Magnetic Brake Question

I'm having trouble understanding how the brakes work on MF, and I'm hoping you guys can help.

From what I know so far, they're failsafe magnetic brakes. I'm reasonably sure that they don't take any power to run, or anything like that. Am I right so far?

If so, then how do they stop the trains? I have a reasonable understanding of physics, but this escapes me. Each train weighs 26 tons (prez. of Intamim said so at CoasterMania at CP), and I'm going to assume that coming off the last turn and into the brakes, the train is going 60 MPH (which is probably low - anybody know for sure?) So we've got 26 tons going 60 MPH - and it gets stopped by those magnets and the fins on the cars? I dunno. I've never heard of any metal or alloy with *that* much magnetic force in it.

So, in my logic, if the magnets don't take any power, they're too weak to stop the train, but they're supposed to be failsafe and not require external power, which means they're not electromagnets or LIMs, etc.

So how do they work?

I'm probably missing some important piece of info, or my facts are wrong, but that's why I'm trying to clear it up! :-)

Thanks GTTPers.

-Ken

*** This post was edited by Ken Kogler on 8/18/2001. ***

You're right, the brakes are just rare earth magnets which use no power whatsoever.  This will help.

http://www.guidetothepoint.com/thepoint/cpplace/thread.asp?ForumID=2&TopicID=3490

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Dream viewspot at CP: The middle support on the first turn on Millennium Force.

OK, so that helps a bit: the brakes are just plain on magnets.

But we've still got a 26 ton mass going 60 MPH, that brakes in a very smooth way in a very short amount of track. Is the amount of magnetic metal in each brake different? (That is, proportional to the speed of the train when it passes through it? Stronger magnets at the entrance to the brake run, etc...)

I still don't get how they stop the train with a souped-up version of a refrigerator manget. Anybody know what metal is used? I'd love to look in up in a geology book somewhere.

-K

The metal is most likely steel. The magnet is probably something far rarer.

What it does is set up an inductance between the fin and the magnets. If you induce a field, you can propel a metal mass. You can also use a propelled metal mass (the train) to induce a field. This will bleed off the speed, at a rate proportional to the current speed, right?

If so, I believe, the effect would be roughly similar to something like really high air resistance.

You can generate a magnetic field by using really insanely fast motion (electricity through a copper wire loop, etc)

Could the fins on the train be generating some kind of static electricity as they pass through? I'm trying to figure out how the train would induce that field.

Any idea what that rare-earth element is? I bet it costs a whole ton of money per ounce! :-)

Could they find a way to make the train go up a lift hill using non-electric magnets?
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2001 MF Count: 0
Favs:
1. Iron Dragon
2. Raptor
3. Gemini
4. Magnum
5. Demon Drop
I would assume so, since magnetic poles with like charges repel charges.

But again, 26 tons worth of train - it takes a biga$$ magnet to get that to get it moving, then go *up* a big hill.

I'd hate to be the engineer tasked to that one! :-)

-K

I didn't think that a MF train was 26 tons, i didn't even think it was 1 ton
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2001 MF Count: 0
Favs:
1. Iron Dragon
2. Raptor
3. Gemini
4. Magnum
5. Demon Drop
http://capital2.capital.edu/admin-staff/dalthoff/adventures/tr2001/coastermania.html

It's halfway through the Q & A with Sandor Kernacs, president of Intamin. And he says a train is 28 tons, not 26 like I thought.

It's a big ol' page of text, so run a search on "28 tons" and it should come right up.

It *does* sound like a lot of mass, but I'm not gonna argue with Mr. Kernacs. :-)

-K

It's true, one car weighs 3 1/3 tons!!
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Dream viewspot at CP: The middle support on the first turn on Millennium Force.
Thats one heavy train! I never would've guessed that. But that 28 ton train going at 60 MPH doesn't stop, it only slows down to... uhh... a significantly slower speed.
Probably won't help the equation much, but it's a small reminder.
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http://coolforce.cjb.net -{Where The Cool Stuff Goes 93MPH}-
'OMG Tommy you're obsessed!'
The brakes are all magnetic no power what so ever.
I belive that the speed of the train entering the brakes after the over-banked turn has been clocked at 55 mph(which is on the high end, I saw trains several times going really slow around the last turn).They use rare earth magnetics that are very powerful.

