Perhaps the unpowered position is closed. But maybe it needs the air pressure to maintain the braking.
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"Looks like you've been missing quite a bit of work lately"
"Well, I wouldn't say I've been MISSING it, Bob."
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scoaster said:
The brakes on superman are magnetic, but in order for the brakes to work, they are pushed up against the track.
Regardless of the brake type (magnetic, clamp, etc.) the concept of using the pneumatic cylinders is still the same - the question is whether the cylinder was designed to fail the brakes in the "closed" position. You're right - but the type of brake makes no difference since you're extending and retracting a cylinder.
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Chaindog said:
The question remains - why did they fail in the disengaged, or "down" position?
That's the key question: the controls engineering should have failed the brakes in the closed position.
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thrustmachine said:
I think it's funny how you guys think you know everything!
No, we don't think so. Controls engineering is far from rocket science - but it does require extreme attention to detail. What Chaindog, Jeff, and I are pointing out is that it appears someone overlooked a small detail (i.e. failing a brake system in the "closed" position).
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I would think that the coaster designers (and not the parks) would design the controls systems for their rides. Am I wrong?
...watch the rocket science cracks...:)
jeremy
--who in one week and one day embarks in an intensive study of graduate "rocket science"..
Well, nothing was covered up. SFNE INVITED the Mass Dept of Public Safety to participate, which they did. The Mass DPS stated to the press that they were satisfied with both the investigation and the fixes.
I suspect not all of the exact details of the cause were released possibly by the press.
Remember that the press has an ability to confuse almost any story, so we have to be careful about following exactly what they say. Next time that I'm at SFA, I'm going to study the braking system on SROS there.
I disagree with the idea that controls design is not rocket science. The principals are the same on a roller coaster or the space shuttle, the shuttle just has a lot more systems. Modern redundant controls were actually first developed for use in chemical plants. NASA then copied what the chemical plants were starting to do. Now, the same people who make controls for roller coasters also do controls for chemical plants and other industrial facilities.
Several people above seem to be assuming that the brakes did not function at all. If that had been the case, there would have been much more serious injuries, probably fatalities. The trains would have been severely damaged and would not have been running this quickly. The brakes apparently slowed the train from 50 mph or so to the 20 mph crash speed.
*** This post was edited by Jim Fisher on 8/19/2001. ***
To the best of my knowledge most roller coasters with air operated bakes work on the same principal as heavy duty truck brakes(18 wheeler). Being a truck driver it is required that I know exactly how air brakes operate, and the accident COULD NOT happen exactly as the news report said if they work the same. All trucks built in the last 40 or 50 years have what are known as spring type air brakes. They use the air pressure to hold the brake spring in the open position, known as the emergency supply, and the primary supply applies the brakes. If the pressure in the primary system drops below a preset pressure(35 to 50 psi on most trucks) the system opens a valve and dumps the emergency air pressure releasing the spring and applying the brakes. Hope this helps in understanding air brakes, and I'm not 100 percent certain this is how roller coasters are set up.
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Just a couple of G-force junkies!
Isn't this an earlier version of the brakes? Also, what if SF cut corners a bit and opted for a modified version of the brakes used on MF. In either case, it's probably a sure bet that the brakes are different on MF in which case, you can't argue that the same of MF woudl apply to Superman.
How do you cut corners on a braking system? It's supplied by the designers of the ride, not the park.
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And then Jerry said, "Take care of yourselves, and each other".
I am very surprised that brakes (the single most important safety system on a coaster) don't have some sort of standard back-up. When the first system fails (in this instance, a computer would have recognized the lack of air pressure) another set of brakes would be applied. I DO recognize the additional expense, but what is the cost to SFNE in terms of lost revenue and consumer confidence? Just a thought...
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My first thought on reading about the crash was "What?? But those magnetic brakes are permanent, there is no way that could've happened." Now I know, the brakes are not in a fixed position & can close & open.
Now for a burning question; why doesn't Intamin leave the brakes closed permanently? Or is it because the train will slow down so much it will need a lot of energy to pull it out of the brakes?
