We should use this amazing mechanism that's inside a grasshopper leg

[@SteveMould]

Also, the hinge from an overhead cabinet! That's like the last mechanism too. The sponsor is Incogni: Take your personal data back with Incogni. Use code SCIENCE at the link below and get 60% off an annual plan: incogni.com/science

[@welbow]

What about a ZIF (Zero-insertion force) socket?

[@bilboswaggings]

a foldable phone also snaps open at a certain point and gets locked

[@Aliplus]

@stevemould Mole grips, or some folks call them locking pliers, use the locking mechanism - an "over-center" cam action.

[@Alfred-Neuman]

A kiss is a bit like that, you build up potential energy in your mouth (vacuum) and when you open it the air rushing in makes a "kiss" sound.

[@ThereIsNoSp00n]

pistol shrimp and/or mantis shrimp

[@jsincoherency]

This video is all about storing energy slowly and using it quickly, but there might be interesting instances of the opposite as well. For example, when winding a mechanical clock, you are storing energy quickly and then using it slowly. The purpose there is to allow the energy to be released over the coming week so that you don't need to apply energy continuously to keep it going.

[@MattH-wg7ou]

Mechanical watches fascinate me. The escapement mechanism is so clever.

[@SteveMould]

Nice!

[@somitomi]

The really interesting question here is are there any examples of such a mechanism in the animal kingdom?

[@MattH-wg7ou]

@@somitomi interesting question! There are obviously chemical versions like hibernation and such, but I wonder if there are any mechanical ones.

[@octopeople]

@@somitomi maybe gliding in birds and things like flying fish/squirrels/frogs. Build up gravitational potential to release over a long descent.

[@bibbyflatman7412]

The linkage you are thinking of is called an over-center mechanism and they are used everywhere! Some common examples would be vice grip pliers, toggle latches, and clamps.

[@alec4672]

I think the closest equivalent to what he built would be a clay pigeon throwing machine.

[@omaristephens2143]

Yes, this. Also, snap switches like common light switches

[@recurvestickerdragon]

and of course, firearms. for instance, the Luger's funky look is mainly cuz it uses a toggle to delay the chamber from opening

[@bertilbusch]

I believe horses and other prey animals use them to rest standing, so they are always ready to run for their lives

[@SteveMould]

Thank you!

[@bluedistortions]

I noticed as a kid the best way to catch a grasshopper was to get it right after it landed, as it seemed to take a second or two to get itself ready to jump again. It would then jump half cocked, only going a short distance, making the follow up quite easy.

[@JWQweqOPDH]

My family has ducks. They love eating grasshoppers. They almost always forage as a team. One reason is likely that a bug hopping out of the path of one duck will be easy pickings for the next one over.

[@jpdemer5]

Also true of the Spotted lanternfly - they jump quickly enough to escape your first attempt, are easier to get on your second attempt, and they're sitting ducks for your third swat (or stomp).

[@TheButlerNZ]

@@JWQweqOPDH (guessing your not in NZ...) we have a sparrow sized bird called a fantail.. basically has a wide fan for a tail it flits around, scaring insects into moving/flying, only to turn 180de in its own body length and catching them... While throwing plastic at trees (I play Disc Golf) they often flit around your ankles or shoulders if your by a bush, getting the insects you disturb as a freebee... (They aren't very scared of humans.. I've had several momentarily land on a foot/arm then gone again in a flash.

[@the1khronohs40]

That last mechanism is called an ‘over center hinge’. They are absolutely everywhere! Shampoo bottles, mason jar hinges, trailer hinges, vice grips, some cabinet door hinges, and yes, the lever arch file as well. Plus’s many, many more! Refer to KZbinr ‘This Old Tony’s video on this concept! It (and his whole channel) is brilliant, especially for makers, advanced DIY’ers, and machinists!

[@honor9lite1337]

Interesting!

[@oiytd5wugho]

I was gonna leave a comment saying so before I noticed the upload date. But what's funny is if you type "over center mechanism" into google in suggests "over center mechanism in nature". I wonder if this video had anything to do with it

[@flashbangbuhfgdsg43]

Also a guitar shubb capo using same mechanism

[@blank4305]

The last mechanism reminds me of staplers -- when you open them up to refill them, there is a similar mechanism with a hinge and a spring.

[@SteveMould]

Oh yeah!

[@fergalkeating]

That's 💯 what I was trying to think of

[@OMGclueless]

Spring assisted knives are another example of this, in the other direction: While closed, the spring holds them closed, but if you open them slightly the spring pulls them all the way open.

[@QuargCooper]

This was my thought too! But there is also something else it reminds me of, I remember the feeling of playing with something similar as a kid, trying to balance it on the unstable point. I wonder if there is something like a venus flytrap which makes use of a similar mechanism.

[@gavs928]

@@QuargCooper I remember having a toy that was a series of wooden blocks connected by elastics that was something like this. there were notches in the blocks for the elastic so you could position the blocks either end to end or at a right angle to each other in a stable state, or if you put the corner of a block into the notch of the next one, you could try to balance it at a 45 degree angle (or 135 if you prefer). Steve's model also had me wondering about what kind of mechanism venus flytraps use!

[@CODX10]

"[...] For example, the soft living actuator of a Venus flytrap leaf (Figure 1A) has two stable equilibrium states, namely, an open convex shape (one stable state) and a closing concave shape (the other stable state). It can switch rapidly between these two stable shapes to achieve fast closure in about 100 ms.[53, 54] It utilizes the so-called bistable snap-through in engineering.[55] Similar bistability is observed in hummingbirds for rapid beak closure in a few milliseconds to eat flying insects (Figure 1B),[56] in the earwig wings to fold and lock their wings[57] (Figure 1C) [...]" - Chi, Y., Li, Y., Zhao, Y., Hong, Y., Tang, Y., & Yin, J. (2022). Bistable and Multistable Actuators for Soft Robots: Structures, Materials, and Functionalities. Advanced Materials, 34(19), 2110384.

[@HunterJE]

^^^^^^This is the one!

[@hallohoegaathet7182]

I am pretty sure crocodiles do the same with their mouth.

[@jacen60]

great citations too. hope he sees it; seems to be exactly what he was looking for

[@RevJR]

I knew it when I saw it. I think clams might be similar too

[@justinbrown7444]

I was thinking Venus Flytrap too, although it seems it goes from one equilibrium state to another (convex to concave), so doesn't seem like it stays in that sweet spot between the two. The jumping popper toy seems like an equivalent human invention.

[@isedki]

Hi Steve. An example of the mechanism you showed can be found in the human body. The "tensor fascia lata" originates from the pelvic bone "the iliac crest" and inserts onto the outer side of the knee. It is a long thick fascial structure that is tightened by a small muscle originating from the pelvis called "the tensor fascia lata". This muscle's function is intriguing, as it spans and controls two major joints -the hip and the knee-, and operates as a joint extensor when these joints are in extension, and a flexor when these joints are at 20 degrees or more of flexion. It effectively operates as a locking mechanism for the hip and knee to allow us to stand without having the spend too much energy through the major muscles -glutes and quads-. Its resistance to motion follows the same pattern of change that you highlighted in your hinged joint with an elastic band, and is least effective at 20 degrees of flexion.

[@TheEgede]

What he said :)

[@michaelsbasement]

Woah, thats so cool

[@SteveMould]

That's really interesting, thank you!

[@СоюзниксОкинавы]

I didn't get how it helping us to stay without spending too much energy, where I can see this on video or something?

[@CloudCuckooKing]

@@СоюзниксОкинавы Have you ever locked your knees when standing in place? This is what OP is referring to.

[@yat0ro358]

0:16 From the moment you said “we get around it (our muscles’ limitations) with tools” I couldn’t stop thinking about the parallel universe in which a grasshopper makes a video called “we should use this incredible mechanism found inside a human car” and it’s a 20 minute video in which a grasshopper geeks out about combustion engines

[@_ayushmehta]

Yes I agree, cause Evrything u can imagine is possible .

