Engineers Develop 'Ultrarope' For World's Highest Elevator 248
HughPickens.com writes: Halfway up the Shard, London's tallest skyscraper, you are asked to step out of the elevator at the transfer floor, or "sky lobby," a necessary inconvenience in order to reach the upper half of the building, and a symptom of the limits of elevators today. To ascend a mile-high (1.6km) tower using the same technology could necessitate changing elevators as many as 10 times. Elevators traveling distances of more than 500m [1,640 ft] have not been feasible because the weight of the steel cables themselves becomes so great. Now, after nine years of rigorous testing, Kone has released Ultrarope — a material composed of carbon-fiber covered in a friction-proof coating that weighs a seventh of the steel cables, making elevators of up to 1km (0.6 miles) in height feasible to build.
Kone's creation was chosen to be installed in what's destined to become the world's tallest building, the Kingdom Tower in Jeddah, Saudi Arabia. When completed in 2020, the tower will stand a full kilometer in height, and will boast the world's tallest elevator at 660m (2,165ft). A 1km-tall tower may seem staggering, but is this the build-able limit? Most probably not, according to Dr. Sang Dae Kim. "With Kingdom Tower we now have a design that reaches around 1 km in height. Later on, someone will push for 1 mile, and then 2 km," says Kim. He adds that, technically speaking, 2 km might be possible at the current time. Anything higher would require new materials and building techniques.
Kone's creation was chosen to be installed in what's destined to become the world's tallest building, the Kingdom Tower in Jeddah, Saudi Arabia. When completed in 2020, the tower will stand a full kilometer in height, and will boast the world's tallest elevator at 660m (2,165ft). A 1km-tall tower may seem staggering, but is this the build-able limit? Most probably not, according to Dr. Sang Dae Kim. "With Kingdom Tower we now have a design that reaches around 1 km in height. Later on, someone will push for 1 mile, and then 2 km," says Kim. He adds that, technically speaking, 2 km might be possible at the current time. Anything higher would require new materials and building techniques.
just put a motor on the elevator itself (Score:5, Interesting)
i would do away with the motor at the top of the shaft, and instead electrify each individual elevator so it has motive power. seems like the best solution to me.
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You still need a counterweight or else you are lifting the entire mass of the elevator instead of just passengers. That means a cable.
Re:just put a motor on the elevator itself (Score:4, Interesting)
you can build as high as you want as long as you can build a cable long enough to service the elevator. Cable length isn't a problem, the weight of the cable is. In systems such as this very simplified model of a counterweighted elevator http://s.hswstatic.com/gif/bt4... [hswstatic.com] it's assumed that the rope weighs nothing, therefore the counterweight only needs to weigh 25lb - even taking into account the rope's weight, all other things being equal it balances itself. That's handy, scaling up you only need a 400lb counterweight for a lift rated at MGW: 1600lb (ten persons (800lb) + 800lb car). This arrangement does of course necessitate four times the length of cable as the height of the shaft, and with another shaft-length you can actually mount the motor at the bottom, negating the requirement for a counterweight - the motor only has to overcome the weight of the car through the system, which practically means it's pulling against a quarter of it. For some reason that's not really practical, so in this arrangement you'd have a counterweight one side, top-anchor the other end of the rope and have the motor roll the cable somewhere in between. FWIW when you see an elevator car with four cables, you're not seeing four cables, it's one cable. It's this arrangement of three (strictly, four, but the car pulley can be and often is a twin) pulleys, a counterweight and a top anchor. Other setups have the anchor point actually on the roof of the car, still others have the car and the counterweight on their own bottom pulleys, both ends top-anchored and the motor in the middle sharing rope between essentially two double systems.
(grew up in a tower where the elevator spent more time stuck between floors than enough, often with me trapped in it. Hearing firefighters clambering around up there to attach car batteries to the brake solenoids so they can lower the car to the ground after eight hours is a terrifying thing for a four year old. Nerd points for spotting the ropes and asking about them when they were fixing the thing, though).
