My recently expanded HO layout (PDF attached) is DC powered. It has double reverse loops, which I've successfully wired to their own dedicated mainline direction and reverse loop center-off DPDT toggle switches. The reverse loop-operations function perfectly and as intended. (The two sets of double red lines within each loop in the schematic indicate that both rails are gapped.) I don't believe the reverse loops are relevant, however, to my questions below (but I could be wrong!) and mention them here for informational purposes only (I hope!). Please refer to the north yard and south yard tracks in the bottom right of the attached PDF track schematic (you may have to rotate it that so it's upright): The Task At-Hand: A) I want to wire each yard to its own dedicated center-off SPDT toggle switch so that each can be operated independently of the other (idle locos and a few cars will be parked there, next to the depot). Turnout #10 leading to both yards is a DCC-friendly Walthers/Shinohara, which will be operated manually. In the schematic, the north rail of each yard's track is gapped (shown by the single red line) where it joins the manually-operated turnout. Some Background B) On a very similar, slightly smaller and recently dismantled version of the current layout (also with the same double reverse loops, north and south yards and one SPDT for each yard in the same location as in the attached PDF), I wired: 1. the ungapped rail in each yard to its respective toggle's center lug (yellow and red wires); 2. an end lug of the south yard's toggle to the center lug of the north yard toggle (white wire); 3) the blue wire from an end lug of the north yard toggle to the orange wire of the right-side loop's inside rail; 4) the other end lug of each yard's SPDT was not connected to anything I'd attach the PDF of the old layout's wiring schematic too, but my scanner is currently not working. So I hope the wording above is clear enough to envision how the previous layout's yard-SPDT wiring was configured. The Conundrum: C) On the old layout, the wiring between the north and south yard tracks and their respective toggles worked as they should have (with a minor hiccup here and there), rendering each yard's tracks either "live" or "dead" when flipping the toggles. However, when I tried duplicating this wiring configuration on the current layout, I got no current at all to either yard. I even switched the wires to the gapped rails as a test. Still no go. My questions: D) To which rail - the gapped or ungapped - in each yard should I connect a wire to the middle lug of its dedicated SPDT? E) Is it even necessary to wire the two SPDTs together as described in "B) 2." above? Again, I want to have each yard operationally independent of the other. F) Is it at all necessary to wire the north yard toggle to the right-side loop's wire as I did before? As I recall, I thought this may have been the cause of the occasional hiccup I experienced when running a loco into and out of the yards. It seemed that the two toggles were at times in electrical combat with each other! Lots of information, I know. Thanks for reading it over carefully and providing your thoughts and advice on exactly how I should wire the two yard tracks and their SPDTs. If you have the capability, a detailed, color-coded wiring schematic would be most helpful. Visual helps a lot!
Well, I can't see your diagram. That said... Buy two SPST switches. Wire your power pack directly to each switch. Wire the other lug of each switch directly to the rail you want them to control. You don't need double throw switches unless you want to choose between two power packs--and then you're asking for trouble unless you use double pole switches controlling both rails. All your double throw switches with one lug not connected gets you us two off positions. You don't need to wire two independent yards together. Doing so is asking for trouble.
Tulsan, Thanks. I've already got the SPDTs, so I'll stick with them. I'm using one power pack for track power (this is a one-train operation); the other power pack runs nine Tortoises. The gapped rail should be wired, correct? You can view the PDF attachment by downloading the free Adobe Acrobat Reader if you don't already have it installed.
Yes, it's the gapped rail that needs to be wired through the switch. It's not a bad idea to also wire the other rail in more than one place, to increase reliability and reduce resistance.
Tulsan, Well, I wired as you suggested, but it didn't work as I want - and as it did flawlessly on an identical track configuration I tore down early this year. I'm just trying to duplicate the wiring I had before, but can't seem to achieve. I used the SPDTs I already have, leaving one lug unconnected, the center lug wire going to the track and an end lug wire going to the power supply. But to move locos either direction into or out of the yard, I have to flip the toggle on the mainline direction control DPDT, as well as a SPDT. Flipping the SPDT toggle alone only results in one-way movement of the loco. I want each yard to function independently of the other and independently of the mainline DPDT.
