Practical Magnetic Levitating Transmission Gear System Loses Its Teeth

Zothecula writes: A new transmission device that uses magnetic levitation to almost completely eliminate friction and wear has been developed as part of the MAGDRIVE research project, a collaboration of seven European nations. The creation of the unit entailed the development of a magnetic gear reducer and corresponding frictionless magnetic axles. Aimed primarily for use in spacecraft due to its extended mechanical life, the system is also adaptable for use in automobiles, railways, and aircraft.

Comments

PBS had a documentary...

[Anonymous Coward]

On 5-10 years back about classic cars from some museum in SoCal or something.

The 3 primary vehicles they discussed were:
A 1900s era Battery Powered car with a 25 mile range.
A Steam powered car capable of 'gas-like' performance, given ample 'warmup' time.
And a 1920s or 30s electrocoupled automatic transmission car that I believe used increasing rotational speed to more closely couple the engine to the output shaft (Can't remember if it also had gears or if the coupling mechanism doubled as the 'gears'.)

Point being: So they're finally getting back to R&D on 'non-mechanical' coupling mechisms in modern vehicles. Yay! Only took like 90 years.

Re:PBS had a documentary...

[ledow]

If something has been abandoned for 90+ years with no significant advances in the area, it's probably for a reason.

The upper limit on what such gearing could do is quite low. You're comparing a steel-pushing-steel scenario with one of trying to turn one magnetic wheel by pushing another near it. It's a loser except in ultra-specialist applications with exotic materials (Space? Fine. Your car? Unlikely).

Battery powered cars have been around forever. UK milk floats were entirely battery powered for decades, delivering hundreds of pints of milk to every house in the local town - they just used lead acid batteries and charged overnight. If you ever got stuck behind one, you quickly (!) found out the limitations of the technology of the time. We've moved on from there now, but only very, very recently.

Some huge trucks still have things based on variable transmission technology, so the entire gearbox doesn't have gears but just slides into the most convenient gearing automatically. They've been around for decades. And they work by using a strong belt that can slide up and down a conical shaft. I kid you not. Every few years, they are re-invented under another brand / patent / material and actually do quite a good job. But they are still considered specialist parts because we can't overcome their weaknesses.

Wankel engines were still in mass production until very recently (I believe Mazda don't have newer models that still use them?). Again, they do everything you would want and were constantly reinventing themselves for decades.

The problem is not that it's been done before. It's that it's been done an awful lot and not much more can be done that way. As such, although we have stronger room-temperature magnets, they aren't THAT much stronger. Superconducting magnets might be considered "new" but we can't make them practical yet - except in the absolute zero and vacuum of outer space.

There's nothing wrong with going back to the old, but you have to add something new (e.g. the clockwork radio was hailed as genius because it took the old and made it do something "new").

And I'm not sure this does that at all.

Re:PBS had a documentary...

[jafiwam]

Some huge trucks still have things based on variable transmission technology, so the entire gearbox doesn't have gears but just slides into the most convenient gearing automatically. They've been around for decades. And they work by using a strong belt that can slide up and down a conical shaft. I kid you not. Every few years, they are re-invented under another brand / patent / material and actually do quite a good job. But they are still considered specialist parts because we can't overcome their weaknesses.

For someone asserting they know all kinds of "unknoiwn" details, you sure are behind.

The description above is called a "Constant Velocity Transmission" and both Nissan (recently) and Subaru (since the 70's) have these. Subaru has had MOST of their new non-performance car fleet use CVTs for the last three years. Nisssan's CVT uses a "pusher" belt made of stacked plates connected by a chain. Subaru, a regular chain.

This is not "specialists" parts anymore. This is just a different type of automatic transmission.

True, "going back to the old" works sometimes, often that is because materials and engineering concepts have advanced far enough to actually make the stuff work now. That doesn't mean tinkering with, or taking another try at these old methods isn't worthwhile.

Re:Efficiency???

[SharpFang]

Way more efficient than gears for loads it's designed to handle - but it's not meant for heavy lifting; the "magnetic gears" will "slip" if the load is too high, and in this case "too high" is quite low (think force required to move two magnets oriented in "repulsing" way against each other).

It would be great for stuff like stabilizing flywheels - things that once set in motion stay in motion for years, and may take a long time to spin up or stop. It would work well for things that require very little force, like reorienting the solar panels or aiming the antenna.

OTOH, stuff like lander wheel bearings or drills for picking samples are better handled with normal bearings that can take much heavier loads.

It's not a cure-all solution, it's just a good new option for specific applications. You won't use it to build a better crane but gyroscope flywheels could immensely benefit from that!

Re:Efficiency???

[drinkypoo]

Way more efficient than gears for loads it's designed to handle - but it's not meant for heavy lifting; the "magnetic gears" will "slip" if the load is too high, and in this case "too high" is quite low (think force required to move two magnets oriented in "repulsing" way against each other).

If you couldn't move high forces with a transmission like this, then you also couldn't generate them with an electric motor, because you couldn't hope for the magnetic fields to turn the stator against high loads.

OTOH, stuff like lander wheel bearings or drills for picking samples are better handled with normal bearings that can take much heavier loads.

What happens when you put too much torque through a drill? You shatter your bit. What happens when you put too much torque through an axle? All kinds of exciting things can happen, check out some four wheeling videos. There's lots of reasons why some slip designed into the system is not an undesirable thing.

Re:Might be a fit for EVs

[Charliemopps]

It looks too bulky to provide a lot of gears in an automotive application, but if it could provide just two that you couldn't strip out no matter how much torque you put through them, it could be a really nice match for EVs. They would benefit from a transmission, but it's difficult for any transmission of a reasonable size to handle the output torque.

Electric cars don't need gears in the first place. The only reason we have gears in IC engines is because, 1. it would be expensive and hard to keep the engines in sync if you had a separate one for each wheel, 2. IC engines operate in most efficiently at very specific RPMs. Notice how the tachometer tends to hover around 2000 rpm as you shift gears? That's what the gears are for, to keep the engine at a constant RPM. Electric motors work just as efficiently at just about any RPM.

Re:Efficiency???

[rgbatduke]

The other point being that it could be designed only to replace the kinetic friction parts of a transmission, the parts that synchronize the system. The gearing itself can probably still be mechanical. Not having to replace clutch plates, for example, might be a nice and relatively easily doable thing.