Why do coasters stall?

Tuesday, January 16, 2001 7:39 PM
I don't understand how a coaster can just stall in mid loop or anything! Only thing is a brake run. I don't get it. Don't caosters run on momentum? How can they just stop if gravity would pull them right back were the came from and in a comfortanble possition to be rescued!
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Tuesday, January 16, 2001 8:12 PM
Things break... literally. The accident on Great America's Demon was caused by a wheel assembly that broke clean off, if I remember correctly.

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Matt Lynch
Co-Webmaster, Kennywood Boulevard
http://kennywood.coasterbuzz.com
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Wednesday, January 17, 2001 12:37 AM
Let Rideman explain this one, but on the demon, if you look at the wheel assembly, there is a mid point where the axles are held. somehow, something came loose and the whole right side fell off. If you look now, there is a new cap to give it extra strength. Many Arrows were updated with this in 1998, except Steel Phantom, strange enough.

There have been other cases of coasters having a wheel lock and cause the ride to stall. On a side note, one of the main familys interviewed in the Demon case had some physical problems, including a heart condition, and he mentioned it on air. Now, there is a sign warning you not to ride if you have these problems.... I wonder if the park could have counter-sued them had he died. I doubt it.
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Wednesday, January 17, 2001 7:18 AM
Todd...most stalls in odd places are in the trough of a cobra roll...thus they're high above the ground, but not inverted. The people at either end of the train aren't too comfy. However, a train can stall in a loop if the wheels break and lodge on the track, preventing any forward motion...if the center of mass is beyond the top, and the wheels are jamming the train, it'll stay stuck.

Jman
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Wednesday, January 17, 2001 11:06 AM
Okay, since john peck begged for it, I'll explain... :)

On the Demon, or any of the other Arrow looping coaster trains, the front of each car is attached to the axle with a two-axis coupler which allows the car nose to pitch or yaw relative to the axle. Two steel bands wrap around the axle, and are attached to the front end of the car chassis; that way, if the two-axis coupler fails, the train stays hooked together.

The axle (except for the front axle) has a pin which extends out of the forward end of the axle, and fits into a roll pivot bearing at the back of the car ahead. The end of this pin is threaded, and to assemble the car, the pin fits into the pivot bearing, and is then secured with a castle nut and a cotter key. If you stand at the back of the station platform, you can see this nut through an opening in the sides of the rectangular box-beam just ahead of the last axle.

