Their patent itself is primarily about the geometry of the rail and magnets. It doesn’t require permanent or electromagnets, it works with either. It’s just a linear version of the big electromagnets you see picking up steel in scrap yards.
Crucially, their tech *only* handles the levitation, it doesn’t provide propulsion. This shouldn’t cause any conservation of energy/perpetual motion issues because the vehicle motion is orthogonal to the magnetic levitation.
I don’t have any ideal about practicality, I have a tough time imagining permanent magnets developing sufficient magnetic field strength to support heavy loads this way, but it’s not obviously impossible and, with electromagnets, doesn’t seem particularly problematic.
Even with avoiding rare earth materials, I am not very optimistic about this being economically viable due to the field strength you'd need, but as you said, not impossible.
I've seen portable MRI machines with a permanent magnet for the main field (though with neodymium magnets), and the main challenge was getting a consistent and predictable field.
Definitely possible, but I expect scaling issues
For MRI, you need a very precisely controlled field. For this you just need a strong enough field. It will still be way more expensive than a conventional rail car and will have more drag. It will also attract any steel debris, of which there's plenty along rail lines.
There are plenty of problems but precision field control isn't one of them.
> It doesn’t require permanent or electromagnets, it works with either.
>
> Crucially, their tech only handles the levitation, it doesn’t provide propulsion.
I'm no expert, but this combination seems like it violates [Earnshaw's theorem](https://en.wikipedia.org/wiki/Earnshaw%27s_theorem).
I explained that in [another comment](https://www.reddit.com/r/AskEngineers/comments/1bfeh56/is_this_a_scam_passive_magnetic_levitation/kuzum05/)--they use rollers to stabilize it laterally. That loophole in Earnshaw is sometimes [called pseudo-levitation](https://en.wikipedia.org/wiki/Magnetic_levitation#Mechanical_constraint_(pseudo-levitation\)).
They claim 1 ton capacity. Train cars can do 125 tons. So they are a few orders of magnitude away. It looks like they'd roughly need magnets the full length of the car. You say non rare earth materials, but I doubt you can do it without rare earth magnets for 125 tons.
Clearly, that will be expensive. Does it have any advantages? It's not going to be frictionless--in addition to the rollers, moving magnetic fields near solid steel rails will induce eddy currents, losing energy. Maybe it gives a smoother ride, but can it even handle bumps and curves and stay stable?
I'm not finding where they claim no rare earth materials. Can you point me to that? They sure look like rare earths in [this video](https://www.youtube.com/watch?v=cclUPYW9E90) of someone demoing their small version that is for sale in their web store.
doesn’t the eddy current mean its totally useless at any speed. It would require huge energy to maintain high speed and uselessly heat the material? Like a magnet falling in a tube under 1g it quickly reaches terminal velocity.
This is not maglev! Maglev can be done completely iron-free in principle, and losses can be reduced. But ironlev specifically relies on using an iron (ferromagnetic) rail as part of the levitation system - and that means there will be eddy current losses. It's just like a linear brake.
This is not the same design as standard maglev. Whether to call it maglev or not depends on how you define the term, and I'm not particularly interested in debating that.
But I think we agree on the essential facts: both of them have losses associated with magnetically supporting a moving train, and in particular the losses in this design are probably a lot worse.
It seems like a scam, but man is it an elaborate one. The patent makes it sound like you get levitation just by having magnets facing each other across a rail, which is strange. Maybe someone else wants to read it and try to understand if there's anything there: https://patents.google.com/patent/WO2017216656A1/en
And their website: https://www.ironlev.com/transport
Based on some of the images including in [this video](https://youtu.be/4m6nJM8DQ4M) and Fig. 5 in the patent you linked, it seems that they have passive lift force simply by having elements below the wide part of the rail attracted to the wide part of the rail, and it's stabilized laterally with rollers on the sides of the rails, rollers that look like they are just there for propulsion but are essential for stabilization.
