Magneto magnet

Craig45 · Mar 3, 2016

Got to thinking about my old tractors with magneto's. Does the magnet get stronger when the engine is run for a while or do you need to remove the magnet and have it' magnetism renewed?

Bob · Mar 3, 2016

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netos

John T · Mar 3, 2016

You ask good questions, here are my thoughts:

"Does the magnet get stronger when the engine is run for a while"

I DO NOT see the magnetic rotor gaining any magnetic field strength when the engine is running, nor loosing any either. However, as the mag turns faster (or if the magnet were stronger) more energy can be stored in the coil.

"or do you need to remove the magnet and have it' magnetism renewed?"

I'm NOT a fan of removing the magnetic rotor out of the armature because in the process its similar to removing the "keeper" on say a horseshoe magnet. Thats NOT to say rotors cant be magnetically recharged or may require it if they have been removed long periods, I'm ONLY saying theres usually no need to have on charged up as running the engine DOES NOT use up their magnetism.

I usually agree with Bobs excellent answers, for whatever that's worth ???

John T

Craig45 · Mar 3, 2016

Thanks for the info. I'am talking about an F-12 here. Seems when I use my left hand and pull up on the crank it doesn't start easily, but if I crank downward (dangerous) with my right hand it starts easily. Never had it kick back. Don't know if I am spinning the mag faster that way or not. Seems I started another question here.

John M · Mar 3, 2016

If it has the horseshoe magnet, they can easily be "charged", Ive done a few IH mags. BUT it doesnt seem to hold long, maybe a couple of years, then it starts getting weak again. If you take it off, and it has good resistance to the side of frame rail and wont fall off if you let go of it, it should be OK enough for it to run. A couple Ive recharged made no difference in how it ran.

teddy52food · Mar 3, 2016

A permanent magnet will not get stronger but can get weaker. Excessive heat can make them weaker. The power of a magnet comes from E=MC2, so you can use them a long time before they weaken if made from the right materials. The old F4 mags on the F12 will lose as they are of inferior material.

dr sportster · Mar 3, 2016

I read that you are supposed to pull out the rotor into an iron sleeve as when it is not in the body of the mag . When removed and just left on the bench un-sleeved it will lose magnetism. It wants to be surrounded by metal. There is a book on how to make a mag magnet recharger as shown in the link below .Bad thing is it was from Linsay Books and someone here posted there were out of business.

tractorguy2 · Mar 3, 2016

I have removed the rotary magnet from several magnetos to grease the bearings. I put the magnet on a heavy angle iron I don't leave the magnet out for more than a few minutes while I clean and pack the bearings with grease.

I could never tell the magnet was any weaker after doing this. The magnet would spin faster and much easier after cleaning the hard grease out of the bearings.

CenTex Farmall · Mar 3, 2016

"Your Old Time Bookstore" bought out Lyndsay and offers the books he had and maybe some more.

youroldtimebookstore.com

dr sportster · Mar 3, 2016

Thanks , that's good to know. I always wanted a few more of those titles they had.

Magneto magnet

Craig45

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Bob

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John T

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Craig45

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John M

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teddy52food

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dr sportster

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tractorguy2

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CenTex Farmall

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dr sportster

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