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Here is a video I took a couple of years ago demonstrating this voltage drop:

Some more info: there are 4 lock-ons with drop wires for power and ground on that reverse loop (1 just before the O22 switch, 1 just after that switch, and 2 before the insulated track sections). The power is drawn from the right throttle of a Z4000.

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Arnold, something to ponder: Even though the ZW is sending power to the crossing gates (hot side), since they're activated by the insulated rails, their common connection is through the track Common.  Gate activation increases the current flow which causes a slight voltage drop through the Track Common part of the wiring back to the Common ground bus connection.  Another matter is since the slow down only occurs in one direction, it may have something to do with the fact that only one outside rail has a hard connection to the Z-4000.  The other outside rail has the added resistance of the train wheels and axles.

All that aside, since the major slowdown evident in the video only appears to occur just before the switch where the train re-enters the mainline, there may be a couple of causes for this.  Depending on which outside rail is insulated and where the common feed is tied into this section of track, there may be poor conductivity between track sections on the Common powered outside rail.  If this Common powered outside rail is also the side which has the fibre insulating pin at the switch, then that last piece or two of track just before the switch only has it's Wired Common connection feeding in from one side and not the switch side.  Without more details on exactly how the Common wiring is configured, its difficult to know for sure how much any of this may be affecting the slow down.

If a locomotive has traction tires and they are all on the same side or has traction tires on the same side and the Common collector is only on one truck, that's also something to consider.

If you haven't already tried this, tightening the track around the Common connected outside rail pins, cleaning track, train and loco wheels may help.

Last edited by SteveH

My thought it was on the ground side as well, I don't think this is voltage drop caused by the hot side.  If you run a lighted car over the area, do you see the bulb dim (was thinking of this bc of the thought about traction tires). If the traction tire is on the ground rail that isn't insulated, it could cut down the return side significantly. You could try running several drops (ground) to the rail in the insulated section that is the return (non insulated) side and see if that helps (me I would find a way to attach them temporarily, like to each section of track in the insulated section, and see if it helps).

I would say maybe the transformers are out of phase (since they have to share a common ground for your setup to work ie one transformer powering the gates, the other the track), but it wouldn't be like this, I don't think they can be 'slightly out of phase' to cause a small power drop, it would be pretty evident, and not one way, either.

One other way would be in the insulated section to solder the rail joints on both common rails (within the section), to make sure that there is good flow on the negative rails, insulated and not and see if that helps, but making sure the connection is tight may be easier.

Steve and Bigkid, I believe what you say sounds like it has merit, though I don't fully understand all of it. Thank you for your input.

One reason I have not left no stone unturned in correcting this voltage drop is because for the train to slow down going through My Little Town is prototypical. A real train would also down down going through town.

Arnold- I just fixed the exact same problem on my upper loop. I only had one common wire connected in the rear of the loop. When I tested the voltage, it would go from say 10v with nothing on the track to 6v when a loco was drawing power. I added a second common drop on the front, and on the opposite outer rail from the rear connection. Problem solved. The current couldn't make it back to the transformer between the three switches. Good common connections are just as important as good hot connections. You would be amazed at the damage a loose neutral can do in building wiring.

This is a WbB conventional loco running at 8v. It would stall out before.

Bob

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2021-10-24 21.54.49

To re-iterate, I'd suggest starting by improving the outside rail conductivity (lessen the resistance) at the track joints by either tightening the rail connection around the pin (pliers or crimpers) or as Bigkid mentioned by soldering the joints at the problem area.

If that doesn't improve operation, then identify where the Outside rail connection back to your Track Common is located in relation to the problem area.  If you do add another Common connection to the outside rail, you'd need to keep DCS track drop numbers and location recommendations in mind.

Last edited by SteveH

Continuity is King!

Big improvement:

I simply wired in series the ground terminals of 3 lock-ons around the curve and ending just beyond the switch as the train completes the reverse loop.

After having the trains down for 10 days or so while I re-wired the main lines, I am luxuriating in running trains again and - they have never run better thanks to all the outstanding advice I got on this thread.

Most of the re-wiring is done.

Next main project will be to get the sectional couch in the basement out of the house and then adding a 6 foot extension to the layout on the far left side where I will have a weathered custom made Lionel factory and a 2 stall engine house. That will give me 2 additional sidings to park trains. This layout expansion will be a very exciting and fun project and I will run a new Forum  thread about that project too. Arnold

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