Well, I'm having trouble following exactly what's going on here. But IF I understand you correctly... You talked about reversing loops. Do you reverse polarity of the main line? If so, you need to feed the single pole switches from the mainline feed. When you throw the DPDT to reverse direction, you disconnect the continuous rail from one power pack lug and connect it to the other. If you wire the single pole switches directly to one lug or the other, then half the time you'll have a complete circuit and half the time both yard rails will be wired to the same power pack lug. Figure out which of the center connections of the double throw reversing switch goes to the gapped rail, and wire that connection to the single throw switches. That way, when the continuous rail is connected to one power pack lug, the gapped rail--whether main line or in a yard--will be connected to the other.
Tulsan, My original posting was far too wordy and complicated, so I've simplified it here with the PDF agan attached. You'll have to rotate it to see it in the proper orientation. Hope this helps. Using two separate, center-off SPDTs (not DPDTs) for the south and north yards, how can I wire them so that the yards operate independently of each other - and independently of a separate mainline direction center-off DPDT, which controls the entire layout and is also a component of a double reverse loop operation? My layout is DC. I understand I could also use SPSTs, but SPDTs are what I have in quantity - and used successfully for two years to power a nearly identical yard configuration on a former layout - so no need to recommend them. The yard wiring I used on the old layout doesn't seem to want to work here! In the attached PDF schematic a single red line = one rail gapped, and two red lines = both rails gapped. I gapped the north rail of each yard track between the end of turnout #10 that leads directly into the yards and the end of the yards. However, when I wired a switch's center lug to a gapped rail and one end lug to the power pack, I got only one-way polarity within the yard. To get two-way polarity within the yard, I also had to toggle the mainline direction DPDT - an extraneous motion I want to eliminate so that I only need to toggle a SPDT and be able to run locos into and out of the yards. My objective: to make each yard either "dead" or "alive" and electrically separate from the other - and separate from the mainline DPDT. How should I wire the two SPDTs to achieve this? Wire all three lugs or only two? To what? Gap more rails and/or add feeders? If so, where?
As I understand it, you use the DPDT to reverse direction by reversing polarity, right? So.... 1. You don't make a block 100% independent of the main line with one gapped rail and a single pole switch. You can do it with two gapped rails and a double pole switch--or two single pole switches. But not with one. You cannot make a block 100% independent if it shares an un-gapped rail. The two blocks cannot be running reversed polarity from the same power pack if they share an un-gapped rail. 2. You don't want to make them 100% independent. Wire them as I detailed above and your DPDT controls direction for the main and both yards, while the single pole switches are merely on/off switches for each yard. If the engine enters the yards from the main, and exits the yards to the main, you don't want three switches which all reverse direction. Right? Do you really want to have to align the yard switch to match the direction of the main line switch whenever the locomotive enters the yard? Or would a single direction control and two simple on/off switches be much, much more convenient?
Tulsan, Good points for further thought. The mainline direction DPDT ("A") controls direction along the mainline tracks only, but not within the reverse loops. The reverse loop DPDT ("B") governs only the two loops (forward, reverse or off within the loops). So, when a loco is in one loop or the other and just before it exits (that is, before it crosses the double-gapped rails in the loop) - about to enter the mainline - I must toggle only mainline direction DPDT "A" to change the polarity. And as long as the loco continues to travel in and out of the two loops (plus along those short sections of the mainline leading back into and out of the loops), the only switch I must toggle is switch "A" - the mainline direction. Once the loco is traveling along the mainline only, then I leave switch "B" alone. 1. From above: On my former, nearly identical layout I had for two years, each yard did operate with its own dedicated SPDT and single-gapped rails - forward, backward and off - along the yard tracks. Once a loco crossed the double-gapped reverse loop rails, then I toggled switch "B" to keep it moving within the loops. This is what I'm trying, unsuccessfully, to duplicate now. It's indeed puzzling. Could this be because of the slightly different positioning of turnout nos. 8, 9 and 10 to each other on the new layout? On the old layout, there was a sectional track between nos. 8 and 9 and between nos. 9 and 10 (all were Atlas Snap Switches). On the current layout, nos. 8 and 9 and nos. 9 and 10 (all are Walthers DCC-friendly) are directly connected to each other. Does this make a difference? I can understand that the yards would not be independent of the mainline, which, of course, turns the juice on and off throughout the layout. Point taken. 2. I can see that this is a workable and probably simpler alternative to what I used before on the old layout. But, the locos can't enter or exit the yards from the mainline, since they're accessible only from the loop on the right side of the layout. The yards are wholly within that loop. Were you able to view the PDF? However, just after exiting a yard and crossing over its single-gapped rail, the loco traverses turnouts nos. 10 and 8 and then crosses over the double-gapped loop rails, entering that loop. Are, then, turnouts nos. 10 and 8 electrically on the mainline here? I'm beginning to think that once we answer these questions, the solution - and whether I'm right or wrong about duplicating my former SPDT setup - may reveal itself. I'm also keeping in mind your more convenient option. Thanks again for all your help!
