I run a continuous set of bus wires and cap them at their ends. Then I splice all feeders into them. Of course the variable post bus wires are broken and capped at the ends of their blocks. But the base post bus wire never gets broken, except at it's very end. Equally acceptable, IMHO is to cut each bus wire and use wire nuts to join the feeder wires to the ends. For all practical purposes, that still represents and unbroken wire because it's an unbroken contact. I don't see any problem with joining the ends of the base post bus wire to create a loop. Electricity always takes the shortest and easiest route, so it just may be that the short and easy route is from the end that would have been capped. I have heard the argument that the base post bus wire ought to be at least 12 gauge because of the combined current it carries. In my case, I don't buy that. Again, electricity takes the shortest and easiest path. So a section of track returning 0 volts back to the base post won't send the current all the way around the layout, it will send them straight to the base post that is closest to where the current came from in the first place. In my arrangement of 8 transformers, each transformer is getting current back from the block it sits on. There isn't a combined load. The only way that it would be a combined load is if I had a separate transformer with a base post lead dropped straight down to the base post bus wire and I used that transformer to run an accessory way down at the other end of the layout. Then that current would travel back along the base post bus wire with the track current until it got to it's rightful transformer post. If there were a lot of transformers for a lot of accessories, lights, etc and they were all active at the same time, then I would agree that a heavier bus wire would be appropriate. At any rate, it won't hurt, if the wallet can stand the extra cost of a larger gauge wire. That's how I understand it all. OBTW, physicists are still debating if an electrical charge runs over the surface of a wire, through it or both.
Assuming that the problem is not with the reverse unit or field, then the best way to tell if an armature is fried is to swap it out for a known good one. If the problem is solved, then by the process of elimination, the problem has been isolated. Measuring the resistence of the poles with a meter is a little tough. I would use small alligator clips to get a stable measurement to help confirm that it is a weak pole. There is one other thing to do with that old armature before having it rewound or discarded. You could try flattening out the face of it. The problem could be from a cupped face on the armature. At any rate, what do you have to lose by attempting to flatten its face? There are several ways to do it. I chuck up the long shaft of the armature in my drill press, then hold a piece of very, very fine Emory cloth wrapped tightly around a small, narrow block of wood up to the face. Or, you could just drill a hole in a wider block of wood to accept the short end of the armature shaft, wrap the Emory cloth around that block of wood, poke a hole in the cloth and present it to the armature face as squarely as possible several times. Don’t worry too much about wearing the face away to nothing. It can take a good pollishing or three. This is the home repair guy’s way of leveling a cupped armature face. The professional train repair guy would mostly likely put the armature on a lathe and present a micro-cutting bit to it to level it, then pollish it. Make sure you clean out the slots afterwards with a toothpick or something like that.
Although lots of people refer to the American Flyer mechanical reverse unit as an eunit - that is a misnomer and a Lionel term. American Flyer trains use a mechanical reverse unit. If your loco is not running, here are some things to check.
- Make sure it actually IS the reverse unit at fault. Do that by disconnecting the tender and jumping the ports on the jack panel. Jump port #2 with port #3 (two inside ports). Feed your transformer leads to port #1 and port #4 (two outside ports). The loco should run in either forward or reverse. You can wire the male part of a jack panel as a tester for future use. If you do, use a red wire on port #1 and a black wire on port #4. That way, you can first check for forward by putting the red lead on the variable post and the black lead on the base post. Swap them to test for reverse. Let's assume the loco works just fine.
- Are the fingers actually making solid contact with the drum. Sometimes it looks like they are, but they actually are not or not enough to make good electrical contact. The trick is to have the fingers make solid contact, but not SO solid that they impede the drum from revolving.
- See that the fingers are in alignment so as to make contact with the metal parts of the drum.
- Check to see that the wires are soldered on their contact points securely.
- Look at the little contact knobs on the reverse unit fingers. Are they worn through? If they are, a dab of solder will fill and fix them.
- Does the drum rotate freely? If not, there may be dirt, lint or animal hair tangling the pivot points.
- Does the flapper fall back down or hang? Sometimes a small nut or washer taped or glued to the underside provides enough weight.
- Are all the metal parts clean and shiny? Contact cleaner is usually all that is needed to clean the parts.
I suppose they still exist, but I have never seen one operate correctly after being in storage. Here are some bullet points on what I have done to get them going.
