Three way switch examples

[davefoxx]

Sheesh Dave, talk about tight gauging.  When ya gonna built that sucker?

Heh, I thought the same thing!  No Atlas flanges are going through a scale model of that switch.

DFF

[Philip H]

BLMA might . . . might.

[Bob Bufkin]

Reminds me of the old Atlas 3 way (which I still have somewhere).  Everything would stall with all the plastic they used.

[Philip H]

Bob,
You put one of those Atlas 3 ways at my house . . .

[nkalanaga]

Stub switches are easy to build - no points to file and fit.  I've built a 3-way in Nn3 and it works fine.

Now for the hard part.  The 2-way is easy, as you can use wire pins as throw limiters, and use any throw device with a spring mount.  The 3-way has to be able to stop in the center, reliably, in either direction, and there is no way to put a mechanical stop there.  A servo motor might be able to do it, but I've never heard of anyone trying it.  Mine uses a Caboose Hobbies sprung ground throw with the middle eyeballed and the handle straight up.  It works - on a board, as a demonstrator.  I wouldn't recommend that method for a layout.  A double-pole 3-position slide switch might work, and would allow for powering both frogs.  Mine are powered with microswitches activated by the other ends of the CH ground throw throwbars.

[rswinnerton]

I checked that switch at York, PA. The points are slightly lapped. (8")

[nkalanaga]

Russ:  I imagine all "symmetrical" 3-ways have the points like that.  Otherwise the throwbars would interfere with each other.  At a casual glance they still look like one turnout, not two overlapped.

Incidentally, I've always thought that the Pasco, WA yard had 3-way turnouts at the hump.  The railroad's plans show them that way, but on Google images they're clear lapped turnouts, as the switch motors are 20 ft or so apart, not across from each other.  I've spent nights there, with my father, in the early 70s, and never noticed that.  Of course, there were too many other things to watch from the retarder operator's office to pay much attention to turnouts, at least until one fails...