Henry,
No. The reverse loops begin and end where you see the two red lines, indicating that both rails are gapped, drawn across the loop tracks.
In the above diagram, though, the two double-gapped loop rails at the bottom are not visible. Single red lines mean only one rail is gapped.
Kerry
*IF* I'm reading the schematic right, AND understanding that you want to use SPDT switches like SPST switches....
(1) take the "north rail" power wire from your mainline DPDT switch, and wire it to one lug (e.g. center) of the SPDT
(2) wire one of the other two lugs to the north rail of your yard track. (you'll end up with "up = on" / "center = off" / "down = very off")
(3) should be good to go.
(EDIT) -- you can also use the third pin to control a second track, so you end up with "up = track1" / "center = neither" / "down = track2")
-Dan
Builder of Bowser steam! Railimages Site
NeO6874 *IF* I'm reading the schematic right, AND understanding that you want to use SPDT switches like SPST switches.... (1) take the "north rail" power wire from your mainline DPDT switch, and wire it to one lug (e.g. center) of the SPDT (2) wire one of the other two lugs to the north rail of your yard track. (you'll end up with "up = on" / "center = off" / "down = very off") (3) should be good to go. (EDIT) -- you can also use the third pin to control a second track, so you end up with "up = track1" / "center = neither" / "down = track2")
You did indeed grasp the question correctly. I'll let you know how it works.
However, I'd like to continue to use the two SPDTs (one for the north yard, the other for the south yard) that I used on the prior layout.
For the other yard, I should then wire the "south rail" power wire from the mainline DPDT to the center lug of its SPDT and one end lug of the SPDT to the gapped (north) rail of its yard track. Correct? Both yards' north rails are gapped.
HOmainlineFor the other yard, I should then wire the "south rail" power wire from the mainline DPDT to the center lug of its SPDT and one end lug of the SPDT to the gapped (north) rail of its yard track. Correct? Both yards' north rails are gapped.
Both rails would be getting "south rail" power if you do that.
You need to wire it the same as the other switch, only going to the other yard gapped track.
A SPDT switch does only 2 or 3 things. It takes power from the center lug B and sends it to A or sends it to C. If it is a center off type SPDT, with the toggle in the middle, it doesn't send any power. It does not change the polarity of the power.
A--------B--------C
Henry
COB Potomac & Northern
Shenandoah Valley
BigDaddy HOmainline For the other yard, I should then wire the "south rail" power wire from the mainline DPDT to the center lug of its SPDT and one end lug of the SPDT to the gapped (north) rail of its yard track. Correct? Both yards' north rails are gapped. Both rails would be getting "south rail" power if you do that. You need to wire it the same as the other switch, only going to the other yard gapped track. A SPDT switch does only 2 or 3 things. It takes power from the center lug B and sends it to A or sends it to C. If it is a center off type SPDT, with the toggle in the middle, it doesn't send any power. It does not change the polarity of the power. A--------B--------C
HOmainline For the other yard, I should then wire the "south rail" power wire from the mainline DPDT to the center lug of its SPDT and one end lug of the SPDT to the gapped (north) rail of its yard track. Correct? Both yards' north rails are gapped.
As I suspected. That confirms that I indeed may have incorrectly labeled the wiring schematic for the former layout. On it, both yards' south rails were shown as gapped.
However, if the south (or north) rails of both yards are gapped, is there another way to wire them properly using a dedicated SPDT (center-off) for each yard?
I don't know why this is so hard, nor how to explain it differently.
You've said you wanted to use both switches.
Wire A to the gapped rail in North Yard. The wire input into B has to be same polarity as the gapped rail. The source of the B wire can be as close as the rail on the mainline side of the gap or it can be elsewhere but not in the reversing section.
When turned to A the yard will be live. Center off or toward B and the yard will be dead. Same for the other yard.
I wired it exactly that way some days ago and again just now with one loco in a yard and another on the mainline: the SPDT's center lug (B) is wired to the mainline direction DPDT's +/positive center lug (B); and the SPDT's end lug (A) is connected to the corresponding +/positive north rail in the yard.
However, I get the same result as before: both locos can move simultaneously in the same direction, but toggling the SPDT only moves the yard loco in one direction; otherwise, it's "dead." In order to move it in the other direction, I have to toggle the mainline DPDT. That's the problem.
I want to move the loco within each yard - forward and backward - using only its SPDT, as I did on the former layout. Is that possible and how should it then be wired? Also connect SPDT lug "C" to ??? maybe?
