I have a locomotive variable speed issue on my layout that happens in a few spots. It always seems to be most prevalent in the same spots give or take a couple of inches but not always the exact same point. I really do not know how to overly describe it. I "think" it may be some sort of voltage irregularity - if I had to make a guess. My train is wired for DC and is broken up into numerous blocks. It is wired and built according to the Atlas Plan N-109 or plan N-18 as it now known. The problem seems to happen with all of my locomotives and like I said, it pretty much happens in the same spots but not always exactly the same places. The best way for me to describe it is like this: The locomotive let us say it is going hypothetically 30 mph around the track, it sometimes slows down to 25, then to 20, then will speed back up to 30 again. It is not a jerky motion at all it is more like it shifting gears or just gearing down. The layout is almost level where it is doing it, but it can be compared to going up and down small grades. Any ideas of what it could be and how I could test the track to find out what it is? I have not dismissed any of these theories below as of yet, but I would like suggestions for other thing to try: I thought my track may be dirty - so I overly cleaned it recently I have already thought of loose wires - but if it were a loose wire I would think it would be the entire block that is affected not just certain sections I have thought of a bad connector here and there but since it does not always happen at the exact same spot it makes me wonder. I just cleaned my track twice maybe three times with 70% isopropyl alcohol and then cleaned it once again with 50% isopropyl alcohol. Assuming that this increase and decrease in speed does not always occur in the exact smae spot but fairly close, how can I test it to see what is going wrong? I do have a multi-tester but really am unsure how to use it in this particular case. Mr X
Mr X, you're going to have a tough time finding out why the train slows down, since it doesn't happen at the exact same spot each time. It could be a multi-headed problem: dirty track, dirty locomotive wheels, loose wires or loose rail joiners. You've already addressed the dirty track. Check the locomotive wheels, too. It could be a small spot on a wheel that restricts current without stopping it. It can happen in slightly diferent areas because the wheels travel around the layout and the same spot on the wheel won't always contact the exact same spot on the track. That may be why it isn't consistant. I think you're correct that a loose wire would cause more than a slow-down. A slow-down is caused by a lessening of current, not an open circuit. What lessens current is anything that increases the resistance of power. Dirt can do it, loose connections can do it. A loose or dirty rail joiner may be the culprit. It can increase the resistance in the track enough that the trains slows down. The weight of the engine on the track may cause enough movement for the problem to appear and the loco doesn't have to be in the exact same position each time. I don't know how you're going to be able to check voltage in the rails since the problem is intermittant. Hook your leads to the rails and apply pressure along the tracks and see if the meter registers any changes. I think your problem may have multiple causes. You'll have to find and resolve ALL the possible causes to get it running correctly. Hope this helps. Darrell, quiet...for now
It pretty much happens in the same ‘area’ but not in the same exact spot. Make sense? It is not where the locomotive automatically cross this specific joint and you go ‘ah ha there it is gotcha - bad rail joiner!’ I tried to make a color-coding chart of where it happens compared to the insulated rail joiners and track sections. The red is where it really slows down and the yellow is where it just slows down a little. It is not a constant speed through these areas. The loco will act like it is slowing like you are pulling the throttle back. Hope this helps. Does it make sense? So most of block 7 goes slow with the end of block 7 in between the switches almost crawling, part of block 5 but reallu speeds up as soon as you hit the bridges, block 5 slows a tad by the power lead, then smooth sailing until you almost get out of the tunnel, then it really slows through two of the 9 3/4 inch and then speeds back up and gets to normal speed through switch number three all the way to the second 9 3/4 track to the left of switch 1. Also through the entire reverse loop it seems to act up. P.S. all of the locomotives have been cleaned. I would not think the locomotives are the issue since they all seem to do it in the same areas. Mr X
Add a set of feeders to each section of track in the yellow and red areas, Also add a set of feeders to each arm of the 90 degree crossovers. They are notorious for voltage drops. Stay cool and run steam....