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I saw a programme that dealt with this a while ago, it was using the WTC Twin Towers as a use case in splitting elevator loads and why the decision was made to stagger the system rather than have shafts that went from the basement to the roof. It wasn't a question of cabling, it was a question of how many full-height shafts can you cram into a building and stil have a habitable space?
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With today's ultra capacitors it seems like you could recapture 70% of the energy on the way down again. Maybe more.
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And how do you handle the counterweight? What's that? You don't actually understand how an elevator works?
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you wouldn't need a counter weight cuz of the motors in the elevator itself. got questions? yo I'll solve it.
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And how do you handle the counterweight? What's that? You don't actually understand how an elevator works?
If your electric motor is powerful enough, you can dispense with the counterweight. It might not be very efficient, but it's possible.
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I have been down a 2km mineshaft(the shaft is deeper, but they only go down in +/-2km sections) in a 'cage'. There is no counterweight, but the AC winder that drops (yes, 'drops' is the right word) you and hauls you back out is pretty powerful. They account for cable weight and extension because there are rails in the cages and they need precision to match them up. They get about +/- 1cm. Operator skill is important..
Yes. It is possible even with old style cables, but to get anywhere in a reasonable time, y
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Why do you suppose they generally never do that?
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All the engineers who actually have to build these devices obviously never had the brilliant flash of insight after a few minutes of thought that our intrepid slashdot armchair engineers had, of course!
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slower speeds, more noise, more danger, I would imagine.
btw KONE means MACHINE.
Re:just put a motor on the elevator itself (Score:4, Informative)
The cable doesn't arrest the fall - brakes do.
Re:just put a motor on the elevator itself (Score:5, Informative)
He has it exactly right. The tension on the cable pulls on the elevator brake to release them. If there is no tension on the cable, ie pulley or cable fails, the cable looses tension and the brakes apply.
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yes, but the cable is only used as a triggering mechanism, used as it is obviously there and is simple. There is nothing stopping that triggering mechanism being anything from an acceleration fired mechanism, or pressure held open by the motors when they have power or any number of other methods.
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yes, but the cable is only used as a triggering mechanism, used as it is obviously there and is simple. There is nothing stopping that triggering mechanism being anything from an acceleration fired mechanism, or pressure held open by the motors when they have power or any number of other methods.
The beauty of the current brake is that it engages immediately on failure, regardless of what the elevator is doing at the time. If the cable breaks, the car stops. If you rely on an acceleration fired mechanism, the car will have to start falling before the system knows to shut down, and that could lead to serious injury. Power failure is also only one failure mode -- the next issue is loss of traction. The current system has one mode of failure and a brake that is physically bound to it. There is no safet
Re: just put a motor on the elevator itself (Score:5, Interesting)
No, you could use a conductive rail, like a subway, and rack and pinion system to move the elevator. The rack and rail would add a fair bit more total weight to the building compared to a cable. But more importantly, the motors would have to be much much more powerful! Modern elevator systems have a counter-weight balanced on the other side of that cable, which means the motor only has to overcome friction and the small difference in weight between the elevator and counterweight (which varies depending on current payload). The motor on an elevator like Noah is suggesting would have to provide enough force to counteract the entire weight of the elevator + payload + motor + friction, which is at least an order of magnitude more than a traditional elevator.
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Add in a battery or a flywheel and recover the energy on the way down.
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"Add in a battery or a flywheel and recover the energy on the way down."
Batteries and engines weight. A lot. You don't want them atop a high building.
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The batteries do not have to be on the elevator. They can be on the building side of the high powered rail. For example in the basement.
Armchair engineering at its finest (Score:5, Insightful)
I'm probably going to lose some karma for this...
I, too, could come with a half-dozen answers that would be "far superior" to what 100+ years of the finest minds in the industry could come up with. But in reality, I really, seriously doubt that my designs would hold up because there's a *reason* that things are done the way they are.
