Comment by Animats | Hacker News Reader

Comment by Animats | Hacker News Reader

The elevator industry has been playing around with multi-cab systems for many years. The Otis Odyssey system (1997) [1] had cabs that could move both horizontally and vertically. The cabs were more like containers carried vertically in ordinary elevators and slid out sideways for horizontal movement. Otis built a full-sized prototype, but nobody ever ordered one.

Otis considered ropeless elevators, but in 1997 it looked like it would increase the energy consumption by 7X. Without counterweights, the motors have to do a lot more work. But maybe Multi can recover some of the energy via regeneration.

There are automated parking garages that can move cars sideways.[2] Those go back to the 1960s, and tend to be high-maintenance.

The Multi system looks really complicated mechanically. All those moving parts. Worse, they're on vertical surfaces in the shafts, where maintenance will be difficult. With regular elevators, the high-maintenance items are in the machine room. This will probably go into some prestige tower, but not be replicated much.

[1] http://www.barkermohandas.com/images/Integrated%20Vertical%2...

[2] https://www.youtube.com/watch?v=w3vtpGtyw1k

> Worse, they're on vertical surfaces in the shafts, where maintenance will be difficult.

Maybe - but movement on two axes lets you get creative with your tools. You could for instance store a "maintenance car" with special fittings that expose the shaft mechanisms. The car could be introduced into the system as needed and removed when it would just be in the way.

A forgotten concept is the Paternoster elevator

https://en.wikipedia.org/wiki/Paternoster

A paternoster lift is a passenger elevator which consists of a chain of open compartments (each usually designed for two persons) that move slowly in a loop up and down inside a building without stopping. Passengers can step on or off at any floor they like. The same technique is also used for filing cabinets to store large amounts of (paper) documents or for small spare parts. The much smaller belt manlift which consists of an endless belt with steps and rungs but no compartments is also sometimes called a paternoster.

Nowadays certain safety concerns from the 1970s could be solved by incorporating modern safety features like auto-stop, automatic doors, etc in newly built ones. Express elevators could be built too, if they skip certain floors.

My first read is that this system would be useful for inventory or parts management / movement. Rather than pepole movement, cargo.

This would also be 1) more forgiving of "whooses", and of what I suspect are going to be some pervasive acceleration and directional issues.

Crates of goods don't get motion-sick.

Wow. Kinda off topic, but looking at the complexity of the automatic parking garage makes me wonder whether, in the future, growth of jobs will look like, e.g. automatic parking garage repairer...

I am wondering if the solution is to use modular counterweights that can also be moved sideways and swapped around too.

I wonder how you wonder to use that.

Do you know the principle of a traditional elevator, and the role of a counterweight?

Yes I do know how a counterweights work. In principle if the elevator can be shift sideways then the counterweights can be too. Of course when the elevator goes up and down it will need to be linked to a counterweight, but as long as this linkage can be made transient then should work.

I am not convinced by your understanding.

The elevator conserves energy by having a counterweight, and the work needed for moving the elevator (disregarding the loss of the system) is 0 if the elevator is empty and the counterweight is the same weight of the elevator.

This is true for the length of the rope.

Now if you have a 99 storey building, with side moving elevators, you cannot have counterweights, as the ropes would be in each others' way when moving sideways. Either having a rope in way for 99 storeys in worst case, or with shorter ropes you increase complexity even further and negate the energy saving. if travelling further than the length of the rope.

The only advantage of this design is the lack of ropes. The downside is increased energy use.

Regarding transient linkings: even more complexity, and possibly the cabins need to wait for the counterweight to arrive, and hand over the counterweights? Even scheduling complexity is increased. Totally useless, as to have it a bit feasable you need to sill keed the functionality of counterweightless motion.

You can understand this by drawing if still not clear.

Discarding system losses, an elevator without counterweight will also use 0 energy for the up/down cycle (assuming load goes up and some time later down): the energy invested while pulling up the system can be recovered when descending.

Yes, at the cost of even more complexity. The problem with this idea is insane complexity.

One of 3 elevators in the office building is out of operation every two weeks. ThyssenKrupp comes and repairs it every now and then. They are simple elevators. The reliability I can imagine from my experience with TK elevators I think the floors will be a better option.

Once I was working for a TK company, and the TK elevator broke down. It was not repaired by the sibling company for a whole month because of some component shortage... That was a simple elevator in a 5 storey building.

> floors i mean stairs.

You don’t need ropes to have a counterweight. The same effect can be accomplished with track and gears.

I do agree with you that having independent counterweights would increase the complexity and the likelihood of a breakdown. Ultimately any solution would depend on the value being provided by the solution verse the increased cost or either maintenance or energy costs.

More importantly the purpose of me suggesting this solution was not to solve the elevator problem (I am sure lots of engineers have thought more deeply about this than me), but to discuss the problem.

Oh, OK. I think that an energy recuperation system and simply a "vertical railway" is simpler and more robust overall. No ropes needed just electric wiring, and elevators moving down are the counter weights. But this is basically what is demonstrated.

What I thought parent meant was using counterweights in the more traditional sense.

And yes, moving down also returns the energy, after all gravitational field is conservative. The real use of the counterweight is that the power needed to lift is less (you only need to work to lift the cargo), which means cost savings in motors, wiring, electricity, etc. Those saving by a mechanical counterweight system cannot be had with this setup without insane complexity. With today's solid state power electronics it is simpler and more reliable to use an electronic solution.

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