[@mystifoxtech]

the steve mouldtiverse

[@harleyAtdk]

@@mystifoxtech Underrated comment, kudos

[@therealchriscunningham]

Okay so never in my entire life have I been able to snap my fingers due to inadequate explanations of what I'm supposed to even be doing and then at the age of 42 a single Steve Mould explanation has me doing it first time. What a world we live in.

[@chtechindustries4174]

Never been able to snap, still can’t. My issue is I just can’t get the right angle and my fingers either slip, or the nails bend and cause extreme pain, then my flesh slips quietly, or the nail breaks, or both… My soloution? I don’t snap (:

[@kurtillerbrun4634]

@@chtechindustries4174 Perhaps you understand this, and if so please disregard, but I think a common misconception is around *where* the sound is produced, which leads to confusion around how to produce it. The "snap" we hear is the sound of the finger, having slipped off the other finger, slapping into the fleshy bit at the base of your thumb. The interaction of the fingers with each other is only relevant to the extent that it stores energy to allow one of them to subsequently slap into the bottom of the palm with greater force. To directly address what you said, you WANT your fingers to slip after a moment of friction, and quietly is really the only way they'll ever do so. Moreover, nails shouldn't factor in at all since you're aiming to squeeze flesh against flesh (typically, the fingerprint of your middle finger against the fingerprint of your thumb--this allows more friction than anything involving nails). Because, again, the sound you're trying to produce happens AFTER your fingers have slipped off each other, when the middle finger slams downward and impacts the flesh at the base of your thumb. So, basically: Lightly curl your pinky and ring finger against your palm. Now, squeeze the flesh of your middle finger against the flesh of your thumb as hard as you can, so that your thumb and middle finger are effectively parallel. Your index finger can either help squeeze the top of the middle finger, or else stay out of the way entirely. Now, while holding this squeeze, gently move your thumb off to the side, as if you were going to make a thumbs-up gesture. In other words, destabilize the squeezy equilibrium you've established. This will "release" the middle finger to slide off and quickly snap downwards (all four fingers should now be resting across the base of your palm with your thumb in a vaguely thumbs-up position). When your middle finger impacts the fleshy base of your thumb, it should produce some kind of sound. The faster you can make it slap downwards, for example by increasing the friction between your finger tips and, commensurately, the squeeze force this allows, the louder and more percussive that sound will be. Any adjustments you may have to make should be with a view to increasing this impact, NOT increasing any sound from your fingertips interacting prior to the actual snap.

[@mrsquid_]

YES I JUST FOUND OUT HOW TO DO IT! i've been rubbing my thumb and index finger togetehr thinking thats what made the sound

[@Vodkanir]

bit obvious what you're supposed to do. it's not as wild of a world as you say upon realising you're just not too bright

[@MatsMatsuo]

"inadequate explanations" i think nobody even cared of explaining it since its an intuitive thing to do by observing someone else doing it. I'm only finding out through this coment that there are people that don't know how to do it.

[@BigStreams_]

The hinge mechanism shown around the 12 minute mark is quite similar to a motorcycle kickstand. It uses a fairly strong spring to keep it in the upright position, as you wouldn't want it coming down while riding. But pushing the kickstand down will eventually find a new stable position where it will stay down all on its own, but give it a little tap backwards and it will release and swing all the way to its upright position. And of course when fully down its actually canted forwards so the weight of the bike also holds it in place securely. Also, I'm glad you mentioned clicking or snapping your fingers. That was on my mind for some time there, lol

[@bmxerkrantz]

that's what was in my mind during that part. cept bicycle kickstand of course. it was a metal arm and spring that went past the hinge... I just couldn't visualize what it was attached to lol

[@jordanshilander7402]

I agree, I was thinking about one of those over center mechanisms as well like a kickstand or a latch.

[@OneWheelDrive365]

Passenger trains where i work on have over center door locks. Used as a safety feature.

[@kingofenglandthethir]

Tiddlywinks.

[@jtjames79]

Says calling it a catapult would be confusing and shows a trebuchet. 🤔

[@Fourthof7sons]

I was going to make this same comment.

[@SteveMould]

A trebuchet is a type of catapult.

[@KeeperOfKale222]

@@SteveMouldthank you was going to make this comment

[@iveharzing]

@@SteveMould A catapult wishes it could launch a mass of 90kg over 300m!

[@Fourthof7sons]

@@SteveMould for the definition of catapult to be wide enough to include trebuchet, it then also includes slingshots and bows.

[@TheSythkiller1]

I love how for the example of a catapult you used a trebuchet, the superior siege engine.

[@tom_h_producer]

Yeah but hearing a fellow Brit use the term "slingshot" instead does make me wince. Like if he'd said flashlight instead of torch.

[@tristanwegner]

Trebuchets are superior, because they can launch 90kg projectiles over 300 meters

[@salxrn]

@@tristanwegner catapults also can't launch flaming projectiles or the whole thing would set alight

[@JoshuaEisenbart]

For those wondering, the difference is this: A trebuchet holds the payload in a large sling, and uses a counterweight to generate the necessary force. A catapult holds the payload in a large spoon-like arm, and the force is generated via the elasticity of the wood, which is strained by a rope wrapped around a spool. The trebuchet has mechanical advantage thanks to the sling and levering actions, while the catapult is limited by the elastic strength of the wood.

[@kylen6430]

@@JoshuaEisenbartbesides the advantages you already mentioned, the trebuchet is also more dependable and less dangerous. Storing a bunch of potential energy with tension in a catapult time and again can get a bit risky

[@Berend-ov8of]

If I'm not completely mistaking, this is the way wild oat seeds 'walk'. The power of each 'jump' is build up by the seed drying during the daytime, whereas the release is triggered by humidity at dawn.

[@blipboop5594]

Nice! I was thinking of those little rubber dome toys that can be inverted and then ping up. The same sort of mechanism is used in venus flytrap leaves, as somebody already mentioned

[@LeftSoulz]

never heard of these plants seeds. thx, i'll read some more about them

[@mpa9583]

I came here to comment on the seed pods, but will settle up voting your comment.

[@gollossalkitty]

They don't really use a small and kinda quick force to start that motion, so that's not an example of his idea, but yea thats a cool example in general

[@Sylfa]

Found a very cool video demonstrating this ability of wild seeds from Planet Earth. Not so sure it'd count for that particular mechanism though; while the sun applies energy and stores it in the fibres, it doesn't take any energy to release it as the water soaking in doesn't contribute any energy as far as I can tell. It's not held past a pivot point and doesn't snap out of its position, but rather unwinds. I suppose it depends on what you call fast release and whether the whetting of the fibres count as unlatching it. It's at least adjacent to the mechanism mentioned and deserves an honorable mention though. Either way it was an interesting video to watch so thanks for the suggestion!

[@workbenchz]

Ballistic Seed Dispersal (ballochory) - cress pods, touch-me-nots and others, tension is stored in a 'just barely stable" state in the pod wall, the smallest disturbance tips the balance and a huge elastic release of force expels the seeds.

[@kozmaz87]

Nice. @Steve Mould here is the answer to your question about where this is found in nature.

[@hugoperhammer]

Well yes, and no.. The tension comes from either the pods drying and causing tension, or the seeds growing more than the pod until it's ready to burst. It doesn't really go through the "loading and locking" phase Steve asks for. It's a however a really cool example of mechanical tension stored and released in nature anyway.

[@3XP3RIM3NTA7B0Y5]

IDK if this counts as "found in nature," but lifting free weights. Using the bench press as an example, it's pretty easy at the bottom, but get halfway up and that is where failure happens. Get past that point and it's easy to lift. Typing this out now makes me think that this does not qualify :(

[@user-yr5nv2gv7m]

@@hugoperhammer hmm and what about its almost exact mammal equivalent? ("seed"... or maybe giving birth too donno)

[@capacitatedflux]

12:35 Light switches function almost identically to this mechanism to initiate contact quickly. It's why they have the "snap" sound effect (thank you Technology Connections) and why you can balance a light switch between On and Off positions.