Take another look at turnouts nos. 8 and 10 on the schematic to see which rails are gapped (single and double) and where. The configuration of those turnouts to each other is somewhat different than they were on the former layout (they're now directly connected to each other), when the two SPDTs worked in their respective yards independently of the mainline DPDT.
I'm still thinking the turnouts may somehow be interfering. That's my wild guess anyway.
Dan,
Done. See my 5:02 pm reply above to Henry and look over the schematic once more please. Is what I want to do possible?
HOmainlineI'm still thinking the turnouts may somehow be interfering.
I don't think so.
The power going to ungapped rail is a constant. It is never going to change polarity with a SPDT switch. You can only turn the gapped rail power on and off. I don't see how it could have worked differently on your old layout
To change direction you have to use either the mainline DPDT or the power pack reverse switch, or you are going to have to gap both rails and install a DPDT switch to control the yard, one for each. Doing the later means the yard can be a potential reversing section, if you aren't doing your job with the switches.
HOmainlineI wired it exactly that way some days ago and again just now with one loco in a yard and another on the mainline: the SPDT's center lug (B) is wired to the mainline direction DPDT's +/positive center lug (B); and the SPDT's end lug (A) is connected to the corresponding +/positive north rail in the yard.
the SPDT should be wired to same terminal on the DPDT that the gaped "north" rail would have been wired to, not the center terminal which I assumed is connected to the throttle
otherwise, when the DPDT is in one position, both rails are either positive or negative and tere is no power to the yard.
greg - Philadelphia & Reading / Reading
Greg,
You wrote: "the SPDT should be wired to same terminal on the DPDT that the gaped "north" rail would have been wired to, not...." The italics are mine.
Would have been wired to or is wired to, or...?
the ungapped "south" rail in the yard is ultimately connected to one of the end terminals of the DPDT reversing switch. The ungapped gaped rail in the yard is connected to the SPDT switch
edit: see correction
the other side of the SPDT should be connected to the other terminal of the DPDT reversing switch that the "north" rails are connected to
did you read Model Railroad Wiring?
the DPDT reversing switch flips the polarity of the rails. in one position north is (+) and south is (-). In the other position, north is (-) and south (+).
the polarity of the center terminals of the DPDT switch are connected to the power supply and do no change polarity when the DPDT is toggled.
HOmainline NeO6874 *IF* I'm reading the schematic right, AND understanding that you want to use SPDT switches like SPST switches.... (1) take the "north rail" power wire from your mainline DPDT switch, and wire it to one lug (e.g. center) of the SPDT (2) wire one of the other two lugs to the north rail of your yard track. (you'll end up with "up = on" / "center = off" / "down = very off") (3) should be good to go. (EDIT) -- you can also use the third pin to control a second track, so you end up with "up = track1" / "center = neither" / "down = track2") Dan, You did indeed grasp the question correctly. I'll let you know how it works. However, I'd like to continue to use the two SPDTs (one for the north yard, the other for the south yard) that I used on the prior layout. For the other yard, I should then wire the "south rail" power wire from the mainline DPDT to the center lug of its SPDT and one end lug of the SPDT to the gapped (north) rail of its yard track. Correct? Both yards' north rails are gapped.
I understood "North Yard" to be a yard of N tracks, likewise, "South Yard" being somewhere else (not pictured).
Essentially all you've got to do is cut the feeder wire for the "north rail" (i.e. the gapped one) of each yard track somewhere, and install the switch (ideally, you'd use a SPST, as you only need to make or break a single wire).
Beat me to the picture, Greg
gregc
Many thanks for the schematic! It really helps.
I've hand-drawn a color and lettered "translation" of how I see it from the viewpoint of the DPDT's lugs and the two SPDTs' lugs. It's easier for me to visualize that way. I've saved it as both a JPEG document and a PDF document.
I don't see a way to attach docs here, though I believe I can do so via a PM. Let me know when you've received it and whether I got it right and where any corrections need to be made.
in the diagram below, the track is connected to what is shown as a motor
presumably you know which 2 terminals on the SPDT switch to use.
gregc in the diagram below, the track is connected to what is shown as a motor presumably you know which 2 terminals on the SPDT switch to use.
A handsome looking schematic indeed! The two DPDTs (mainline and double reverse loop) have long been wired and operating perfectly.
If you have a drawing in this format that illustrates your earlier schematic, send it along.
