Class 88 UKDual & EuroDual

Discussion in 'Traction & Rolling Stock' started by Sunbird24, 13 Oct 2014.

  1. 43096

    43096 Established Member

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    You're either an idiot, or a troll, or both.

    Either way it's pointless having any form of discussion involving facts with you.
     
  2. Sunbird24

    Sunbird24 Member

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    No, it was still here on Monday morning.
     
  3. Peter Sarf

    Peter Sarf Established Member

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    From my point of view a locomotive has power. Except that is usually quoted as the power of the ENGINE inside the locomotive. Not all that power makes it to the rail due to losses. Now its been said that electric generators/alternators, control gear and traction motors have got cleverer and more efficient over the last forty years (or longer). So, for a given number of horsepower from the engine inside the locomotive, there will be more of that horsepower doing actual work at the rail in a newer design locomotive than an older locomotive.

    So therefore an engine (the fuel burning lump in the loco) that is rated at 1000hp in a new locomotive may well be able to perform as well as an older locomotive that had, say, a 1,500 horsepower engine.

    So an 88 on diesel may perform as well as a class 31 does. The 88 will probably also be able to start a heavier train due to its cleverer transmission. Certainly either a 88 or 31 will have its adhesion qualities limited due to weight bearing down on the powered axles. The 31 has its weight shared over six axles and the power is only used on four of those axles so might well be at a disadvantage.

    Whether a 88 has a really useful amount of diesel power is open to conjecture. it is certainly not a pathetically small amount of power it has. But it all depends on what sort of train you want to use it on, for how long away from the wires and what the desired performance is.

    I am not an expert. But I did study Nuclear Physics so Newtons laws are a bit further back in my knowledge :oops:.

    Anyway its nothing to have a fight over, so no need to be rude.
     
    Last edited: 15 Dec 2016
  4. furnessvale

    furnessvale Established Member

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    I presume you are referring to me rather than yourself? I also note that within a few posts Sunbird24 has also been branded an idiot.

    I invite you to retract or alternatively point out, without selective editing, which posts of mine,
    or Sunbird24, are idiotic.
     
  5. 43096

    43096 Established Member

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    If you can't see it yourself, then you're just proving my point!
     
  6. furnessvale

    furnessvale Established Member

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    Fair enough. Your lack of debating skills and evidence is duly noted.
     
  7. Sunbird24

    Sunbird24 Member

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    For all those who appear not to understand the huge differences between 60 year old DC designs and modern AC replacements here is an article explaining it: http://www.republiclocomotive.com/ac-traction-vs-dc-traction.html
    It might open a few eyes.
    The SW1200 is about as near to a BR class 20 of those quoted, though the SW900 was from the same era. The SW1000 came a few years later.
    The clue to the differences between a class 20 and a class 88 is in the power of the traction motors, 212HP each for the class 20 against 800HP each for the class 68/88. Clearly they will not be anywhere near full power in diesel mode but will be working far more efficiently than those in the class 20.
     
  8. Peter Sarf

    Peter Sarf Established Member

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    Thanks for the nice description of modern drives. A useful set of facts laid out quite well. It describes the limitations of old DC drives well and how AC drives can exploit the power of the locomotive's engine better.

    All subject to a maximum of course. Comparing an 88 to a monster DC drive locomotive might show that the older locomotive cannot use all that power all the time but that the 88 might reach its limit quicker as the engine is smaller. But it suggests that the 1,000 - 1,500 hp in the 88 is able to do as much work as an older locomotive with an engine power of 2,000 - 3,000 hp (Class 40 to Class 50).

    Obviously the Co-Co arrangement of the older locos will reduce the adhesion requirements because the power can be spread over more axles. That's assuming the Co-Co is heavier - by 50% more than a 88. But Co-Co arrangements are out of fashion as they cause more track wear on bends as I understand it so the Bo-Bo arrangement rules. I think that was one of the downfalls of the Class 89.
     