[@oll13]

The funny thing about this, is that while Steve was trying to think of good examples he probably used a light switch multiple times lol. Sometimes a good example is so mundane you just don't see it!

[@danemoeckel2518]

Lol I was thinking the same thing. Light switches, and all kinds of rocker switches use this. Because if you turn it slowly with a load the contacts will arc, the over center mechanism snaps quickly between open & closed to prevent the majority of the arc. Circuit breakers actually work alot like his compliant mechanism with the stop on it, where it's easier internally for it to trip and turn off than on

[@capacitatedflux]

@@danemoeckel2518yeah, circuit breaker was another thing that came to mind when he described the mechanism at play. Definitely fulfills the "minor force -> major force" requirement.

[@MichaelRWolf]

Over center mechanism. Great example.

[@MichaelRWolf]

Vice grips use over center mechanism to both provide (function of tangent) force multiplier a past center latch.

[@yetanother9127]

This kind of release of energy comes up on a small scale in linguistics; there's a whole set of sounds called plosives (say "puh, tuh, cuh, buh, duh, guh") where the sound is made by forming a seal with your lips/tongue, building up air pressure behind it, and then releasing it. Blowing a raspberry or buzzing your lips works the same, only you're holding your lips in such a way that when the seal is broken, it closes again a split second later and the pressure resumes building up, resulting in that oscillating "thppppt" sound.

[@bomafett]

The vocal folds (aka vocal cords) themselves are another example in the same realm. They open and close rapidly as air is pushed past them. The difference in these examples compared to what Steve is talking about is that the purpose is not force amplification, but sound production.

[@protoborg]

@@bomafett This is NOT amplification, just force storage and measured release. Steve is simply wrong.

[@Andreas0427]

@@protoborg Steve isn't wrong, you just seem to have completely misunderstood what force is. "Force storage" doesn't make any sense, you can't store a force. What you can store is energy, and energy storage can be used for force amplification just like the video explains.

[@orsonjgmail]

And very similar to this would be coughing.

[@SteveMould]

Yes! Great example, thank you

[@johanneskramer8003]

THE KNEE! The mechanism can be found in our knees. The force of the rubber band is the gravitational force on our upper body. This way we don't need much energy standing upright. Also, this is the reason why the toggle mechanism is called 'knee lever' in German :)

[@mandowarrior123]

Yep. What is the german for 'tension clasp?' The actual device, not literal translation, because that is likewise one.

[@johanneskramer8003]

@@mandowarrior123 You mean Kniehebelspanner (Knee-lever-tensioner)? But yes, that's exactly what I thought of!

[@helicoidcyme]

this is the one i thought of

[@aibaratygaev6766]

and some people's knees can bend further allowing them to stay upright with less effort (but it looks painful and a little unnatural)

[@FrankFurther]

I was thinking about folding smartphones

[@DreIsGoneFission]

STEVE! I am a mechanical engineer who has competed in powerlifting and strongman. I still go to the gym every day, and I can’t tell you how many times I’ve tried to explain these things in the gym! Thank you for continuing to explain awesome principles better than I can.

[@Huwbacca]

"...and what things interest you dear child? What do you want to work with when you get older?" "LEVERAGE!!!"

[@GetMoGaming]

There's a window-breaking tool that does that sort of thing. My mate had one years ago. It's a heavy, cylindrical metal device with a moving spike inside like a plumb-line weight. You push the pin back harder and harder, then it suddenly juts out with a force sufficient to easily break toughened glass.

[@davecoop9579]

Good example. I have seen a centre-punch that works in a similar way.

[@Greenicegod]

Someone tried to break into my car using one while I was sleeping in the back. I was fully asleep when it happened, so it took me some time to figure out what they used. My window didn't break because it was open half an inch, and the extra flexibility absorbed the force safely. Then I got into the driver's seat and saw them walking up in the mirror with a rock.

[@GetMoGaming]

@@Greenicegod they may have used a glass hammer, they're cheap and easy to get (I have one in my car because I'm paranoid of drowning in a river, lol). I used to know people who would do that sort of thing, though. They were always pretty dumb. Just youths being dicks for kicks, really. Btw, if the window was open, they could have hit the edge, as toughened glass is extremely fragile in places like the edge but mainly the corners. I used to work in a factory that produced double-glazed units for uPVC windows and if you even touched the floor with a corner of toughened glass, it would just shatter with just a quiet "tsssss" as the pane became a pile of glass particles at your feet. What happened next anyway, did you drive off?

[@kaikash]

I found it!!! The Goblin Shark launches its jaw at its prey and uses two of those in tandem. From the 2 minutes of jaw research I just did, it is in the same shape as the green test object you used. It pushes its jaw forward and snaps it down. However, it does not keep the mouth portion in the 'open' position, and instead uses the energy to open it and then snap quickly. This is in conjunction with the alternate mechanism behind it, being always in the 'open' position, ready to snap!!

[@gollossalkitty]

BIG😊

[@gollossalkitty]

Sad this didn't get attention though

[@gollossalkitty]

STEVE THIS GUY FOUND IT LOOK

[@Langorithmic]

BUMP

[@kaikash]

@Langorithmic I'm hoping he sees this as well! :)

[@0xCAFEF00D]

That footage of the ant flinging itself several times it's body length from its attempt to bite the skin is amazing.

[@xtnuser5338]

The mechanism you're describing is an "over-center" one with a spring (or any elastic deformity in one or more of the parts that effectively acts as a spring). The tension or compression can be applied an many ways. An elastically compressible cam shape, or an elastic bit that a solid cam shape rides against, can be made to work. Vice grip pliers, all manner of electrical switches with a snap action, toggle style latches, ring binders, old-school skeet launchers, some folding sofa-beds, etc. use this type of mechanism.

[@kiranaun9593]

RING BINDERS! That's what I was thinking of, and I bet it's what Steve was thinking too.

[@afee451]

Don't forget butterfly patches on a road case. You see them a lot on mobile sound equipment.

[@garb7477]

Smarter folk than I: is this the same mechanism the dung beetle takes advantage of while rolling dung? Each roll starts hard as the beetle pushes with it’s coiled legs against gravity however as it extends it becomes easier once the tipping point is reached.

[@xtnuser5338]

@@garb7477 In seeking to answer your question, I tried watching a couple of dung beetle videos. No, I do not think they're using a sprung over-center mechanism. I think they're just going from a low lever advantage to a high lever advantage as the pivot points of their legs come closer into alignment. It's the same thing as standing from a squat position. It's the most difficult at the lowest point, and gets easier as your legs straighten up.

[@Ra-Hul-K]

something similar that came to my mind: as kids we used to put rubber bands around pencil boxes with a hinged lid and a latch to hold it close.. the latch gets damaged over time and we used to put rubber band around the box to prevent it from opening while inside the bag.. but when it's time to open the pencil box, we rarely pull the rubber band off and instead stretch the lid open along with the rubber band, and once the lid has opened more than 180 degrees, the rubber band would keep the lid open.. then all you need to do is give it a slight push under the lid and it will slam shut

[@sandollor]

Exception is a fundamental part of nature. Variance is the name of the game, and the game is natural selection.

[@cmel7841]

what im learning from a LOT of your videos is that springs were a very important invention

[@jeanrazier2439]

I don't know if you've ever done physics or mechanics before but the world is basically springs and dampers :)

[@Monkey_D_Luffy56]

​@@jeanrazier2439wheels and seals?

[@adamcetinkent]

They're what got me hooked on the channel!

[@anonyslime]

ah ah ah noooo springs

[@baconthevainglorious7371]

@@Monkey_D_Luffy56I’d argue we couldn’t use wheels to their fullest before we invented springs. So both equally important imo.

[@mxguy2438]

It's an over center latch. You'll find it in all sorts of mechanisms. Usually, whatever its latching provides the "spring" effect over a very short distance. The effect is used everywhere in nature, but not to create sudden movement like you suggest. Humans use it in the knee joint in order to stand without wasting energy.

