

Fist-sized 11M-to-1 gearbox - p4bl0
http://makezine.com/2015/07/08/bet-cant-find-use-11-million-1-gearbox/

======
kcorbitt
The Space Needle's spinning top level is powered by a 1.5hp motor[1] at a gear
ratio of 360,000:1 [2]. It makes one complete rotation every 47 minutes.

[1]
[https://en.wikipedia.org/wiki/Space_Needle](https://en.wikipedia.org/wiki/Space_Needle)

[2]
[https://books.google.co.uk/books?id=Jox4CAAAQBAJ&pg=PT262&lp...](https://books.google.co.uk/books?id=Jox4CAAAQBAJ&pg=PT262&lpg=PT262&dq=space+needle+gear+ratio&source=bl&ots=nzwsgU5HSu&sig=UTGSr7mBcaSWfjWJpXm8qjJ_Utc&hl=en&sa=X&ei=DGKeVdbGKMvn-
QGZxquABQ&ved=0CC4Q6AEwAg#v=onepage&q=space%20needle%20gear%20ratio&f=false)

~~~
BuildTheRobots
I can't find any diagrams explaining the mechanics of the restaurant (or even
exactly what rotates); which upsets me. -Can someone provide more
information/pictures? Even with amazing balance I don't understand how there
isn't massive friction caused by whatever it's running on...

Nearly everything says it's a single 1.5hp engine (upgraded from 1hp), however
there's a case study by Graybar who did a retrofit in 2013 [0] which makes it
very clear that there is (and was) actually _two_ motors, both in play. -once
again, if anyone has more information? I'm massively intrigued.

"The major problem was that the two existing drives were fighting to share the
load – one was lagging and the other leading. The two gear boxes were
constantly adjusting according to inputs from the motors, which caused both
the noise and roughness during the rotation. The team determined that the best
solution was to upsize the motors, drop motor revolutions per minute (RPM) and
reduce the reduction ratio with the new gearboxes. So they recommended
Schneider Electric drives as well as various automation and control products
to the Space Needle engineering staff. The new motors were equipped with
encoders feeding the drives in a master/slave configuration. Along with this,
all new controls were installed, including a wireless control system.
Schneider Electric also provided engineering and software support, both at the
integrator and jobsite facilities."

>>> edit: I'm wondering what wattage this/these 1.5hp motors are; the Falkirk
Wheel is a rotating canal lock up in scotland. It manages to simultaneously
lift/lower two canal boats + water 35 meters for only 1.5kWh of energy (and
has a pleasing gear system) [1] [2]

[0] [http://www.graybar.com/documents/graybar-keeps-tables-
turnin...](http://www.graybar.com/documents/graybar-keeps-tables-turning-atop-
space-needle)

[1]
[https://en.wikipedia.org/wiki/Falkirk_Wheel](https://en.wikipedia.org/wiki/Falkirk_Wheel)

[2]
[https://www.youtube.com/watch?v=n61KUGDWz2A](https://www.youtube.com/watch?v=n61KUGDWz2A)

~~~
WalterBright
The restaurant floor, a ring around the core, rotates. The observation deck,
exterior and center do not.

------
po
I highly recommend going through Oskar's other puzzles and contraptions which
includes tons of very very strange cubes, puzzle rings and other oddities:

[https://www.youtube.com/user/OskarPuzzle](https://www.youtube.com/user/OskarPuzzle)

[http://oskarvandeventer.nl/hanayama.html](http://oskarvandeventer.nl/hanayama.html)

He also has done a ton of collaborations with Bram Cohen of Bittorent fame
like this one:

[https://www.youtube.com/watch?v=RTcGCqz4ajs](https://www.youtube.com/watch?v=RTcGCqz4ajs)

He's definitely one of those guys who just can't stop creating puzzles and new
ways of thinking about problems.

