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Gresley Valve Gear - non-LNER

Discussion in 'Steam Traction' started by andrewshimmin, Jan 10, 2018.

  1. Jamessquared

    Jamessquared Resident of Nat Pres

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    By NZ standards, they've got rather high-slung boilers to clear the middle cylinder. I've got a photo of one double heading with a 2 cylinder AB (same boiler) and the difference is quite marked.

    One odd feature I have noticed - re. the point about maintenance and keeping ash from the conjugating levers: all the photos I have seen of the G class Garratt's show a large cover over the gear. That was kept when they were rebuilt as conventional 4-6-2 locos, but by the early years of the war onwards, it seems to have been discarded, with the levers exposed to the elements. I wonder whether it was perceived that having them in the open actually helped maintenance by making them easier to clean and oil?

    Sean Millar, in "The NZR Steam Locomotive", gives a somewhat confusing picture of their efficacy. On the one hand he notes maintenance problems, difficulties keeping the valve gear adjusted, breakages and so on. But then he notes that they achieved "respectable"mileages during the war and had lower operating costs than any other NZR pacific except the ABs. Perhaps that reflects the way NZR apportioned their operating costs between running and repair?

    Whatever the truth about relative running costs, the one known factor is that as soon as main line diesels arrived on South Island, they were amongst the first engines to go, whereas the ABs, which had been introduced more than twenty years earlier, outlived them by a decade. Whether that was on the basis of cost or specific difficulties with the valve gear I don't know: it may simply have been an issue of removing a small (6 locos) non-standard class early while allowing a large (152 locos) class to survive to the end of steam.

    Tom
     
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  2. Jimc

    Jimc Well-Known Member

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    Interesting, thanks for that, I had never heard why the gear was replaced. Interesting that it ran into problems as Holcroft specifically designed it to avoid valve rod expansion problems.
     
  3. fish7373

    fish7373 Member Friend

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    800px-UP_9000.jpg Union Pacific 3-Cylinder 4-12-2 9000 this one must be the best one or the biggest 1b536c1a0bce81f1de73e34ba6b2a5e4.jpg Union Pacific 3-Cylinder 4-12-2 9000 this one must be the best one or the biggest

    https://en.wikipedia.org/wiki/4-12-2

    Only one type of 4-12-2 was built: the Union Pacific Railroad's 9000-series locomotives, 88 of which were built by ALCO between 1926 and 1930. These locomotives were used to increase the speed of freight trains in flat country, and were fairly successful, but were maintenance nightmares, largely because of their use of an inside third cylinder driving the cranked second driving axle between the frames. There was no inside valve gear to worry about, however. ALCO had obtained permission to use the conjugated valve gear invented by Sir Nigel Gresley. This system used two hinged levers connected to the outer cylinder's valves to operate the inner cylinder's valve. The 9000 class locomotives were the largest to use Gresley gear.
     
    Last edited: Jan 11, 2018 at 8:29 PM
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  4. RLinkinS

    RLinkinS New Member

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    The information came from D L Bradley's book on SECR locos. Reading through the section on the N1s it was suspected that the problem was caused by slack in the conjugation gear bearings but contact still occurred when this was reduced. This suggests to me that flexing in the levers was part of the problem.

    If you have a few thousand pounds to spare an interesting 5" gauge loco with conjugated gear has come up for sale, see https://www.stationroadsteam.com/5-inch-gauge-missouri-pacific-2-8-2-stock-code-7804/ I believe I saw this running in an efficiency competion in Bristol about 15 years ago; it hauled a heavy load at high speed. The resulting efficiency was poor was the driver had a big grin as it thundered around the track

    [​IMG]
     
    Last edited: Jan 11, 2018 at 8:42 PM
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  5. torgormaig

    torgormaig Active Member

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    OT I know, but if @paulhitch sees this - how can he possibly consider a Bulleid Light Pacific to be classed as "Big Chufferitis"? This is the real Big Chufferitis for you and it ain't half impressive too.

    Peter
     
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  6. flying scotsman123

    flying scotsman123 Part of the furniture

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    Perhaps it could be called "'F*** me that's big' chufferitis" :)
     
  7. paulhitch

    paulhitch Part of the furniture

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    This was for hauling "mile long" freight trains which needed the horsepower, not b*******g about with five coaches on tourist railways.

    PH
     
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  8. Spinner

    Spinner New Member

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    So it's just what the Ongar - Epping people need then. Perhaps with one of our 57s for quieter days.
     
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  9. ragl

    ragl Well-Known Member

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    Once the Big Boy is up and running, this one next please U.P. ........

    Cheers,

    Alan
     
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  10. huochemi

    huochemi Active Member Friend

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    Rather nice, Baker valve gear with the Gresley conjugation is a bit recherché. Trouble is you would need a crane to lift a 5" gauge US loco.:(
     
  11. 30854

    30854 Well-Known Member

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    It wouldn't surprise me in the least if this one is on UP's "to do" list
     
  12. torgormaig

    torgormaig Active Member

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    I think that you fail to understand the reason behind UP's restoration and operation of the few locos that they keep in steam. The best we can hope for is that the Challanger will be overhauled again in due course, but even this is by no means certain. That is not to say that the 9000 would not be some spectacle.

    Peter
     
  13. ragl

    ragl Well-Known Member

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    Indeed Peter, this falls into P.H.'s WIBN category; however, I am still reeling from the fact that the Big Boy has actually been rescued from open display for complete restoration to working order, so I am in the mode that anything is possible....

    Cheers,

    Alan
     
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  14. 30854

    30854 Well-Known Member

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    T'was not that long ago, in the grand scheme if things, that the idea of a "Challenger" ever steaming again was pie in the sky! My previous post wasn't based on any definitive UP statement, more just a general impression from watching updates on 4014's restoration (which has it's own thread in the 'International' section).

    Will 9000 ever run again? I honestly don't know, but with 4014 coming back to life (and who'd have put any money on that happening a few years back?) plus 844 (which was never formally withdrawn, according to UP themselves) apparently isn't a sole survivor either. During a recent UP tour of the Cheyenne shops, staff even mentioned the notion of restoring a sister loco put by as a "spares mine" (AFAIK, there's no plan to do so for the time being).

    UP's senior management seem well aware of the PR value of working steam as well as the strategic need to keep alive the relevant heavy engineering skills (including maintaining the specialist workshop machinery older than most of the locos they're working on). So, no, nothing official though I'd not bet against any further restorations - steam or diesel. Just call it a gut feeling.
     
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  15. fish7373

    fish7373 Member Friend

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  16. ragl

    ragl Well-Known Member

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    Fabulous!! What a remarkable facility and the quality of the work looks to be outstanding, lots of new parts for the Big Boy and the diesels look superb. Many thanks for sharing.

    Cheers,

    Alan
     
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