Crazy Idea: Magnetise your gearbox gears

[Logic]

Originally Posted by oil pan 4

My nearly 30 year old t56 transmission had magnets in the bottom of the case. Along with about 1/8 inch of transmission mud all along the bottom.

Yep That 'mud' is worrying!
I'm hoping that a well run in gearbox will have finished producing 'mud' and that the repulsive force between teeth will avoid more being produced, but who knows!?
This is just a 'crazy idea' atm.

[Logic]

Originally Posted by wdb

What's the point? You still need oil. Sturdy stuff too. There are heavy loads inside a gearbox, not just on the gear teeth themselves. Plus it is impossible for the gears to do their jobs at all if they don't impart force from one to the other.

Yes you would still need oil.

"impart force":
Like magnetic poles repel and, according to the maths, the force with which they repel is squared as the distance between them decreases:
So Force = Magnetic Constant /Distance squared.
So the maths says; when D is 0; F is infinite, regardless of how strong the magnet is...
https://socratic.org/questions/the-f...ionality%20%23

ie: You will still get all the force/torque, but without the gears ever physically touching, much like you can't get the like poles of a bar magnet to ever touch... theoretically..?

[Logic]

Originally Posted by oil pan 4

Then they will attract iron particles and wear even faster.

yep, probably. Remember; this is just a crazy idea / thought experiment.

The idea is; if Force goes to infinity as Distance goes to zero; the gears will never touch... theoretically..? and no iron particles will be produced.
https://socratic.org/questions/the-f...ionality%20%23

But that's from the gear teeth only.
The syncromeshes rely on friction to get the 'lose' gear shaft spinning at the same rpms so the gears don't grate.
This would require electromagnets that come on/off at the right times, or the use of a non ferrous metal (brass?) if you don't want to produce particles there.

[Ecky]

Originally Posted by Logic

Yes you would still need oil.

"impart force": Like magnetic poles repel and, according to the maths, the force with which they repel is squared as the distance between them decreases:
So Force = Magnetic Constant /Distance squared.
So the maths says; when D is 0; F is infinite, regardless of how strong the magnet is...
https://socratic.org/questions/the-f...ionality%20%23

ie: You will still get all the force/torque, but without the gears ever physically touching, much like you cant get the like poles of a bar magnet to ever touch... theoretically..?

Unfortunately, the force is only infinite if the magnet is a point source with no physical dimensions - a bit like those physics textbook problems talking about ladders moving at the speed of light through an open barn door. Doesn't actually exist. From my reading, in practice all magnets have the center of their pole somewhere inside their structure (not at the very edge), and the pole is really only where the electromagnetic field lines converge, and it moves around depending on how it interacts with other fields. With a purely steel gear of that size, you're likely to get a few fractions of a pound of repulsive force.

Originally Posted by Logic

Yes one gear shaft is a solid piece.
My guess was that as long as one kept all the norths in the same direction; you'd be fine.
I too looked, but couldn't find info on this. Link?

The other shaft is all separate gears. Easy enough.

And yes; Just a Thought Experiment at this stage.

I spent a few hours reading on this but didn't save any links. Best I can tell, to build this, you'd need to recast the gear where the alloyed metal in the middle is not ferromagnetic (possibly in a face centered cubic crystalline structure), while having the atoms in the teeth all aligned outward with a different crystalline structure, such as body-centered. The magnetic fiends of the different teeth would interact with each other, and there needs to be a path for the field lines to make their way around to the underside of the teeth without interference. You also risk any shocks to the gear (such as when changing gears) completely reorienting the magnetic fields. I expect this to be a multimillion dollar project to produce one set of gears, which would have a repulsive force under a pound, that might demagnetize the first time you put it in gear.

[Logic]

Originally Posted by aerohead

Two things came to mind.
1) The gears are hydrodynamically lubricated. In operation, they never actually make physical contact with one another. So we'd be working on a problem that never existed in the first place.

In theory aerhead, but most geaarboxes have magnetic sump plugs that collect all the ferrous particles that 'don't occur'.
See the various other posts here and the end of your comment.

According to the maths the force between 2 like poles goes to infinity as the distance between them goes to zero:
https://socratic.org/questions/the-f...ionality%20%23

So, for the gear teeth at least, magnetising them should mean that what you said is true for the 1st time...

Originally Posted by aerohead

Two things came to mind
2) Secondly, if one were to magnetize the gears, they'd be in a position to attract any ferrous metal debris suspended in the gear oil.
It would in essence be like pouring 'sand' into the transmission.

Yep. And its not just the gear teeth; its the syncromeshes and 'gear lockers' ( that grate sometimes) that come into contact, producing particles.

The syncros are often non ferrous/magnetic brass, but the 'lockers' aren't.
So its just a crazy idea atm, unless a plan can be made there. I have some half baked ideas that may solve that.

[Logic]

Originally Posted by Ecky

Unfortunately, the force is only infinite if the magnet is a point source with no physical dimensions - a bit like those physics textbook problems talking about ladders moving at the speed of light through an open barn door. Doesn't actually exist. From my reading, in practice all magnets have the center of their pole somewhere inside their structure (not at the very edge), and the pole is really only where the electromagnetic field lines converge, and it moves around depending on how it interacts with other fields. With a purely steel gear of that size, you're likely to get a few fractions of a pound of repulsive force.




I spent a few hours reading on this but didn't save any links. Best I can tell, to build this, you'd need to recast the gear where the alloyed metal in the middle is not ferromagnetic (possibly in a face centered cubic crystalline structure), while having the atoms in the teeth all aligned outward with a different crystalline structure, such as body-centered. The magnetic fiends of the different teeth would interact with each other, and there needs to be a path for the field lines to make their way around to the underside of the teeth without interference. You also risk any shocks to the gear (such as when changing gears) completely reorienting the magnetic fields. I expect this to be a multimillion dollar project to produce one set of gears, which would have a repulsive force under a pound, that might demagnetize the first time you put it in gear.

Well there goes one crazy idea!
I'm glad it caught your imagination and thx for researching it and replying Ecky.

[Ecky]

Originally Posted by Logic

Well there goes one crazy idea!
I'm glad it caught your imagination and thx for researching it and replying Ecky.

It was fun! I learned a few things. I would also suggest not taking me as the final word, I'm simply a moderately educated layman.

[serialk11r]

That magnetization will be negligible compared to the contact forces on the teeth, probably far less than the eddy current losses you're introducing by having magnets spinning around.

Gearbox losses can be reduced with a better oiling system like they use in F1 cars, but it's a lot of expense for a small gain.

[aerohead]

Originally Posted by Logic

Yes you would still need oil.

"impart force":
Like magnetic poles repel and, according to the maths, the force with which they repel is squared as the distance between them decreases:
So Force = Magnetic Constant /Distance squared.
So the maths says; when D is 0; F is infinite, regardless of how strong the magnet is...
https://socratic.org/questions/the-f...ionality%20%23

ie: You will still get all the force/torque, but without the gears ever physically touching, much like you can't get the like poles of a bar magnet to ever touch... theoretically..?

Any effect which varies with the inverse square law would achieve the highest magnitude ( unity ) at radius = zero, however, say the Gauss measured at the 'surface' of a dipole magnet would only measure what it measures.
I've got some neodymium rare earth magnets, and I can squeeze like poles together with hand pressure.
Micro-finished hard facing would still require a few thousandths clearance for the gear oil, so, while 'close', would never contact.

[markweatherill]

Remember that conventional manual transmissions use helical-cut gears which engage their teeth across a large area, which may affect the repulsion / attraction envisaged.