[@loganmoody1816]

2:56 The irony of saying that calling a slingshot a catapult is a little confusing when showing a trebuchet and calling it a catapult is too rich. Love your videos.

[@Globss]

I thought the same thing xD

[@threeforthsstudios]

@@Globss Same I was just about to comment this xD

[@Trenz0]

A trebuchet is a catapult. What most people call a "catapult" is technically called a 'mangonel' or 'onager'.

[@MonkeyJedi99]

Slingshot? Let me show you its features!

[@chaos.corner]

Right. So we're using a planet's gravitational mass to change our trajectory then...

[@computer_toucher]

You are such a good science communicator. Even for someone who knows _a bit_ of "everything," you make me grasp basic concepts that I've had a hard time wrapping my head around since forever. Sometimes, learning things is all about having the right teacher, because that can literally change the way you think about things. Nothing better than getting that tingle in your mind when you suddenly truly grok something you've struggled with, or just understand by rote memorisation.

[@halsti99]

i think the mechanism you are talking about is called an "over center mechanism". its also used in vice grips or any storage box latch. i think teaching tech once did a video on 3d printed examples.

[@joshuajohnson5121]

I knew someone would have pointed it out. Over center mechanisms!

[@Tux.Penguin]

Yes, Vise-Grip tools came to mind immediately.

[@drthmik]

Fun bit of new information the plant hopper was recently found to have GEARS in its hips so that when it jumps both legs are forced to move with the same speed and power, keeping its jump straight

[@dtnicholls1]

The over centre mechanism you're looking for in nature can be found in the snipefish. It has a 4 bar linkage mechanism where the hyoid bone goes over centre, just waiting to be released to capture its prey.

[@ivanblogs]

Some nice diagrams in Sarah J. Longo's "Extremely fast feeding strikes are powered by elastic recoil in a seahorse relative, the snipefish, Macroramphosus scolopax" (July 2018 Proceedings of the Royal Society B )

[@SteveMould]

Thank you

[@brayanalvarez8469]

At the door of the electric ovens, there is a similar mechanism with a spring. Many greetings from Chile, Steve.

[@hs3881]

Mantis shrimp: offended

[@GrayCowMan]

Exactly what I was thinking

[@useyourheadpliz]

@@GrayCowMan Same, I was writing the comment before thinking, "wait, pretty sure someone got it covered".

[@justinware8789]

This.

[@gastonmarian7261]

There's some species of planthopper insect that uses a biological gear as a youth to support jumping, before maturing to a form whose exoskeleton lacks the adumbrations

[@greyareaRK1]

Pistol Shrimp as well.

[@firstnamelastname1748]

Your green folding thing immediately reminded me of a similar mechanism as well. I was once working on an engineering project where we needed a bistable hinge. A small door was open, we needed it to fully snap shut after only nudging it in that direction. In prototyping the design, we ended up tearing apart a lot of eye glasses cases to steal the hinges out of them. As I recall, that's exactly how we sourced the part even for our final build. Glasses case hinges use a different mechanism than the rubber band on the side of your widget, but they accomplish the same thing. Relatively slow to open, but kind of snaps into its final position, and very quickly releases that energy when you start to close it. I'm surprised I haven't seen anyone else mention it yet! I bet you'd have some fun tearing apart a glasses case to see how that hinge is designed.

[@kingofenglandthethir]

I’m happy for you. ;)

[@ashen0001]

Oh yea glasses cases might be it, I haven't seen those in at least a decade, even though I still wear glasses... I just got used to the fact glasses sit on my nose 24/7 unless I'm sleeping, so with every new prescription, I tell the guy to keep the case because I don't need it.

[@j10001]

Nice example!

[@Nighthawkinlight]

If you can make a functional example of the saddle shaped spring and mechanism of a mantis shrimp club I'll be the first to click. That would be so cool to see mechanized.

[@waveplasma1369]

Can't believe the mantis shrimp wasn't mentioned in this video!

[@Bulldogg6404]

You won't beat me. I have a mantis shrimp ready to click the mouse for me. (and a replacement mouse for after)

[@jasonhildebrand1574]

@nighthawkinlight Harvard Robotics has you covered : kzbin.info/www/bejne/f5eXeoiIlpd9pdE

[@matiasvaris8495]

I thought about your question (15:40) , the first thing which came to mind was how a person can kind of lock your knees when you are standing, though it doesn't store much more energy than your own body weight...

[@sebastiandanielsen5515]

in Parkour(also other gymnastics but thats my reference frame), if we want to jump into a dive or flip, we use a jumping method where we jump as if we were on a trampoline on flat ground, by running forward, using a small jump where our feet barely leave the ground just to collect our feet, then we initiate the jump just before landing, essentially donkey-kicking the ground forwards. then, with corect timing, the combination of a pole-vault effect from having your feet infront of you and storing elastic energy in your muscles you get a spring effect that is quite effective :) i think everyone has done something similar as a kid on the playground but i allways found the method facinating. hight jumpers do the same but they also swing one leg to get more lift, but that method isnt that great for speed and power forwards

[@andyputch]

Immediately thought of the "swing top" or "flip top" used on glass bottles! (the little wire mechanism with a plug and rubber gasket used in resealable beer bottles + glass bottles used to serve tap water at restaurants)

[@macgyveriii2818]

No joke, that is used on glass maple syrup bottles here in Canada ;)

[@paulcrouchley6289]

Here in Western Australia we have the "trigger plant". Evolved to trap insects for pollination or some species for consumption. The stamen and style of the flower are fused into a column, which can look like a club. The column is slowly pulled back under the flower and "locks in place, when a insect lands on the flower and touches the trigger hairs the column is released and strikes the insect where it is stunned and releases previously collected pollen for fertilization or trapped to be slowly dissolved for food. The strike is one of the fastest movements in the plant kingdom, taking as little as 15 milliseconds.

[@indoorjetpacks]

oooooh thats a good one

[@eightdogstreet]

hello

[@hatac]

Best savvy gold rush trick. A tiny bit off topic. The Chinese were chased off Australian gold fields so they set up bath houses and laundries. They sold the miners cheep baths with free laundry. All the miners would get clean and the Chinese would get their gold. Tiny amounts of gold would get trapped in clothing, hair and on the skin. It was too small for the miners to see. The wash water was panned and processed in the night. The Chinese were also banned from sending the gold back to china so they developed some amazing smuggling tricks. Gold dust in the ink in calligraphy, gold coated with pewter statuettes and containers. One sent eucalyptus oil in one of these disguised gold containers only to get a message back from his herbalist uncle, "Forget the gold send more eucalyptus its worth more". That family got very rich.

[@SteveMould]

Interesting!

[@jayytee8062]

Sounds like an obscure fairytale.

[@hatac]

@@jayytee8062 Its Australia. even our fairy are new, 1913-20's. Search May Gibbs gum nut babies. But the gold rush reports are very well documented. Sadly one of the rich Chinese families went back to Nanking China days before the Japanese invasion arrived.

[@OutbackCatgirl]

as an Australian, this seems fishy. Like the kind of story my dad would tell, except my dad is the sort of bastard who would not use the word "chinese" because he has the racism brainrot. The amount of gold you'd get from this would be absolutely miniscule, surely. Panning an entire miner, no matter how hairy, cannot possibly be a plausible way to get an income and I'm pretty sure that there were other, equally distasteful, yet far far more practical methods of getting money to live by in the i n c r e d i b l y xenophobic colonies

[@OutbackCatgirl]

Also, the chinese were more often used as forced labour on our aussie goldfields. Google is giving me no reputable sources on this story so I'm calling bull until proven otherwise.

[@forethoughtx2846]

i hope you continue to make successful, non click bait, videos like these for decades

[@clayre839]

The human knee is an example of that bi - stable mechanism. Think about how it stabilizes when you lock your knees, you know that thing they tell you not to do. It allows us to stand requiring very little energy while quickly being able to shift into a more athletic configuration

[@Tux.Penguin]

I came to the comments to see whether anybody else had already brought up this example. Steve gave an open request for this example at about 15:20

[@mju135]

This is isn't related, moving your knee into the straight/extended position doesn't require or store any energy.

