I need some ideas on how to de-magnetize locomotive engines. I have a couple of engines that have been left for quite a while, but do not want to discard them. Some of the engines are very dear to me.
What do you mean de-magnetize them? If you are taling about the motors, they cannot be de-magnetized. The motors have magnets in them, which must be magnetic in order for the motor to operate.
I second what JPM335 said. First of all, what leads you to the conclusion that the locomtives need to be demagnitized? Also, saying “locomotive engines” is like saying “I drive an automobile car”. What are you trying to accomplish?
Cheers,
Ed
Do you mean re-magagnitize? Some of them old old open frame motors needed that done occasionally. I don’t know anybody who has the equipment anymore. I would ask a LHS who have been in business a LONG time if they could do it if that’s what you are needing. Fred
Thanks for the probing thoughts. I came to the conclusion that the motors were magnetized competely leaving the “rotor” unable to rotate. Yes you are correct that there must be some magnetism but the electricity needs to go through the rotor to cause the rotation. If the rotor is magnetized then the electricity then creates an electro-magnet.
As far as I know, magnetism wouldnt cause this. When you apply power to the motor does it buzz or hum? does the motor warm up? Or does it do nothing at all?
Buccaneer, you are right about the creation of an electromagnet. But, that’s only the beginning. There are actually TWO magnets in a locomotive motor. The permanent ones that surround your armature, and the electromagnet that you create when you supply electricity. That’s how they work. When the electromagnet you create has its magnetic poles opposite to the permanent magnet poles, they are attracted to each other, causing the armature to rotate. The more poles you have wired in the armature, the smoother the action of the motor. See, you can learn something from Phineas J. Whoopie and the 3DBB!! (You Tennessee Tuxedo fans know exactly what I’m referring to.)
The armature is supposed to be an electromagnet. It gets electricity when the brushes are lined up with 1 pole on the armature and a magnetic field is energized. When this happens the 2 permanent magnets have a push pull effect on the armature pole that is being energized and it moves. The next pole is lined and the process repeats itself.
Radio shack used to sell a demagnetizer for use on audio equipment heads. It looked like a small wand. Lets assume, for the sake of argument the armature is magnetized. You then demagnetize the armature. How long will it remain that way when placed between 2 permanent magnets and being used as an electromagnet itself? What are you going to demagnetize, the shaft that goes through the armature or the wiring /pole assemblies? Not a lot of mass there to make a permanent magnet out of an armature. That is not your problem.
If you are generating a magnetic field and the motor is not rotating I would look at the following: Shorted armature, weakened permanent magnet(s), bound bearings and any trouble with the mechanism of the loco itself, provided you have not disconnected it.
If you provide us with more details we can help you, such as what type of locos, can or open frame motors and any troubleshooting you have done so far.
Jim
The other option here is to find a suitable replacement motor - or better - and keep those older loco’s running like brand new… That should solve the problem.
Here is a little more information on the problem with the motors. I have some that do “humm” and some that do exactly nothing. The motors that do operate are not operating at full potential. By full potential is meant that the voltage required to move the motor slightly ( idle speed) is about half on the controller. Full speed then on the controller then gives the motor enough power to move at a nice pace on the track. However, any grade then slows down the movement quite substantially.
The main three suppliers of the motors would be “Minitrix”, and “Fleishman”. (please excuse the spelling) but as for the id of the type of loco that i can not do. The cases that these loco’s came in are not the originals.
It does sound like my magnets have lost some of their magnetism. Will use an “earth Magnet” to boost the magnets.
Any further information though would still be greatly appreciated.
Have you tried disassembling the loco and it’s motor, and giving it a proper cleaning and lube? When a loco is unused for a long time, this should be pretty much SOP.
Back in the 1950’s there were magazine articles on re-magnetizing the field magnets in motors. My father made one out of a large rectifier and a large electromagnet which narrowed to only about a 2 inch gap between the poles. Looking back, I believe the components were from WW II salvage and actully dseigned for lower currents and voltages but we operated it on house current and got a terrific magnetic field. After placing the weakened magnet, properly orientated, between the poles, we would plug the contraption in then immediately unplug it before it melted its own wiring or blew a house fuse. A few shots did markedly increase the permanent magnet’s strenght.