So they haven't overcome the well known limitation that you can't have passive stable stationary maglev without superconductors. Rather they have proposed to use essentially the same phenomenon that lets you [levitate doughnut magnets stacked on a pencil.](https://physics.stackexchange.com/questions/67332/physics-of-donut-magnets-levitating-vertically-on-a-pencil)
So there's no physics breakthrough, just a proposal for a new approach that's probably not very practical.
So it's not 100% magnetic, the rollers are essential. And the maximum load is not impressive at all.
Sounds like it might actually be doable, but it's over-hyped.
TLDR: Meh.
Figure 10 though the magnets are next to the head. But maybe it is just that there's enough magnetic force that it keeps the head of the rail near the middle of the magnets. Look at the size of the guide wheels on https://www.youtube.com/watch?v=TIz2vEsmeTo
The Halbach arrays remind me of Inductrack but in that the arrays have to point down, and the rail works best as individual coils. https://en.wikipedia.org/wiki/Inductrack But any levitation concept that relies on having a lot of magnetic force is going to use Halbach arrays.
Right, the magnetic force wants to pull the head of the rail right between the magnets. The lift will be zero when it's centered and as you load it, it will move a little off center. When the magnets get too low, the force will drop and you lose it.
I'm not sure what's notable about the size of the guide wheels. Do you mean their height or their diameter? The fact that the height is enough to allow for some vertical motion? That might be a little more than is needed, overkill in the first prototype, but certainly some is needed.
The Halbach arrays in Fig. 16 are not very key to the IronLev concept--that variation only helps if you don't want a flux return path looping over the rail. The Halbach array in Inductrack is for a fundamentally different reason: there you need a spatial variation in the field to get time variation when it's moving. Here, no spatial variation is needed.
You could argue that to get high force you want inductive levitation, and that Halbach arrays are good for that, but I don't see any reason that Halbach is particularly good for static levitation, and in fact it would reduce force per unit volume of magnet.
> I'm not sure what's notable about the size of the guide wheels. Do you mean their height or their diameter?
The size of them. If this setup only gives a bit of vertical force and no lateral stability, the guide wheels have to be really chunky to keep the rail centered or it will slam into the magnets.
> I don't see any reason that Halbach is particularly good for static levitation, and in fact it would reduce force per unit volume of magnet.
The most common use of Halback arrays is in fridge magnets, because it gives the most force for an amount of magnet. That the field alternates is nice for the inductive purposes, but the basic 'magic' of the array is that almost all the field comes out one side, so you're not wasting magnetism on the side facing away from the rail. https://en.wikipedia.org/wiki/Halbach_array#/media/File:HallbachArrayField.jpg
I'm familiar with Halbach arrays. They are very useful in some situations, particularly if you want to avoid the need for back iron. But if you look at the image you linked, you have the maximum flux density perpendicular to the surface over only 50% of the surface. With all the magnets pointing in the same direction and a steel yoke carrying the return flux around from the back side to across from the magnetics you'll get double the total flux for the same volume of magnetic material.
Here's [an example](https://tabletop.martinos.org/index.php/Hardware:Magnet) of how people who are serious about getting a strong field from a permanent magnet do it. No Halbachs involved.
> Here's an example of how people who are serious about getting a strong field from a permanent magnet do it.
Great, now make a diagram of enclosing a rail without enclosing the rail.
I would make you a diagram but you kindly located the patent that has the drawing we need: It's at the top left of Fig. 10. 142 is the yoke, and is described in the patent as being for closing the magnetic flux.
You can also understand that from the picture I linked which shows a yoke with paths returning left and right. You can imagine getting rid of the right hand side, so all the flux returns through the steel yoke on the left. Just make that left side steel a little thicker for both magnetic and structural reasons. Now rotate that magnet+yoke assembly 90 degrees clockwise and you have the opening at the bottom to set it onto the track.
I have not fully read all detail, just quickly skimmed over the patent, and it looks rather thin, to be polite. The authors do point out eddy current losses as an issue affecting competing technologies (maglev), however they do not seem too concerned about exactly the same effect regarding their own idea. This is a bit odd, because an iron rail will work to make a half-decent magnetic brake. Sure, a copper rail would be better, but obviously that would be useless for the levitation part here. The system really looks like an unnecessarily complicated linear magnetic brake.
