Mounting bracket failure caused Wild Thing brake to malfunction

Posted Friday, May 26, 2006 11:16 AM | Contributed by Timo

A mounting bracket supporting brakes on the track of Valleyfair's Wild Thing roller coaster malfunctioned Sunday, damaging two cars, including one that separated from the train, park officials said Thursday as an investigation continued. The accident, which sent 15 people to a hospital with minor injuries, happened as the roller coaster train was slowing to approach the ride station.

Read more from The Star Tribune.

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Friday, May 26, 2006 11:24 AM
Wow, that's a freakish kind of failure. Sounds like it could have been much worse too. Who knows, that could be from a bad weld made ten years ago.
Friday, May 26, 2006 11:35 AM
Freakier is that there was a trouble light twice the day before. But its not like it was ignored, they just couldn't find the problem. I'm wondering if because of the broken bracket, it caused the fin to slam into the caliper instead of gliding through it. That could have caused more stuff to happen.

I'm kinda hoping they'll have it back up by June 6th. I'm going to be in St. Paul for 3 days on business and am planning to head out there one evening.

Friday, May 26, 2006 11:58 AM
Freaky indeed as you usually expect mechanical problems with the trains or computer related control failure but not structural problems of this sort to be responsible for most well as the occasional rider who willfully disobeys safety warnings.

Obviously they were getting warnings from the PLC about the brakes which shut the ride down automatically but when no source of the problem mechanically could be located they must've suspected a faulty proxy switch & simply reset the apparently didn't occur that there could've been a misalignment of the brake caliper that was causing the PLC to shut down the ride.The PLC can detect problems witthin the system,unfortunately it can't diagnos what the precise cause of the problem is.

Friday, May 26, 2006 12:55 PM
I'm thinking that because the ride was stopped twice the day before people may want to throw a suit out there because they had a 'clue'
Friday, May 26, 2006 2:17 PM
I have never operated a coaster before, but, it is my understanding that the 'trouble' light goes off whenever the computer stops the ride for ANY reason. The trouble light could have gone off for many, many reasons, but I DON'T think the trouble light could have gone off because the computer had sensed an imminent brake bracket failure. It's not possible. I don't believe the brackets that support the brakes have sensors, as I don't see how you could construct something to sense that possible problem.*** This post was edited by SVLFever 5/26/2006 2:33:43 PM ***
Friday, May 26, 2006 2:52 PM
Although I'm completely ignorant about such matters, it seems to me that this could have been almost unavoidable. (As opposed to accidents that could have clearly been avoided by better upkeep....several past Disney incidents come to mind) Thankfully it was a rather minor incident and no one was seriously hurt. Even the best parks with the best upkeep have accidents, that's just the price of having something built, operated, and maintained by humans.
Friday, May 26, 2006 3:02 PM
I don't think the computer could catch such a thing. That's like TTD's computer saying the cable is going to break.

The computer stoping a ride is a normal thing.

Friday, May 26, 2006 5:34 PM
Agreed. The ride stopping twice the day before is most likely completely unrelated. Leave it to the newspaper to pick up on that though! :) I expected to hear there was something wrong with the train - either a substandard part used in the axle or hitch or someone not putting it back together correctly. I never expected to hear that a mounting bracket caused it.
Friday, May 26, 2006 10:01 PM
Wow, that's really strange. A person would think that there would some kind of fault protection in place for different structural problems. I havn't seen the movie "Rollercoaster" for years, but didn't they detect the bomb thru the PPLC? I could be wrong but it seems like I remember something like that.
Friday, May 26, 2006 11:43 PM
Batwing, please try not to chime in when you obviously know nothing about the subject. If a PLC detects a specific problem within a ride, it will certainly display what the exact fault is.
Friday, May 26, 2006 11:55 PM
Yeah, the faulting means absolutely nothing. Most rides will fault even for things as simple as a button being held down for too long, or a bird landing on a sensor.
Saturday, May 27, 2006 2:38 AM
What kind of information you get back from the ride varies from ride to ride. On some rides, all the operator gets is a red light marked "FAULT". All the operator knows is that the ride is unhappy. Maintenance can then come through and get a fault code, but all the code will really tell you is why the computer thinks it is unhappy...typically some input out of range or unexpected.

In the case of a structural fault, the computer is unlikely to detect anything because every weld on the ride is not monitored. Even if the ride had a pressurized rail system on it to detect cracks in the structure, this failure would not have been detected by that method because the Morgan track ties are solid plate steel, and the mounting brackets are probably welded to the steel plate. There is quite simply nothing to detect.

--Dave Althoff, Jr.

Saturday, May 27, 2006 6:18 AM
fault lights mean very little other than "we have a fault light at the so and so". If the PLC has a preprogrammed ladder logic and a code for that particular error, hell yeah we know exactly what to look for. However, many times you will get a fault light with no code, or the the ride will break fault light! *** This post was edited by mr_darkmatter 5/27/2006 6:47:00 AM ***
Saturday, May 27, 2006 7:47 PM
Space Mountain at Disneyland Paris has a very advanced system. The control tower and maintenance office got a computer screen that shows everything happening during the ride. If for example, the ride is having a malfunctioning trim brake, the ride will stop and show the message "trim brake xxx is not closing correctly". Across the park, the Temple of Peril coaster originally came with the system Dave described. The computer give a code for maintenance to interpret. In 2000, they upgraded it to the same system as Space Mountain. Would something like that helped in this situation?
Saturday, May 27, 2006 8:44 PM
No, because there are no active sensors monitoring every weld on the structure, and it wouldn't be practical to do so. This really is one of those very rare things that I don't think anyone would have ordinarily found, but I suspect from now on they'll do a visual check of the welds where the mounting brackets attach to the track.
Tuesday, May 30, 2006 12:16 AM
To my knowledge, there are no strain or stress gauges on coaster structures prediciting when a support or bracket will fail. This can be done, but it really isn't practical. The best method as Jeff mentioned would be to utilize a visual check. This approach is used by many parks.

When a coaster shows a fault, if the ride has a panelview, it will show a fault code. This fault code can be back tracked in the PLC program (usually Controllogix or RSlogix) and the sensor identifying the fault can be located. This will then show if the issue is a mechanical (train placement for example) or a electrical issue (bad drive, bad prox or cable for example). Once the sensor detecting the 'non-normal' situation has been found, the issue can be addressed. A bracket failue would never have been predicted by anything in the program. The only way to prevent it would have been with visual checks.

*** This post was edited by Jon Smith 5/30/2006 12:17:47 AM ***

Wednesday, May 31, 2006 5:50 PM
Knowning only a little about metal fatigue from my days as a Battlebots competitor I would agree that there is practically no way that you could engineer some kind of system to monitor general metal fatigue or "This peice is going to break RIGHT NOW" in real time.

There are ways to detect metal fatigue, and I would expect that it might be possible that in the future, during a routine maintanance check, if no other obvious signs are found, they might scan for it on "high use" areas of the ride such as the break runs or lift / launch areas...

Don't know though... it might not be that practical. As many have stated, this really was just a freak accident and thank goodness no one was seriously hurt.



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