Popsicle49 Posted January 30, 2015 Share Posted January 30, 2015 Hello, I need to pick some brains if poss please; I think I'm going nuts.. This is a newly-constructed analogue N gauge layout using PECO 80 track and insulfrog points throughout. The attached diagram shows the problem. At extreme left a loco is reversing from the main line onto track 2 to using the L/H points A. The R/H points B are set straight on to to the end of track 2. The L/H points C are also set to track 2 so effectively, track 3 should be isolated as the R/H points D are switched to main line. A loco is parked on track 3. As soon as the loco hits the L/H points A, the loco parked on track 3 starts to move. With points C&D set to other tracks how is power (all of which is coming from the mainline L) reaching track 3? There are no power attachment on the sidings, all power is from the mainline L and is shown as small arrows. Reversing the power sees both locos move but the loco on track 3 stops moving when the other loco clears the points A!! (The track at the top is track 1, I just didn't write it but it's out of the equation anyway. many thanks in advance. Popsicle 49 Link to post Share on other sites More sharing options...
gordon s Posted January 30, 2015 Share Posted January 30, 2015 If the left hand point A is set to access track 2, power is being supplied via the frog. If you follow that through you will see that will feed the lower line of of track 3. With point D set to any position, that is feeding the upper track on line 3 which is why the loco moves. To stop that make a break in the lower line of track 3 next to point B. Line 3 will then only be fed when point D is set to track 3. Link to post Share on other sites More sharing options...
Shadow Posted January 30, 2015 Share Posted January 30, 2015 Not sure if this is going to help (or confuse things more!) Agree with Gordon above, but if putting a break in at left end only, then this means that you have to have point D set to siding if you want to enter from the other (left) end. If you break it both ends and then use a switch to select power from either Left or right ends, then that removes that limitation. A three way (centre off) switch would allow you to isolate totally from both ends. Dave edit two remove duplicate image! Link to post Share on other sites More sharing options...
Popsicle49 Posted January 30, 2015 Author Share Posted January 30, 2015 If the left hand point A is set to access track 2, power is being supplied via the frog. If you follow that through you will see that will feed the lower line of of track 3. With point D set to any position, that is feeding the upper track on line 3 which is why the loco moves. To stop that make a break in the lower line of track 3 next to point B. Line 3 will then only be fed when point D is set to track 3. Thanks very much Gordon, I'm indebted to you. One thing though - I don't understand why the parked loco on track 3 doesn't move until the loco reversing from the main line crosses points A? Link to post Share on other sites More sharing options...
Popsicle49 Posted January 30, 2015 Author Share Posted January 30, 2015 Not sure if this is going to help (or confuse things more!) wiring layout.jpg Agree with Gordon above, but if putting a break in at left end only, then this means that you have to have point D set to siding if you want to enter from the other (left) end. If you break it both ends and then use a switch to select power from either Left or right ends, then that removes that limitation. A three way (centre off) switch would allow you to isolate totally from both ends. Dave edit two remove duplicate image! Thanks very much Dave, appreciate that. I still can't understand why the loco parked on track 3 only moves when the reversing loco crosses points A? Any ideas\? Link to post Share on other sites More sharing options...
Shadow Posted January 30, 2015 Share Posted January 30, 2015 Guess it might be the chassis of the loco is providing the link across the insulfrog break rather than the switch blades Link to post Share on other sites More sharing options...
gordon s Posted January 30, 2015 Share Posted January 30, 2015 I agree with Shadow. The frog switch may well make a poor contact and not allow sufficient power to move the loco. Once the wheels/chassis bridge that gap they will allow a higher current to flow and the loco moves. Link to post Share on other sites More sharing options...
LongRail Posted January 30, 2015 Share Posted January 30, 2015 There is a simple solution which doesn't require any switches. please refer to the attached mark up insert 2 isolating joints as shown in green and then provide the linking wires as shown in red and blue. Link to post Share on other sites More sharing options...
LongRail Posted January 30, 2015 Share Posted January 30, 2015 Should mention the switching of the points will isolate the sections automatically. This will work with elecrtofrog or insulfrog points Providing the points are not set to road three the loco will be isolated Link to post Share on other sites More sharing options...
gordon s Posted January 30, 2015 Share Posted January 30, 2015 Surely you have the same problem. There is no power to the upper line of track 3 unless point B is set to access track 3. If you have a long train in track 2, it may be necessary to leave point B in the straight ahead position and then you have no feed to the upper line of track 3. It's a little like 2 way switching of room lighting and Shadow's solution allows you to do that irrespective of which way the points are set. Link to post Share on other sites More sharing options...
DCB Posted January 30, 2015 Share Posted January 30, 2015 I can't work out why the loco on 3 does not move without the other loco hitting the points as as soon as points A are set to the left track 3 gets the upper rail fed from the right hand end and the lower from point A when ever it is set to the left. If yiu stick to movements which are anything remotely prototypical a single isolator part way along the lower rail of track 3 should solve the problem, ok you can't run a train along 3 against the points D but why would you want to? Link to post Share on other sites More sharing options...
Shadow Posted January 30, 2015 Share Posted January 30, 2015 Does the loco on track 3 still move when it has cleared point A? Or only when the loco is straddling the frog? Link to post Share on other sites More sharing options...
LongRail Posted January 30, 2015 Share Posted January 30, 2015 It shouldn't matter if the train is straddling the frog or not what is not explained in the first post is where the power connection is made. Link to post Share on other sites More sharing options...