The last axle on the train, of course, lacks the 2-axis pivot because there is no car attached to the top of it; it is itself only attached to the last car using the roll pivot arrangement previously described. At the time of the Demon incident, that axle also lacked any backup safety means. If the cotter key were left out, the castle nut could rotate and fall off, releasing the axle assembly from the last car. Upon final separation, the back end of the last car, which is normally suspended on the roll pivot pin, will drop, and may come into contact with the track ties on the track. The sliding action acts like a giant skid brake, which, in the case of the Demon removed enough energy from the train that it couldn't complete the loop. Because the train's center of gravity didn't pass the high point of the loop, it rolled backward out of the loop, but instead of clearing the loop as it normally would, the back end of the car...being detached from its axle...lodged between the rails and we最攀搀 愀最愀椀渀猀琀 愀 琀爀愀挀欀ⴀ琀椀攀Ⰰ 瀀爀攀瘀攀渀琀椀渀最 琀栀攀 琀爀愀椀渀 昀爀漀洀 最漀椀渀最 戀愀挀欀眀愀爀搀猀⸀ 㰀戀爀㸀 㰀戀爀㸀吀栀椀猀 椀猀 眀栀礀 椀琀 眀愀猀 椀洀瀀漀爀琀愀渀琀 琀栀愀琀 琀栀攀礀 猀攀挀甀爀攀 琀栀攀 琀爀愀椀渀 琀漀 琀栀攀 琀爀愀挀欀 戀攀昀漀爀攀 爀攀洀漀瘀椀渀最 爀椀搀攀爀猀⸀  䤀昀 琀栀攀礀 爀攀洀漀瘀攀搀 眀攀椀最栀琀 昀爀漀洀 琀栀攀 戀愀挀欀 漀昀 琀栀攀 琀爀愀椀渀Ⰰ 椀琀 眀漀甀氀搀 猀栀椀昀琀 琀栀攀 琀爀愀椀渀✀猀 挀攀渀琀攀爀 漀昀 最爀愀瘀椀琀礀 昀漀爀眀愀爀搀Ⰰ 愀氀氀漀眀椀渀最 琀栀攀 琀爀愀椀渀 琀漀 昀椀渀椀猀栀 最漀椀渀最 琀栀爀漀甀最栀 琀栀攀 氀漀漀瀀⸀  吀栀攀 昀爀椀最栀琀攀渀椀渀最 戀椀琀 椀猀 琀栀愀琀 椀昀 琀栀愀琀 眀攀爀攀 琀漀 栀愀瀀瀀攀渀Ⰰ 琀栀攀 氀愀猀琀 挀愀爀 挀漀甀氀搀 攀愀猀椀氀礀 搀攀爀愀椀氀 最漀椀渀最 琀栀爀漀甀最栀 琀栀攀 琀漀瀀 漀昀 琀栀攀 氀漀漀瀀Ⰰ 愀渀搀 琀栀愀琀 挀漀甀氀搀 最攀琀 爀攀愀氀氀礀 洀攀猀猀礀⸀ 㰀戀爀㸀 㰀戀爀㸀㰀戀㸀䄀猀 琀漀 琀栀攀 漀爀椀最椀渀愀氀 焀甀攀猀琀椀漀渀Ⰰ 㰀椀㸀圀栀礀 搀漀 挀漀愀猀琀攀爀猀 猀琀愀氀氀㼀㰀⼀椀㸀⸀⸀⸀㰀⼀戀㸀 㰀戀爀㸀吀栀攀 猀椀洀瀀氀攀 愀渀猀眀攀爀 椀猀 琀栀愀琀 昀漀爀 眀栀愀琀攀瘀攀爀 爀攀愀猀漀渀 琀栀攀礀 猀椀洀瀀氀礀 搀漀渀✀琀 栀愀瘀攀 攀渀漀甀最栀 攀渀攀爀最礀⸀  吀栀攀 氀愀甀渀挀栀 眀愀猀渀✀琀 昀愀猀琀 攀渀漀甀最栀⸀  吀栀攀 最爀攀愀猀攀 椀渀 琀栀攀 眀栀攀攀氀 戀攀愀爀椀渀最猀 椀猀 琀漀漀 琀椀最栀琀⸀  䤀琀✀猀 琀漀漀 挀漀氀搀⸀  吀栀攀 琀爀愀椀渀 椀猀渀✀琀 栀攀愀瘀礀 攀渀漀甀最栀⸀  䤀琀✀猀 琀漀漀 眀椀渀搀礀⸀  䄀 眀栀攀攀氀 栀愀猀 猀攀椀稀攀搀 甀瀀⸀  匀漀洀攀琀栀椀渀最 栀愀猀 樀愀洀洀攀搀 愀 爀漀愀搀 眀栀攀攀氀⸀  吀栀攀 琀爀椀洀猀 愀爀攀 琀漀漀 琀椀最栀琀⸀  吀栀攀 栀椀氀氀 椀猀 琀漀漀 栀椀最栀⸀  䄀 挀漀洀洀漀渀 挀愀甀猀攀 漀渀 琀栀攀 㰀椀㸀䈀漀漀洀攀爀愀渀最㰀⼀椀㸀 挀漀愀猀琀攀爀猀 椀猀 琀栀愀琀 琀栀攀 戀爀愀欀攀猀 攀渀最愀最攀 愀猀 琀栀攀 琀爀愀椀渀 最漀攀猀 戀愀挀欀眀愀爀搀 琀栀爀漀甀最栀 琀栀攀 猀琀愀琀椀漀渀 戀甀琀 搀甀攀 琀漀 猀眀椀琀挀栀 昀愀椀氀甀爀攀 搀漀渀✀琀 挀愀琀挀栀 眀栀攀渀 椀琀 挀漀洀攀猀 昀漀爀眀愀爀搀 愀最愀椀渀Ⰰ 猀漀 琀栀攀 琀爀愀椀渀 栀愀猀 攀渀漀甀最栀 攀渀攀爀最礀 琀漀 挀漀洀瀀氀攀琀攀 琀栀攀 昀椀爀猀琀 椀渀瘀攀爀猀椀漀渀Ⰰ 戀甀琀 渀漀琀 琀栀攀 猀攀挀漀渀搀Ⰰ 爀攀猀甀氀琀椀渀最 椀渀 愀 猀琀愀氀氀 戀攀琀眀攀攀渀 琀栀攀 琀眀漀 匀椀搀攀眀椀渀搀攀爀 椀渀瘀攀爀猀椀漀渀猀⸀  伀爀Ⰰ 琀栀攀 挀漀愀猀琀攀爀 猀琀愀氀氀猀 漀甀琀 戀攀挀愀甀猀攀 琀栀攀 琀爀愀椀渀 昀愀氀氀猀 愀瀀愀爀琀 愀渀搀 猀琀愀爀琀猀 搀爀愀最最椀渀最 愀最愀椀渀猀琀 琀栀攀 琀爀愀挀欀⸀  㰀椀洀最 猀爀挀㴀∀⼀昀漀爀甀洀猀⼀椀洀愀最攀猀⼀猀洀椀氀攀⸀最椀昀∀ 戀漀爀搀攀爀㴀∀ ∀㸀 㰀戀爀㸀 㰀戀爀㸀ⴀⴀ䐀愀瘀攀 䄀氀琀栀漀昀昀Ⰰ 䨀爀⸀
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Wednesday, January 17, 2001 11:48 AM
Wow, Rideman, you are a genius!