I also just replied to your PM.
sounds like you're not familiar with reading schematics
in the schematice representation of the DPDT switch on the right below, there are six terminals, the circles. The three on the top are the same as for an SPDT switch. So the DPDT has 2 SPDT. The dashed line shows that they are connected mechanically.
in the reversing switch diagram on the left, the 3 terminals on the left are effectively 1 SPDT and the 3 terminals on the right a 2nd SPDT.
the 3 terminals on the left in the left diagram are represented by the the 3 terminals on the top in the right diagram and similarly the right 3 and bottom 3.
the center terminals in the left diagram connected to the power supply are the left most terminals in the right diagram. the schematic (right) shows that the left terminal with the diagonal lines going up and right can make contact with one of the 2 terminals on the right which are the top and bottom (left) terminals on the left diagram.
is your DPDT reversing switch wired this way? or are the power supply and motor terminals reversed?
SInce there is a reversing section ont he alyout, that is why there is the DPDT wired as a direction switch. SO you have main lien direction and reverse loop direction independent - one is the power pack's reversing switchmt he other is the added DPDT. To change direction of trains in the yard - one of these direction switches has to be oeprated. That's just the way DC works. If you want the yard direction to be independent of the main lien direction controleld by the DPDT, then you must gap BOTH rails and use DPDT toggles wired for reversing to feed the yard, you can't make this work with one power pack and SPDT switches, it's not electrically possible. Frankly, it doesn't sound workable with oen power pack anyway, why would you have a train in the yard go one way and a train ont eh main go the other, powered by the same power pack? It's not like you can have one train circling the main and do switching in the yard at the same time with only one power pack. TO simply cut power int he yard independent of the main, the SPDT is fine, and any of the diagrams already presented are the wya to wire it. However, if you feed the SPST from the main track side of the DPDT, then the DPDT will control the direction in the yard. This is how it normally would work. This is how it works on any of the Atlas track plans with reverse loops if you use their control components as shown in their books as well.
If you have 2 power packs, it's actually still the same. EACH power pack needs a second direction switch (DPDT) because of the reversing loop, and the DPDT is what controls the direction of a train anywhere on the main OR IN THE YARDS. The power pack's reverse switch is used just in the reverse loop section. Remember with DC, when in a reverse loop, you flip the polarity of the entire rest of the layout (hence the DPDT switch) so the train can exit the reverse loop and not short.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
BigDaddy gregc See the 4 circles vertically in a row, just to the right of throttle SW ? Imagine the middle two are just one. Those are the 3 lugs on 1/2 of a DPDT switch divided down the middle. Notice the top circle goes to the rail that is gapped. Rereading your posts, I have no idea if that is the north or south rail is gapped nor if the same rail is gapped in the second yard. Whatever lug that feeds the mainline rail that is gapped has to feed the SPDT switch too. In Greg's diagram it is the same side rail in both yards.
I appreciate the explanation! On my layout, the north rail in each yard is gapped.
gregc sounds like you're not familiar with reading schematics in the schematice representation of the DPDT switch on the right below, there are six terminals, the circles. The three on the top are the same as for an SPDT switch. So the DPDT has 2 SPDT. The dashed line shows that they are connected mechanically. in the reversing switch diagram on the left, the 3 terminals on the left are effectively 1 SPDT and the 3 terminals on the right a 2nd SPDT. the 3 terminals on the left in the left diagram are represented by the the 3 terminals on the top in the right diagram and similarly the right 3 and bottom 3. the center terminals in the left diagram connected to the power supply are the left most terminals in the right diagram. the schematic (right) shows that the left terminal with the diagonal lines going up and right can make contact with one of the 2 terminals on the right which are the top and bottom (left) terminals on the left diagram. is your DPDT reversing switch wired this way? or are the power supply and motor terminals reversed?
It took just a few minutes of looking at your first diagram to figure out the relationship between the circles and terminals (lugs). I better visualize such things when I can see the actual lugs and their wires leading to wherever.
My reverse loop DPDT is wired similarly to the one in the diagram, but with two additional wires leading to their respective loop tracks.