Mechanical engineering is a *very old* industry, and any radical, new design would have significant hurdles to pass before it could be accepted and used in a real scenario. The cost of failure is very high and there are real lives on the line.
My first thought was to use something like a caterpillar drive along the sides of the shaft, each of which would operate like a mini elevator for perhaps 10 floors. But, very quickly, I can see that this type of system would have many, many more moving parts and consequently many more points of failure.
So, I think it *might* be best to trust that 100+ years of experience are, in fact, at work, and that we should first understand that there is *real knowledge* at work before assuming that our half-baked and thoroughly unproven ideas hold any merit in reality.... ?
Re:Armchair engineering at its finest (Score:5, Interesting)
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Indeed, and I think it's reasonable to call out the posters who say "oh they're idiots, why don't they just..." and so on and so forth.
However, it IS fun to speculate with a bunch of reasonably knowledgable people on mechanisms for going beyond what is currently technically feasible.
The powered lift with a rack and pinion is an interesting idea. I'm struggling to work out how much additional power it would take. With a short lift, you can discount the weight of the cable, and so you can have the lift counte
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Ah, rampant speculation -- I'm game. I'm wondering about the possibility of a three part lift -- a car with two independent cradles. The first cradle is cabled for a third of the height of the building, and is left behind when the lift goes above that point. The second cradle is cabled for two-thirds of the building, and disengages once the car ascends above two-thirds of the building. On descent, the car reaches the cradles again and continues down. Each of the cradles is counterweighted to provide a displ
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Very true, but we also know companies and how they 'think'. Anything new would have to be proven by someone else because no one will take the risk.
And when we run out of options do do things, well then we have to think outside the box.
Though this is slashdot, so let's get creative. ;)
I also instantly thought about how roller-coaster cars are pushed up the rails. Also like how scaffolding is assembled and you have guys vertically in a row, passing on the pieces to the next guy above. Same could be done with
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I wouldn't presume to know more than a mechanical engineer at an elevator company. But I might still be able to figure out why someone who has spent their entire career building one style of system, with the only variance being the size of the motor and the length of the cable, with investments into the supply chain for those specific components and technicians familiar with working and installing those components, might tell you that the old way is the best way without seriously considering an alternative
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Well, not only is it entrenched in that way, there are a lot of laws and regulations that detail the mechanics of an elevator. This is even before liability issues and indurance consideration even come into play. So it isn't that just anything else could be used either. Of course there is no telling how much of those regulations are because of what you mentioned and what is pure safety.
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The motor on an elevator like Noah is suggesting would have to provide enough force to counteract the entire weight of the elevator + payload + motor + friction, which is at least an order of magnitude more than a traditional elevator.
Not necessarily, no. Put fixed motors on the shaft walls, not in the elevator, and put pinions on the outside walls or corners of the elevator. The only extra weight would be of the elevator itself, less the weight of the hanging cable which elevators today have to move, and less the weight of the braking system, which would now be in the building, not the elevator.
And the much smaller building mounted motors can recuperate some of the energy whenever the elevator is descending.
Because each motor would on
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Re: just put a motor on the elevator itself (Score:5, Funny)
With a magical lightweight power cord, perhaps?
The British already have a twenty mile long extension cord that they use to power the trains going through the Channel Tunnel. They reel it out as each train goes through, and then wind it up afterwards to prepare for the next train. There is no other way to do it, since it is totally impossible to transfer electricity to a moving object through, say, a power rail.
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The real question.
First how do you get it up there? Stairs perhaps?
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Er, helicopter. I just woke up. :P
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With a magical lightweight power cord, perhaps?
Power it using lasers - duh.
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Re: just put a motor on the elevator itself (Score:5, Informative)
Calling out a person for behavior you present is not going to change anything.