[@tissuepaper9962]

@@mju135 yes it does, the flexor tendons in your legs are stretched and then very slightly slackened as you extend your legs into that "over center"/"locked" position. This is much more apparent in the legs of ruminants, especially horses, who take advantage of the "locking" effect to rest while standing.

[@geraldrossouw4425]

@@mju135 It stores the potential energy of your body weight, try standing with your knees bent at 90 degrees for any length of time. Remember the schoolboy prank of "unlocking" someone else's legs by bumping the back of their knees and having them buckle as that potential energy is released?

[@robertstonephoto]

The locked knee is an example of an 'over center lock', something also used in some aircraft landing gear. When on the ground, the weight of the aircraft stabilizes the gear, but once airborne, easily overcome by hydraulic or mechanical means. In the video at ~12 minutes, allowing the device to rotate just a few degrees beyond flat would make such a lock.

[@jorislindner1392]

A bear trap uses this same mechanism. Once something steps on it, it pushed the pivot point below the stable spring point and thus pushes both claws up.

[@protoborg]

Nope. The trigger plate in the center of a bear trap merely releases the latch which allows the springs to slam the jaws of the trap shut. Without the latch, the trap would simply not stay open. Further, the trap does not store large amounts of force. It simply uses very large springs. It functions exactly like a mouse trap, genius.

[@dielaughing73]

​@@protoborgYou right, mate? Might want to ease up a bit there

[@fredhughes4115]

@@protoborg "the trap does not store large amounts of force". OK. "It simply uses very large springs". To do what? Springs store force. That's all they do. Perhaps you can clarify that, genius.

[@skenzyme81]

3:01 People... trebuchets, onagers, mangonels, and ballistas are *all* types of *CATAPULTS.* The first uses gravity, and the other three use torsion, but they are all *catapults.*

[@MrDogfish83]

Seriously, wtf is wrong with people!

[@goodrabbi7176]

@@MrDogfish83are you commenting on this comment, or the state of the general public?

[@elitearbor]

Catapult is a very versatile word. A catapult catapults a catapult's missile.

[@ChrispyNut]

Look, I played Civ V a bunch and they were clearly different things, so, 😝

[@JTCF]

What about bows, they are basically the same thing, just different shape of the projectile.

[@harmanpreetbhatti4354]

It certainly is an itch that I scratch unconsciously after you asked about similar mechanisms. And I got it. It is the ** Toggle Latch ** on the old sewing machine boxes. And also the ** Quick release clamps ** like in the bicycle seat, bicycle tire release etc. And also the ** Nail Cutter lever **

[@moonhowler667]

A super common example: Mason jars. That little snap-down lock on the lid uses this kind of resistance-redirection mechanism.

[@King_Dugga]

The mechanism with the rubber band is essentially working like an over-center mechanism. A natural example of this can be seen when a weightlifter locks their elbows to hold a barbell over their heads.

[@freezingDaniel]

Or even just the human knee when standing? Or not?

[@adamneil4576]

@@freezingDaniel Yes, any "locked" joint is an example of an over center linkage. The restoring force (the rubber band in Steve's example) is usually gravity (weight of your body over your knee joint, or weight of the weightlifter's weights over the elbow joint).

[@juanmurillo8143]

Presión = fuerza/Área para perforar no necesitas fuerza sino presión. Es decir, entre menor sea el área mayor es la posibilidad de perforación

[@EvelynnEleonore]

I feel like the most intuitive example of this I can think of is flicking something with your finger! You build up the pressure of your index finger against your thumb, and then release it suddenly, right?

[@marklundeberg7006]

Yes exactly what I was thinking of!

[@michaelbloom8270]

I was about to make this comment.

[@HunterJE]

Or "popping" your tongue by using suction to hold the tongue to the roof of your mouth until the down force overcomes the suction and releases the stored energy

[@AlexanderNash]

Also snapping.

[@protoborg]

That is NOT building pressure. That is overcoming friction. It is much the same way lighting a match works.

[@Alexand3ry]

9:14 - The other neat thing about the angle of the (blue) extensor muscle is that it's *perfectly* aligned to prime the spring. I love the double purpose of (1) priming the spring strongly while (2) extending the leg weakly enough for the flexor to hold it.

[@glenngreenough5261]

I saw that bistable switch model before in a Veratasism video called "Why machines that bend are better." All good electrical switches have a mechanism that stores energy one way or another to make sure the contacts close firmly or open completely. There is always an energy hump as the mechanism goes from one stable state to another, which is why there is a snap action. As the contact points come together, the motion continues just a bit before it stops. This causes a wiping action that cleans the contacts so they work reliably. The handle that you touch and the inner electrical part are connected with a spring, so two bistable parts work together. That way, the handle can be at that state in between the stable points and the electrical part is fully stable.

[@mmeettwwoo]

Compliant mechanisms video. He might ve took that exaple from there...

[@C3darCr33k]

In flatbed trucking there are chain binders that use a similar mechanism. They store the tension indefinitely as a way to secure the load rather than being stored for the purpose of release.

[@ConceptualQuanta]

There are two animals you need to know about. As impressive as the speeds in air are, moving fast underwater is even more difficult. Pistol Shrimp - Able to kill small fish with a jet of cavitating water fired out of a specialized claw. This is so fast it produces shrimpoluminescence. Mantis Shrimp - Similar to the pistol shrimp, except the mechanism of energy storage is a hyperbolic/saddle shaped plate. They also have uniquely high color vision.

[@YodaWhat]

*shrimpoluminescence* Hah, funny. But it is the *shock wave of the water hitting itself* in the final stage of cavitation collapse that produce the light. That process is called *sonoluminescence* because of the connection to sound... Which @ConceptualQuanta probably knew, but any others not familiar with the field might be confused and believe "shrimpoluminescence" was a real term.

[@VoidDustMuffin]

as a fellow mantis shrimp fan, I must give you the unfortunate news that Mantis Shrimp cannot, in fact, see more colors than us. While they have 12 different types of photoreceptors (4x as many as humans), they use each of these to detect a different color, while human brains can take how red and how green an object is and say "this is yellow."

[@YodaWhat]

@@VoidDustMuffin - Some humans have FOUR different kinds of photoreceptors for colors, a condition known as *tetrachromacy* which enables them to see _many more colors_ than normal. But tetrachromacy only occurs in human females, and only if their fathers had red-green color blindness. Once such female is Mila Kunis. All strange, and all true.

[@ConceptualQuanta]

@@VoidDustMuffin Would love a source paper for this. While I don't expect the range of colors to be significantly distinct from other animals (NIR to UVA), having the extra sensitivity to specific frequencies allows for the disambiguation of multiple combinations of source colors yielding what we would perceive as a single color. For example 1. Red+Blue is purple, but their average frequency or wavelength would be green, which implies we encode the chord as distinct. There's no reason for me to believe that more color channels does not yield new bitwise color compositions like this with a type of receptor per channel. I also am not implying they perceive only on or off, because neurons are comfortably analog. 2. Most people see two versions of orange light as identical: Orange (single frequency) vs Orange (Red + Yellow). With sufficient distinct receptor spectra profiles within the same region, these could be distinguished.

[@ConceptualQuanta]

@@YodaWhatSonoluminescence is the physical process. Shrimpo... refers to shrimp doing it. Happy to say it's not a term I made up. See Shrimpoluminescence, American Physical Society, 54th Annual Meeting of the Division of Fluid Dynamics, November 18-20, 2001, Bibcode 2001APS..DFD.EA009V

[@jonathan_60503]

There actually are crossbows where the latch moves forward to catch the string and is only afterwards forced rearwards to tension it. (One example is the so called "assassin" crossbows where after moving the latch forward to catch the string you use a screw mechanism to draw the latch and string backwards -- Todd Cutler has some good video on those)

[@TaberIV]

"I want to get this ball moving fast enough to-" I gotcha, gunpowder!

