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#10023 - 03/10/14 05:16 AM
Scenario based technical question
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Joined: Mar 2014
Posts: 13
driver
stranger
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stranger
Joined: Mar 2014
Posts: 13
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Hi everyone... I was surfing the internet hi and low, but was unable to find any answers for my question, so I was hoping that some of you guys would be able to answer this for me. I apologize in advance, if this is the wrong forum and moderators please feel free to move this post to where you think it belongs. I don't know much about elevators, so try to avoid getting too technical if possible...:)
I always wondered if the following sequence is possible, or if such occurrence was ever recorded? I do know, that there are records of all of these events happening separately, but never in one shot...
I'm going to suggest a following scenario and I would like to know, if something like this would be possible under certain circumstances?
Suppose that one person steps onto a traction elevator at the ground floor and at the same time, there is some sort of a catastrophic malfunction, in which the brake mechanism/gearbox or any form of mechanical resistance fails. Assuming, that the counterweight is heavier than the one person + the elevator car, could the following happen:
The elevator starts ascending towards the top of the shaft and it is gaining speed...for the sake of argument let's assume this is a tall building, so it has time to build up quite the momentum. By the time it reaches the top of the shaft, it crashes with so much force, that the ropes will somehow separate from the cab and the emergency braking mechanism (which from my limited understanding is located on the top of the car) is now too damaged to deploy properly. So now the elevator car is plunging to the bottom of the shaft at free fall. The car hits the bottom pit and the ceiling of the shaft gives away moments later due to the structural failure sustained by the car running into it, so now all of the elevator machinery along with chunks of concrete come crashing down on top of the car...
Would this be possible? What would all have to go wrong for something like this to happen all in one sequence? Thank you for any reply's.
Last edited by driver; 03/10/14 05:31 AM.
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#10025 - 03/10/14 09:10 AM
Re: Scenario based technical question
[Re: Johnny]
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Joined: Feb 2012
Posts: 3
pkl125
stranger
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stranger
Joined: Feb 2012
Posts: 3
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#10031 - 03/10/14 04:53 PM
Re: Scenario based technical question
[Re: pkl125]
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Joined: Mar 2014
Posts: 13
driver
stranger
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stranger
Joined: Mar 2014
Posts: 13
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Thanks for your reply Johny.... The reason I thought this would be possible is, that I have stumbled across a documented case on the internet a while ago, in which the elevator at some sort of a textile factory in the US took a plunge and the machinery has followed shortly after...I will do my best to try and find that news article and will post a link.
The reason I personally thought that the machinery falling through the ceiling wasn't so far fetched is the fact, that just like any other structure, the ceiling of the shaft is not immune to being damaged... Being that there is so much weight sitting directly on top of it means, that it already has some stress load on it to begin with... I have no idea what the weight of the elevator car is, but I don't think it is too light to cause damage, especially if it has sufficient time to build up the upwards momentum. I'm pretty sure that the mass X velocity of the car and the strength of the ceiling shaft could be brought to light through some sort of a calculation, which I'm unable to perform... I will do my best to find you that link about this case..
Last edited by driver; 03/10/14 04:58 PM.
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#10032 - 03/10/14 04:56 PM
Re: Scenario based technical question
[Re: driver]
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Joined: Mar 2014
Posts: 13
driver
stranger
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stranger
Joined: Mar 2014
Posts: 13
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pk125...Yes I'm aware of the barrel of bricks urban legend. I think it was on Mythbusters when they put it through the test and found out that it was feasible, as they were able to replicate this sequence as described in the legend...:)
Last edited by driver; 03/10/14 04:59 PM.
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#10033 - 03/10/14 05:13 PM
Re: Scenario based technical question
[Re: driver]
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Joined: Mar 2014
Posts: 13
driver
stranger
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stranger
Joined: Mar 2014
Posts: 13
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Ok...I was able to find the link for the machinery crashing down on the car. I could not find a separate link, so this link gives you a list of 10 elevator accidents, all in one article... This one is at number 9 and it is listed as "American Woolen Company" http://listverse.com/2011/12/23/10-tragic-elevator-accidents/
Last edited by driver; 03/10/14 05:16 PM.