It's pretty much their Giant Drop braking system on a horizontal level, except the other way 'round with the fins on the cars & the permanent magnets on the sides of the track.
Here's my take. The brakes opening is most likely controlled by by an spring open/ air close piston. This may sound incorrect by it's not. When the piston has air being applied to it, the rod sticking out of the end will be pulled into the cylinder thus opening the magnetic brakes. When the air pressure is removed the brakes most likely have an internal spring which forces the piston out of the cylinder and thus puts the brakes in the closed position. Therefore you ALWAYS need air to open the brakes. With no air they should be in a closed position. In addition I have not noticed anyone mentioning the large weight that is on the base of the brake. This weight will hold a brake shoe closed even if the cylinder fails. I know this because I witnessed a bracket on one of the cylinders at Darien Lake break. There was at that point nothing holding the brake closed other than the counter weight. What happend? The train came into the brakes, it stopped, all the other brakes opened. The train moved into the station and the brakes closed. The ride was then shut down while the braket was replaced and quickly reopened. No big deal. How this all relates to the accident. Something sounds odd as many of you have pointed out. If there is no air(due to a ruptured line) then the brakes should in no way have been able to open. If a piston bracket broke, then the brake would have been closed as I have pointed out. In addition if a air line would have ruptured you would most likely hear a loud hissing sound. I have never heard this mentioned anywhere. While I don't have all the deatils something definately sounds odd here.
What if a burst air tank caused an "explosion" that damaged something else?
OK, What the heck is up with you people? You gripe and complain that the government should not get involved with these things, that the industry can police itself. Then when they do police themselves you start screaming coverup??? What are you on? Must you constantly speculate? The state was on hand during the inspections, do you really think SFNE is capable of a coverup with the state involved when they aren't capable of keeping their new coaster plans out of the hands of coaster geeks? You people have watched way too many episodes of the X-Files. Why doesn't somebody just get in touch with Intamin and find out how the brakes really work instead of speculating and talking out of your ears as if you really know? But really make up your minds, do you or don't you trust the industry? If you are going to complain like this then the next time Markey or somebody else yells regulation you have no right to argue with them.
Yes, go Figaro!
All we should really care about is that the ride is up and running and they have fixed it to the best of their ability. This was a costly, almost tragic, and embarrasing event that no one wants to occur again.
Why not just assume that something has been gained that will benefit us all in the long run: additional knowledge for the park and Intamin and state inspectors. This must have been a learning experience for all of them
In the meantime, is it now just a one train operation? Anyone know?
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I totally would believe this because when I was a sfne a about a week before the accident and I heard a loud hissing and the air gates were opening really slow. This meant that there was a leak in that pipe so there could just a easily be a leak in the braking system.
phil, you're on the right track, so to speak, but you're all missing something important here.
I'm looking at a photograph of one of the Darien Lake brake calipers. There are clearly TWO air lines feeding the cylinder. One air line hooks to the top of the cylinder, the other goes to the bottom, and they are both hooked to the primary air supply through some kind of solenoid valve. What this means is that the cylinder is always full of compressed air. If the rod is extended (brake closed) then the air is below the piston and holds the brake closed. If the rod is retracted, the air is above the piston and holds the brake open.
I'm still trying to figure out this pneumatic circuit to see if I can figure out which line failed.........
--Dave Althoff, Jr.
Figaro: No one is shouting conspiracy, settle down. We're just trying to better understand
exactly what happened. That's what coaster geeks do.
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Jeff
Webmaster/Admin - CoasterBuzz.com
"From the global village... in the age of communication!"
Watch the grass grow: http://www.sillynonsense.com/subdivision/
Well when people start saying "cover up" it sounds a little foolish. I still don't understand why there has to be all this rampant speculation. Simply contact Intamin and find out how the breaks work.
Bottom line is the general public will never really know
What Dave Althoff is decribing is an air to open/air to close cylinder system. In this case, if the air to close air line fails, the brake won't function. This doesn't represent the usual method to design coaster brakes. I can imagine that this might be done if very high forces are required to operate the brake making a spring vs. air unit excessively large. Still, I want to get down to SFA and check out their brakes.
Dave, is the picture that you are looking at on the web?