------
urschrei
The application is obvious: DIY "Machine with Concrete"
([http://makezine.com/2012/04/25/arthur-gansons-machine-
with-c...](http://makezine.com/2012/04/25/arthur-gansons-machine-with-
concrete/)) kits. I'm sure Arthur Ganson won't mind.

~~~
jacquesm
Really neat, thank you!

------
IshKebab
This is not too different from a harmonic drive. In fact it's basically a
single-planet epicyclic drive inside a harmonic drive. Kind of nice but I
don't know if it counts as a new type of gearbox.

[https://en.wikipedia.org/wiki/Harmonic_drive](https://en.wikipedia.org/wiki/Harmonic_drive)

~~~
drostie
Well, harmonic drives are cycloid drives that use elasticity rather than
eccentricity to do the same task, so let's focus on cycloid drives.

It's not quite the same your typical cycloid drive, but it has a strong
relationship. Cycloid gears are about having an inner circle of radius A
rotating within an outer circle of radius B by putting the center of A's
circle on its own circle of radius C = B - A.

If C is small, then a fast rotation of C produces a slow off-center rotation
of B relative to A. Since it's off-center, usually a bunch of holes
(theoretically also of radius C, I think?) are drilled in B and filled with
"output rollers" which connect to one single shaft which is on-center relative
to C. Thus C connects on-center to this asymmetric B, which connects to an on-
center output shaft that otherwise rotates as B does.

In his case, these holes don't exist and the rotation is never on-center. But
you can use the same mechanism to convert his amateur cycloidal drive to one
that has an on-center rotation of the input shaft.

Now normally in a cycloidal drive, A is regarded as fixed, while C is
rotating, and B is still. In this case his C is totally implicit, his B is
rotating, and he is at _two different_ A's which rotate relative to each
other. There are therefore presumably two different Cs, too.

It's hard to really isolate the exact mechanism in terms of connected cycloid
drives. It is _not_ as simple as fixing C and watching a _single_ cycloidal
drive's A rotate as a response to a rotating B, because that would have the
reverse mechanical advantage. It's also not obviously "two cycloidal drives
connected together by C", which would have a mechanical advantage near 1.

So I'm not sure what it is, but I don't think you can just say "oh, it's a
harmonic drive."

------
userbinator
This "extract the difference of speeds between two parts" method is quite
common to get extremely high reduction in a small amount of space; this is a
~70:1 single-stage gearbox found in a rearview mirror positioner, and it only
has 6 parts:

[https://en.wikipedia.org/wiki/File:Rearview_Mirror_Epicyclic...](https://en.wikipedia.org/wiki/File:Rearview_Mirror_Epicyclic_Gears.jpg)

Put 4 of those in series and you'll get 24M:1.

------
yiyus
> We live in a world where an idea that does something that has never been
> done before can be built at home and shared without cost [...], all without
> it having any use or any place in the market. Outside of art, that is
> something we did not have a few years ago.

I do not agree with this idea. Many inventions have been driven by curiosity.
People playing with magnets or 8 bits computers were not trying to solve any
market problem. Even physics were developed by simple people sharing curious
"unuseful" experiments for centuries.

~~~
weego
If anything, individuals seem to have stopped inventing/investigating. It used
to be that persons of means would use their means in the pursuit of some
expansion of their knowledge. Now it's in pursuit of more means.

~~~
knodi123
This is a common historical fallacy. Like "It used to be that Greeks would sit
around inventing geometry, philosophy, and democracy. Now they just ruin
banks."

There were always both kinds of people, and the inventors who are driven by
the love of science and learning have always been a minority. It's just that
the people who only care about personal wealth rarely make it into history
books, whereas the iconoclastic scientists frequently do. And the same is true
today.

~~~
edanm
"It's just that the people who only care about personal wealth rarely make it
into history books, whereas the iconoclastic scientists frequently do."

Arguably even this isn't true - Many people know the name of, say, Archimedes
and Newton, but I doubt it's more than the people who know Julius Caesar and
Genghis Khan. Might be close though.

~~~
knodi123
What I'm trying to say is, what percentage of people can name a couple of
great thinkers from the classical era? Now compare that to the percentage of
people who can name a wealthy merchant or banker from the same period.

------
new1234567
The article mentions slippage, grinding, play, noise and vibration. These are
generally undesirable in machinery. Slippage and grinding suggest significant
problems with wear and durability. That would limit the lifespan of the
gearbox.