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#10034 - 03/10/14 05:17 PM
Re: Scenario based technical question
[Re: driver]
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Joined: Jun 2013
Posts: 72
Postal
journeyman
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journeyman
Joined: Jun 2013
Posts: 72
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#10045 - 03/11/14 02:22 AM
Re: Scenario based technical question
[Re: sbrmilitia]
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Joined: Mar 2014
Posts: 13
driver
stranger
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stranger
Joined: Mar 2014
Posts: 13
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This is dumb, Rope Gripper, CWT safeties, buffers, car safeties, buffer.....Elevators aka redundant safety factors in that order I'm not sure what you meant by "this is dumb", as I have already admitted above, that my knowledge of elevator systems is very basic at best... This however does not mean that I'm a complete idiot...it only means that I'm not familiar with the technical jargon and inner workings of the various elevator systems... I was basing my scenario question on the known laws of physics and some documented cases from the past regarding elevator accidents... Again, I have no idea by what you mean by CWT safeties or buffers, as I'm not an elevator tech...could you elaborate in more details? All I'm looking for is for someone to explain this to me in laymen's terms, without insults or suspicions of having ulterior motives...
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#10046 - 03/11/14 03:57 AM
Re: Scenario based technical question
[Re: driver]
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Joined: Jan 2012
Posts: 419
Broke_Sheave
addict
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addict
Joined: Jan 2012
Posts: 419
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I don't chime in much here anymore but Driver, I think a lot of the hesitancy to address your questions, is that it just takes too much time to respond. For instance. The link below if just for the QEI recertification test. https://naesai.org/UserFiles/5_Houston_TX_flier_2014_2.pdfNotice all the books required just to prepare and take this test. A17.1 / CSA B44 Safety Code for Elevators and Escalators • A17.2 Guide for Inspection of Elevators, Escalators and Moving Walks • A17.3 Safety Code for Existing Elevators and Escalators • A18.1 Safety Standard for Platform Lifts and Stairway Chairlifts • NFPA 70 National Electrical Code • QEI-1 Standard for the Qualifications of Elevator Inspectors • Elevator Industry Field Employee’s Safety Handbook • And more These books alone require a couple of grand and hour upon hour of study just to be up with the current codes, which are constantly changing. And that's just to inspect them and be up on current code. And to work on them opens a complete new set of educational requirements. A rigoruous 5 year course with overseer's from the government, Companies and Unions. Course descriptions below. http://www.neiep.org/courses/default.aspxThat's not counting all the company classes, adjuster classes,Night classes for advanced degrees (Usually in electronics or computer architecture, or programming). And yes. In my 35 years I have witnessed the scenario you describe. An older open loop control from the 60's. Not seen it on any of the newer controls because of built in safety redundancy. There are just so many possibilitys to your scenario, I'm sure everyone here on this board could dream of this happening if X,Y,Z happened on Control type Q... Probably wont post here for a long time again, but that's just too much hassle. Hope that helps Driver
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#10048 - 03/11/14 06:07 AM
Re: Scenario based technical question
[Re: Broke_Sheave]
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Joined: Nov 2009
Posts: 413
Johnny
Journeyman
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Journeyman
Joined: Nov 2009
Posts: 413
Portland. Oregon
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Driver, I followed that link and there several differences with the two scenarios. That car didn't go up before it fell down. The machinery (overhead drum) and the supporting members all came tumbling down. They said 500 tons, however even a tandem geared Otis drum would likely top out at about 5 tons, so weight is off a tad. Still, the scenario that you started with had some unique requirements and that was what I went by. Broke Sheave has some good points and is correct with his assessment. Buffers are the items that retard the elevator and counterweight at the extreme ends of travel and are checked regularly for proper operation. However, slower cars (under 200 fpm) have springs and these wouldn't help a lot if you had enough rise to gain momentum. Also, buffers are rated for speed and capacity. Obviously, rated speed would have been exceeded. If you have occupiable space below the elevator shaft, you would have to have counterweight safeties as well as car safeties, and that would have stopped the upward motion of the car by stopping the downward motion of the cwt. In late model elevators, you have rope brakes and sheave brakes that work independently of the safeties and stop the upward movement of the car. You also have UIM (un-intended motion) circuitry on later model elevators. Like I said earlier, If God has it in for you, it's gonna get messy.
