LIM moter experiment

Monday, October 1, 2001 2:41 PM
Im not a wiz on knowing LIMs but can  you use small magnets and line them up + - + - + - + - + - + ect....., would a small train like object move if you add fins like the Chiller? Not as fast of course but would it atleast move a couple feet. Or are LIMs more complicated
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Monday, October 1, 2001 2:45 PM
I do think that would work, I tried it but I got all the magnets screwed up.
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Monday, October 1, 2001 2:57 PM
Nope. If the fin was metal, it would be attracted to either end. It would simply 'stick' there. You would need a way to reverse the polarity of the magnets as the fin moves by. Also, the fin would need to be magnetic. When the fin approaches one magnet, the magnet must be switched so that it attracts the forward pole. Then, as it passes, it needs to switch polarity so that it repells that end and then attracts the other and so on. Complicated? Very!  
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Yeeee Haaawwww!

*** This post was edited by janfrederick on 10/1/2001. ***

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Monday, October 1, 2001 3:21 PM
couldnt you just wrap a wire around a pipe would that work?
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"It was sure nice of Mr. Crab to give me a job here!" "And he was sure nice to start you off at $50 an hour! When i started, i had to pay Mr. Crab $100 an hour!"
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Monday, October 1, 2001 3:31 PM
The repulsion of magnets is what causes movement in the train. I musy say janfrederick explained it quite nicely.
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Monday, October 1, 2001 3:46 PM
Wire around a pipe? Nah. That would just make a single magnet out of the pipe. I really don't think anyone could make a usable LIM at home out of magnets or batteries. If they did, they must have too much time on their hands.
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Hey, SFGAm management, can I buy a couple cages of Sky Whirl?
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Monday, October 1, 2001 3:54 PM
Yea, you need motors, magnets, and countless other parts. That is why LIM coasters never open on time. It is too complicated for the designers. think about you trying to do it.
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Monday, October 1, 2001 3:56 PM
wow! that's really complicated! I'll find something else to do. LoL, Oh I spelled motor wrong, my bad, plus the M in LIM stands for motor.
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*** This post was edited by nitro230ft on 10/1/2001. ***

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Monday, October 1, 2001 4:14 PM
Im glad I dont have to make LIMs. Sounds complicated but interesting. I dont know if I am smart enough for this stuff.

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Scream your coaster opinions and ideas! Its the ThemeParkBigShot!!!

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Monday, October 1, 2001 8:11 PM
It's all just basicmagnitesme with a computer changing the charges ofthe LIMS!:). I really didn't understand this until science last year its all makes perfect scnece. The magnet under the train is just an ordinary possitive charging magnet. The Lim's becuase of electricty start out as negative. They simply beucase of the opposite charge, attract the car becuase opposites attract. Then once the train is there, the charge switvches to possitive, and then is repelled. Ingenious I tell you! Thing I don't under stand is how the charge of the magnets changes, i guess its really 2 different magnets. Its amazing the power they generate, I bet if the LIM/LSM's where fired with now train you could hold a bunch of metal and you would get sucked into the magnets!
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SFMM line cutters are the braviest in the world.
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Tuesday, October 2, 2001 4:38 AM
While you could build a pseudo LIM with a steel fin, I believe the fins on actual LIM trains are aluminum.  An opposing field is created by induced currents in the electrically conductive fin.

Rideman has a page that explains a considerable amount about LIMs:  http://capital2.capital.edu/admin-staff/dalthoff/lim.html

*** This post was edited by Jim Fisher on 10/2/2001. ***

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Tuesday, October 2, 2001 5:08 AM
You could build a LIM without too much trouble because LIMs are simple. Getting it to work reliably could be a bit of a problem because most people don't have 3-phase power available. Remember, with a linear induction motor, you don't use magnets. For a small-scale demonstration, the easiest tactic might be to do a single-sided LIM, the only problem with that is that your reaction plate, then, has to be an aluminum plate with a steel backing plate.

A single-phase LIM would work, the only thing is, you might have to push-start it, or you might find that the direction is unpredictable.

--Dave Althoff, Jr.

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Tuesday, October 2, 2001 11:12 AM
Well, first of all, you're descriding LSM technology...pull, push.  LIMs are completely different.  Basically, a wave of magnetism forms around the fins when the magnets are turned on and it just pushes.  Once the train passes, the LIMs are shut down.  So, LIMs are off...as soon as the first car hits, it turns on...a split second later, when the train is gone, it shuts off.  It goes down the entire row like this.  All it does is push as if it were carried by a wave.
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Bomb Squad Technician

If you see me running, try and keep up!

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Tuesday, October 2, 2001 11:19 AM
Is is just me, or when Rideman (Dave) talks, I just have this overwhelming urge to just shut up, read, and try to absorb as much as possible?
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I rode "X" and never went upside down.
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Tuesday, October 2, 2001 12:29 PM
hehe, you go Dave!

Don't answer this if you don't want to, but do you work as a teacher?

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Tuesday, October 2, 2001 12:37 PM
Coaster131 has got it...if you'll excuse the shameless plug, there is that article I wrote for First Drop available on my web page... :)

bigkirby, I'm not officially a teacher by trade, but I do work for a University, and I have to do a certain amount of informal teaching...but more important, everybody on this campus is in the teaching business one way or another... :)

--Dave Althoff, Jr.

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Tuesday, October 2, 2001 1:47 PM
Rideman, since the wave is based on the frequency of the three phases, would it be safe to say that the LIM increases the frequency as the train accelerates? (Since obviously the train will be accelerating?). If this is the case, it would seem that some sort of control would be needed to create a model.

Ok Ok...I just read further (imagine that!). Seems that this is solved by spacing and switching? Correct? Either way, it seems a model would be difficult.
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Yeeee Haaawwww!

*** This post was edited by janfrederick on 10/2/2001. ***

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Tuesday, October 2, 2001 8:37 PM
The first test of S:TE resulted in the train moving about 10 feet.  Those were proffesionals.  this would be extremely hard to do at home.
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"Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away and you have their shoes."
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