[@pluribus_unum]

As soon as we evolve gun hands, we're golden. h/t _Harry Potter_

[@apollo7557]

“There is an object in the distance that I would like to puncture a hole in” He’s got a bit of American in him

[@MichaelShock-q1y]

My exact thought the moment he explained his issue, I was already listening to the eagles outside and the national anthem

[@TheDarkfighter101]

Just call it a chemical spring and you are good to go.

[@T3sl4]

Please. He's talking about naturally occurring mechanisms. Try and keep it realistic? ... **Bombardier Beetle has entered the chat**

[@ChrissieFrahm]

My friend and I were talking and it ignited this current comment. Neat look at 3rd lever systems and latches and the mechanics behind them. In the video, a lot of examples were showcased, and would love to expound upon that list. Gorilla's are a prime ideal of the 3rd lever i think utilizing the 3rd type of system and that is why they are so extraordinarily strong, their joint is farthest from their hand so they have maximal strength. . As far as nature-based examples of latches, an alligator's jaw would be a prime example of this. Be well and keep your sense of wonder, everyone, that and curiosity. Don't let the spark run dry!

[@MythicLionMan]

The mechanism that popped into my head first was toolbox latches (I've been spending time in the garage lately). Most of my old metal toolboxes have thumb latches that work like the 'sprung hinge mechanism' but I also have several plastic toolboxes that use metal clips to hold them closed that operate on the same principle. Tent trailers use a similar latch for holding the top closed. These include a nut to adjust the 'yield point' where the latch becomes easy to move again so that you can have the maximum clamping force.

[@PonyCraft]

Same thing for car hoods and overhead cabinets in RV's and boats with vertical hung doors, single hung pivot windows as well!

[@RobotShield]

A trebuchet is a type of catapult. I can’t tell if this was a ingenuous ploy for engagement, knowing that people would take to the comments to ‘correct’ him. But either way I’m glad you’re going to get more comments on this video Steve. Great vid

[@mandowarrior123]

Either it is, *OR* catapults are explicitly bolt throwing crossbows as opposed to ballista which fire balls but are otherwise the same. If onagers are catapults so are mangonels, including trebuchets.

[@RobotShield]

@@mandowarrior123 it is, it wasn’t a sarcastic comment. Apologies if it came across that way. But yes a trebuchet is a catapult, also interestingly a mangonel is a type of trebuchet.

[@Qwarzz]

Definitely was :)

[@VikingTeddy]

But is a revolver a type of pistol then?

[@HiyuMarten]

@@VikingTeddy Yes

[@chewbacka1952]

Your common household light/plug socket switch has such a mechanism. The fast action prevents electrical arcing.

[@TheBjhauhnar]

yep! 1st thing that came into my mind also. Because I repaired one last Saturday

[@SamPrince]

Thank you for this fascinating comment! I had never even considered before why light and socket switches have such a "harsh" click between on and off

[@m1k3y_m1]

When throwing a ball or when punshing, you first move the arm in the opposite direction. This gives more distance to accelerate, but it also gives negative momentum to work against. This is really similar to the described effect.

[@stayawakestudios]

I'm glad that you brought up compliant mechanisms, I was going to say how awesome it was that the grasshopper's exoskeleton is basically a biological compliant mechanism!

[@bpark10001]

The "over center" mechanism you refer to is called "toggle". These are used in suitcase latches, fire sprinklers, some large clamping presses, keyboard switches. The thing you totally miss in this video is the inertia problem. The reason you can't throw the small marble fast is that the inertia of your own arm/hand is so much more than the marble. Most of the energy you expend is accelerating your own arm. Put that marble on the end of a long lever, you can throw the marble fast despite muscle reaction speed. The grasshopper has all the massive parts (muscle & spring) close to the axis of rotation. Effective inertia is proportional to the SQUARE of the distance from the axis. Only the small leg mass at the tip moves as fast as the working load. For the bow-arrow, only the center of the string moves at arrow speed. The leverage ratio approaches infinity at the moment of arrow release.

[@protoborg]

Aside from being wrong about suitcase latches (that's more spring tension than an overcenter), fire sprinklers (that's a small glass tube that applies pressure until it is shattered by the heat), and keyboard switches (they don't toggle), you are correct.

[@bpark10001]

​@@protoborg I am NOT wrong about some suitcase latches, nor fire sprinklers either. The latches I am referring to are the ones that go over center such as this one: www.google.com/search?q=tobble+latches&rlz=1CAIEIT_enUS807&oq=tobble+latches&aqs=chrome..69i57.3087j0j7&sourceid=chrome&ie=UTF-8#vhid=vt%3D16/prds%3Dcatalogid:4897673629388163995,gpcid:8491858234117819194,headlineOfferDocid:-5038498684872209881,imageDocid:7171287479730224857,mid:576462452498884126,mno:3,pvo:3,pvt:hg,query:dG9nZ2xlIGxhdGNoZXM,rds:/vs%3D0&vssid=uvpv-713 Look at this image of fire sprinkler heads www.radfiresprinklers.com/wp-content/uploads/2017/07/Grinnell-sprinkler-heads.jpg The "1919Niagra" & the "1956 CSB" & others in the photo have toggle mechanisms. The 3 points of the lever are ALMOST in line, so a weak fusible alloy in shear can hold the valve plate shut. Like the grasshopper leg, the toggle is never allowed to go over center. Regarding keyboard switches (not the cheap "silent" crap that is sold now-days, I'm talking about REAL IBM keyboard), it uses an "over-center" mechanism, like the Cherry switch shown in this video: kzbin.info/www/bejne/aanGe2qjbpuSl6M The spring tension crosses over the fulcrum point, causing the mechanical advantage to switch signs, just like the suitcase latch I reference. This introduces hysteresis into the mechanism. Instead of contact, the mover is conductive plastic. It gets closer to conductor on circuit board where difference of capacitance is sensed, so there are no contact to get dirty.

[@reverse_engineered]

@@protoborg You are wrong again. The spring tension of a suitcase latch is held in place specifically because it is an over-center mechanism. An over-center mechanism always involves some kind of tension (a spring) which holds itself in place when the two halves are folded past center, causing the line of force of the tension to be "over center". Why do you insist on "correcting" everyone so strongly when you are so often wrong in your correction?

[@peterwysoczanski9391]

there are plants that shoot seeds with all sorts of fun ways they use mechanisms to spread their seeds

[@racingmat13]

great video! About examples in the human body: sneezing (pressure is building and release quickly) or tongue click

[@thatoneguyfrombefore]

15:06 "...your arm is QUIVERING holding the bow at full draw." Good one.

[@jamescheddar4896]

has a modern compound bow that appears to be doing most of the work for him lol

[@josephburchanowski4636]

​@@jamescheddar4896 Ok, but if you weren't using a modern compound bow, and were using an old warbow, your arm will be *QUIVERING* if you try to hold it for too long; you probably wouldn't be able to empty your *QUIVER* after giving your arm all that PUNishment.

[@jamescheddar4896]

@@josephburchanowski4636 he was using a compound bow in the clip as he was talking about the draw force of an old school english yew bow

[@josephburchanowski4636]

​@@jamescheddar4896 So your issue isn't the pun; but the fact that he didn't show two different clips of bows. When at 14:59 he was talking about how the compound bow becomes easier to draw back beyond a certain point; oh so horrible that when he later said "compare that experience to a normal bow" that he didn't switch the clip to a normal bow, cardinal sin. As punishment he better start counting red birds, all the way up to ω, and then after an eternity he can start counting to ω+1, ω+2, ω+3 ... all the way to ω+ω.

[@Wawwior]

@@josephburchanowski4636 ordinal sin

[@Thestorminator89]

You might be thinking of the wrist snap bands. They are flat, then you give it a little tap on your wrist, it springs close around it.

[@OzAndyify]

Hair clips too.

[@protoborg]

@@OzAndyify Wrong.

