Another turnout linkage thread (with images)

gary60s Dec 12, 2015

  1. gary60s

    gary60s TrainBoard Member

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    I always felt that Tortoise and other switch machines went about throwing the points in the wrong way. It involves drilling a hole larger than necessary, or making an unsightly slot, so the arm can throw the points. IMHO there is a better way, by making a turnout linkage between the actuating device and the turnout. This is nothing new and has been referred to as the "bellcrank linkage". I first did these linkages 10 years ago but only drew sketches 3 years ago to help illustrate the method. Some of you may have seen this thread on other sites.

    There are numerous actuating devices including switch machines. The most recent are servos (used with great success by several others) and I started with linkages for them. The sketches detail the procedure for installation and bending the linkage. This method should work with almost all turnouts with a throwbar.

    By using .020 spring steel you take advantage of its resiliency for long life, but with a long vertical leg you also gain its ability to absorb torque. Horizontal section lengths of the linkage should be adjusted to provide a firm seat of the points to the stock rails in both directions. This method can also be used with a manual set-up with a rod and knob control. For manual control, make sure you include rod stops in both directions, to prevent bending of the linkage. (not shown)

    LINKAGE AND INSTALLATION:

    Linking the machine or servo to the turnout is done with 1/16” tubing and .020 spring steel. To install the linkage, adjust the turnout throwbar so that points are midway between the side rails. Most throwbars have holes in each end. If your throwbar does not have a hole in it, you will have to drill one or two. Decide which end of the throwbar will be unused by a machine or ground throw and mark roadbed (in a line perpendicular to the throwbar) two ties back toward frog (see sketches).

    Drill a 1/16” hole through roadbed and table. Cut a piece of 1/16” tubing to the length of the hole depth plus ¼”. Make a note of the tubing length for future installations. De-burr the tubing and test fit a .020 piece of spring steel thru it. Remove the test wire and insert the tubing into the hole and lightly tap in with a hammer. Tubing should be flush with roadbed on top and sticking down ¼” from table bottom.

    Put a 90 degree bend at the end of a length of .020 spring steel 1/8” from end. Cut the 1/8” end to the height of the throwbar. Make another 90 degree bend a distance equal to 2 ties back from throwbar. Cut the long end to the length of the tubing plus 2”. Place long end of spring steel through hole and insert short end into throwbar hole (see sketches). Position the turnout points in the middle of travel and temporarily tape the points and linkage to the roadbed and throwbar.

    The remaining sketches show procedures for linkage with servos and other switch machines.

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    Last edited: Dec 12, 2015
    randgust likes this.
  2. Rocket Jones

    Rocket Jones TrainBoard Member

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    This could go into the Resources section.
     
  3. gary60s

    gary60s TrainBoard Member

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    I wasn't sure Rocket. Lets see if anyone else agrees. If so, it'll be easy to do, and the images can then be thumbnails.
     
  4. RBrodzinsky

    RBrodzinsky Staff Member TrainBoard Supporter

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    If this is a "finished" item, then having it as a resource would be good. Do you have a video of this working, for something like this, that may help folks understand it better.
     
  5. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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    Resources, yes. Please!
     
  6. gary60s

    gary60s TrainBoard Member

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    just put in resources. An admin can delete this if desired. Unfortunately no video was ever taken.
     
  7. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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    Topic is also good here. No need to delete. :)
     
  8. randgust

    randgust TrainBoard Member

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    Once you get under the table, there's a million and one ways to move the crank. The other great advantage is that the vertical distance can be as long or short as necessary. I now use Tortoises on a horizontal alignment by mounting them to a bent-up 2x3" steel reinforcement plate that you use for carpentry, already pre-drilled with lots of holes, and you can also drop out the whole works if necessary from the roadbed area.

    I"ve also put every possible way to put a Rix solenoid machine (which is a redone old-school Lambert HO machine) under the table as well to move the crank around. Because those have contacts, as well as auxiliary contacts, they are nice for signals and turnout position indicators. My entire ATSF layout is done that way. Other than the racket when you throw five or six of them at once from a capacitor-discharge system, they have been very satisfactory. I did my first one back abut 1977 when I melted out an Atlas N #6 switch machine and discovered it was easier to put a new Lambert HO machine under the table this way than cut out a soldered and ballasted switch already in place or replace those underpowered N switch machines. Never looked back again.

    But my crank design in the tube is identical. The only thing I can add is that you want to put a drop of oil in there before you do ballasting or scenery so that glue doesn't creep down the tube.

    As you can see, by increasing the pivot distance back from the throw, the pivot throw distance decreases and point torque decreases. You can also put the crank between the rails, off to either side, and in front or in back of the throw bar.
     
    Last edited: Dec 14, 2015
  9. Rocket Jones

    Rocket Jones TrainBoard Member

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    Another option is the give the wire a good wipe with petroleum jelly before inserting into the tube. Lubricates and protects without dripping out the bottom.
     
    gary60s likes this.
  10. jdetray

    jdetray TrainBoard Member

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    gary60s likes this.

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