It's still pretty cool and could be very useful. That doesn't mean there
aren't useful applications. It just means there are design tradeoffs.

~~~
cgearhart
It looks like a pretty rudimentary prototype. Many of those issues are
addressed with better manufacturing tolerances, different materials, and tooth
profiles. I'm not sure those features are inherent limitations as much as
drawbacks to the prototype implementation.

------
stephengillie
> _Headed in a different direction, Van Deventer has a new type of gear he
> calls “grinder gears” that comprise an inner gear with one fewer tooth than
> the outer gear, causing it to wobble its way through the rotation. For the
> engineers, it’s a variation of a cycloidal drive._

Oh, he reinvented a Gerotor.

> _A gerotor unit consists of an inner and outer rotor. The inner rotor has N
> teeth, and the outer rotor has N+1 teeth. The inner rotor is located off-
> center and both rotors rotate._
> [https://en.m.wikipedia.org/wiki/Gerotor](https://en.m.wikipedia.org/wiki/Gerotor)

------
kukx
It's not completely something new
[https://www.youtube.com/watch?v=MBWkibie_5I](https://www.youtube.com/watch?v=MBWkibie_5I)

------
mjlangiii
The article points out issues with this exact implementation at an 11M:1 gear
ratio but begs the question whether a less extreme ratio using "grinder" gears
has any application or not.

Regardless, the conclusion about new innovations at the end of the article was
exciting/encouraging to read.

------
chrisBob
I am most concerned about the efficiency of a design like this. People usually
look for a gear reduction to increase torque, but an inefficient gearbox can
make the output both slower _and lower torque_ which is rarely desirable.

The wobbling input shaft would also be tough to work around.

------
sj4nz
Perhaps not with this ratio, but something like this with a quartz movement,
with the right ratios should be able to advance a "day of year hand" around
the face of a clock.

If you wanted to get really fancy, advance a DoY-hand for Venus, Mars,
Jupiter, as well as the Earth's.

------
Thiz
I want to see the inverse.

Eleven million spins with one rotation of the shaft.

~~~
cgearhart
Friction will prevent that, similar to the self-locking behavior of a worm
gear. Even if you could get it started, it would take as much energy to spin
the output shaft once as it takes to spin the input shaft 11 million times. If
you tried to quickly spin the output shaft, the forces exerted on the gears
would shred the materials almost instantly.

~~~
Florin_Andrei
It would be fun to calculate the power input required for that. I suspect it
would be in the range of megawatts or so - instantly vaporizing the gearbox
(assuming you could somehow push that power into it before you destroy it
mechanically).

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HeyLaughingBoy
The mechanism is reminiscent of the one in the Newbould Indexer:
[http://www.imperialnewbould.com/the-newbould-
indexer.html](http://www.imperialnewbould.com/the-newbould-indexer.html)

This discussion has a link to RJ Newbould describing how he invented the
indexer:
[http://www.chiefdelphi.com/forums/archive/index.php/t-68265....](http://www.chiefdelphi.com/forums/archive/index.php/t-68265.html)
It's a really interesting explanation for us mechanism geeks :-)

------
struppi

        Gune: [holding up a small device] Does this look familiar? Do you know what it is? 
              Neither do I. I made it last night in my sleep. 
              Apparently I used Gindrogac. Highly unstable.
        Preed: Gune...
        Gune: I put at button on it. Yes. I wish to press it,
              but I'm not sure what will happen if I do.
    

[http://www.imdb.com/title/tt0120913/](http://www.imdb.com/title/tt0120913/)

Seriously, this is a cool device. And I have no idea what I could use it
for...

------
LoSboccacc
I wonder what's the highest torque it can sustain without breaking. That will
in turn severely limit applications because with that demultiplocation little
torque will be huge at the other end.

------
na85
Reminds me of a fun trick that was popular when I was in undergraduate
mechanical engineering: A gear train that has one end spinning, powered by a
small DC motor, and one end bolted/welded/glued/otherwise fixed solidly to a
wall.

Increase the ratio enough and you can have an output shaft that will take
years to go through even a fraction of a revolution ;)

~~~
dominicgs
There is one by Arthur Ganson in the MIT museum[1]. It's part of a great
exhibit of fun/quirky machines and there's an interesting video about it on
youtube[2].