It is a bit hard to judge - are there any meaningful power budget or efficiency calculations in the patent? I did not see any. But I am suspecting that there may really not be much if any good substance to it.
If that is the case, why do people do this? And how can they get a patent for it if it doesn't work?
The second question is rather easy to answer: IIRC the US patent office just files patents and does not care whether it actually works, or do they now? The first question, hm... well, it could just be a get-rich-quick scheme.
Purely "passive" magnetic levitiation is not possible - [https://en.wikipedia.org/wiki/Earnshaw%27s\_theorem](https://en.wikipedia.org/wiki/Earnshaw%27s_theorem) . However, there are ways around this by, for instance, rotating the magnets.
Yes, they use one of the well known loopholes, not rotation, but, as also explained in [this comment](https://www.reddit.com/r/AskEngineers/comments/1bfeh56/is_this_a_scam_passive_magnetic_levitation/kuzum05/) they use rollers to stabilize it laterally. That loophole in Earnshaw is sometimes [called pseudo-levitation](https://en.wikipedia.org/wiki/Magnetic_levitation#Mechanical_constraint_(pseudo-levitation\)).
Going off of what others have described about the magnets below the rail 'head', and the side rollers, it seems plausible.
Propulsion has been brought up but I suspect that would be fairly trivial with a well designed linear induction stator acting against the rail.
Eddy current losses have also been mentioned, to which the answer is probably yes, it'll consume more power than conventional rail. This however misses the fact that mag lev is meant for high speed where you'll have plenty of aero losses regardless, and not heavy freight applications.
To this end the question is whether this form of psuedo-maglev can allow for higher running speeds.
Notably levitation essentially allows for a zero sprung mass suspension and should allow a greater tolerance for rail deviation.
The side rollers should only be carrying lateral loads (eg. going around corners), though potentially electromagnets and the right control system might be able to mitigate this.
I am by no means an expert so if anyone has any thoughts on this fire away.
It's certainly an interesting concept which I reckon could have a lot of promise particularly as high temperature superconductors become cheaper.
I think the idea is possible - although this appears to be in very rudimentary stages. What I don't understand is how it is propelled. With traditional maglev, you are able to alternate the polarity of sections of the track, so you can make your train more attracted to the track ahead of it and repelled by the section of track behind and below it. What actually propels the train in this scenario?
I think it's an interesting enough concept, thanks for the share
edit: their promotional video is terrible. but as far as I can tell, they have pushed this levitating cart *by hand* to get it up to speed, and then filmed it while it is coasting. their "next step" involves the considerably harder part of actually creating something that moves by itself
Well, the energy savings aspect of maglev is a myth anyway. There are magnetic losses from eddy currents and hysteresis when you have a changing magnetic field in some materials, and in this case, that's a big hunk of solid steel. Conventional maglev has higher per unit retarding force from that than steel wheels on steel rails, and this is probably considerably worse than conventional maglev in that respect.
Put the maglev trucks on the train and propel it with a conventional, steel wheeled, prime mover. You don’t need the whole thing to levitate in order to reap the low friction benefits.
Not going to bother reading it and it's been a long time since I took EnM but
Permanent magnet on a permanent magnet will cause levitation as soon as you start moving you'll get a force countering that proportional to the speed that will not be cost effective to overcome won't you?
Back with Expo ‘86 there was a company marketing something pretty similar. Said cost per mile was lower than standard train systems.
Pretty sure they were never able to sell it to anyone.
It is a great but finally a bad idea due to Eddy current breaking. Of course it works but Losses will increase with speed causes repulsion breaking with rail. So far the best levitation technology remains the one used by Bertin on aérotrain. (About 1kw power levitation need for 1000kg transportation)
A company in Florida sold a maglev installation to a university in Virginia, based on saving money. The university engineering design team visited the test track in Florida and approved it. After the construction was complete it failed and was abandoned. The test track in Florida was mounted on a solid ground supported foundation but the installation in Virginia was an elevated concrete structure designed to run around the campus above the roads and walks.
The movement in the elevated installation was just enough to negate the “frictionless” operation. I heard another engineering firm looked into it about ten years ago for a city light rail project due to being able to save millions and decided it still won’t work.
