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The Six Flags Magic Mountain (SFMM) Discussion Thread


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I hate to be the guy who asks a million questions. But does anyone know the difference between LSMs and LIMs?

 

The image below is the best description I've ever found reguarding the difference between LIM and LSM magnetic propulsion. Everyone can try and impress you with college terms, big fancy words and technical jargon but as far as actually understanding how they work: this takes the cake.

 

From a reliability standpoint, LIMs do the job. There's only one path they follow and they all fire in line. But as you can see (referring to the numbers on the image) they take a high amount of power each cycle. Costly.

 

LSMs or Synchronous motors are a bit more complicated (although these days with computers they're much easier to control) but take up much less power (referring again to the diagram) but require you to fire off the magnets "in sync" with eachother. These magnets are required on a ride like Superman at Magic Mountain because they both control the launch speed and the decceleration. This type of electromagnetic control was amongst the first of its kind on Superman, which, most of us know, plagued it with downtime. The synchronization is so precise that any kind of faulty speed or loss of car location caused a launch or return failure, resulting in magnets shutting off, and friction e-brakes at the end of the launch or behind the station stopping the car. Most novice visitors of the park are familiar with such events occuring on Superman.

 

 

 

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That's a nice graphic, but it's completely wrong.

 

The LSM part is correctish. The electro-magnets behind and in front of the train push/pull big heavy permanent magnets on the train. The downsides are that, as mentioned above, the timing has to be very precise, and because you have to know exactly where the magnet on the train is, you can't have more than one magnet on a train. That's why most LIM rides are either a single car (Superman at SFMM) or use a sled to push the car (Rock'n'Roller Coaster).

 

In LIMs, the electromagnets pulse in a wave, turning on and off in series like chaser lights:

Conductive aluminum or copper plates on the train, through the magic of magnetic induction, try to keep up with this wave, accelerating the train to just under the speed that the wave is traveling. You don't really need to know where the train is, although most LIM launched rides closely monitor train position so that they can only put power to the electromagnets near the train and save electricity.

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Based on your post I can't seem to find a description where you've differentiated LIMs or LSMs much differently than I have (although I suppose that blinking light graphic is a nice touch). I'm also not sure when "correctish" became a technical term. It might also be fitting to notice you neglected to come up with a description most people would understand, or a source that proved the nice graphic I shared was, in fact, "completely wrong."

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That's a nice graphic, but it's completely wrong.

 

The LSM part is correctish. The electro-magnets behind and in front of the train push/pull big heavy permanent magnets on the train. The downsides are that, as mentioned above, the timing has to be very precise, and because you have to know exactly where the magnet on the train is, you can't have more than one magnet on a train. That's why most LIM rides are either a single car (Superman at SFMM) or use a sled to push the car (Rock'n'Roller Coaster).

 

In LIMs, the electromagnets pulse in a wave, turning on and off in series like chaser lights:

Conductive aluminum or copper plates on the train, through the magic of magnetic induction, try to keep up with this wave, accelerating the train to just under the speed that the wave is traveling. You don't really need to know where the train is, although most LIM launched rides closely monitor train position so that they can only put power to the electromagnets near the train and save electricity.

 

Yeah has always been my understanding... Also its pretty cool fact I just learned about Rock'n Roller Coaster.... I was wondering how they got LSM to work on that ride. Do you have any links that show this "sled" ... Does it work like a catch car but it has a permanent magnet on it?

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Based on your post I can't seem to find a description where you've differentiated LIMs or LSMs much differently than I have (although I suppose that blinking light graphic is a nice touch). I'm also not sure when "correctish" became a technical term. It might also be fitting to notice you neglected to come up with a description most people would understand, or a source that proved the nice graphic I shared was, in fact, "completely wrong."

 

My nomination for Doucheiest post of the month. But you may be able to argue that "Doucheiest" isn't a technical term.

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Douchy or not, I kind of agree that the explanation with the chaser lights wasn't very well explained. I didn't quite get the difference he was describing between LIM and LSM. The simple graphic made sense to me, but apparently that's all wrong. Bummer!

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That's a nice graphic, but it's completely wrong.

 

The LSM part is correctish. The electro-magnets behind and in front of the train push/pull big heavy permanent magnets on the train. The downsides are that, as mentioned above, the timing has to be very precise, and because you have to know exactly where the magnet on the train is, you can't have more than one magnet on a train. That's why most LIM rides are either a single car (Superman at SFMM) or use a sled to push the car (Rock'n'Roller Coaster).

 

In LIMs, the electromagnets pulse in a wave, turning on and off in series like chaser lights:

Conductive aluminum or copper plates on the train, through the magic of magnetic induction, try to keep up with this wave, accelerating the train to just under the speed that the wave is traveling. You don't really need to know where the train is, although most LIM launched rides closely monitor train position so that they can only put power to the electromagnets near the train and save electricity.

 

I understand this, but that "christmas light" graphic seems to work exactly like a LSM. Explain?

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Im guessing no one read what I wrote lol.

 

A linear motor is essentially a regular rotating motor laid out flat.

 

Some definitions

 

Stator - part that stays stationary

Rotor - part that moves

 

 

Both systems work on the push/pull concept. Induction motors require "slip" to produce torque, where the rotor moves at a different frequency than the stator. Sync, is the opposite, where the rotors moves at the same freq has the stator.

 

Ex: Household voltage is 60hz, meaning a sync motor would run at 60hz(this can be varying using other factors).

 

Note: They both are AC motors

 

Induction

-Requires Slip

-Stator is electromagnet

-Rotor becomes magnetized through eddy currents induced by the stator

 

 

Sync

-No slip

-Stator electromagnet

-rotor permanent magnet

 

 

Linearly they both work the same. Theres other technical advantages/disadvantages, but it would be hard to put it in layman terms lol.

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LIMs are more reliable than LSMs however not nearly as efficient because all stators are energized simultaneously regardless of vehicle position. LSMs are a lot more efficient as only the stators that are needed for vehicle movement are energized in synchronization with vehicle position.

However, LSMs are more prone to down time due to "drive trips/errors." (Synchronization issues)

 

^This.

Edited by DJeXeL
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Even with my degree in ME, I am completely confused and clueless at this point.

 

But I will say this blinking graphic is GREAT. I could look at this all night! It's so purty!

 

Attempting to get back on topic (anyone wanna ride bikes?), I'm curious to the difference in the system MACK uses on blue fire Megacoaster. Supposedly the energy absorbed at the final brakes is re-used. How much and do any of our US *magnet* coasters do that?

 

Anyone know how much it costs to fire a train on one of these mag-launch coasters? Hrm.. now my brain is spinning. I wonder how much a standard lift hill costs. Maybe new topic time. Or bed time. Or time to ride bikes

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I have actually thought of that approach for Superman. It would feel like a 1st generation freefall on steriods. However, the issue is they already have Lux Luthor. S:EFK is not an intense ride, but it is very "fun" to be able to look straight at the ground 400 feet in the air.

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