Db Br 155 Tap Changer / Traction Lockout

Discussion in 'TSW General Discussion' started by li150special, Oct 15, 2021.

  1. li150special

    li150special Well-Known Member

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    I apologize in advance if this has been discussed elsewhere already, but I have not found anything on the forums or the internet. And yes, I have played the introduction and read the manual.

    From that, I know that the BR 155 has a very clever "tap changer" system and I basically understand how it works. I also know that there is a traction lockout if you operate the brakes. Fair enough.

    The problem I have is that, when I have selected and am running in a certain number on the tap changer and now want to change that in any direction, up or down, there seems to be a traction lockout I cannot explain and the tractive force immediately goes down to zero.

    As an example, I set the tap changer to 5 and the train starts and moves along nicely. If I now increase the tap selector to, say, 6 or 7, tractive force is zero (the blue bar disappears and the tap changer display shows "00").

    However, if I set the tap changer to zero and THEN increase to 6 or 7, the blue bar builds up again.

    Could some of the more experienced BR 155 players please explain what I am doing wrong? Thank you in advance!
     
    Last edited: Oct 15, 2021
  2. Lamplight

    Lamplight Well-Known Member

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    I‘d bet you have messed with the electric brake force selector. Moving that will cause the traction lock-out you describe upon moving the tap changer. I‘m not sure if that is how it works in the real 155, but that‘s what happens in TSW.
     
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  3. li150special

    li150special Well-Known Member

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    That's interesting, thank you. I have not changed it when starting up the train, but I will try different settings tomorrow.

    Is there anything else during startup I have to take into account (e.g. brake overcharge or anything)?

    Once again thanks!
     
  4. stujoy

    stujoy Well-Known Member

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    I’m not sure if it’s supposed to do this but the issue you describe only really happens if you are trying to add too much power too early, such as when the brakes aren’t fully released on a heavy train. Starting off at 5 is probably too much. There is another control, the tractive force selector, and if you set that lower when starting off, say to 50%, it should stop it from happening as the tap changer value won’t try to increase too early even if you set the target value higher. You can then increase the tractive force to 70% or higher once you are up and running and you are sure you are not putting too much strain on the system. Alternatively, leave that control where it is and increase the tap changer one step at a time, allowing some time in between each increase. That usually works for me and I drive the 155 a lot.
     
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  5. li150special

    li150special Well-Known Member

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    Thanks! I will try this, although I experienced the traction lockout also when going in single changes, e.g. going from 8 to 9 or from 8 to 7, on a running train. Strangely enough, sometimes the loco accepted the increase or decrease, but most of the time the lockout occurs.
     
  6. Lamplight

    Lamplight Well-Known Member

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    I can actually add to this with some real life information. I have a DVD copy of a German documentary on the 155 which includes an interview with a 155 driver. In this interview, the driver explained how extremely heavy trains (as in one 155 was barely enough to move the thing) were started while on a gradient: Traction selector to 70%, sand on, and tap changer to 10.
     
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  7. stujoy

    stujoy Well-Known Member

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    That probably means that 70% is a high number to be starting off at but it is what the traction force selector is set to as default in TSW. I suppose setting the tap changer to 10 right away means that you don’t have to touch it again until you have gathered some speed, as it will still take time to reach tap 10 as the speed increases.

    There is the other mode, where you can force the train to go to the actual tap you select by bypassing the force selector completely, that’s always fun to use. That uses the up/down/hold positions on the tap changer and you see what it is up to only on the readout and you can max out the amp meter if you dare. That wouldn’t be advisable in real life!
     
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  8. li150special

    li150special Well-Known Member

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    So I went back and experimented a little bit today. You are right, when starting with 1 or 2 and increasing one notch at a time, slowly, it is in fact possible to avoid the lockout.

    The thing is, though, when you are running down a gradient, e.g. on MSB westbound, and the train has a certain speed, it is virtually impossible to use the tap changer that way. It will automatically shut down power, maybe because the traction force and the movement of the train do not "match"?

    Also, on a general note, using it is very sensitive. Once you go one notch too far, or a bit too quickly, the thing shuts down power.
     
  9. Lamplight

    Lamplight Well-Known Member

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    Not necessarily. Due to the gradient and heavy train, you need to be very careful with how much force you apply to stay just barely below wheelslip. The actual words of the driver were reduce traction force selector to 70%. However, with just that one quote as a reference, it‘s difficult to extrapolate what a normal (for lack of a better term) position for the traction force selector would be.
    Indeed! Quick way to fry the loco, as is using taps 28-30 by the way. Those taps would instantly fry the loco under normal circumstances since they‘re only intended for use when less than 15kV are supplied by the catenary.

    li150special, I don‘t think I can help you any further based on your reports. Try the advice of stujoy and see how it goes. Sorry :(
     
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  10. delucadomenico2009

    delucadomenico2009 Active Member

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    With my experience in real life too, this loco is much easy than it seems. After you take a bit of skill on it, this is the much confortable mode to drive it: at start. Tractive selector 70%, sand and tap 3. As soon as you start move, increase the force tap by tap with a moderate speed 4,5,6 ecc. When you reach the coast speed of the train near tap 10/12, set the power on 0 and start with the increase/neutral/decrease selector to mantain the correct speed. Ps. Remember to overcharge the brakes everytime until you reach 5kmh minimum
     
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  11. li150special

    li150special Well-Known Member

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    Thank you for your interesting and informative post. I will definitely try it. Just one quick question, the brakes are to be overcharged with every increase/decrease of the tap changer?
     
  12. delucadomenico2009

    delucadomenico2009 Active Member

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    No need. Just when you start moving the train.
     
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  13. li150special

    li150special Well-Known Member

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    I think I finally found out what I was doing wrong all the time.

    When you are using the tap changer and touching the "release brake" button, the traction will lockout on the next change of tap.

    Similarly, when you are using the "up/hold/down" and touching the "release brake" button, the traction will lockout immediately.

    So, at the end of the day, the solution is to keep my finger away from that button.

    D'Oh!
     
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  14. Lamplight

    Lamplight Well-Known Member

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    Very glad that you managed to find the issue :)
     
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