Kato #4 turnout on main line?

french_guy Jul 18, 2007

  1. french_guy

    french_guy TrainBoard Member

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    Hi,

    Is a Kato #4 turnout really bad on a main line? I don't really have choice with my trackplan, I need to have a #4 on the main line...Is it bad? do I have to expect some issues?
    Thanks
     
  2. Night Flyer

    Night Flyer E-Mail Bounces

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    I guess it depends on what you mean by "bad"? My recollection of John Armstrong's book Track Planning for Realistic Operations would conclude a #4 turnout on a main line is "less than ideal". However, if that's what you have to do, go ahead.

    I'm thinking you're in N-scale? If so, the Kato N-scale #4 turnouts have some issues than can be fixed without much trouble according to John Sing. Here's a couple of links to some of his material, including how to tune up Kato #4 turnouts (lots of photos, may take some time to load):

    http://community.webshots.com/album/63811183jlGNcs

    http://home.comcast.net/~j.sing/Peavine_Layout_Overview.html#Track_Plan

    John Sing does some impressive stuff with that small layout, hope this is helpful.
     
  3. GM

    GM TrainBoard Member

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    The reason many people avoid putting #4 turnouts on the main line has to do with the frog angle and speed. As the speed of a train increases, the sharp angle of the #4 tends to jerk the train to the side and often this jerk results in an engine overturning.

    To avoid the jerk a smoother transition is needed hence a larger frog number is used for the turnout. It is quite common to use #8 or larger number frogs on the mainline and #6 for the industrial sidings.

    You can see the effect of the frog # by making a simple drawing. Just follow these steps to make the drawing
    1. On a piece of graph paper rule a line parallel with the x axis and mark a point on the line near one end.
    2. From the point you made in step 1, draw lines to a point located one (1) unit above the x axis and 4 units to the side. That line represents the slope of the divergent track from the mainline.
    3. Continue as in step two (2) above with horizontal dimensions of 6, 8 10 and 12.
    When you have finished you will have a drawing showing the angles of the #4, 6, 8, 10 and #12 turnouts. On real railroads it is not uncommon to see a #22 frog where high speed trains move from one track to another without slowing.

    Now back to your question: It's not bad, just not done very often on a model railroad. Yes, you can expect some issues in the derailment department, especially if you attempt to run through the turnout at high speed or if you attempt to back a long heavy train through the turnout.

    The best way to find out if a #4 will work for you is to try it and find out what happens.

    I hope this helps,
    Jerry
     
  4. jagged ben

    jagged ben TrainBoard Member

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    It's bad in the sense that...

    -It's not very realistic.
    -It might cause problems if you run a bullet train through the diverging route at prototypical speeds.

    It's not bad if...

    -It goes to a siding or spur and...
    -You're running your trains slow on the diverging route.
     
  5. SteamDonkey74

    SteamDonkey74 TrainBoard Supporter

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    I personally would avoid using a #4 for much of anything, unless it was a very low volume of cars, low speed of traffic situation, where nothing running over the switch was very long, either. An example where I would consider a #4 would be a logging operation where the log cars were short and the engine would be something like a Shay.

    I would NOT use these in places where I wanted trains to seamlessly run from one mainline to another. I would also not try and back up a string of cars over one of these. The number 6 turnouts are almost too tight for this already.

    Is it possible to cut down the the tracks leading into the two-track end of the switch to get at least a #6 in there? If so, it will probably save you a lot of headache later. Even better, get a #8 in there if you can do it.

    Best of luck!

    Adam
     
  6. okane

    okane TrainBoard Supporter

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    Well first off if you are using Kato Unitack as I am you have two choices number 4 or 6 turnouts. I try when possible to use number 6 turnouts on all my mainlines.

    However I use the number 4 in yards and on all the spurs where I need turnouts. I followed the advice from John Sings tutorials on the number 4 turnouts. I have experienced no problems as in the case's I use the number 4 turnouts I am not running trains at a high speed.

    Sure you need to be careful when backing up a long train through the number 4 turnouts, but that is part of the operational challenge.

    I have one number 4 turnout on my mainline, I am going to see how that works and if I have problems I will change it out.

    I agree with Jim above try it.
     
  7. Triplex

    Triplex TrainBoard Member

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    Does the main run through the straight side or the curved side, or is it a junction where both routes are mains?
     
  8. french_guy

    french_guy TrainBoard Member

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    Hello,

    This is my layout....I removed the 2 x #4 turnouts!!! let me know what you think
    Thanks
     

    Attached Files:

  9. ppuinn

    ppuinn Staff Member

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    Although the configuration of a Kato #4 turnout is a little different, I have not had problems using hundreds of Atlas N-scale #4 turnouts in mainlines, usually with the main through the straight rails and diverging rails to sidings and spurs. I usually maintain a slow to medium pace through the diverging rails and have rarely had difficulties with properly installed #4 turnouts.

    If problems have occurred at #4 turnouts on a main, I have discovered problems are usually related to:
    1. not laying the tracks to and from the turnout perfectly square to the turnout;
    2. points not filed sufficiently to permit a smooth transition onto the point from the outside rail (as mentioned in John Sing's thread linked above by Night Flyer);
    3. improper gauge (mostly noticeable only in some of my older turnouts that have seen service on several previous layouts);
    4. inadvertent (and on some occasions, intentional) installation of the straight #4 turnout with a very slight bend in it...so slight it was only noticeable when holding a straightedge nearby or when sighting carefully down the length of the turnout); [FWIW--there was a thread in the Inspection Pit last fall, I think, that asked about new Atlas turnouts that were very slightly bent/warped...and the consensus was that they could be straightened if needed, or left bent if it didn't affect performance.];
    5. installing the turnout over a seam in the surface which produced unevenness and/or led to twisting of the turnout. Sometimes the transition from mainline level down to the siding level was made too abruptly, so the turnout was subtlely twisted, which caused unreliability until the problem was corrected by lengthening the transition;
    6. installing the turnout where the surface started a vertical curve up or down into a grade...even though the transition didn't look that sudden.
    7. installing the turnout on a flat surface that tilted to one side or the other. (I have a number of #4 turnouts that work quite well on the flat portion of a 2% grade; that is, they work fine despite being tilted lengthwise--lengthwise tilt seems ok, only side to side tilt seems problematic).

    All of these factors would probably affect performance on Kato (or any brand) turnouts. If you have problems with #4 turnouts on the mainline, I think it is much more likely to be caused by one of these problems rather than by the fact that you are using a #4 turnout.

    [FWIW--Atlas N-scale #4 turnouts make a perfect 19 inch radius curve through a 15 degree arc.]
     

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