Has anyone here who operates brass ever noted any odd signs of deterioration in open frame motors? I ask because I have lately noticed an odd tendency to short in some of my stuff - two of my oldest models in particular. I have a Fujiyama 2-6-2 (a CMSTP&P prototype) that was imported in the 1950s or early 1960s that I recently bought secondhand, if not third- or fourthhand. It ran very well, but developed a short. I tested it thoroughly, to make sure the insulation wasn’t wearing out on the tender truck bearings (a problem I have had before), and I determined it was not shorting at the trucks; the drawbar and all of the other likely suspects were OK. I removed the boiler shell and it ran faultlessly; after I noticed some oxidation marks on the inside of the shell, right near the top of the motor frame, I put a little electrical tape on the inside of the shell near the top of the motor frame and it once again ran well, when I replaced the boiler. But I’m still perplexed: is this a phase open-frame motors pass through on their way to the great junkyard in the sky?
Has anyone else ever noticed this phenomenon? If so, any ideas on the cause?
Sounds to me like the motor mounting shifted a bit is all. If an open frame motor contacts the brass shell in the right place (or wrong, depending on your perspective) it will definitely short at any age. If the contact tab or a short section of uninsulated wire on a can motor touches the shell the same thing will happen. I can vouch for that one.
I’ve had the same thing happen occasionally–and generally I find that the contacts are throwing sparks against the inside of the boiler frame. Though I’ve replaced a great many of my open frame motors with NWSL cans–an extremely easy operation, BTW–I have a couple of large open-frame motors in several of my Articulateds that I want to keep as long as possible. I’ve found that cleaning them with alcohol usually clears up the problems right away. I take a toothbrush, dip it into alcohol, run the motor and VERY CAREFULLY apply the toothbrush to the contacts and the armature. It only takes a few minutes, and the motor runs like new.
I do this about once a year–if I’m using the locomotive a lot–and it seems to be adding years to the motor’s life.
But your idea of adding electrical tape to the inside of the loco where it fits over the motor is spot-on. I’ve done it just as a matter of course with several of mine.
And after seeing the DC-71 on my 2-10-2, I can understand EXACTLY why you want to keep those old motors in for as long as possible! The thing’s a beast.
I appreciate the suggestions - I’ll have to do some cleaning: I didn’t think to try it at first, because the engine ran so smoothly out of the box - the previous owner (or the seller) sent it on well-lubed and tuned, and it ran (and runs) very well. It could use a new paint job, but the model itself held up well - I think it was fifteen or twenty years old when I was born!
I’d hang onto the open-frame as long as possible. I’ve got an old PFM L-131 Rio Grande 2-8-8-2 that has the strangest reduction gear I’ve ever seen on an articulated, and looking at it, I don’t see how I can replace the open-frame with a can, without tearing the whole gearing apart, and I’m not that willing to try! Therefore, I keep that big open-frame clean and lubed and running like a kitten. It was the first loco I put the Tomar track-shoes on, and it runs like a little watch. And with that big, hunking motor in it, I can use it to raise and lower the garage door, LOL! Those big open-frames might take a little more voltage than a can, but in a BIG loco, they’re well worth the upkeep.
It’s nice to have the power they give you, esp on a big engine. I bet on an L-131, that thing draws so much amperage that the only way you know it’s shorted out is when it stops moving.