LongRail Posted January 30, 2015 Share Posted January 30, 2015 If you can take the points out it may be worth checking with a meter that as the point blades move across the power switches across the frog Link to post Share on other sites More sharing options...
DCB Posted January 30, 2015 Share Posted January 30, 2015 I was assuming the layout was a continuous run, However if it is only fed from the left hand end and if the engine in road 3 only moves when the other loco is actually on point A I reckon the fault is the back of the loco wheels rubbing against the point blade on point A. If I am right setting point D to road 3 should stop it, as would Shadows suggestion and the single isolator as log as the loco was the D end of siding 3. I have this problem on some old Peco curved points in my hidden sidings, they are live frog and the sparks as Duchess of Montrose passes through at speed are quite impressive Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted January 31, 2015 RMweb Premium Share Posted January 31, 2015 One thing you need to realise, is that when insulfrog points are used, that feature relies on the convention that points are fed from the heel of points, or a group of points. When you start building more complex track formations, then as you have discovered, back feeds come into play and can be very confusing. Basically, when the toe of points face each other (regardless of distance separating them), then you need to insulate them. The exact location of this insulation, very much depends on the configuration & how you intend to run the trains. DavidCBroad, asked if you track layout is a continuous run. That's a very good way of 'sneaky' back feeds and as I mentioned, the distance, could be very long & not easily spotted if your track plan is complex. Link to post Share on other sites More sharing options...
The Bigbee Line Posted January 31, 2015 Share Posted January 31, 2015 I had a similar problem with two locos moving at once. I had skimped the insulated joiners between the frog and the siding. The frog was powered by blade contact. This should make the rails on the siding set by the points plus and minus. The other track should have both rails the same and any loco parked there should not move. When a loco is driven into the other siding all is well until it has passed onto the switch rails. Then if the electrical contact of the switch rail is weak. The current flows from the stock rail to the frog through the parked loco as it becomes the easiest path. Both locos then moving. It took me some while to figure it out. Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted January 31, 2015 RMweb Premium Share Posted January 31, 2015 I had a similar problem with two locos moving at once. I had skimped the insulated joiners between the frog and the siding. The frog was powered by blade contact. This should make the rails on the siding set by the points plus and minus. The other track should have both rails the same and any loco parked there should not move. When a loco is driven into the other siding all is well until it has passed onto the switch rails. Then if the electrical contact of the switch rail is weak. The current flows from the stock rail to the frog through the parked loco as it becomes the easiest path. Both locos then moving. It took me some while to figure it out. This only occurs on live frog points, with insulfrog points the two rails are NOT at the same polarity for a siding, but one side is electrically dead. Link to post Share on other sites More sharing options...
Suzie Posted January 31, 2015 Share Posted January 31, 2015 The problem you are seeing is the loco shorting something on the chassis or the back of a wheel to the switch rail on point A as it passes applying power to the top rail of the main line. Changing the other point in the main line should stop it happening until you fix the cause of the problem. Link to post Share on other sites More sharing options...
Popsicle49 Posted January 31, 2015 Author Share Posted January 31, 2015 Again, thank you to all. My ambitions have clearly dwarfed my capabilities and the nub of the problem is my assuming that insulfrog points are completely insulated and that's that - clearly it's a significant misunderstanding. In answer to some posts, power comes from both ends and the points at A are new so I assume there shouldn't be probs. I'll work through your observations and re-post as appropriate, Sorry I'm not familiar with the terms heel and toe when describing points. I really appreciate the detail to which everybody has gone; I've learned a lot and am v frateful. Popsicle49 Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted February 1, 2015 RMweb Premium Share Posted February 1, 2015 Again, thank you to all. My ambitions have clearly dwarfed my capabilities and the nub of the problem is my assuming that insulfrog points are completely insulated and that's that - clearly it's a significant misunderstanding. In answer to some posts, power comes from both ends and the points at A are new so I assume there shouldn't be probs. I'll work through your observations and re-post as appropriate, Sorry I'm not familiar with the terms heel and toe when describing points. I really appreciate the detail to which everybody has gone; I've learned a lot and am v frateful. Popsicle49 Thanks to Gordon S, I've learnt something & deleted my wrong information. Link to post Share on other sites More sharing options...
gordon s Posted February 1, 2015 Share Posted February 1, 2015 Sorry Kevin, it's the other way round. The toe end is the single track end. The heel has the two diverging tracks. You feed power to the toe end..... http://www.gauge0guild.com/manual/02_D2_2_1_1.pdf The visual clue comes from holding it side on. The two tracks take the appearance of the shin/ankle going down towards the toe. Looking at it flat on the trackbed is what causes the confusion..... Link to post Share on other sites More sharing options...
DCB Posted February 1, 2015 Share Posted February 1, 2015 Sorry Kevin, it's the other way round. The toe end is the single track end. The heel has the two diverging tracks. You feed power to the toe end..... http://www.gauge0guild.com/manual/02_D2_2_1_1.pdf The visual clue comes from holding it side on. The two tracks take the appearance of the shin/ankle going down towards the toe. Looking at it flat on the trackbed is what causes the confusion..... The convention is that power is fed to the "Toe" of the points, but actually power is fed to the stock rails, the outermost rails of the points, whether Live frog or Dead frog. I often feed power to the stock rails at the heel end of points simply to shorten the feed wires. Link to post Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.