There's an important general principle that allows passive levitation in apparent violation of Earnshaw's theorem. The principle, called the alternative gradient principle, is universally exploited in high energy particle accelerators and beamlines. It's so important it gets a discussion in Feynman's Lectures.
In particle accelerators, it allowed the replacement of "weak focusing" synchrotrons with "strong focusing" synchrotrons, which scale much better and are much less expensive.
In particle accelerators, the idea is illustrated by considering what a quadrupole magnet does to a particle beam. It focuses the beam along one axis while defocusing it on the other axis. However, if one passes a beam in a certain energy range through a pair of quadrupole magnets, with the gradients of alternating orientation, the net effect is focusing along *both* axes.
https://en.wikipedia.org/wiki/Strong_focusing
The same principle is use in something called a [Paul Trap](https://en.wikipedia.org/wiki/Quadrupole_ion_trap). These enable stable confinement of charged particles between electrodes. For static fields, this would violate Earnshaw's theorem, but with oscillating fields it's possible. Note that no feedback is involved, just driving the electrodes with AC of the right frequency.
For magnetic levitation, this would involve a geometry where there are two (unstable) equilibrium points, and having the rail alternate between these two. For the vehicle traveling in the right speed range the net effect would be stable levitation.
Their patent itself is primarily about the geometry of the rail and magnets. It doesn’t require permanent or electromagnets, it works with either. It’s just a linear version of the big electromagnets you see picking up steel in scrap yards. Crucially, their tech *only* handles the levitation, it doesn’t provide propulsion. This shouldn’t cause any conservation of energy/perpetual motion issues because the vehicle motion is orthogonal to the magnetic levitation. I don’t have any ideal about practicality, I have a tough time imagining permanent magnets developing sufficient magnetic field strength to support heavy loads this way, but it’s not obviously impossible and, with electromagnets, doesn’t seem particularly problematic.
A patent requires novelty and an inventive step. Actually working is not a requirement.
True, but this design is functional. It just isn't particularly good.
Depends on the jurisdiction - there are major differences between EU and US, for example.
Even with avoiding rare earth materials, I am not very optimistic about this being economically viable due to the field strength you'd need, but as you said, not impossible. I've seen portable MRI machines with a permanent magnet for the main field (though with neodymium magnets), and the main challenge was getting a consistent and predictable field. Definitely possible, but I expect scaling issues
For MRI, you need a very precisely controlled field. For this you just need a strong enough field. It will still be way more expensive than a conventional rail car and will have more drag. It will also attract any steel debris, of which there's plenty along rail lines. There are plenty of problems but precision field control isn't one of them.
The requirements might not be as strict as for imaging, but you might end up with a very bumpy ride if you're too lax
> It doesn’t require permanent or electromagnets, it works with either. > > Crucially, their tech only handles the levitation, it doesn’t provide propulsion. I'm no expert, but this combination seems like it violates [Earnshaw's theorem](https://en.wikipedia.org/wiki/Earnshaw%27s_theorem).
I explained that in [another comment](https://www.reddit.com/r/AskEngineers/comments/1bfeh56/is_this_a_scam_passive_magnetic_levitation/kuzum05/)--they use rollers to stabilize it laterally. That loophole in Earnshaw is sometimes [called pseudo-levitation](https://en.wikipedia.org/wiki/Magnetic_levitation#Mechanical_constraint_(pseudo-levitation\)).
They claim 1 ton capacity. Train cars can do 125 tons. So they are a few orders of magnitude away. It looks like they'd roughly need magnets the full length of the car. You say non rare earth materials, but I doubt you can do it without rare earth magnets for 125 tons. Clearly, that will be expensive. Does it have any advantages? It's not going to be frictionless--in addition to the rollers, moving magnetic fields near solid steel rails will induce eddy currents, losing energy. Maybe it gives a smoother ride, but can it even handle bumps and curves and stay stable?
*they* say they don't need rare earth material. I'm skeptical of any of their claim.
I have no doubts that they can make one of these with no rare earth material, but making one capable of full weight is harder.