No, I can't view the PDF. The yards may be within the loops--a very convenient place for them--but what matters is the switch trains use to enter the yard. As a train enters the yard, the polarity in the yard must match the polarity of the track just outside the yard. If the yard entrance is on the main between loops, and shares one rail with the main, the SP kill switch must be wired to that other main line feed. If trains enter a yard from trackage which is within the loop, and shares a common rail with that loop, the kill switch must be wired to that other loop track feed. What matters is, when the locomotive is halfway into the yard, and the insulated gap in the one rail is directly under the middle of the locomotive, is the front truck always getting the same polarity as the rear truck? When the answer is yes, you aren't having any more problems.
Tulsan, As for your point in the last paragraph above: With the current layout's direct connections between turnouts nos. 8 and 10 and between nos. 8 and 9 being different than on the former layout (that is, no sectional track between them any more), therein may lie the problem and the main question. That's my theory anyway. Once you've see the schematic, it'll become clear. Send me a PM with an e-mail address, and I'll send you the PDF. You'll need to re-orient it to view it properly. Once you've looked it over closely, you'll be able to see more clearly what I'm describing. The locos do enter the yards from one loop via turnouts nos. 8 and 10. The loop is double-gapped where its rails join turnout no. 8. There is no common rail within either loop, as both are double-gapped at both ends of the loops. Turnout no. 10 is single-gapped to each yard's north rail. There are no gaps where turnouts nos. 8 and 10 or where turnouts nos. 8 and 9 join each other. By "kill switch" do you mean the SPDT's center lug, the off position? As was the case with the former layout, the locos would use only the SPDTs to enter and exit the yards. Before entering or exiting a yard, I need to toggle only the correct SPDT for the given yard while the loco is on turnout no. 10 and before or after it enters or exits the loop. Again, the yards' entrance is at the very end (south) of turnout no. 10, which, as with the old layout, is manually operated.
There is a common rail, because a single pole switch wouldn't be able to power both rails. That common rail gets its power through a double pole switch. Park the locomotive half in the yard and half out of the yard, and turn all three double pole switches off. Turn up the power and turn each double pole switch on one at a time. When the locomotive moves, connect that switch you just turned on to your single pole switch. That is the DPDT which determines which lug of the power pack the ungapped rail in that yard connects to. If that's not the same DPDT which determines which lug the single pole is connected to, there will be times both yard rails are connected to the same power pack lug (and you won't have a complete circuit and the locomotive won't move). So park the locomotive half in and half out if the yard and turn the switches on one at a time until it moves, then connect to that switch. Then turn all three DPDT switches back off, park halfway in to the other yard, and repeat.
Tulsan, Send me a PM with an e-mail. It'll make a whole lot more sense when you can see the schematic and offer suggestions and insights based on it.
I'd rather not, thank you. You have a yard inside your left loop, entered from your left loop? Wire it from the same DPDT that powers the left loop. You have a yard inside your right loop, entered from your right loop? Wire it from the same source that powers your right loop.
