A question about Class 800s/801s/802s

Discussion in 'Traction & Rolling Stock' started by Kurolus Rex, 8 Sep 2019.

  1. Kurolus Rex

    Kurolus Rex Member

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    Hi there!

    Does anyone know if any of these units have speed sets? If so, what type are they? Are they similar at all to those fitted on 390s or are they another design?

    Also, has the current cab been changed from that of the prototype during the initial test runs?

    Thanks for the help!
     
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  3. Railperf

    Railperf Established Member

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    As far as I understand there is a speed hold device that will only hold speed at a maximum of 200km/h - 124mph.
     
  4. hexagon789

    hexagon789 Established Member

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    As in that's the only speed it can hold as opposed to only be able to hold a max of 124mph/200km/h?
     
  5. Railperf

    Railperf Established Member

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    no it will hold lower speeds too. For the full 125mph, a driver needs to manually manage the power.
     
  6. hexagon789

    hexagon789 Established Member

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    How exactly does that work then?

    Surely it doesn't set speeds in increments of km/h?
     
  7. Railperf

    Railperf Established Member

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    From another forum..this was the answer:
    "The 123.9mph will be as a result of using the speed limiter. If you set it for 125 it tends to sit at 124. Cannot be set for 126. I would not normally use it, but on 125 sections in electric saves you taking off if you take eyes off the speedo. In diesel forget it.

    You select the speed limiter for any speed and just open the power brake handle to max. It will accelerate to your set speed and hold it. It will over speed on falling gradients though."
     
  8. hexagon789

    hexagon789 Established Member

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    So basically it holds speed about 1mph below the set figure and will not allow a setting of more than 125mph.

    Presumably if they ever do run at 140mph that would be adjusted
     
  9. Doomotron

    Doomotron Member

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    Since this is a question thread for these trains, can the 800s and 802s actually reach 125mph on diesel power? Apparently they can but the HST fanboys beg to differ.
     
  10. hexagon789

    hexagon789 Established Member

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    The rail performance logs I've seen suggest not.
     
  11. 800 Driver

    800 Driver Member

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    It doesn't have a speed hold button. It has a speed limiter which can be set for any speed, (though there are presets for various speeds eg 90, 100, 125 mph). eg if you set the power controller to coast then the speed will gradually reduce.
     
  12. 800 Driver

    800 Driver Member

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    802s can easily reach 125mph, 800s - depends on how the engine ratings are set, but yes, eventually (even on the most environmental setting)
     
  13. hexagon789

    hexagon789 Established Member

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    Thank you for confirming that, it was generally suggested that 117-119 was about the maximum attainable on diesel and some logs seemed to bear that out.
     
  14. Railperf

    Railperf Established Member

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    Yes - on level track...but very few rail lines are level for long distances. But it appears diesel outputs and performance levels are continually being tweaked and refined.
    In the early days of Paddington to Reading, the train would switch to diesel at Maidenhead and lose speed - dropping to 113 -114mph.
    I am told now that some 800's are being remapped to produce more power than 802's do currently. And that the whole fleet are similarly being upgraded to that level now.

    A driver reports 800313 seemingly having very similar performance to an HST over 60mph - though he took no readings to verify that. In his words 'the unit was not hanging about'.
    Any further reports / news will be welcome.
     
  15. Railperf

    Railperf Established Member

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    Yes, it was said in a previous thread that Hitachi set the power curves up for the train's diagram.
    That suggests that if the train is diagrammed to meander through the cotswolds at no more than 90 to 100mph the power curve is setup differently than a power setup for runs at up to 110mph down the B&H to Exeter and Penzance. But what that means when diagrams are swapped around in the last minute or while in service - suggests you could end up with a gutless unit trying to get to Penzance with a power setup designed for a less demanding route.
    Anyway it does seem that constant tweaking is being done to find a setup that is at least as good as HST's were on diesel while retaining some reliability and not accelerating wear unduly. With almost two years hard running in passenger service under their belts - you would think Hitachi / Rolls Royce / MTU should now be on top of things - and it does sound like they are getting there.
     
  16. Kurolus Rex

    Kurolus Rex Member

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    Isn't this normally the case with "speed sets" such as on 390s? As far as i'm aware, the driver must apply power to use the speed set and the speed set will only use whatever percentage of that power is needed to maintain the speed. Is this what you're talking about or is it simply a way to prevent over speed?
     
  17. hexagon789

    hexagon789 Established Member

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    Upping the performance for the tighter timings from December.

    I did read on another forum of a set with one engine out managing 118mph, so with all engines 125mph doesn't seem unlikely.

    I'm quite pleased that they've decided to tweak performance on diesel - a reflection of the reduced electrification?
     
  18. Railperf

    Railperf Established Member

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    Yes, but we understand there is supposed to be some power augmentation when an engine is lost. So rather than having - three engines producing power at 70% say at 100mph - you would end up with the two remaining engines being uprated and probably delivering closer to 100% power each to make up for the lost engine. But it is all a dark science and only Hitachi really know exactly what is happening.
     
