In June 2015, I went to Sheffield, and I saw a paternoster lift,
an obsolete design of elevator with a looping chain of open cabs.
In June 2016, I travelled to Genoa in Italy,
and I saw an elevator that also moved sideways.
Except, spoiler, it's a bit of a cheat,
it's actually a little horizontal car
that moves inside a bigger elevator that does the heavy lifting.
And now, it is June 2017.
And I'm in Germany, at the brand-new Thyssenkrupp Elevator Test Tower,
and they have flown me out here to show off Multi:
their actual, full-size, working elevator
that moves sideways without cheating.
For us, it was very important to have a tower to test the new technology.
We don't want to test it at the customers' site.
The tower is 246m high, and this means 1,700 steps.
I know that exactly, because I walked up once!
This is a building made almost entirely of elevator shafts.
Some of them test regular lifts,
but some of them are reserved for this new system.
The principle of having a continuous rotating flow of cars
was one of the best inventions in our industry ever.
And to achieve this, we have to exchange cabins from one shaft to another.
And to have this exchange, we need an exchanger,
which you see just behind me.
And this exchanger allows us to go into horizontal movement.
The exchanger can be placed at every point in the shaft
so it allows us to do all kinds of configurations.
Coming down vertically, and then going into the horizontal movement.
One of the problems with elevators in really tall buildings
is that you need a cable so long that it can't support its own weight,
let alone the weight of the cab that's then connected to it.
The solution here is a bit different, and it doesn't use cables at all.
It uses linear induction motors.
Linear drive - it's also a synchronous motor with permanent magnets.
And you maybe know it from a rotating motor.
If we just take this motor and cut it on one side
and just lay it on a table flat,
then you already have a linear drive.
And this is what we have, vertical and also horizontal.
In a regular elevator, it's called a traction elevator,
you've got cables holding the cab,
any one of which can hold more than the design weight.
Also, you've got emergency brakes which will pop out
and slow the car down with friction if it's moving too fast.
And, absolute worst case, even if all that somehow fails,
you have a buffer at the bottom that should reduce a freefall drop
from "fatal" to just "severe injuries"(!)
Elevators are incredibly safe because they're incredibly well-regulated.
So before this is allowed to carry humans,
this system needs to be at least as failsafe.
The safety is not just in the ropes of a conventional elevator
but in the brake system.
In conventional elevators, you have the brake
on the machine on top of the shaft in the machine room
now we have the brake directly on the cars.
This new component, the exchanger,
where we go from vertical into horizontal movement,
also needs to be checked by our safety controller.
What is the position of the exchanger?
Is it locked?
Is it safe?
And in case of any violation of a safety rule,
then we go to a 'safe state'.
There are, of course, some catches.
Linear induction motors are expensive and heavy.
Each one of the cabs needs to have its own set.
And the whole elevator shaft, from top to bottom,
needs to be lined with the magnetic coil units that power them.
To save weight, these cabs are made of carbon fibre and aluminium.
So will it work out in the real world?
Thyssenkrupp's models say it will,
but everything's been tested and approved here,
the next step is to sell it.
To the kind of enormous multinational companies who build skyscrapers
and who do not like risk.
And that might be a greater challenge than making the elevators in the first place.
Thank you very much to all the team at Thyssenkrupp who've invited me over here.
You can pull down the description for more about Multi.