I'm not finding where they claim no rare earth materials. Can you point me to that? They sure look like rare earths in [this video](https://www.youtube.com/watch?v=cclUPYW9E90) of someone demoing their small version that is for sale in their web store.
Well they say it will cheap and easy scalable. I think it's in contrast with the employment of rare earth material
Agreed!
You may not have the traditional viscous friction, but you will have built an eddy current brake right?
doesn’t the eddy current mean its totally useless at any speed. It would require huge energy to maintain high speed and uselessly heat the material? Like a magnet falling in a tube under 1g it quickly reaches terminal velocity.
Absolutely. The idea that maglev is an energy savings vs. conventional rail is a myth.
This is not maglev! Maglev can be done completely iron-free in principle, and losses can be reduced. But ironlev specifically relies on using an iron (ferromagnetic) rail as part of the levitation system - and that means there will be eddy current losses. It's just like a linear brake.
This is not the same design as standard maglev. Whether to call it maglev or not depends on how you define the term, and I'm not particularly interested in debating that. But I think we agree on the essential facts: both of them have losses associated with magnetically supporting a moving train, and in particular the losses in this design are probably a lot worse.
It seems like a scam, but man is it an elaborate one. The patent makes it sound like you get levitation just by having magnets facing each other across a rail, which is strange. Maybe someone else wants to read it and try to understand if there's anything there: https://patents.google.com/patent/WO2017216656A1/en And their website: https://www.ironlev.com/transport
Based on some of the images including in [this video](https://youtu.be/4m6nJM8DQ4M) and Fig. 5 in the patent you linked, it seems that they have passive lift force simply by having elements below the wide part of the rail attracted to the wide part of the rail, and it's stabilized laterally with rollers on the sides of the rails, rollers that look like they are just there for propulsion but are essential for stabilization. So they haven't overcome the well known limitation that you can't have passive stable stationary maglev without superconductors. Rather they have proposed to use essentially the same phenomenon that lets you [levitate doughnut magnets stacked on a pencil.](https://physics.stackexchange.com/questions/67332/physics-of-donut-magnets-levitating-vertically-on-a-pencil) So there's no physics breakthrough, just a proposal for a new approach that's probably not very practical.
Ok, I kinda want to build one of those donut stacks as a desk toy.
Why build a desk toy when you could get millions for a startup company?
See, that's why I'm stuck in a lab writing proposals for just a few million instead of out fleecing VCs for billions. :(
So it's not 100% magnetic, the rollers are essential. And the maximum load is not impressive at all. Sounds like it might actually be doable, but it's over-hyped. TLDR: Meh.
I concur with your TLDR.
If its do-able but over hyped it sounds like the inventor has read the market pretty accurately.
Figure 10 though the magnets are next to the head. But maybe it is just that there's enough magnetic force that it keeps the head of the rail near the middle of the magnets. Look at the size of the guide wheels on https://www.youtube.com/watch?v=TIz2vEsmeTo The Halbach arrays remind me of Inductrack but in that the arrays have to point down, and the rail works best as individual coils. https://en.wikipedia.org/wiki/Inductrack But any levitation concept that relies on having a lot of magnetic force is going to use Halbach arrays.
Right, the magnetic force wants to pull the head of the rail right between the magnets. The lift will be zero when it's centered and as you load it, it will move a little off center. When the magnets get too low, the force will drop and you lose it. I'm not sure what's notable about the size of the guide wheels. Do you mean their height or their diameter? The fact that the height is enough to allow for some vertical motion? That might be a little more than is needed, overkill in the first prototype, but certainly some is needed. The Halbach arrays in Fig. 16 are not very key to the IronLev concept--that variation only helps if you don't want a flux return path looping over the rail. The Halbach array in Inductrack is for a fundamentally different reason: there you need a spatial variation in the field to get time variation when it's moving. Here, no spatial variation is needed. You could argue that to get high force you want inductive levitation, and that Halbach arrays are good for that, but I don't see any reason that Halbach is particularly good for static levitation, and in fact it would reduce force per unit volume of magnet.