  19. Railperf

    Railperf Established Member

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    This thread seems to prove exactly why the 'Class 800 performance and reliability upgrades' thread should not have been locked prematurely.
     
  20. hexagon789

    hexagon789 Established Member

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    You wish Hitachi would be a bit more open about what tinkering they're doing.
     
  21. Railperf

    Railperf Established Member

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    They probably are to the right people that they have to inform contractually - but not to us the general public.
     
  22. hexagon789

    hexagon789 Established Member

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    Could they not even just say - "eventually will will be uprating the 80x to XXhp in diesel mode"?

    Surely that's reasonable enough information.
     
  23. Railperf

    Railperf Established Member

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    Probably because it is not the maximum output that is being changed. But it is what percentage of power is being delivered through the speed range. It is too complex for the average person to grasp. In the same way most people know their car has an xxhp engine - which is the maximum amount of power that it will produce at xxrpm. But the manufacturers won;t list the exact figures it produces at every point in the rev range. Even tuners will only tell you that they can deliver up to xx% more power. The exact figures will be given to you in the form of a print out should you take it to a rolling road. But that ain't gonna happen with these trains! Not unless you can borrow one and try and get it down to your local rolling road.
     
  24. TractiveEffort

    TractiveEffort Member

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    Absolutely no truth in that suggestion whatsoever. The engine software is the same on the 800 and the 802 and it’s not possible to ‘tinker’ or alter parameters without an elongated process, involving Japan, MTU, the train owner, maybe the DfT and GWR and for them to all sign it off.
     
  25. Railperf

    Railperf Established Member

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    Then you are forgetting what was posted by @Clarence Yard in a previous Class 800 thread "
    The difference in the power setting is that the 800 sets were (and are) set to a different acceleration curve to the 802 sets. That is for DfT/Agility contractual reasons, to reduce engine wear on the 800 sets. It's purely a software variation between the two, which can be altered with the aid of a laptop."

    And he also.made these further clarification on the situation..
    "What Hitachi have done is try and match the engine performance curve to the required overall journey time whilst at the same time minimizing the torque variation to maximize engine life between overhauls/repairs.

    So when we talk about "unmuzzling" the 800 sets to provide 940hp, Hitachi will only increase the raw power up to a certain speed level. People talk about 750hp/940hp as if it were a switch - it's much more sophisticated than that - they set the whole speed range up for a variety of hp "settings", taking into account the natural power curve limit and also the projected demand on the engines under certain operational conditions. They effectively create their own power curve to satisfy the journey time requirements and minimize the cost of engine wear.

    Obviously, they regard how exactly they achieve this as their own intellectual property."
     
    Last edited: 10 Sep 2019
  26. jimm

    jimm Established Member

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    Why? So you can continue to obsess about IET operation on diesel power at speeds above 100mph, despite the handful of sections of track where this now takes place following the extension of electric operation to Bristol Parkway.

    And write baseless stuff about 'gutless' Class 800s, which somehow get to spend lots of time standing around at stations along the meandering Cotswold Line waiting for departure time to tick round, due to still having to operate on HST timings which they somehow manage to beat despite their gutlessness.
     
  27. TractiveEffort

    TractiveEffort Member

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    People keep talking about the engine software, which, as I said, is the same for both. The traction software is what demands the power from the alternator and the demand controls the engine speed to allow the alternator to produce that power.

    The fact that the power curve, acceleration rates and many other parameters can be adjusted, doesn’t mean they are continually being altered and they certainly aren’t set up by diagram. The software has had several revisions and I am sure it will have many more over the coming years.
     
  28. Mintona

    Mintona Established Member

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    Plenty of 800s have had the software update now and they’re flying around all over the place. Acceleration is just as good, if not slightly better, than an HST now.
     
  29. class26

    class26 Member

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    I sampled the 802`s whilst on holiday in Cornwall a month ago on the Cornish mainline. OK, speeds do not get above 75 mph but working within HST timings they were departing stations on time and having to wait time at every station , usually 2 - 3 minutes. Get away from a station is pretty quick and the end of slam doors are saving the time. There must be a fair bit of slack that can be taken out of the schedule.
     
  30. Railperf

    Railperf Established Member

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    In the first few months of Class 800 operation they were indeed gutless. Thankfully we are seeing the performance improved further. And i'm not the only one who feels that way.
     
  31. Railperf

    Railperf Established Member

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    Yes, station to station timings in Cornwall are not the tightest. The 800's surefooted handling, more driven wheels, and better initial starting acceleration to 40mph and better braking mean they seem to keep time in Cornwall very well.
    In contrast - i've seen quite variable performance from the short 2+4 HST's - which are supposed to have as good an acceleration to 40mph and better beyond. But cautious handling of the power and brakes on my journeys aboard them saw us lose time way too easily. Station stops were tardy too! Some blame this on the fact they are being driven by 'unit drivers' where the driving style is different.
     

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