Double crossover mechanism

Discussion in 'Track Planning' started by LoudMusic, Nov 10, 2006.

  1. LoudMusic

    LoudMusic Member

    I've been looking for a way to mechanically (without electronics and motors) throw all four sets of points on a manually assembled double crossover section.

    I found this ...

    ... but the cost of four tortoises for less than a square foot of realestate is a bit out of my league ;)

    I'd like to use one, but I could settle for possibly two, ground throw levers for realigning all points simultaneously. I figure it's going to take push/pull wires inside of piping. The best I can think of (way past my bedtime) is a to have the throw mechanism travel the direction the rails are going and curve off of it to 90 degrees four times pushing the four sets of points in and out together.

    Surely there's some really simple method I'm missing here. Help!
  2. MilesWestern

    MilesWestern Active Member

    Yes, buy a peco with the easy snap switch feature, with the flick of the wrist, next load, any road! ;)
  3. LoudMusic

    LoudMusic Member

    Hmmm, I don't think the parallel tracks are spaced far enough for On30, though. I can't find any dimensions on it so I can't be sure.
  4. MasonJar

    MasonJar It's not rocket surgery

    You do not need to align all points simultaneously - only in pairs.

    In the drawing below, there are four possible routes:
    A-C & B-D (or reverse)
    A-D & B-C (or reverse)

    Turnouts A & D and B & C must always be thrown in those pairs, so... you need some sort of device to do this. I think it could be done with the "choke cable" approach, and a (large) triangular plate (or at least rigid wire frame) to provide the opposing movements that are required. I.e. A's points have to move "north" and D's points have to move "south" in order to make the crossover from one track to the other.

    This approach would require two throws, but only one at a time would need to be activated to make a cross from one track to the other.


    Attached Files:

  5. AlienKing

    AlienKing New Member

    You can simplify the situation by assuming that there are only 2 possibly states for the swtich, crossing and strait through. Any other combination will cause at least one train to hit an opposing switch if coming from any of the 4 possible directions.

    In this situation, all the switches are either pulled towards the center, or they are all pushed away from the center.

    Building on Andrews approach, you could do it all with a single throw.

    Attached Files:

  6. MasonJar

    MasonJar It's not rocket surgery


    I knew someone better at geometry could figure it out! ;) :D Great sketch 'King! :thumb:

  7. LoudMusic

    LoudMusic Member

    That is exactly what I was hoping for. Thanks man!
  8. AlienKing

    AlienKing New Member

    Err, looking back at my diagram, the cam on the left is hooked up backwards. The stiff wires should be swapped, so they are the same as the one on the right.
  9. steamhead

    steamhead Active Member

    With any mechanical set-up. as drawn by King (& revised), you have to make sure there is no "slop" in the linkages, and that you get some mechanical advantage by hooking up the "input" on the outermost holes of the bellcranks, and the "output" (the ones going to the turnouts) on the inner holes (closer to the pivot point).
    Good luck!!!
  10. Russ Bellinis

    Russ Bellinis Active Member

    If you use Peco turnouts as Miles suggested with AlienKing's sugesstion for a linkage, the Pecos will use the built in overcenter spring to lock into the correct position even if there is a little bit of play in the mechanism.

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