Thanks for the above elaboration too!
rrinker SInce there is a reversing section ont he alyout, that is why there is the DPDT wired as a direction switch. SO you have main lien direction and reverse loop direction independent - one is the power pack's reversing switchmt he other is the added DPDT. To change direction of trains in the yard - one of these direction switches has to be oeprated. That's just the way DC works. If you want the yard direction to be independent of the main lien direction controleld by the DPDT, then you must gap BOTH rails and use DPDT toggles wired for reversing to feed the yard, you can't make this work with one power pack and SPDT switches, it's not electrically possible. Frankly, it doesn't sound workable with oen power pack anyway, why would you have a train in the yard go one way and a train ont eh main go the other, powered by the same power pack? It's not like you can have one train circling the main and do switching in the yard at the same time with only one power pack. TO simply cut power int he yard independent of the main, the SPDT is fine, and any of the diagrams already presented are the wya to wire it. However, if you feed the SPST from the main track side of the DPDT, then the DPDT will control the direction in the yard. This is how it normally would work. This is how it works on any of the Atlas track plans with reverse loops if you use their control components as shown in their books as well. If you have 2 power packs, it's actually still the same. EACH power pack needs a second direction switch (DPDT) because of the reversing loop, and the DPDT is what controls the direction of a train anywhere on the main OR IN THE YARDS. The power pack's reverse switch is used just in the reverse loop section. Remember with DC, when in a reverse loop, you flip the polarity of the entire rest of the layout (hence the DPDT switch) so the train can exit the reverse loop and not short. --Randy
Randy,
Thanks for the additional details.
A little background for review: this new layout is nearly identical (and a little larger) to the one I tore down in January. It's got an added mainline run, a short yard off to the west and a slightly different confiruration of turnouts nos. 8, 9 and 10 in the layout schematic shown some number of posts above. The two DPDTs controlling the mainline and the reverse loops - and their respective operations - worked flawlessly on the old layout and continue to do so now.
It's basically a one-train operation with very limited opportunity to run a second loco (a switcher) and a short train in the loops or have one sitting on a siding. One power pack provides the juice, and another powers nine Tortoises.
I was train-less for some eight months while planning and building the new layout and, so, certainly may have some fuzzy memories about what did what for the two years previous. All your collective comments and the mini education above have helped to bring some of those back.
And yep, I do understand that mainline trains and yard trains can only run in the same direction, controlled as they are by the mainline DPDT. Cutting power in one or both yards is indeed one of my objectives. I've wired two sidings on the north side to just that to to allow a a train to pass on the newly laid mainline north of them while any train on a siding takes a break.
rrinkerIf you want the yard direction to be independent of the main lien direction controleld by the DPDT, then you must gap BOTH rails and use DPDT toggles wired for reversing to feed the yard,
he doesn't
HOmainlineI better visualize such things when I can see the actual lugs and their wires leading to wherever.
Here's the SPDT wiring then ...
gregc rrinker If you want the yard direction to be independent of the main lien direction controleld by the DPDT, then you must gap BOTH rails and use DPDT toggles wired for reversing to feed the yard, he doesn't
rrinker If you want the yard direction to be independent of the main lien direction controleld by the DPDT, then you must gap BOTH rails and use DPDT toggles wired for reversing to feed the yard,
NeO6874 HOmainline I better visualize such things when I can see the actual lugs and their wires leading to wherever.
HOmainline
I better visualize such things when I can see the actual lugs and their wires leading to wherever.
Got it, Dan. Thanks for the drawing.
I did that a few days ago and then realized the yards are still under the control of the mainline DPDT. It's an acceptable solution and one that I may stick with. And it may well have been the setup I used on the old layout, though probably forgot about after eight months of no trains.
I'm trying out Rinker's yard-DPDT solution as well.
How do you propose using a SPDT toggle to reverse the polarity of the yard with only one rail gapped? Only if you feed the SPDT froom the power pack side of the DPDT reversing switch, then you cna use the power pack reversing switch, but that will still reverse the main line direction as well, unless you flip both the power pack direction switch and the DPDT at the same time.
Besides using a variable AC power supply and a pair of diodes wired in opposite directions to the outer terminals of the SPDT, with the center lug going to the insulated rail, and the common fed fromt he other side. Half wave DC isn't the most healthy, but absent coreless motors it shouldn't really hurt anything. But that's a rather silly way to go about things. Since the layout is only suitable for single train operation, I don;t see what the big deal is about flipping the DPDT toggle to change direction of the train when it's in the yard. Those extra sidings could also use a SPDT to isolate them, allowing a train to be parked there and shut off so another can pass. Of course only SPST toggles are really needed, but since the OP has a supply of SPDT - just use those. Leave on end unconnected. Done.