  9. ac6000cw

    ac6000cw Established Member

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    The EMD 710 diesel engine is still in production, it's only the US and the EU where it can't be fitted to new locomotives. Even in the US, loco rebuilds can have new engines fitted that don't meet Tier-4 provided the emissions are improved over the original. There has been a surge in rebuilds recently fitting Tier-3 compliant 710s to older EMD GP and SD locos (aided by emissions improvement grants in some cases). Upgrading older 645 and 710 engines with modern computerised fuel injection has also become popular (better fuel consumption and lower emissions). I suspect that *might* happen to the early 66s eventually, if it's cost effective/possible.

    On the DC versus AC drive question, the rule-of-thumb seems to be that a good, modern DC drive can get to about 30-33% adhesion factor (tractive effort/weight), a good AC drive 45%+ at very low speeds.

    As a comparison example, below are some figures for the DC and AC drive versions of the US 6-axle GE ES44 locomotive:

    GE ES44DC: Tractive Effort (starting) 142,000 lbs, Tractive Effort (continuous): 109,000 lbs @ 13.7 mph, Weight: 416,000 lbs http://www.thedieselshop.us/Data ES44DC.HTML

    GE ES44AC: Tractive Effort (starting) 183,000 lbs, Tractive Effort (continuous): 166,000 lbs @ 13.7 mph, Weight: 432,000 lbs http://www.thedieselshop.us/Data ES44AC.HTML

    (In reality, the AC drive version can produce over 200,000 lbs of very low-speed tractive effort - up to 36,000 lbs per axle - but normally the software limits the overall TE to avoid putting too much stress on the couplers. During GE's long-term 'high TE' test/development program on CSX railroad, a pair of the predecessor AC4400CW's pushed a coal train upgrade in a sub-zero snowstorm for over an hour, while producing over 200,000 lbs of TE per loco at times. GE has sold a lot of AC-drive locos on the back of that sort of performance...)

    The upshot of that is (most of the time), a 4-axle AC drive loco is roughly equivalent to a 6-axle DC drive loco of the same engine power in intermodal and general freight service. In fact GE also sell an A1A-A1A version of the ES44AC/ET44AC i.e. four driven axles, as a replacement for the Co-Co DC-drive version that they used to offer. Two fewer axle drives brings the price down to the same level as the old DC version.
     
  10. captainbigun

    captainbigun Member

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    Quite the opposite in fact.
     
  11. Peter Sarf

    Peter Sarf Established Member

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    I was lead to believe that it was advantageous to spread the horses over more axles but that there was something wrong with more than the two axles on a bogie. Reason was to do with wear on curves rather than pounding of the track. Always hoped that was wrong though.
     
  12. Sunbird24

    Sunbird24 Member

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    Went past the factory this morning, at least 6 88s were visible outside, being 2 and 6-10. Most are still without their own bogies, as are some of the PrasaDuals. Still only one nameplate visible but more, including 10 (2860/2016), now have works plates.
     
  13. ac6000cw

    ac6000cw Established Member

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    The gist of it is that if maximum adhesion is important then there is no substitute for wheels-on-rails (other things being equal). But more axles, motors and traction electronics costs money (initially and in maintenance), and the extra complexity of a three axle bogie makes it harder to design for high speeds. The DB class 103 Co-Co and the 'monomotor' bogied SNCF CC 6500 are other examples of 125mph six-axle locos. The Swiss Re 6/6 (Re620) uses the alternative approach of a Bo-Bo-Bo configuration to reduce track wear on the curvaceous Gotthard Pass route (a problem with the earlier Ae 6/6 Co-Co). The Italians also built many Bo-Bo-Bo locos. But of course using three two-axle bogies is probably even more expensive...

    You can reduce the track wear of a three-axle bogie by 'steering' the outer axles - the EMD 'radial steering' bogies on the class 66 are an example of this (it also improves adhesion in curves because the wheelsets follow the correct path).

    Advances in traction control electronics mean that nowadays you would probably only consider building an electric six-axle design for the heaviest freight work, or where the added weight of a large diesel engine and fuel is more than four axles can accommodate.
     
  14. Peter Sarf

    Peter Sarf Established Member

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    Thanks for the good explanation. That all makes sense.
     
