Atlas O Switch Question #2

Ugh. .I think I found my problem, though I didn't think this would a issue with 3 rail.   In debugging my issue I isolated my 2 reverse loops (like I would with HO or 2 rail) and that appears to resolve my issue.

 

However, in reading an add on sentence to one of the posts, the statement leads me to believe that I need an "Atlas Snap Relay" or DPDT switch to reverse the polarity.  For some reason (since I am not very electrically acute) I didn't think that would be an issue with AC - 3 rail.     Again, I am using Atlas 3 rail turnouts.

 

Would someone please confirm.   Thanks

If you're running three rail track there is no polarity involved. The middle rail is the hot and the outside rails are the common. A reverse loop makes no difference the middle goes around the loop and connects back to the middle and the outsides are cross connected anywhere on the layout and connected to the common. Atlas switches run fine as I have 16 operational on my layout now with more to come. What I do on the track between the turnouts is run a hot feeder to the center rail between the turnouts

or a least a jumper from the center rail before the turnout to the area in between the turnouts. I never have any problems with dead spots but I have power drops every 6 to 8 feet throughout the layout. No TMCC signal issues or dead spots. Make sure you have good track connectors and make sure they are TIGHT for trouble free operation. Do not apply the same rules for DC HO to 3 rail. With the frogs being hot tells me your track connections might be loose or you don't have enough power feeds.

Ron

Ron - thanks for your reply and suggestions.  After tightening the rail joiners per your suggestion, I still had a short somewhere.   So, I began to dismantle the track sections at a time and whata ya know.   One turnout without one of the reversing loops must have a short within it.  Once isolated all work well.   Just to be sure I install the same turnout elsewhere on the layout and it shorted the entire layout again.  So there you go.  Problem solved.

 

Thanks again Ron.

I would look at the underside for your problem. There is a jumper wire the jumps the center rail power into the middle of the switch. These wires are pretty small (maybe 20 gauge) and brown or black in color. If it got overloaded from a short it could have burned the insulation off of it. The older Atlas switches were more apt to have this problem than the newer ones.

Ron

Newer switch (turnouts) Older turnouts had the connection wires in the plastic.






The moveable rails should be isolated, sometimes there isn't enough space between the hinge point of the moveable rail and the stub rail behind it. There could also be issue with the two dead rail sections touching live rails.

I don't rely on the jumpers to give me power to the rails or transfer it past the switch. I wire a power drop near each end of the switch and then put them at 6ft - 8ft in between. That way the only thing the jumpers have to power is the track in the middle of the switch. If I notice a drop out on a switch in the middle I immediately put a drop in the center of the switch. My switches are almost all used (low budget class 3 rr) and I've had no problems with this approach.

Ron

Could it be that the frog is in contact with the closure rails? This would cause less than a dead short (which would trip your breaker) but a resistive circuit which would heat up just like a light bulb or toaster element.

 

If you have dead spots within the switch, you must momentarilly power the closure rails, one at a time, depending upon which route (normal or reverse) is being travelled upon.

 

I can provide more detail if you wish.

 

I have been using two 3-Pole Double throw relays for each switch. This has been extremely reliable for over 12 years now, and it never gets out of co-ordination with the switch points since the relays are activated by the wheels passing over the closure rail of either route.

 

Hope this helps!!

Just wired power between the rails of an Atlas switch on our club layout.  Seems that a lot of them lose their connection.  You'd think it wouldn't be that hard to do that connection properly...

I'm renewing this old thread, because I have a similar problem that none of the remedies fix.

I have two O45 Atlas switches (smallest radius on my layout) joined back to back.

Loco hiccupped upon entering outbound switch on the horseshoe.

Took both switches out and examined back.

Exit switch had continuity between all jumpers.

Entry switch did not have continuity, but that's not where the loco stopped.

Entry switch has jumpers replaced - one has no screw - just hole.

I added power drop between the switches and connected each end to end with a jumper.

There is continuity on the inner rail where common is connected downstream.

All that made matters worse.  Now loco stops on outbound switch.

Back of both switches look like the newer style.

What now?

Are you sure you're not facing a pickup roller spacing issue since the switches are back to back?  When the locomotive stops, see where the rollers are.