Engineers Develop 'Ultrarope' For World's Highest Elevator

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.

Comments

just put a motor on the elevator itself

[Noah Haders]

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.

Re: just put a motor on the elevator itself

[pavon]

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.

Re:just put a motor on the elevator itself

[ihtoit]

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... 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).

Re: just put a motor on the elevator itself

[Anonymous Coward]

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.

LSM

[jklovanc]

Linear Synchronous Motor Elevators Become a Reality

Re:Worthless

[TechyImmigrant]

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.

Re:Armchair engineering at its finest

[NoNonAlphaCharsHere]

That has GOT to be the most trollish post I've ever ever ever read here. You have NO IDEA how Slashdot works, do you?

Better Way

[JimSadler]

The RCA building in NYC uses compressed air and the elevator is effectively a dart flying up the shaft. With an accelerometer installed to trip the brake if too rapid a descent occurs there is no need at all for cables.