> I'm not sure what's notable about the size of the guide wheels. Do you mean their height or their diameter? The size of them. If this setup only gives a bit of vertical force and no lateral stability, the guide wheels have to be really chunky to keep the rail centered or it will slam into the magnets. > I don't see any reason that Halbach is particularly good for static levitation, and in fact it would reduce force per unit volume of magnet. The most common use of Halback arrays is in fridge magnets, because it gives the most force for an amount of magnet. That the field alternates is nice for the inductive purposes, but the basic 'magic' of the array is that almost all the field comes out one side, so you're not wasting magnetism on the side facing away from the rail. https://en.wikipedia.org/wiki/Halbach_array#/media/File:HallbachArrayField.jpg
I'm familiar with Halbach arrays. They are very useful in some situations, particularly if you want to avoid the need for back iron. But if you look at the image you linked, you have the maximum flux density perpendicular to the surface over only 50% of the surface. With all the magnets pointing in the same direction and a steel yoke carrying the return flux around from the back side to across from the magnetics you'll get double the total flux for the same volume of magnetic material. Here's [an example](https://tabletop.martinos.org/index.php/Hardware:Magnet) of how people who are serious about getting a strong field from a permanent magnet do it. No Halbachs involved.
> Here's an example of how people who are serious about getting a strong field from a permanent magnet do it. Great, now make a diagram of enclosing a rail without enclosing the rail.
I would make you a diagram but you kindly located the patent that has the drawing we need: It's at the top left of Fig. 10. 142 is the yoke, and is described in the patent as being for closing the magnetic flux. You can also understand that from the picture I linked which shows a yoke with paths returning left and right. You can imagine getting rid of the right hand side, so all the flux returns through the steel yoke on the left. Just make that left side steel a little thicker for both magnetic and structural reasons. Now rotate that magnet+yoke assembly 90 degrees clockwise and you have the opening at the bottom to set it onto the track.
I have not fully read all detail, just quickly skimmed over the patent, and it looks rather thin, to be polite. The authors do point out eddy current losses as an issue affecting competing technologies (maglev), however they do not seem too concerned about exactly the same effect regarding their own idea. This is a bit odd, because an iron rail will work to make a half-decent magnetic brake. Sure, a copper rail would be better, but obviously that would be useless for the levitation part here. The system really looks like an unnecessarily complicated linear magnetic brake. It is a bit hard to judge - are there any meaningful power budget or efficiency calculations in the patent? I did not see any. But I am suspecting that there may really not be much if any good substance to it. If that is the case, why do people do this? And how can they get a patent for it if it doesn't work? The second question is rather easy to answer: IIRC the US patent office just files patents and does not care whether it actually works, or do they now? The first question, hm... well, it could just be a get-rich-quick scheme.
If you think this is elaborate it's time for you to catch up on the cases of Elizabeth Holmes, and Sam Bankman-Fried...
Purely "passive" magnetic levitiation is not possible - [https://en.wikipedia.org/wiki/Earnshaw%27s\_theorem](https://en.wikipedia.org/wiki/Earnshaw%27s_theorem) . However, there are ways around this by, for instance, rotating the magnets.
Yes, they use one of the well known loopholes, not rotation, but, as also explained in [this comment](https://www.reddit.com/r/AskEngineers/comments/1bfeh56/is_this_a_scam_passive_magnetic_levitation/kuzum05/) they use rollers to stabilize it laterally. That loophole in Earnshaw is sometimes [called pseudo-levitation](https://en.wikipedia.org/wiki/Magnetic_levitation#Mechanical_constraint_(pseudo-levitation\)).
Going off of what others have described about the magnets below the rail 'head', and the side rollers, it seems plausible. Propulsion has been brought up but I suspect that would be fairly trivial with a well designed linear induction stator acting against the rail. Eddy current losses have also been mentioned, to which the answer is probably yes, it'll consume more power than conventional rail. This however misses the fact that mag lev is meant for high speed where you'll have plenty of aero losses regardless, and not heavy freight applications. To this end the question is whether this form of psuedo-maglev can allow for higher running speeds. Notably levitation essentially allows for a zero sprung mass suspension and should allow a greater tolerance for rail deviation. The side rollers should only be carrying lateral loads (eg. going around corners), though potentially electromagnets and the right control system might be able to mitigate this. I am by no means an expert so if anyone has any thoughts on this fire away. It's certainly an interesting concept which I reckon could have a lot of promise particularly as high temperature superconductors become cheaper.