- Make sure the mat is not stuck down to the metal base anywhere. The mat must be completely floating on the metal base
- A mat can be made to look “like new” again with a coating of liquid black shoe polish. When it dries, make sure it isn’t stuck down anywhere
- The metal guides are there for a reason. Oftentimes they need re-bent a little to keep the little people on track. Especially critical is the turn they make to go down the ramp. There needs to be a little curl at the end of that one guide
- The mohair or fiber “feet” of the little people sometimes gets so worn it needs replaced. Our parts dealers have that material. On the one I just installed, I needed to stroke them down the face of a steam iron at a slight angle to “set” the fibers in the correct direction for them to travel forward and hug the guide rails
- The intensity of the vibration needs to be regulated. Some guys use a small, dedicated vintage AC transformer, which is a great idea. There should also be an adjusting rod coming through the one side. Turn that rod with a pair of pliers to adjust the coil so the mat is vibrating with the correct amount of robustness. Too gentle and the little people won’t move well. Too much and they go spastic. If there is no adjusting rod, then you can make one with wire from an old coat hanger
- The Platform must be level. Use small shims on one or more sides if it is not
- Sometimes, but not often, the coil needs rewound. Those coils are pretty robust and engineered to work for long periods of time. But they are also 60+ years old by now. Rewinding is easy. Just discard the old enameled wire and match it to gauge at Radio Shack. You can go a wee bit heavier and it will take a few less turns, but I wouldn’t go lighter.
Here are my thoughts and tips on repairing vintage diesel motors. Take the easiest approach first and carefully work to the most difficult. It could be as simple as spraying a volume of Radio Shack tuner cleaner on it to clean it, then lube it and test it. Usually, that is all that is necessary. I can't tell you how many times I have smoked a motor and feared the worst. A burnout does happen, but usually it can be saved to run another day - for a while. So first, lube & clean all motor parts. You should also check the gearbox. They sometimes have age-old encrusted grease that needs cleaned out and re-lubed with something such as a white lithium grease - or nothing at all but some machine oil. I would not use Vaseline - except as a temporary measure to rule out a gunked-up gearbox. Also oil the pads that lube the shaft. If there is sparking or arcing of the wheels to the frame, it could be from a chassis that needs re-bushed, but hopefully you won't need to go there - although that is a common enough problem in old diesels that have been run to death. Next, you could examine the brushes to see if they need replaced. Check for any broken wires. Use a good light to look at the motor and shafts. I have pulled cat hair off of axles by using a pair of forceps with the non-running problem solved as simply as that. Lastly, try re-centering the commutator in the field by way of the small setscrews on the top of the yoke. If these things don’t get the disel motor running, then tear it down & rebuild it. If the commutator is shorted out, then it probaly won’t turn at all. More on that later…
I can't remember if the commutator is one continuous winding or three separate windings. The field is one winding and when it goes, it goes. At any rate, there should be continuity between all three poles on the commutator. Bob Hannon's repair manual can tell you what the actual resistance value should be. Determining if an armature is shorted is tricky. An armature winding can be worn on one pole so as to have a different resistance than the other two and the motor will still turn, albeit not all that well. As mentioned in the above paragraph, some might say that either the commutator works or it doesn't. That actually is over-simplified reasoning. If one pole is slightly or totally burned out, the motor may still turn - depending on the size of the motor and how well it overcomes friction, but it won't be good. Probably the best way for us home repair guys to determine if an armature is toasted is by the process of elimination. Check everything else and thoroughly service the motor, including checking for worn or broken brush springs, the possibility of a cupped armature face or worn shaft bushings, which would knock the armature out of line a little. If you have done everything and the motor still does not turn - guess what; it’s probably a bad armature. Diesel motors are tougher to get running well than steamer motors, IMHO. When I ran diesels on my layout, I always kept a good spare motor or two to swap out when all else failed. A field can be rewound at home with good results. I never tried to rewind an armature. It’s just too difficult to do at home.
When buying a diesel loco at a train show, turn it over and see how much – if any – lateral wiggle there is on the wheels. There should be very little or none. The more wiggle, the more the axel has rounded out the axel hole in the chassis. That’s not good. It will result in increased friction on the motor, as the worm gear gets thrust into the motor and/or it will result in sparking between the wheels and frame. In this case, the best thing for that diesel is: either a drill-out, re-bush of the axel holes or replacement of the whole motor & chassis. For most home repair guys, a drill-out is not too practical. It requires a tool-up and skill set jack. Consider that you will have to pull the insulated wheels off and tap out the axel from the gear and chassis. Then, after a successful drill-out and pressing in of new bushings – you will have to press the axels back into the gears and insulated wheels. That can often – very often – be much easier said than done. More often that not, the wheels will not be true to the axels and they will have a wobble when they turn. The amount of wobble may be slight or severe. Either way, it’s not good. And even if all the above can be accomplished by the average home repair guy, how often would one do it? Real repairs guys do it often enough to know all the sublties of how to do it right. Home repair guys don’t. Bottom line for me is that unless I am willing to stock another inventory of repair parts, tools and jigs and I’m willing to go through all the difficult repair steps necessary on the worst cases – then I’ll just stay away from vintage diesels and only run steam. The exception would be to buy a diesel in E or E + condition. They are a little expensive. However, in the average life span remaining of an old baby-boomer, I probably will not have to do an extensive repair on it.