Powersteamguy1790, Good idea for the crossing. I think how my track is currently it would not be all that hard to do this suggestion. I think I may have found at least part of the problem. Sometimes just talking it out makes you think of all the different possibilities, and of course having two or more heads are better than one. Thank you dgwinup. The problem may have been one or at least one rail joiner (replaced 7) on the common rail that seemed to be affecting a wider area. The entire left side of the layout seemed to be affected by only one bad joiner. What causes rail joiners to go bad? Will this be an issue after I finally end up ballasting the track? Anything I can do to prevent this from happening other than the obvious and not setting anything heavy on the track? Any ideas in the reverse loop section on why that would have a problem across the entire thing? Also since I only have one common rail feed for the top and one for the bottom of the layout is it recommended to add more of these as well or was this the type that you were suggesting? Thank you for the help! Mr X
Solution Found! Well I just was fed up with it today and replaced the entire reverse loop section and fitted it all with new rail joiners. I did re-solder the terminal lead wires in the reverse loop. This is where I think the biggest problem was. Things seem to be working fine for the most part. Thank you for suggestions. Mr X
If you haven't done it, I would suggest soldering a majority of the rail joiners. You still need to leave some free to make up for expansion due to changes in temperature. The changes in temp. causes the rails to contract and expand and this is what causes the joiners to "fail" in the first place. Any dry fit connection is susceptable to corrosion. The track contracting and expanding will exasterbate that by loosening the joiners as the rail moves. I hope all that makes sense. The voltage drop through clean rail joiners is measurable, as they loosen and age, it get's worse.
Mr X, In the DCC world, the standing rule is feeders for every 3 to 6 feet of rail (about 2 sections of flex track). The reason for so many feeders is to maintain signal strength to the decoders. The DCC solution is adaptable to DC operations particularly where common rail wiring is used. Most common rail layouts have only a few feeders to the common rails (Mea culpa! Mea culpa! LOL!). Adding several feeders will insure better electrical distribution. If a section of track has multiple feeds, one bad rail joiner won't cause a problem because power is being fed to the track on both sides of the bad joiner. With common rail wiring, you can add as many common rail feeders as you have patience to install! Overkill is NOT a problem! LOL Like the rails, rail joiners suffer from corrosion. Any bit of looseness in a rail joiner can allow corrosion to occur between the rail and the joiner and disrupt the flow of power. After the track is glued down and ballasted, replacing that rail joiner is going to be a major operation! Having multiple feeders won't completely eliminated the problem, but it will lessen the occurances. I was wondering about the reverse loop. Even though DC wiring is fairly simple and straight-forward, it does have it's little quirks! Reverse loops have been known to cause problems and reduced power to the rails can happen. Glad to hear that you seem to have solved your problems! But keep thinking about adding more common rail feeders. It may help prevent a re-occurance in the future. Darrell, quiet...for now
Mr X: On a previous layout...several decades ago...I had a very small power pack and common wire to one rail and block feeds from Atlas selectors on the other rail. I was using telephone wire of 26 or 28 gauge. Between unsoldered rail joiners, crossovers, and insufficient feeders to my common rail, I had several sections where the trains always slowed down, despite cleaning track and wheels diligently. The problem was completely eliminated when I followed someone's suggestion and rewired with larger wire (20 or 22 gauge bell wire if I recall...I don't think it was as large as 18 lamp wire) and dropped feeders (same gauge) from my common rail to the common rail bus (also same gauge) (although I didn't know to call it a bus wire back then) opposite everywhere I had a block feed. My longest distances to the far blocks (where I had the most trouble) were 10 to 15 feet, and I suspect there was enough resistance in the smaller wire and a weak enough amperage in the power pack to cause the slowing. I don't remember the timing on when I got a larger power pack, but it was also around about that time, so that too may have played a part in resolving the problem. On more recent DC layouts I used Radio Shack 24 gauge solid 4-strand telephone wire (yellow/black, red/green) feeders to 18 gauge wire buses serving rotory switches, heftier power packs, and lots more (but not all) rail joiners soldered. No problems with 20 ft runs from power packs to distant rails. On my current DCC layout I have 12 gauge buses with 24 gauge feeders every 5 or 6 feet and do not have any trouble with passing the "quarter test" at the ends of 80 foot blocks (with boosters in the middle). However, I DID have trouble passing the quarter test at the top of an 800 inch long helix (16 inch rise at 2%) when the only feeders into the helix rails were at the end of the bus wire and at the very bottom of the helix. That problem went away as soon as I finished putting 2 pairs of feeders on every loop of the helix.
It's a tuff problem to solve, And I think you are on your way to solveing it. As others here have said and with good cause, Either solder your joints or install jumper wires between pieces of rail, Drop feeders from every piece of rail, and heavy buss wire (which you did not say how heavy it is) and the heavier the better. with a small N scale layout #14 should be about right. I'm perty sure it's a resistance problem and the above soluitions should help. And it couldn't hurt to check out Lionel Stang's book DCC Made Easy if you haven't already. "Still Training After All These years"
