Try this: https://www.trovestar.com/generic/blog.php?Article=421 The author defines some of what your looking for. That really is not enough by itself. What is the impact of a .010 axle length difference? Some of that is dependent on the trucks, the average length from bearing cone to bearing cone & the tolerance in the manufacturing process. As indicated in an earlier post, I am looking into this problem. Will try to answer some questions along the way.
Over the years I have acquired a bunch of different trucks. Some with wheelsets...some without. I have also acquired....hundreds of single wheelsets. My next great adventure will be to size all those single wheelsets. Seperate them into a BIG divided clear plastic stoarge box...by size. I will mark the size on the lid over said compartments. When I come across a wheelset on a car that is 'dragging anchor' so to speak I will measure that wheelset axle size. I will then go to that plastic storage box and start with the next smaller size until I find a size that will work. In that same compartment I will look for a wheelset that matches 'cosmetically' ...or comes as close to matching the one I am replacing. I know it may sound 'cavemanish' but I believe such a system will work. Rule #1
There has been a great deal of good info on this thread, and some of that info, can apply to different scales. I would like to offer the following. It might have been said before, but only the tips of the axles are intended to contact the truck side frames. Some packaging (bulk) will endeavor to blunt, bend, brad or plain bend the ends of these brass, or similar (if so equipped) axles. And those discrepancies will add to the weebley, wobblies and slow rolling characteristics. I dare say, that we should pay more attention to the tolerances of the tips. If we have a tool that "trues" the side frames. Do we not need a tool that will true the tips?
This thread makes me glad I just convert everything to MTL trucks to get reliable magnetic uncoupling.
Here's a chart I found on a website that I use as a reference. I have found it to be very accurate. If anyone has something different, please let everyone know. Arnold-Rapido: 0.573 Atlas: 0.553 Athearn: 0.540 Bachmann: 0.560 BLMA: 0.540 Con-Cor: 0.563 Deluxe Innovations: 0.553 Exactrail: 0.540 Fox Valley: 0.540 Intermountain: 0.553 Kato: 0.563 Lima: 0.549 Micro-trains: 0.540 Model Power: 0.567 Roundhouse: 0.549 Rivarossi: 0.549 Walthers: 0.545
Magnetic uncoupling seems to have fallen out of favor as of late with manual uncoupling increasing in popularity. Converting everything to MT trucks, along with weighting cars to the NMRA specs or slightly over, does provide consistency in the rolling ability of cars.
First, I need to correct 2 typos in my original post of axle lengths, and the "Modify" option seems to have timed out. It should read: Axle lengths in N scale: 0.526” 0.540” Micro Trains 0.553” Roundhouse 0.563" Bachmann (shorty passenger) 0.568” 0.572” Atlas (short passenger) 0.578” Second, note the differences between what I measured last night and what was posted for the various manufacturers by "NS Top Gon" this morning. I measured the Atlas cars again, and I realized that the ones I pulled last night (in a hurry) were actually 0.568" Fox Valley metal wheels that I already had installed because the original plastic wheels did not roll very well. Measuring the original Atlas plastic wheels (in another Atlas short passenger car) gave me 0.572". And, I made the move in my corrected table to reflect that. Note that the Fox Valley metal wheel set axles I used are 0.568" which is about 0.004" shorter than the stock Atlas wheel axles, but that doesn't cause any problems. They roll better and do not fall out of the trucks. They are a tad easier to remove from the trucks. Also note that neither of those axle lengths match the 0.553" value in the list that "NS Top Gon" posted, with discrepancies of 0.015" to 0.019". Using 0.553" axles in those Atlas short passenger car trucks would probably result in them falling out of the trucks when the car is lifted from the rails. So, I pulled out an Atlas 55 ton Fishbelly Hopper car and measured 2 axles. I got 0.559" and 0.560". Not the same as I measured for the Atlas passenger cars and still not the same as in the list posted by "NC Top Gon". So, this is not going to be a simple list, with one axle length per manufacturer. I had already read that several of the manufacturers had changed their axle lengths at some past points in time, but this also looks like different axle lengths might be used for cars with different trucks at the same point in time by a single manufacturer. The way to get the right number for a car that you already have it to use a caliper and measure its actual axle length. But, with the inability to buy any length replacement that you need, due to Fox Valley being out-of-stock and the other manufacturers not offering multiple axle lengths, it might be of interest to know if you will have replacement wheels already in your stash if you are contemplating buying a car from eBay or elsewhere. About the only way I can think of to figure that our is to ask here (or on some additional RR forums) if somebody else already has that car and can measure the axle length that is actually on it. Asking an eBay seller to measure an axle length is not likely to get a seller to do the measurement. Most sellers simply aren't that knowledgeable or capable. And, a lot of the cars sold on eBay may not have the stock axles in them, anyway. I have received cars with BMA metal wheels that originally had stock plastic wheels - the eBay seller did not know about the original owner's switch, apparently. Conversely, I have received cars from eBay sellers that obviously had good replacement wheels removed before the sale, and a hodge podge of non-matching cheap plastic wheel sets inserted - the good wheels were probably sold separately on eBay, too. Life would be a lot easier if there was a source of good wheels with a variety of axle lengths readily available. Matt at Fox Valley, are you listening?
