Stalling Intamin "Top Hat" Coasters

Friday, April 18, 2008 11:48 AM
Kinetic friction--sliding friction--is not the only type of friction. When you slam on your breaks in an old car(which doesn't have anti lock brakes) the wheels lock up and slide. This is kinetic friction. The other type of friction is static friction--non sliding friction. This is why anti lock brakes where invented. The coefficient of static friction is greater than the coefficient of kinetic friction. So, instead of locking up the wheels to your car, you instead apply an impulse of force on the brakes(controlled by a computer) that causes the brakes to not slide. This creates static friction, which is why anti lock brakes can stop your car faster than locking up the wheels. The frictional force is greater because it is static friction. Now, roller coaster trains roll on their wheel assemblies on the track. The coefficient of friction between the wheels and track is static. Anytime a wheel is involved, you can safely say the friction force is static unless you know that the wheels are sliding, and not rolling (ie a car on ice). So I never suggested a roller coaster is void of friction. What I am saying is there is a difference between "rolling" and "sliding." While there might be "minute" shuffling that you could consider sliding, the majority is static friction.
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Friday, April 18, 2008 12:40 PM
Basically, all I was saying is that it's going to take a great amount of effort to get the train rolling, but once it is, it should have no problem continuing to roll as you've "broken" the static friction.
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Friday, April 18, 2008 1:29 PM
That is very correct. Once you reach the greater than or equal to part of the static friction inequality, the frictional force is quite less. I guess I misunderstood your statement.
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Friday, April 18, 2008 3:12 PM
And besides there is kinetic friction in the wheel bearings.
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Sunday, April 20, 2008 8:35 PM
Easy solution, have a set of friction motors at the top of the tophat that can move into position under the train and gently nudge the coaster in the right direction...
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Friday, April 25, 2008 12:01 AM
Here's a related link I saw today. Apparently this is how you climb, then jump from the top of an Top hat.

http://www.youtube.com/watch?v=k5dfQxjShvQ

Does this indicate that the only way to get to the top is to climb?

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Friday, April 25, 2008 7:36 AM
Cool, but dangerous. I'd like to see tjem try that with TTD or Kingda Ka.
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Friday, April 25, 2008 8:24 AM
^^I was wondering the exact same thing when I first saw that BASE-jumping video. We know from experience how they get TTD retrieved when stalled in the tophat....but Stealth apparently has no such means of getting to the top? If so, that's really poor planning - no ride op I know is climbing that tower, LOL... :)
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Friday, April 25, 2008 1:17 PM
Since both KK and TTD both have LIM's to stop the train in the case of a fall back, why not have 1 or 2 LIM's at the tophat for when the train balances?

Also, when looking at the the basic principle of wheel bearings, there is no kinetic friction. The balls or rollers in the bearing act just like wheels, and therefore static friction within the bearing assembly. There will be minor kinetic friction between the bearing balls or rollers and the grease in the bearings. but thats about it.

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Friday, April 25, 2008 1:37 PM
They don't have LIM's, they have magnetic brakes. Totally passive. KK already has a set of magnetic brakes on the top of the top hat but obviously this won't affect a stalled train (again, passive not active).

However, the additional cost to run any sort of control and power line as well as the cost of the extra motors themselves (be they LIM or tire drive) for the top hat for the 1 in a million chance of a train stall can't be worth it.

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Friday, April 25, 2008 3:18 PM
Simple.

If there's guests on board, just yell to them on the loudspeaker to lean forward,

or fart simultaniously.

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Friday, April 25, 2008 8:47 PM
^In the UK, they'd form a "coalition of the leaning" to get down from the tophat, forward or backward. In the US, you'd have a 50-50 division that couldn't get resolved, so the train would just sit there.

Our (stalled) government sucks... :)

*** Edited 4/26/2008 12:48:20 AM UTC by rollergator***

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Monday, April 28, 2008 12:26 PM

ApolloAndy said:
They don't have LIM's, they have magnetic brakes. Totally passive. KK already has a set of magnetic brakes on the top of the top hat but obviously this won't affect a stalled train (again, passive not active).

However, the additional cost to run any sort of control and power line as well as the cost of the extra motors themselves (be they LIM or tire drive) for the top hat for the 1 in a million chance of a train stall can't be worth it.


I must not have a full understanding of LIM's vs. Magnetic brakes. If the train falls back, the brakes on the lauching straightaway provide a forward force to stop the train. How does that work differently than and LIM which provides a forward force to launch the train? How can one be passive and the other be active when they are both accelerating the train in the same direction.

I cant imagine that the cost of 1 small motor (whether it be a mechanical device or a magnetic device), running a wire or 2, and and extra control or 2 on the control panel would cost more than the entire elevator system they put in so a guy could ride up and push the car with his hands. Not to mention the risk involved with that if the guy ever fell. *** Edited 4/28/2008 4:28:15 PM UTC by SpiketheVB23***

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