[@protoborg]

Nope. That uses the resistance to bending of the curve to hold it flat in the perpendicular direction. The metal is also pre-flexed in such a way that it prefers to curl around the long axis. Thus, when it curls along the short axis it is prevented from returning to its natural state. THAT is how a slap bracelet (that's what they are called) works.

[@RecurringErk]

The plants that explode for seed dispersal is another example of slowly stored energy released quickly, and is a non-animal but still biologic example. It apparently even uses a cellular hinge mechanism.

[@rwsmith7638]

Something that I find fascinating is the toggle mechanism on the Luger P08 pistol. At the flat (chamber closed) angle it is harder to open than when the joint toggles upward creating a steeper angle that is easier to move. This delays the backward movement of the action long enough for the pressure in the barrel to be reduced. Interesting. I just LOVE this stuff!

[@AliceYobby]

The beginning of this video made me want you to breakdown the mechanics of baseball pitching so bad!!! It's so incredible, watching it in slow motion -- and also, pitchers are currently facing an injury crisis, the more they optimize for velocity and spin

[@jpdemer5]

That's the first thing that came to mind: professional pitchers (baseball and, probably, cricket players as well) have been refining their motion to apply as much force to the ball as possible, for the longest time possible. Your rotator cuff can take a beating if you aren't careful.

[@cameronswartzell1362]

Office Stapler seems like the most directly analogous object that exactly matches the device he was looking for.

[@rlinick]

Came here to say this. Definitely the office stapler. The spring makes it harder to open until it's completely open and then it stabilizes. Once you start closing it again, it snaps shut.

[@Lord_zeel]

This is a pretty good example. A lot of people seem to have missed the point of the question, I don't think Steve doesn't understand how a light switch or cupboard hinges work - those mechanisms function by dropping into low-energy stable states, but his rubber-band hinge and his bi-stable switch with a nub on one side don't do that. Rather, they "settle" just past the highest energy state of the mechanism such that the mechanisms can't simply drop back to their low energy states but they only require a tiny amount of force to push them back past the peak energy point at which time they release all the energy in a burst. A stapler does exactly that when open, the spring is still stretched nearly to the maximum putting it in a high energy state but it unable to release the energy due to the angle of the hinge - but it will snap shut as soon as you bring it back past the midpoint.

[@luigipalestino8759]

This is exactly the mechanism of the “worlds highest jumping robot” , the one veritasium made a video about, storing energy with rubber bands and accumulating energy with a small motor

[@Liam_Patton]

Something I've found is that it's actually quite easy to get a surprise strike ready by pre-tensing the muscles in my arms and legs. Pre-tensing muscles allows you to use them with much greater power than expected. They definitely still have the power output limit, but that limit is actually obscured by the time curve of the muscle's activation. In several examples I can think of, from swimming strokes to your heavier ball in this video, the muscle is capable of quite an excessive power output, but only after the sufficient time has passed to fully activate it. It's less a power limit than a delay on that power. By pre-tensing back muscles, for instance, power lifters can handle forces that would otherwise completely violate the supposed power output limit you mentioned here. A very interesting video, but I fear that the nature of muscles was misrepresented. They definitely struggle to handle tasks exactly like you demonstrated, but not strictly due to their actual capabilities as much as the way they receive signals. It doesn't take much time at all for a muscle to contract, even at the large scale. It does take a long time for the signal to propagate through the entire muscle to initiate that contraction, which is why muscles always seem to contract smoothly as a gradient instead of binarily. Most muscle tissue can be made to function as an elastic spring to some degree by pre-tensing, but storing that energy in an auxiliary structure and using the muscle normally otherwise is so much more energy efficient that nature doesn't focus on it much. The best examples of my pre-tense theory are in cats preparing to pounce, chameleons compressing their tongue-launching muscles, and humans preparing a sucker punch. Pre-tightened muscles delivering a power output that dramatically outstrips their normal maximum power output from a resting, non-tensed state.

[@TheHuesSciTech]

Another application of the over-center mechanism you mention is glasses cases (i.e., spectacles cases). These days they're boring and held shut by magnets, but not all that long ago they were hinged using bistable hinges which would hold themselves weakly open when open, but hold themselves tightly shut when shut. If you google "10Pcs Vintage MIni Size Self-Closing Metal Spring Hinges For Jewelry", you'll find examples of the mechanism (and can buy them too): really elegant actually, the black piece is *both* the spring *and* the stop which holds it in the over-center position -- all in a single piece of bent metal.

[@Wulthrin]

i remember. if you weren't careful they'd pinch when closing.

[@sarchlalaith8836]

I'm from northwest UK... We always called it a sling, when the cradle thing is on it it becomes a sling shot.

[@jonsteensen7706]

What your green rubbersprung device is reprecenting, is called an overcentering knee joint, and they are used in a number of special situations. E.g. in the landing gear of planes, that mechanism functions as a locking mechanism. Once the wheel moves past the position where the two links align, one arm hits a stop, preventing it from rotating any further, just like there is a stop build into your mechanism to prevent the rubber band from flipping it closed one of the ways round. The point in the landing gear is, that the weight of the plane prevents the construction from folding back up, which would otherwise cause the plane to do a "belly landing" (and that tends to come with a lot of repair work). Loading the mechanism with a spring, will make it easier for the pilot to extend it/retract it, as he will not have to fight the force of gravity. The spring loaded version is also use on our winch, which is used to start sailplanes. In short the start method works by attaching a wire to the plane, and pulling the other end in on a large diameter drum attached to a big engine. Then the plane will be pulled into the air like a kite. In case of emergency (e.g. if the sailplane can't release the wire, or if another plane is about to collide with the wire while it is in the air), the wire must be cut rather rapidly. In order to be able to do that, the wire runs through a "guillotine" with a big cutting blade held above the wire. That blade is spring loaded by two massive springs, which is held in check by a overcentered knee mechanism (the pendant to your green "mystery mechanism"). When the wire needs to be cut, a handle can be pulled by the winch operator. The handle will pull a wire that will "nudge" the knee mechanism slightly. But due to the way it is constructed, that is enough to release all the energy stored in in springs in a very short amount of time, so the blade come slamming down in under a second, and is cutting a 5 mm steel wire in the process. (edit: spelling corrected)

[@dyningar]

Brilliant, @jonsteensen7706, thankyou! Typo at beginning of your second paragraph, your automatic mis-spelling generator has turned your intended "winch" into an extra "which".

[@norodix6857]

As others have mentioned the thing you are talking about is an over center mechanism. Your knees do that for example. When you are standing up you don't need to strain your thigh muscles because your knees are a tiny bit over center, so your weight keeps them from collapsing. Your elbows do that too. If you search for it by that name you will find lots of examples.

[@matthill94]

Your side quest reminded me of a motorcycle side stand. The spring stretches until it passes the pivot point and then meets a stop. Then it requires very little effort to kick back and then is held up with the tension of the spring.

[@turebata5627]

3:00 "a slingshot, actually a catapult" *shows a trebuchet* | If this was actually intentional I'm impressed!!!

[@___Bruh__]

I was about to come say this lmfao. beat me to it

[@kikoclicks]

and made me think how a slingshot is actually more of a catapult than a trebuchet is.

[@meeperator]

I choose to believe that's intentional, because I'm quite bothered by the "mistake" and have to complain about it here in some way. Engagement?

[@AnthonyHarrisTechrat]

It has to be. There's no way this man doesn't know the difference. He's trolling us to get you in the comments, and it worked.

[@Meyer-gp7nq]

A trebuchet is a type of catapult. Idk how yall don’t get this

[@cinnamonsugarcourtney6073]

A latch mechanism is what let's things like Mantis Shrimp to do their extremely strong punches. They're the equivalent of .22 caliber bullets hitting their prey. A similar mechanism is in the Pistol Shrimp's Claw and it's what lets it close fast enough to cause cavitation bubbles! :3 Edit: That mechanism you show off is the exact same as the Pistol Shrimp's Claw.

