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Magnetic wheels...

  1. Jul 27, 2015 #1
    I have a project I'm working on where I need to have a model train be able to have an electromagnet hold its wheels to the track -- so that it can go "upsides down" and resist derailment.

    I'm making the wheels and the track -- so all options are on the table.

    If I used a steel track (say 1/4"x1/x4" square stock) and soft iron wheels, what would be the best way to put a coil or coils such that the wheels would be "pulled" to the track? Coils inside the hub of the wheels? just wrap the axle of the train and hope the magnetism transfers? Looking for any ideas and theory on this...

    Thanks in advance,

    Ted
     
  2. jcsd
  3. Jul 27, 2015 #2

    DEvens

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    Does it absolutely have to be electromagnetic? If the wheels had some kind of flange that hooked into a groove in the tracks it might work without the need for magnets. You could arrange the flange to be properly tapered, as the wheels normally are, to help keep the train on the track as usual. You would have to support the rails such that the flange could get on the correct side and not interfere with the support of the rails. Maybe look at how "hanging" monorails are supported.

    https://en.wikipedia.org/wiki/Wuppertal_Suspension_Railway

    To take another approach, if it absolutely has to be electromagnetic, does the electromagnet have to be in the wheels? There isn't much room in the wheels of the typical model train for a powerful electromagnet. If there were a nice iron strip down the middle of the track, between the rails, and the electromagnet was in the body of each engine or car of the model train, you would have more room to insert a nice magnetic coil.
     
  4. Jul 27, 2015 #3
    Great thought -- flange idea was considered... but it does have to be electromagnetic... We do have 24VAC to work with at least :)
     
  5. Jul 27, 2015 #4
    If I were to do this, would it be better to use a permanently mounted electromagnet like shown in drawing #1....


    IMG_20150727_155426.jpg


    OR use the wheels, axle and tracks as all sort of a magnet core, similar to the core of a transformer... like shown in pic #2???

    IMG_20150727_160159.jpg

    Any input is appreciated!
    Ted
     
  6. Jul 27, 2015 #5

    berkeman

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    Just use a permanent horseshoe-shaped magnet on the underside of each car and run a ferrous plate between the rails all along the track. Tune the magnet faces to be about 1-2mm above the ferrous plate string, and that should hold each car to the rails pretty reliably. :smile:
     
  7. Jul 27, 2015 #6

    Nidum

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    You need to contrive closed magnetic circuits as far as possible .

    One way would be to use (several) horseshoe electromagnets with poles which faced left and right faces of any rail and with minimum gap ..
     
  8. Jul 29, 2015 #7
    I really like this idea.... I'm going to run a few bench tests with a mock up based on this idea... Thank you!
     
  9. Jul 29, 2015 #8

    Baluncore

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    There was a time when the motor current pick-up wheels on model locomotives were permanent magnets. Rare-earth permanent magnets would be a better way to go if they could be blended with electromagnets. Toroidal PMs as used in microwave ovens will be lighter than electromagnets.

    Magnetic wheels capable of supporting an inverted train will have a couple of problems.

    Firstly; The magnetic poles, N & S, will need to alternate between wheels on each track. So two adjacent magnetic axles will complete their opposite polarity magnetic circuit through individual rails. Each pair of axles forming a bogie should also work in magnetic conjunction with their neighbouring pairs.

    Secondly; Magnetic wheels will only “stick” while they remain in close contact. For that reason each axle will need a free suspension so it does not have to carry any greater share of the load or lose contact where the track twists. That precludes spring suspension on individual wheels or axles. It will need to employ a rocking tandem system that does not break the magnetic circuit. The rocking of the two sides will need to be independent so as to follow helical sections of track.That may require magnetic ball joints.
     
  10. Oct 21, 2015 #9
    I'd use a permanent magnet to hold the train to the track (or even better, do away with the wheels and make the baseplate of each train car of aluminum so you can use maglev). For propulsion, do a search on YouTube for Professor Eric Laithewaite. He's got some videos describing how he perfected making electromagnets set up a travelling magnetic waveform such that the wheels of a toy train were pulled along the track.
     
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