  15. Sunbird24

    Sunbird24 Member

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    Todays status:
    88001 being worked on.
    88002 parked behind 141F2326.
    88003 not visible - last seen with no wheels.
    88004 not visible - last seen with no wheels.
    88005 not visible.
    88006 no wheels, parked on stands.
    88007 not visible - last seen with no wheels.
    88008 not visible - last seen with no wheels.
    88009 running up and down test track.
    88010 no wheels, parked on stands.
     
  16. HOOVER29

    HOOVER29 Member

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    Any firm news on when they'll be coming our way?
    (I'm a newbie so be nice)

    Carl
     
  17. leomartin125

    leomartin125 Member

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    Most recent news states the first unit will be shipped to the UK in January 2017.
     
  18. Sunbird24

    Sunbird24 Member

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    For info only, the cargo ship BULNES left Sagunto this afternoon for Birkenhead, where it is due to arrive on 6th January. I have no info on the cargo nor of any departures from the factory, so it could just be coincidence, it might be full of oranges or olive oil.
    Latest news from the factory, dated November, is that 88002 Prometheus is scheduled to ship in January and will be used for homologation purposes, which should hopefully be completed in February. It is possible that two more, to be used for driver training, will be shipped at the same time as 88002. The remainder should all have been shipped by end of March.
    These will be followed by the remaining 9 class 68s which are scheduled to be shipped by end of July.
     
    Last edited: 6 Jan 2017
  19. Sunbird24

    Sunbird24 Member

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    Update 9th January 2014.
    It appears that still nothing has left the factory. This afternoon 88001 was being shunted around the yard by the local Crab and still has no name. 88002 Prometheus and 88003 (still no name) were coupled together and running up and down a short length of test track between the buildings. Another (I think 88006 due to location) is still on stands and 88008 is visible inside a building where it was before. all else was hidden behind a pair of tram sets and some PrasaDuals. 2 more PrasaDuals were in the engine test bay alongside what appears to be the new prototype EuroDual Co-Co. Certainly does not look like anything else they have produced so far.
     
  20. Mag_seven

    Mag_seven Established Member

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    Are we EVER going to see a class 88 in the UK? :roll:
     
  21. CosherB

    CosherB Established Member

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    Yes. :roll:
     
  22. copernicium112

    copernicium112 Member

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    Are 88s both fully capable diesel and electric? Or are they last mile principle because I thought I saw that they are fully capable...
     
  23. WatcherZero

    WatcherZero Established Member

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    Fully capable though only has about a quarter of the traction power available on diesel as electric.
     
  24. CosherB

    CosherB Established Member

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    You can read back in this thread and see who thinks, on diesel, they're "fully capable" and who thinks they're "last mile". ;)
     
  25. 43096

    43096 Established Member

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    Less than that.

    About as fully capable on diesel as a single Class 20.
     
  26. SGS

    SGS Member

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  27. ac6000cw

    ac6000cw Established Member

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    They are somewhere in-between - more powerful on diesel than typical 'last mile' capability, but only about 20% of the electric power capability.

    However they should have similar starting and low speed tractive effort on electric and diesel, so it that respect they are rather more capable than a 50+ year old class 20. Sunbird24 posted a link to a video of 88001 starting a 1500t train at the Velim test centre back in October on diesel power.
     
  28. CosherB

    CosherB Established Member

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    The day I see one on a scheduled passenger service with LHCS, running on diesel in part, in lieu of a 68 is the day I'll consider it as truly bi-mode. Until then .....
     
  29. ac6000cw

    ac6000cw Established Member

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    I don't think most people consider it to be, least of all me.
     
  30. eastwestdivide

    eastwestdivide Established Member

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    Back of an envelope calculations:
    Wikipedia has the 88's power output of 4 MW electric / 0.7 MW diesel, or a 5.7:1 ratio.
    Compared to that 1960s bimode, the Class 73, at 1600hp/600hp, or a 2.6:1 ratio.

    0.7MW comes in at ~939hp, and 4MW at 5364hp.
     

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