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#10052 - 03/11/14 05:42 PM
Re: Scenario based technical question
[Re: Johnny]
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Joined: Mar 2014
Posts: 13
driver
stranger
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stranger
Joined: Mar 2014
Posts: 13
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Thank you guys so far for all your reply's. As Broke Sheave has pointed out, I'm starting to get the hint that the answer to my question might not be easy, as there are too many factors at play. @Johnny...good point about the CWT safety stops, as this single feature would likely take the wind out of the rapid ascend by stopping the counterweights before the cabin crashes into the ceiling, but I'm getting the sense that most shafts are not equipped with the extra space needed? I think that for most part, I have enough partial reply's to be able to piece together that this sequence could occur (maybe in the past) under certain circumstances, as per Broke Sheave's quote: And yes. In my 35 years I have witnessed the scenario you describe. An older open loop control from the 60's. Not seen it on any of the newer controls because of built in safety redundancy. There are just so many possibilitys to your scenario, I'm sure everyone here on this board could dream of this happening if X,Y,Z happened on Control type Q... @Broken sheave, I know that you said you are not likely to post again, but if you do I would like to ask you if you could confirm, that scenario you said to have witnessed also included the shaft ceiling caving in and spilling out the machinery down into the shaft (as per my scenario), since this is probably the only piece of puzzle that I'm still not sure about? Postal has pointed out earlier, that in the link that I have provided, the fall of the drum machinery was most likely due to the use of timber in the overhead structure (yes I'm aware that the cab has never hit the ceiling in that case, but that is one of very few cases I could find, which involves machinery falling on top of the cab).... At this point I'm still unsure, if a concrete ceiling of later construction could fail structurally, had it sustained a hard enough hit hit from the ascending cab? Again, I very much appreciate all of your answers you guys provided to me so far...
Last edited by driver; 03/11/14 05:54 PM.
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#10061 - 03/12/14 05:18 AM
Re: Scenario based technical question
[Re: driver]
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Joined: Nov 2009
Posts: 413
Johnny
Journeyman
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Journeyman
Joined: Nov 2009
Posts: 413
Portland. Oregon
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Driver, I looked at these links and have several comments. The first one seems to be falling upward, but at a fairly slow rate. I could certainly cause such a problem for the cameras. When it finally stopped, the phone fell off the hook and a ceiling plastic fell out. Whoopee!!! I'm not sure this was even a commercial elevator. It looked like a LULA or a residential, maybe. The second one is harder to comment on. Lots of people claim a free-fall and actually experience a lock clip at speed and assume a free-fall. In the picture, there were definitely some broken cables, but the elevator pictured looked older and different than the one first pictured, They didn't back away quitte far enough to compare jambs, but I think I have seen that picture in somebodies video travel journal. The third one has happened lots of times, mostly with Ward-Leonard systems and failed brake systems. These problems were what prompted the rope brakes, sheave brakes, and redundant braking systems. In summary, you took three unrelated scenarios and tried to weave them into a workable possibility. I'm not even convinced that at least one of these links wasn't staged. I set up several scenes for movies and made elevators do things they would not ordinarily do. Would have required multiple simultaneous failures.
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#10073 - 03/13/14 02:04 AM
Re: Scenario based technical question
[Re: Johnny]
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Joined: Mar 2014
Posts: 13
driver
stranger
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stranger
Joined: Mar 2014
Posts: 13
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In summary, you took three unrelated scenarios and tried to weave them into a workable possibility. Essentially...yes. Assuming those scenarios were real, I didn't think my scenario would be too far fetched if those elements were incorporated in one sequence and then some... I'm sure that everything could be staged for the cameras (I'm assuming you are referring to the first youtube link), but I would have to question the motives, as there is not much if anything to be be gained by doing this... Sure it could be a prank, but those 2 people getting out while the elevator moved would definitely gamble with their life in order to film this, especially one of them being a kid... Suppose that could be fake too, but now it would be getting too elaborate for such a low quality video I think?... As far as the teen free falling 5 stories in Bronx, there were several pics on the internet from different news sources, most showing the elevator cabin resting below the ground level, which looks like the actual elevator pit?. Im assuming, if the emergency brakes have deployed, the elevator cab wouldn't have fallen that far down? Of course I do realize, that when it comes to the news they like to recycle and re-use certain images, since most people wouldn't be able to tell the difference... For example I have seen a news image recently titled "Ukrainian troops are moving closer to the border", while the image shown was taken from the NATO war in Kosovo some 15 years ago...(bunch of guys in fatiques marching somewhere, most people will not analyze it)... Having said that, I think that I do have an above average BS detector as well, but to be honest I really don't think that the first video link was staged...
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