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I understand that the 'gears' synchronize the jump, but can this be considered 'mechanical gears', if it is not a completely independent system where the energy of one gear is being transmitted to the other? Can it be a gear if it does not make a complete 360 degrees rotation? what defines a gear? if there were 3 teeth, does it define a gear?
>What defines a gear?

Intermeshing teeth I would think. What else are you going to call it? gear-like mechanics maybe.

If you wanted to synchronize the motion of two parallel output shafts that are being driven independently, this would be one mechanical arrangement that would get the job done. The two parts that engage in this configuration would be called gears. (most likely they would use sprockets and a timing chain...can't wait till someone finds that in nature)
A rack and pinion is a gear, and the rack definitely can't make a complete 360 degrees rotation.
> if it is not a completely independent system where the energy of one gear is being transmitted to the other

But that is what's happening. That's what the gears are for. They synchronise the motion by transmitting force from either side to the other.

If the left leg faces less resistance (or has a stronger muscle, etc.), then the extra motion that would go into the left leg is instead balanced across to the right leg through the gears.

>Can it be a gear if it does not make a complete 360 degrees rotation?

Well, there are also oval gears, many types of non-circular gears, and so on. Not all cyclical/360 degree, e.g:

https://ae01.alicdn.com/kf/HTB11B0bhviSBuNkSnhJq6zDcpXaG/400...

A gear is about the teeth and the ability to synchronize according to a ratio. If you just need 180 degrees of motion (and e.g. will move it manually or automatically back to the starting point begin with), it's still a gear.

There are many gear-like shapes in proteins.
I'm a big fan of ATP synthase. It brings me joy to imagine a quadrillion spinning doodads powering my body at all times. We don't just have a rotor and stator like a jet engine, we have a quadrillion of them! Possibly even a quintillion! Wheee!
This reads like an xkcd, and that is one of the highest compliments I can give.

Also, where can I read more about this? I assume wikipedia's a good place to start, anywhere else?

Ha, it does feel that way! I can see it now: a framing narrative about hearing the word "protein" in the context of bulk nutrition and derailing into molecular biology. Hover text: One of the figures in the "quintillion" calculation is a bit suspect but the result is still guaranteed to within three orders of magnitude, or your money back!

This feels a bit too good to let it die here. I wonder if Randall Munroe has an idea box I can toss it into and help spread the good word of ATP synthase.

The Rob Lue animation linked by jacquesm is probably a good next step, but it does feel like it was intended to be played in the middle of a lecture. At any rate it's a good excuse to brush up on molecular bio :)

It appears there are forums and an IRC channel, I may drop in at some point and leave a link to this, because I agree, it does seem to good to let die here.

And the video is definitely a good start, as it definitely gives enough search terms, as well as enough background to start building an understanding.

To me, it just adds to the engineering anxiety about maintenance. The whole thing is already a bunch of spaghetti on the macro-level, repair is a major pain in the ass.
Are they also used to transmit power from one gear to another?
This is not the first time, see the Flagellum Motor (which is far more complex) https://en.wikipedia.org/wiki/Flagellum (often used in ontological arguments)
I think you meant teleological argument, it is the one about irreducible complexity.
That's a rotating joint, but doesn't include gears (though it is really cool!). Conversely these gears are not on fully rotating joints, but on pivoting joints.
First time I saw animation of the motor proteins in our cells it kind of freaked me out - it walks and has legs :).
I read about this a decade ago. Cool, but not "the first time"
May be the same instance as the link is to page posted in 2013.
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This website is an example of web designers who hate mobile browser. Their GDPR pop-up takes up the entire screen and then some.
"Unlike man-made gears, each gear tooth is asymmetrical and curved towards the point where the cogs interlock – as man-made gears need a symmetric shape to work in both rotational directions, whereas the Issus gears are only powering one way to launch the animal forward"

What are some examples of man made gears that work differently when rotating the other way?

There's lots of examples of mechanisms that lock out the backwards direction on purpose.

AKa ratchets etc.

HN title here ought to include (2013)
That video became very unexpectedly artsy in the end. Very cool.

Also: I love seeing this sort of collaboration between researchers, artists, community, and so on. Inspiring!

There was an old s.f. short story about the tripulation of an space ship stuck in a planet where they found plastic-eating plants and little animals moved by gears. Somebody remembers the title/author?
Did they roll around on basalt highways?
It's neat to think about how that would evolve. I'm assuming as the beginning those two surfaces where without gear teeth and only relied on friction. As the insect evolved, the insects with a more tougher surface there would be able to get more friction and thus force transfer leading to further hops. Take that to the extreme and you've got gears!
Snooping around for photos on the internet. It looks to me, as someone who made gears for a living, that they are Miter Bevel Gears. (Miter - both gears have the same pitch and bevel angle)

The odd part is they are only used temporarily, then discarded at maturity.

In the real world, it takes 2 hours or so to set up a bevel gear generator like the Gleason 14.

I remember reading this article a few years ago and it's still so simple and interesting to this day.