When can motors came on the scene, we converted rather than re-magnetize. The can motors had other advantages such as slower starting speeds and lower current draw. We had no concept of preserving the integrity of working antiques.
Try the Kalmbach Memorial Library for a photocopy of one of the early articles on re-magnetizing.
Have not tried anything as yet in dis-assembly. Want to know what to do, what to look for, etc… so far the advice here has been excellent. Even though I have responded to certain points made out here, I am also taking the advice of the other mentions.
Thanks for the help.
I am not too familiar with the Minitrix and Fleishman models as they do not seem to be too popular in North America, but basics are basics so here goes.
On the engines that do nothing: connect a 12v test lamp or DMM on the motor connections. Do you have a good glow on the test light at full throttle? Or track voltage on the DMM? If you do then your motor is getting power. You can check the brushes to make sure they are making contact and the armature is clean. If that is okay you will need a replacement motor. I am assuming you have tried manually turning the motor to try and help get it started.
On the engines that hum, is the mechanism free? Can you disconnect the motor from the loco and apply 12volts directly to the connections. Does it still hum or will it run? Can you turn it manually? If not check the end bearings. These sound like mechanical binding. Another possibility is shorted pole windings. Perhaps you could try re-magnetizing the permanent magnet and see what that will do, provided the strength of the magnet is weak. That should be easy to check with a small screwdriver.
The other engines may be just need a good cleaning and lube, as has already been suggested by others. That should help get them moving at a lower speed setting. A lot depends on the power pack you are using and the design of the model. If you have a small power pack and an older loco, which draws a lot of current, the characteristics you are seeing may be somewhat normal.
What brand power pack do you have? Does it list any electrical specs on it like output volts or amps? Are the locos steam or diesel? Can you see the armatures? What voltage does it take to get the locos running smoothly? How many large wheels on the steam engines?
Let us know
Jim
Thanks Jim for the note. The engine that is dear to me is a 2-8-8-2 with the coal tender attached. By attached is meant that the tender is the other lead. (not sure about if it is the +ve or the -ve lead) To see the armature would mean a diss-assembly of the engine. I do agree with the tune up of the motor as in lubrication and checking of the bearings. My thoughts on Magnetized motors now seem to tend to the fact that the armature is the magnet and is being attracted to the metal (weak magnet) of the motor frame.
On going back on these talks I have neglected to mention that these locos are in “N” gauge. I will have to find myself a good lighted magnifying glass to work on these. Thanks for the advice on my problem.
ditto jpm
If a motor humms but doesnt move, that means it is trying to turn but is stuck for some reason. If you keep putting power to it it will heat up and fail. So on those engines, you need to disassemble the loco and find the bind. Once you free everything up those engines should run. For replacement motors, there are several sources. You say the engines mean a lot to you, so if you want them to run great you could try Sagami or Mashima motors. These motors cost quite a bit, but they run great.
Good news people. The first engine, that I challanged myself to repair, is now working at full capacity. The gears were dry, no lubrication, and a wire was off. Once the wire was attached and the gears lubricated the loco now moves fast, too fast for my thinking even with rolling stock behind it. Will continue the “tune up” on the other engines. Thanks again to all whom assisted with their resolutions.
WARNING. If it’s the old style open frame motor that were made in the 40s, 50’s and 60’s, pulling the armature out from between magnets will knock at least 1/2 of the magnatism out of the magnets. Do not remove the armature from the motor unless you plan on remagnizing them. Fred
It is because the magnetic flux loops get interrupted. I have read you can use a piece of iron in place of the armature to give the magnets another path, which should keep them at full strength. When you say old style, are you referring to the type used in Bowser and Mantua? The reason I ask is you said the armature was between the magnets and the open frame motors I have dealt with use 2 square magnets in the end. They are from the 80s.
Thanks,
Jim