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Coasters...the best natural buzz available.
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Wednesday, January 17, 2001 12:01 PM
Well, you must remember, this is what Dave does for a living (more or less). Where it is just a hobby for almost all the rest of us.

For Dave it's not just an adventure, it's a job!

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"X" marks the spot in 2001!

P.S. What happened to your signaure Dave? It was starting to look nice.
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Wednesday, January 17, 2001 1:32 PM
This message is entirely off-topic.
(sigh)
Soggy, I need to dispel a rumor here...

What I do for a living is to support University professors who have A/V requirements for teaching their classes. My background is in communication, and I used to be a recording engineer at a radio station. Perhaps someday I'll put my bio up on my web site (http://captial2.capital.edu/admin-staff/dalthoff)

While I do study amusement rides in great detail, and while I do have a NAARSO inspector certification, my 'day job' has nothing at all (unfortunately) to do with parks or rides.

I've been clipping the signature because for some reason the thing was still coming out in a proportional font, and the crane wasn't lining up right...

--Dave Althoff, Jr.
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Wednesday, January 17, 2001 1:40 PM
Thanks Dave, that was what I wanted to hear... all except the job part! :)
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Wednesday, January 17, 2001 6:28 PM
Sorry Dave, I guess I was misinformed. (once again) I knew you were a certified inspector, I thought that is what you did to pay the bills.

No hard feelings?

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"X" marks the spot in 2001!
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Wednesday, January 17, 2001 6:51 PM
Of course not! It's just that I want to be careful not to misrepresent myself here. The obvious corollary is that there are folks out there who do know this stuff better than I do... :)

(Heck, I wish I was paying the bills dealing with amusement rides one way or another...!)

--Dave Althoff, Jr.
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Wednesday, January 17, 2001 7:59 PM
Did not this also happen on a looper over in England? I thought I remember seeing something about that.

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Joe
Beyond Post, Giga Post
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Saturday, January 20, 2001 8:14 AM
thanks everyone!
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Saturday, January 20, 2001 10:14 AM

Joe E. said:
"Did not this also happen on a looper over in England? I thought I remember seeing something about that.



Actually in Belgium, if you'll pardon my language. :) The situation was different, though...it was a Schwarzkopf launched shuttle loop, and I believe what happened is that it launched slow, and the pusher-plate on the back of the train got hung up on a track tie. Since the train didn't derail or anything like that, the park pulled the train through the loop and unloaded it in the valley between the loop and the spike. My understanding is that there were no injuries, and they didn't lose anybody. That train does not have shoulder bars.

The park was not at that time, but is now a Six Flags park.

--Dave Althoff, Jr.
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Sunday, January 21, 2001 6:54 AM
That always bothers me when there is a looping coaster w/o a shoulder harness. When something like described above would happen, someone could fall out.

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...But that's just my opinion. Unless it's also someone else's.
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Sunday, January 21, 2001 11:26 AM
Funny...the fact that a looper without shoulder bars stalled in an inverted position, loaded with riders, and nobody got hurt seems to me a pretty good argument for why shoulder bars are NOT necessary...!

--Dave Althoff, Jr.
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