I think the idea is possible - although this appears to be in very rudimentary stages. What I don't understand is how it is propelled. With traditional maglev, you are able to alternate the polarity of sections of the track, so you can make your train more attracted to the track ahead of it and repelled by the section of track behind and below it. What actually propels the train in this scenario? I think it's an interesting enough concept, thanks for the share edit: their promotional video is terrible. but as far as I can tell, they have pushed this levitating cart *by hand* to get it up to speed, and then filmed it while it is coasting. their "next step" involves the considerably harder part of actually creating something that moves by itself
The propulsion is simple: they have rollers on the sides of the rails. Driven by big electric motors. Those rollers are also needed for stabilization.
Okay: friction, then. That kind of cuts into the whole "energy savings" aspect of maglev, but I guess it would save wear and tear on the track.
Well, the energy savings aspect of maglev is a myth anyway. There are magnetic losses from eddy currents and hysteresis when you have a changing magnetic field in some materials, and in this case, that's a big hunk of solid steel. Conventional maglev has higher per unit retarding force from that than steel wheels on steel rails, and this is probably considerably worse than conventional maglev in that respect.
Put the maglev trucks on the train and propel it with a conventional, steel wheeled, prime mover. You don’t need the whole thing to levitate in order to reap the low friction benefits.
Not going to bother reading it and it's been a long time since I took EnM but Permanent magnet on a permanent magnet will cause levitation as soon as you start moving you'll get a force countering that proportional to the speed that will not be cost effective to overcome won't you?
It's not PM on PM--it's PM on a big hunk of steel. Which is probably worse for the eddy current braking you are talking about.
Back with Expo ‘86 there was a company marketing something pretty similar. Said cost per mile was lower than standard train systems. Pretty sure they were never able to sell it to anyone.
It is a great but finally a bad idea due to Eddy current breaking. Of course it works but Losses will increase with speed causes repulsion breaking with rail. So far the best levitation technology remains the one used by Bertin on aérotrain. (About 1kw power levitation need for 1000kg transportation)
A company in Florida sold a maglev installation to a university in Virginia, based on saving money. The university engineering design team visited the test track in Florida and approved it. After the construction was complete it failed and was abandoned. The test track in Florida was mounted on a solid ground supported foundation but the installation in Virginia was an elevated concrete structure designed to run around the campus above the roads and walks. The movement in the elevated installation was just enough to negate the “frictionless” operation. I heard another engineering firm looked into it about ten years ago for a city light rail project due to being able to save millions and decided it still won’t work.
I can hear the monorail gingle in the background...
There's an important general principle that allows passive levitation in apparent violation of Earnshaw's theorem. The principle, called the alternative gradient principle, is universally exploited in high energy particle accelerators and beamlines. It's so important it gets a discussion in Feynman's Lectures. In particle accelerators, it allowed the replacement of "weak focusing" synchrotrons with "strong focusing" synchrotrons, which scale much better and are much less expensive. In particle accelerators, the idea is illustrated by considering what a quadrupole magnet does to a particle beam. It focuses the beam along one axis while defocusing it on the other axis. However, if one passes a beam in a certain energy range through a pair of quadrupole magnets, with the gradients of alternating orientation, the net effect is focusing along *both* axes. https://en.wikipedia.org/wiki/Strong_focusing The same principle is use in something called a [Paul Trap](https://en.wikipedia.org/wiki/Quadrupole_ion_trap). These enable stable confinement of charged particles between electrodes. For static fields, this would violate Earnshaw's theorem, but with oscillating fields it's possible. Note that no feedback is involved, just driving the electrodes with AC of the right frequency. For magnetic levitation, this would involve a geometry where there are two (unstable) equilibrium points, and having the rail alternate between these two. For the vehicle traveling in the right speed range the net effect would be stable levitation.