[1] [https://www.youtube.com/watch?v=5q-BH-
tvxEg](https://www.youtube.com/watch?v=5q-BH-tvxEg) [2]
[https://www.youtube.com/watch?v=2Rov_Lriqvk](https://www.youtube.com/watch?v=2Rov_Lriqvk)

------
kokey
Will this also work as a 1 to 11M gearbox? If so it might allow a strong force
(e.g. the weight of a large body of water) to spin a small electric generator.
That will allow small scale hydroelectric storage for renewable sources.

If not it can probably still find some applications for turning something like
weak wind power into something that can create great pressure.

~~~
furyg3
I know nothing about this, but I would imagine that this gearbox would need to
be made out of some other-worldly material in order to cope with the force
necessary to drive it in reverse

~~~
nraynaud
I'm pretty sure it's already potentially self destructive if there is any snag
in the output.

------
jpfr
Looks like a bunch of harmonic drive gears in a row. Every industrial robot
contains a couple of these.

------
jonjenk
What you are describing is called "backdriving" the gearbox. Generally
speaking, gear trains with high reduction ratios don't like to be backdriven.
Small steel gear trains with ratios in the 1000:1 range can destroy themselves
when back driven.

------
Keyframe
Could it be used for high precision movements? For example a stepper motor
with very small and large movements? I know it's mentioned in the article..
but if it could be done then one could maybe create a CNC for DIY CMOS or
something.

------
Animats
Here's a planetary drive using roughly the same concept. This is 64:1 per
stage.

[https://www.youtube.com/watch?v=P-Obt-9tZVo](https://www.youtube.com/watch?v=P-Obt-9tZVo)

------
jglauche
Just a 3D printed gearbox. For me this is rather a promotional article than
something really interesting. We've been able to print these kind of gears for
years with reprap or reprap-like 3d printers.

------
columbo
If it had enough torque (which seems to be a problem given the plastic nature)
I could see it breaking loose rusted or stubborn bolts. Maybe? In a scenario
like that you wouldn't really care about precision or sound. Though 11 million
turns still seems like a lot of cranking... maybe if it had a 9v attachment it
could be a portable bolt breaker. Feels like a stretch though, would be fun to
play with.

Though now that I think about it the holder of the bolt breaker would probably
start slowly turning before the bolt does... weeeee

~~~
chadgeidel
The problem with rusted or stubborn bolts I've encountered is the mechanical
friction on the threads usually greatly exceeds the shear force (??) that the
bolt can tolerate. I've snapped a head off more than once. That's a real
bummer.

------
melloclello
I feel like it could be used to construct mechanical calendars.

~~~
yummybear
Precision could be an issue according to the faq.

------
fredgrott
I know the answer..think Tesla..but instead of a small auto a big truck or
better yet a big ship...

both require a rethinking of the transmission to transfer power from the
engine to the wheels or propeller in order to get bigger torque

this gear device solves that particular problem

------
lisper
Because of the non-back-drivability, I would use this for making winches.

------
birk5437
Its sometimes nice to take a break from software/digital engineering and build
stuff in the real physical world. Feels like a vacation for my brain almost.

------
kordless
Would be good for a telescope mount, maybe.

------
intrasight
Why wouldn't one just use three nested cycloidal gears to achieve the same
result?

------
Semiapies
Why they include an animated gif of someone turning _another_ gearbox with a
far lower ratio puzzles me.

But I'm going to go with "yes, this is useless, unless remade with much better
materials". The current version is imprecise, high-friction, snd can't even
survive one rotation of the output.

~~~
Semiapies
Huh. Was someone under the impression that the GIF _was_ of the gearbox in
question, or did they not RTFA enough to realize I was simply agreeing with
the inventor for the same reasons he enumerates?

~~~
Gravityloss
That is the gearbox. The output shaft is the red one.

~~~
Semiapies
You're right, sorry. I hadn't watched the second video.

