PC Ice3m - Eddy Current Brakes Have No Effect!

Discussion in 'Technical Reports' started by cwf.green, Sep 17, 2020.

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  1. cwf.green

    cwf.green Well-Known Member

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    I wanted to see how quick I could stop the ICE3M with emergency brake the other day and found out that no matter whether you use full service (VB setting, only air and electric brakes) or emergency (SB) the stopping distance is about the same: ~ 700m from 160km/h.

    This means that the magnetic track/eddy current brakes you can see lowering under the middle-wagons during emergency braking are only for show, they don't do anything in the sim.

    Furthermore I think that the stopping distance in full service (VB) is actually the stopping distance that the real train would have in emergency braking. Check out this graph. It seems to be for the ICE3 (BR403) but since the major difference of the multi-power transmission capability it should be similar to the ICE3M.
    The stated retardation for full service braking (VB) is 1.1m/s^2 which gives a stopping distance of around 950-990m (depending on the included brake application time).

    More realistic brakes for the ICE3M (at or below 160km/h) would be increasing brake force up to 1.1m/s^2 at VB and then if you go into emergency there is a bump (a significant one at that) of brake force from the eddy current brakes.

    Assuming that DTG got real world figures for the 700m stopping distance, the eddy current brakes should then give an additional 0.6m/s^2 (or about 290 kN of brake force for a 488t loaded train) in retardation. Interestingly, the eddy current brake force actually *increases* with speed! Something which surprised me when I read it but when I think about it being an effect of Lenz law it does make sense. In any case from my understanding the train simply reduces the magnetic field at higher speeds (to not rip up the tracks I guess) so that the brake force is relatively constant, this should mean it being easy to implement for the devs.

    The lower brake force for the ICE3 according to the linked graph is due to the weak electric brakes and somewhat weaker disc brakes at high speeds.
     
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  2. FD1003

    FD1003 Well-Known Member

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    Correct me if I'm wrong but didn't they remove the eddy current brakes from the BR406 (ICE3M) because it caused damage and lifted up lots of gravel in the non-German tracks togheter with adding a little spoiler in the bogie area?

    From the best source in the world:

    "Problems with flying gravel and its frictionless linear eddy current brake came up during testing. In order to limit the creation of tornado-like vortices that pick up gravel and to limit damage from flying gravel to the train, spoilers have been added under the car joints, under the carbody next to the bogies and under the powered axles on the bogies.

    The linear eddy current brake, which is required for higher speeds, cannot yet be used, because the magnetic field would rip off the magnetic covers of some trackside equipment; those covers will have to be replaced by non-magnetic ones according to the EU Technical Specifications for Interoperability for international rail traffic in Europe."

    Although I don't know how up-to date this piece of information is and the extend to which is accurate, also since we are going to Bruxelles midi we run the exact trainsets which can't use the eddy current brakes.

    Anyway unless they completely removed them or permanently deactivated them it makes no sense they don't work on german tracks.
     
    Last edited: Sep 17, 2020
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  3. cwf.green

    cwf.green Well-Known Member

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    Yes, the eddy current brakes can cause annealing of the tracks, not very good ;). As far as I know they are still used, but some lines (or everywhere) they are only allowed to be used for emergency brakes. It would surprise me very much if they were completely disabled because the ICE3 does not (I think) have the braking performance to stop safely in the normal pre-signalling distance at 160 km/h (1000m stopping distance leaves no safety margin). For 160 km/h and 0 grade you need around 185 BrH which there is zero chance you will achieve without Mg-brake.
     
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  4. FD1003

    FD1003 Well-Known Member

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    I agree, but at least we can give DTG the benefit of the doubt, although I suspect they just decided to be lazy and didn't bother adding an extra mechanic or it was somehow impossible for them to add
     
  5. cwf.green

    cwf.green Well-Known Member

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    Hmmmmm, haha ;) Well, frankly I don't know if the Eddy current brake is used or where it is used, perhaps the use of it in emergency overrides the worry about destroying track side equipment etc. I don't know. But even if it is disabled in the game, why do the magnets lower when in emergency? And why is the retardation 1.7m/s^2 with only air + electric (way too high if you check the graph)?
     
  6. breblimator

    breblimator Well-Known Member

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    I love these considerations on the details of how trains operate. I dream that this game is developing mainly in this direction, but it is probably easier to sell a new route than the new 'simulation module'*. A little understandable.

    *simugraph addition
     
  7. FD1003

    FD1003 Well-Known Member

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    All your evidence simply points out to them either not doing enough research on the subject or them just lazily introducing this mechanic.

    They maybe just got some braking distances and they decided to represent them not keeping in mind the eddy current brakes and adding the animation to show off their animation budget I guess? Jokes apart a lot more people will know the shoes will drop down but much fewer actually know its effect and how to check if the in game performance is realistic, I guess it's only you in this forum with the will and the knowdlege to check these thing out.
     

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