And when the train comes off the "slow down or speed run off brakes" and enters the brake run its going I say... under 10 mph per hour.

The brakes on the brake run before unload can move. When a train comes into the brake run the brakes are up to slow down a train and bring it to a stop. Kicker wheels hold the train in place until unload is clear. When unload is clear the brakes on the brake run move away(at an angle) from the train and the kicker wheels move the train forward.

RideMan should be able to give you some more details...

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Andrew Hyde
http://www.experiencethepoint.com
Author- Experience The Point: The Unofficial Guidebook To Cedar Point

The train comes into the brakes at roughly 65 mph.
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Dream viewspot at CP: The middle support on the first turn on Millennium Force.
Magnetic brakes like those on MF that slow a train down work because some strong magnetic field devlops between the brake fins on the trains and the brakes themselves. Its almos like they attract each other.

Superman: The Escape at SFMM uses magnetics to both propel and slow the train. The magnets along the track on S:TE attract the magnets on the train and then repel them to give you that acceleration.

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Brian Z.
Assistant Webmaster
Kennywood Park Unlimited
www.kpunlimited.com

This is what I know about the brakes and trains:

The brakes are magnetic. They use rare earth magnets (unsure about the element). They require no power, I have heard the train maintaining a speed of 65 mph when it reaches the brakes.

Either Intamin or Cedar Point waaaay underestimated the weight of these trains. Cedar Point announced that each train would weigh 19 tons...somebody was off by 9 tons. The first car weighs significantly more than the others because it has a whole other wheel assebly...and is longer. By my math, I'd say that the first car is roughly 4 tons, with the rest around 3 tons each.

And I remember that Rideman said that the magnetic brakes slow the trains to half its speed with every set it passes through.....Wow! That's a lot! :)

And I'm very intrigued that Rideman has yet to chime in...

I hope that helped...

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MF count: 20

I'd say a fully loaded train, especially the front end comes into the retractable's going a little more than 10 MPH. In any event, such as a power outage, hydraulic pressure loss, etc., the retractable brakes just outside unload should lock into the close position, or it least if I was an Intamin engineer that's what I would make them do. :).

Even if those fail, they have the kicker wheels to stop the train. Then its only a matter if the wheel is in good working order and its not terribly wet out. Hopefully the wheel would stop the train.

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2001 Force Laps -120 
2001 Magnum Laps-249
6/11/01 Gemini Laps- 100

Hmm. Interesting. I'm not so much concerned with the retractables and wheels. I'm more concerned with how the train slows down to the 10 MPH.

I'll have to check with the Physics prof on campus here, but it seems like what we've decided is that the train's fins passing through the magnets (and the like charges repelling eachother) is enough to stop a 28 ton mass going 65 MPH.

Cool.

CP_Bound is attributing comments to me that I never made...I don't think I ever commented on the efficiency of the magnetic brakes. But consider this...

The train is nine cars long. Each car has two fins. The fins are about 6' long and about 12" wide. So on each side of the train we have about 54 square feet of brake fin; that's 108 square feet (or linear feet if you prefer, since it's about a 12" fin) of braking surface, which comes into contact with each and every magnet.

When you pass a conductor through a magnetic field, you induce an electric current in the conductor. Because that conductor is effectively wired into a short circuit, it can sink a whole lot of current, converting the mechanical energy into electrical energy which generates a magnetic field which heats the fin. The magnets are very powerful, but don't have to be as powerful as you might expect because they are quite long and are interacting with a fin that is even longer.

There isn't much detail, but you can learn a little more about magnetic brakes from another company that makes them: http://www.magnetarcorp.com .

--Dave Althoff, Jr.

Dave, your S:ROS brake failure article (http://capital2.capital.edu/admin-staff/dalthoff/sros.html) was very helpful in understanding these brakes.

I now understand these brakes about as well as I can without majoring in Physics! One thing remains unclear, though - how do the brake calipers move away from the fins? It seems like the caliper would slide horizontally away from the train (both going towards the outside of the track). Is that right?

-Ken

I swore I read that over at Coasterbuzz with you being the poster...but maybe it was someone else...

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MF count: 20

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