    When the LMS ordered the Scots it was insistent on three cylinders as four (as on Castles and Nelsons) was just too much machinery between the frames and the necessary cylinder volume could be easily obtained from three. The LNER achieved even greater cylinder volume from three.
     
  12. daveannjon

    daveannjon Active Member

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    Quoting 8126: Powerful two-cylinder 4-6-0s tended to suffer from axlebox wear, some of the (low) mileage stats between works visits for Scottish Black Fives before the introduction of manganese steel liners are eye-opening.

    Was it John Powell who wrote that some of the Scottish Black Fives never did receive the modified valve events that cured the axlebox knock they suffered from?

    Dave
     
  13. Steve

    Steve Resident of Nat Pres Friend

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    That's something I've not heard of and I'd be interested to know more.
     
  14. LMS2968

    LMS2968 Well-Known Member

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    I think it was in one of Eric Langridge's works that new Black Fives were gaining a terrible reputation for knocks in the trailing boxes. They were all Horwich built, and had the valves set cold to the ideal hot settings. Once warm, thermal expansion did the rest. Some adjustment of the valve heads cured the problem. Two outside cylinders of course were never going to run as sweetly as three or four.
     
  15. Courier

    Courier New Member

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    They may have done a lot to make repairs more efficient - but did not understand how to increase mileage between repairs by building to tight tolerances...

    Organisation and control of locomotive repairs on British Railways. J. Instn Loco Engrs., 1953, 43, pages 219-20. (Paper No. 520)
    K.J. Cook (219-20) was strongly critical of Bond's statement: that "The wide variations in mileage at which individual locomotives of the same class require attention in the works, to which reference has already been made, clearly preclude the use of average mileage between repairs as a satisfactory basis for determining when the locomotive should be sent to the works." That, Mr. Cook, suggested, was an illogical statement. Provided there were the fundamentals of accuracy of repair and close tolerances, for which basis accuracy was necessary, then the mileage basis should become and was the only really logical basis on which to make the preliminary selection. He was rather perturbed to see that so many engines of certain main line classes required general or intermediate repair at considerably less than 40,000 miles. He suggested it was due to the fact that there was fundamental inaccuracy. If the basis particulars of the locomotive were dealt with with real precision, then if the engine fell down before it ran to within a very close distance of the specified mileage figure there was obviously some definite cause. From his own experience he could say that where engines were repaired with basis accuracy and close tolerances, it had been extraordinary how closely they ran time and time again and right throughout the classes to their average mileage.

    http://www.steamindex.com/people/cook.htm
     
  16. Steve

    Steve Resident of Nat Pres Friend

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    Thanks. If that's what was being referred to, as you say, it was mentioned by Langridge and I am aware of that. However, I got the impression from the original post that it was a class wide modification, not a limited build error, which is what the Horwich locos effectively suffered from.
     
  17. Courier

    Courier New Member

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    RegionClass of locomotiveAverage mileage between periodical repairs

    L.M.
    4-6-2 "Coronation" 73,188

    4-6-0 "Royal Scots" (taper boiler) and 5X conversions 70,495

    E./N.E.
    4-6-2 Al 93,363

    4-6-2 A4 86,614

    Western
    4-6-0 " King" 78,987

    4-6-0 "Castle" 87,424

    Southern
    4-6-2 "Merchant Navy" 75,687

    4-6-2 "West Country" and "Battle of Britain" 74,650

    4-6-0 "Lord Nelson" 81,611

    http://www.steamindex.com/jile/jile43.htm
     
  18. 35B

    35B Part of the furniture

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    If so, why was it that BR moved away from mileage to operating hours as a working measure for exams and shopping across the diesel fleet?


    Sent from my iPhone using Tapatalk
     
  19. Jamessquared

    Jamessquared Resident of Nat Pres

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    I don't know for definite, but two thoughts:

    1) A diesel engine is always running, even when the locomotive is stationary. So wear in the engine is fundamentally related to engine hours, rather than the mileage covered by the loco.

    2) By contrast, a static steam locomotive undergoes no mechanical wear and tear, but the cyclic reciprocating stresses (which are what fundamentally wears it out mechanically) essentially depend on wheel revolutions and piston / valve strokes, i.e. mileage (and assuming that averaged over time, the proportion of mileage particular types of loco spend running at low and high speeds is broadly constant).

    Taken together, it means a steam locomotive tends to wear out mechanically in proportion to its mileage, whereas wear and tear in the most expensive part of a diesel - the engine - is more related to hours.

    Tom
     
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  20. The Saggin' Dragon

    The Saggin' Dragon Nat Pres stalwart Staff Member Moderator Friend

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    Exactly that; wear for a Diesel engine occurs when it is idling.
     

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