The main problem with rails is that you need a sliding contact. That means arcing at the contact when the air gaps are eventually going to occur (nothing is 100% flat, and air pockets will eventually get between the contact and the brush). Arcing isn't going to cause immediate failure; but, it will leave a carbon / oxidation residue at the arc site. This means that future electricity will have to flow through a very small scale resistor, generating heat. Eventually the heat will cause pitting, accelerating failure.
This is why most in-wall electrical sockets are designed to scrape the plug slightly on insertion. It is a self-cleaning feature of electrical wall sockets, and any wall socket that doesn't provide some modicum of resistance when inserting a plug should be replaced as soon as possible. A loose wall socket will not clean the prongs on the plug, carbon will build up within the socket, and the heat will eventually lead to arcing that will melt the plug, the socket, or both (possibly starting a fire as a side effect).
The issues of contacts on long electrical rails can be fixed by turning the rails into flexible cables; but, that only recreates the cable problem. Even though an electrical cable could be theoretically lighter than the lift cable, it still has to lift its own weight, and an under-built electrical cable cannot entertain even micro-fractures in electrical conductivity without have an accelerated repair cycle.
Now you know why virtually all elevators use cables for lifting with a fixed motor.
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If sliding contacts are such an issue then how do electric trains [google.ca] overcome it?
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why would you make it building length? Have a series of them...
Re: just put a motor on the elevator itself (Score:5, Funny)
Maybe we should apply this great cable technology to subway trains. I do notice the pits on the third rail. They always have to send some poor guy out to sand them out real quick before the next train comes.
Re: just put a motor on the elevator itself (Score:5, Interesting)
Train rails are excessively thick. This coupled with scrubbers around the brushes means that the rail is cleaned prior to contact, and the wear of the (cleaner) rail is minimized. This coupled with the minimal movement of a ground fixed tie and a very large amount of metal to wear through leaves the effective life of the rail in the +10 year range (if not +50 year range).
A building will have few of these advantages. Buildings in the 30+ story range sway. Excessively thick rails get far more expensive to run vertically, so the rail thickness will be minimized. This increases the chance of flex and decreases the amount of rail to wear out by scrubbing or pitting. It isn't that it can't be done, it's just that it can't be done easily, which translates to cheaply.
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Nope: there still needs to be a sliding contact between the wheel and a fixed cable somewhere.
Anyway, sliding contacts work just fine. See, e.g. trains with 3rd rail, 4th rail, pantograph and mixed mode trains and trolley busses and even some whacky covered contact trams.
The latter are particularly interesting. Some cities want an electric tram installed but don't want to have overhead cables or exposed foot level contacts. So, there are studs in the ground and they only switch on after the tram has made co
Re: just put a motor on the elevator itself (Score:4, Informative)
Induction incurs a lot of losses. Yes, it can travel a small air gap easily; however, it does so with a lot of compromises. Some of the main challenges is heat generation and low power transmission efficiency. Increasing the power can attempt to address the latter but only at a cost of more heat. Also, induction has extra challenges when considering a moving receiver, and if you decide to address these by moving the transmitter, you then have a lift problem to solve for your transmitter.
I'm not saying that it is impossible, but it is far, far cheaper and more reliable at this time to not attempt to use inductive charging on a self-powered elevator.
And keep in mind that we are blessed with elevator brakes that are actively held open. A self-powered electrical elevator car would have a pretty high constant draw to replicate the braking system, as it would have to pull solenoids against the breaking springs.
Finally, current elevators don't lift the car. It is counter balanced with a set of stacked weights. The elevator motor (a fixed mounted motor pulling the cables) only needs to lift the difference between the two weights of the loaded car and the counterbalance weight stack. A fully self-powered car of the kind we are considering would not have a counter balance (because it would lack the connecting cable) and therefore would need even more power to lift the entire mass of the car.
That's a large increase of needed power coupled with a large decrease in power delivery. It is far from a trivial engineering problem to solve, and is unlikely to be solved favorable within our lifetime.
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And keep in mind that we are blessed with elevator brakes that are actively held open. A self-powered electrical elevator car would have a pretty high constant draw to replicate the braking system, as it would have to pull solenoids against the breaking springs.
Use just a little more creativity. One possibility: Have brakes that are actively held open; hold them open with a quick release mechanism; for the quick release, hold its release via the constant power. If power is cut, it'll trigger the quick release, which will release the stored energy in the springs. It doesn't take much to hold back lots of stored power. Batteries and capacitors could also be employed at various points. Basically, this isn't a problem.
Finally, current elevators don't lift the car. It is counter balanced with a set of stacked weights.
At the proposed scale, 1km, I'm betting all that c
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Use just a little more creativity. One possibility: Have brakes that are actively held open; hold them open with a quick release mechanism; for the quick release, hold its release via the constant power. If power is cut, it'll trigger the quick release, which will release the stored energy in the springs. It doesn't take much to hold back lots of stored power. Batteries and capacitors could also be employed at various points. Basically, this isn't a problem.
The current system is very simple, and very reliable. The car is suspended from the cable via the brake. The tension generated by the weight of the car disengages the brake (because even when going down, the car still accelerates at less than the rate of gravitational acceleration. If the cable fails, the tension vanishes instantly, and the brake is engaged. This mechanism works instantly, even if the car is at rest when the cable breaks. Your suggestion works when the mode of failure is power loss, but in
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With a km-high vertical shaft, I've got to think some use can be found for that heat (e.g. by putting an electric turbine at the top).
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Induction drives are not safe enough.
This is a design using a worm drive [modernmechanix.com].
If you have exprience with worm drives you know their self breaking properties make this very safe. In addition the designs I saw years back had emergency breaking systems similar to normal elevators.
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If I were in the elevator, I'd rather it didn't break at all.
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What?/ Just 2 Km? That's it?! (Score:5, Insightful)
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Yes I get the reference, and yes I am sarcastic.
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We'll have the space elevator, just as soon as we find someone who's a bit too rich with a dick that's a bit too small that wants to build a monument to themselves.
The rate at which oil prices are dropping ... (Score:2)
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alternatively we could just invent another pretext to invade Syria so we can grab up the land and finish the Qatar gas pipeline.Then oil can do what it wants and Russia can go fuck itself since Eastern Europe will then have another source of natural gas.
Colour me cynical.
Re:The rate at which oil prices are dropping ... (Score:4, Informative)
... we may have use the 2km long ultra strong ultra light cable to dredge the Saudi economy from the bottom of the Persian Gulf.
Nope. The Persian Gulf is very shallow, with an average depth of only 50 meters, and a deepest point of only 90 meters. Citation: Persian Gulf Geography [wikipedia.org]
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Sucks for you. Still going down every day where I live.
Why use a cable? (Score:3)
Too energy intensive? Wears too quickly? Safety breaks infeasible leading to risk of sickening plummet to doom?
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It's mostly the counterweight issue, which you can resolve by using electric motors in the cars and large battery banks.
Draw power on the way up, generate power on the way down. There are losses, of course, but it's doable and not terribly inefficient.
The regulations for battery maintenance make it prohibitively expensive. I think there's only one or two such installations in existence.
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"It's mostly the counterweight issue, which you can resolve by using electric motors in the cars and large battery banks."
Cuonterweight is there to avoid the need of hugh power-hungry engines, since they only need to lift the load. Take out the counterweight and you will need to lift the whole load requiring a much bigger engine. Put the engine on the car and then you'll need an even biigger engine (much bigger) to lift its own weight too.
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Agree, but a hybrid approach is likely the most efficient. Get 50% of the power/braking from the rope and 50% from a cab-mounted motor. Batteries aren't needed; just regenerate into the rails.
The other interesting challenge is water. Every 200m you need a pressure break because the welds in the pipe reach pressure limits. An extremely tall building needs to deal with these issues cost effectively, and efficiently-- think water treatment every 40 stories to recover grey water, treat potable water, recove
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Hell, from an IT perspective you reach the limits of multimode fiber risers pretty quickly.
Yeah, but the lag on the satellite broadband suddenly drops away...
Actually, if you're building a tower that high anyway, you'd be just as well using it as a pseudo-satellite broadband provider -- the horizon is over 100 km away when you're a kilometre up. You can serve wireless internet to a small country from up there....
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that was my first thought as well, until someone pointed out that it's not the cable to the motor that's the problem it's the up and over then attached to the counter balance that is the problem.
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Such lifts certainly exist, and are used on construction and industrial sites.
I expect noise, speed, power use and maintenance cost might be areas where cable wins out.
http://www.gedausa.com/rack-an... [gedausa.com]
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car weight. Bear in mind you're lifting a deadweight vertically potentially through several hundred feet. That is a LOT of gravity well to overcome. The lighter your car, the better. If your combined car+rope is lighter than car+cable+attached motor for the same shaft, it makes sense to go with the cable and offload the motor to the building that isn't moving.
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Cog railways are way too slow...
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"more energy efficient for shorter runs". We're talking about elevators, you know, those things that stop every 3 vertical meters.
No we're not. We're talking long-distance elevators. Or do you think someone will ever get to the top floor of a 1km high building if the car stops at every floor. Every time you're almost there, you'll have to stop for a pee break then wait for the car to come back.
Various skyscrapers have extremely high capacity lifts -- the Petronas Towers have double-decker lifts with a capacity of 52 passengers.
LSM (Score:5, Interesting)
Linear Synchronous Motor Elevators Become a Reality [elevatorworld.com]
hello turbolift? Re:LSM (Score:3)
from the linked article (emphasis added):
Flexible configuration: LSM elevators can propel a vehicle in any direction, and cabs can be switched from hoistway to hoistway, enabling the creation of “one-way” hoistways with multiple cabs in each. Modular stators allow the height of the elevator to be customized at installation and extended in the future with minimal disruption. LSM elevators can also ac
Re:LSM (Score:5, Insightful)
Well this is the best thing I've seen! Why haven't these been pushed out into the commercial area?
For the same reason that maglev trains and HyperLoop-style vacuum tubes aren't ubiquitous: sending a dumb carriage along a smart track is far more expensive than sending a smart carriage along a dumb track, since there's much more track than there is carriage.
Narrowboats used to be the best way of moving materials around in-land, but "laying the track" (digging the canals, building the locks, etc.) took a lot of work.
Dumb boats were overshadowed by smarter locomotives: more difficult and expensive to build, but ran on much cheaper tracks.
Locomotives were overshadowed by smarter automobiles: more difficult to invent and require a smarter fuel network, but in some cases don't need *any* track laying.
The same argument applies to lifts: it's much cheaper to have a smart motor at the top and/or a smart carriage, with 660m of dumb shaft and cable, than having 660m of smart shaft.
World's highest dick-waving contest (Score:4, Funny)
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I went to the top of Burj Dubai* in May last year, and I couldn't see anything that made it look useful for anything other than a tourist platform. If such buildings eventually bring in more tourist dollars than they cost to build, then I suppose they serve their purpose.
* Does that mean that I mounted Dubai's... oh, let's not go there.
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It's okay, I'm sure tourists from all over the world will literally flock to Jeddah to have a look at the world from that high up. Oh wait... it's Saudi which doesn't do tourist visas... maybe not then.
Electrically-coupled counterweight (Score:2)
Many posts suggest doing away with the cable by putting the motor on the elevator car; but this overlooks the fact that the elevator needs to be connected to a counterweight for efficiency reasons.
However, here's a thought: you put motors on the elevator *and* the counterweight. As the elevator goes up, the counterweight goes down and uses its motors as generators to partly power the elevator's motors. And vice versa.
Sure, you're not going to break even due to electrical losses; but it'll be a damn sight be
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While such an elevator system would use more power one of the inherent abilities of any electric motor system is the ability to use regenerative braking. You'd probably have a bank of super-capacitors in a utility room, when the elevator was going up it would use the capacitor bank and some power from the mains, when it was going down it would refill the capacitors. Even if you had to put the motors on the elevator car itself this shouldn't be an issue as we have centuries of technology (subways, trains,
"friction-proof" != "high-friction" (Score:2)
Better Way (Score:5, Interesting)
Dyneema (Score:2)
Vertical Maglev feasible? (Score:2)
Would a vertical maglev be feasible? ... It would be worth a try. ... However, I guess a handful of buildings becoming to high for our current tried and trusted elevator technology is a luxury problem.
Rope? (Score:2)
Rope and cable for elevators is a century old technology, I'm surprised they aren't using linear motors, standard electric motors or something else for record breaking skyscrapers. I can understand continuing to use cable for normal skyscrapers as it is a tested, widely available and is cheaper due to current production. But when dealing with such immense heights (1km) you would think someone would have the sense to develop something better suited rather then putting a small metal box on the end of a gian
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In tribute to the late, great Robin Williams:
Ask Dr. Ruth. No, not the short Jewish woman, the big black mama called Doctor ROOF!
"Ya can't make butter wid' a toothpick!"
Re:trains don't need rope... (Score:5, Informative)
Trains also do not need to pull straight up.
The real reason for the cables is to allow counterweights to balance much of the load. Thus with counterweight you are lifting only the carried weight, without you are lifting also the elevator chassis and any engine and such, a much larger load.
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that's the ticket - you want the car + load to be as light as possible. Basically all you want on the car is the anchor point for hte rope, some way to get power inside the car and power for the emergency system. That's enough weight, the big building that isn't going anywhere can take the several-hundred-pound motor and gearbox and keep it sequestered in the roof.
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With electric elevators riding vertical rails, you can do switching. Essentially, with three or four sets of rails (one up, one down, a couple for parking) you can put as many cars in the same set of shafts as you want - and even have a supply of extras waiting in a subbasement to be added when required.
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Another way is to have long, fast express elevators stopping every 20 floors of the top half, and ground.
Re:Worthless (Score:5, Interesting)
Or build the building horizontally and put in moving walkways.
Just as much space, at a fraction of the cost and it doesn't have to exist to massage the ego of an oil rich prince who murders atheists for fun.
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If you use cables, you are limited to one elevator per shaft. But if you eliminate the cables, and put motors on the cars, then you can have many elevators per shaft. You can even move the elevators between shafts, going up in one shaft, and coming down in another, in a loop. One pair of shafts could run an express loop, that stops only on floor 1, 20, 40, 60, etc. Another pair of shafts could run a slower loop that stops on every floor.
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Indeed. I once read that the limiting factor on how high we can build skyscrapers is not structural engineering but the explosion in space occupied by elevator shafts as you try and go higher and higher whilst preserving reasonable wait times.
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The skylobby design works well enough - to get from the ground to any floor requires a maximum of one transfer, and elevator shafts can be stacked. The (original) NYC WTC towers for example had an elevator pattern which was:
Express elevators to floor 44.
Express elevators to floor 76.
Shuttle express elevator between 44 and 76 that didn't go to the ground level.
Local elevator banks served groups of 7-8 floors and would only take people to the nearest skylobby (or the ground for the lower third of the buildin
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In addition, the floors serviced by the express elevator will also be the floors most likely to be a final destination -- eg the restaurant floor or the viewing gallery
...or in the case of a building over the height of 1.6 km, the "Mile High Club".
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TFA article says nothing of the sort, actually. It's TF submitter. Slashdot, of course, simply copy-pastes anything Hugh says.
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You have failed me for the last time, Admiral.[Chokes Admiral Ozzel using the force.] You are in control now, Admiral Obvious.