[@shop-made2840]

That hinge thingy is an over center mechanism! This Old Tony did a great video on them.

[@deslomator]

One thing I love about Steve's channel is that I know I'll get the very well thought demonstrations every time.

[@cvoisineaddis]

Toggle clamps and vise grips are another example of that mechanism. In that configuration it's called an over-center cam, and does not have a dedicated spring, but uses the slight elasticity of the materials in the mechanism to work.

[@Xa_WEh]

Aircraft landing gear are sometimes kept extended with an over center mechanism aswell.

[@basic-decaf]

Your typical everyday pocket knife (with a liner lock) uses that mechanism. Also known as flipper pocket knives. The liner lock is a spring plate that builds energy as you open the knife, and after a certain point, it releases that energy to assist the final movement as it slides into the locking position. Very satisfying and can be a fidget device.

[@metamorphicorder]

Kinda. Those are assisted openers. They can be on liner locks or other types of knives. They are not inherent to liner locks. They are usually fixed closed by a detent or sometimes a cam. They usually actuate really early in the opening process. So its pretty similar.

[@basic-decaf]

@@metamorphicorder I think you misunderstood my comment. I'm talking about the liner lock mechanism itself. It doesn't matter if another mechanism is added to assist in loading the liner lock. The mechanics Steve Mould is talking about are best illustrated with liner lock pocket knives that aren't considered assisted openers, i.e. flipper knives.

[@metamorphicorder]

@@basic-decaf not really. Thats kinda. But any pocket knife that isnt a slip joint or lock back and can have its pivot tension can be flipped or flicked open. 'Flipper' knives are essientially the same thing as a regular one handed opener with a thumb stud, its just protruding on the other side. Yeah, the finger action to flip it is sort of similar to this. Kinda. But pushing gently can also open the blade. You can also have axis or other types od locks on knives that have a 'flipper', again its not inherent to the liner lock at all. Knives are kinda a hobby of mine. Im not trying to be argumentative, its just that its not a really strong example of the princible. Even if we were talking about flicking, that would be more a kinematic result of the combination of the design of the knife and the motion of the arm. An example that does track really well though is the atlatl, the ancient spear thrower used by early humans and today by primative hunters. Its an elegantly simple version of this.

[@basic-decaf]

@@metamorphicorder You really are trying to be argumentative. If you're a knife enthusiast and had a liner lock knife without an assisted opening, you could easily test this for yourself. The liner lock mechanism itself is a deformed plate, i.e. a plate spring. As you slowly open the knife, it becomes harder and harder to open as the plate is depressed (you are essentially flattening the plate to its undeformed state). Near the very end of this rotation, just as Steve Mould shows in the video, the blade contour finally clears the point of maximum plate deflection, at the point of highest resistance, at the point of peak spring loading into the plate. Once cleared, the liner lock snaps back down to its deformed state with the force it had built up during this motion. The snapping of the liner lock not only "assists" the final opening of the knife, depending on the chamfer/fillet machined into the blade at the hinge, but it effectively locks the blade, such that there is quite a bit of difficulty unlocking the blade without deforming the plate spring again.

[@basic-decaf]

@@metamorphicorder If you have an "assisted opener" with a liner lock, the machining of the blade at the hinge will likely have a very steep contour such that it would be very hard to see any sort of assist at the end of rotation due to the liner lock. But for simple flipper knives without the assisted open, whether they have thumb studs or flipper holes in the blade itself, the blade contour at the hinge will be shallower for smoother action and better assist from the spring plate.

[@giantleprechaun9954]

Something similar to the motion is when an object is rotating imperfectly on an axis and stabilises on the shortest axis. The angle change over time does something similar.

[@samavis4869]

One thing I love about your videos is when it's about a topic similar to what I research, so I think "I can answer that!". Then I scroll down and see dozens of others who have beaten me to it!

[@PortRhouse]

For the green hinge you printed, the perfect real life example of that mechanism is a flip phone! as you pull the phone open, it resists you up until it is almost all the way open, before finally clicking into the stable open configuration. Then it only takes a tiny amount of pressure applied to the back of the phone before it snaps all the way closed again. It's also basically exactly the same form factor as the little hinge you printed as an example.

[@ishbosh]

came here lookin for this. watching him open and close the thing that looked exactly the shape of a flip phone and opens/closes exactly the same as a flip phone and yelling at the screen "FLIP PHONE"

[@t.d.3803]

I thought he was being sarcastic when he nearly held the flip phone looking device up to his ear. "Now where have I seen this mechanism before?" /S

[@iPsychlops]

I'm betting that a pistol shrimp works similarly

[@TheUnluckyLee]

I was thinking just the same. I'm sure i'd seen it before and so looked it up; and it does seem like this could be the case, as the slow motion seen here shows the shrimp pulling the claw to the open stable state, and then pushing it over to the other state to snap it shut. [kzbin.info/www/bejne/jnSZemufhc57ipo - mind the terrible sfx haha]

[@adamcetinkent]

Nah, they're mostly unemployed.

[@Mashugat]

I really appreciate your explanation of the strength/speed trade-off being circumvented at the beginning, showing how these mechanisms are able to have so much power in the first place. It's something I'm sure I learned in school, but I must've forgotten since, and has confused me in my adult life.

[@fraizie6815]

Frogs look like they might be in a stable, comfortable position when sitting all the way down with the upper legs resting against the body. As soon as they move, they quickly release a lot of energy. And of course big muscles help to quickly and comfortably get into the stable position. It also has the ilio-sacral joint specifically built to aid in jumping I'd have to look into this further but I sadly don't quite have the time to do so myself.

[@bombedcarnivore1]

That one you were looking for examples of. It's the operating principle for toggle locked firearms! Think the P.08 Luger or the Maxim

[@fraserturner112]

The way click beetles work is also a great example of stored energy

[@mkbolivianwonder]

Came here to say this! I used to play with click beetles as a kid. They are so cool!

[@timcostello2914]

kzbin.info/www/bejne/aKO0aaeIgJeMa9k i was gonna say the same

[@kilianschoenauer1184]

12:21 some trick cranes use this mekanism to flip the arm for storage to the other side its often on german wood trucks. Like Palfinger is building such cranes.

[@RobBulmahn]

3:01 "...Other things are called catapults..." **shows a trebuchet**

[@bluegizmo1983]

An example of that mechanism (or similar to it) on everyday objects that EVERYBODY has interacted with is a car door! It has more resistance when you're opening the door until it gets about halfway open then it gets easier, and the same in reverse as you're closing the door. That mechanism on car doors is meant to help keep the door open on hills and when it's windy.

[@Draaza]

Steve Mould is the science teacher we wish we had as a child He's also the science teacher we have right now

[@TheButlerNZ]

I had Magnus Pike, Vision on, Beakman, Bill Nye, the outside world (Look out your window)... and a dad that basically said... "THIS IS MY GARAGE! try not to break things"... So I was using a lathe unsupervised when I was 10.. lets see todays parent do that!

[@Draaza]

@@TheButlerNZ Today's parent would lose their kids if they tried to... teach them anything

[@TheButlerNZ]

@@Draaza I love that "A recent study' found the latest generation of kids are the 1st to be DUMBER than the last generation... I know how to set the wheel alighnment on a car... I've never needed to... but it's on a backburner with a million other things I don't actually know how I know (Friends aske me that a lot)

[@eag8999]

The large ball can deliver more energy while still being less likely to puncture than the small ball. .45 vs 9mm

[@Grand-Massive]

10:59 Jeez. Imagine being able to hit something so hard your entire body recoils like 30ft... and your hitting with your face lol.

[@countdown4100]

Did everyone suddenly forget what a flip phone is? They are even making a comeback with the whole foldable craze...

[@RealGhostface-y9b]

Nah,it's not hard to open but gets easier as you do,it's just easy to open. What you're referring to is simply the shape

[@chris-hayes]

@@RealGhostface-y9b I think your flip phone is broken.

[@GraveUypo]

@@RealGhostface-y9b no, it's this exact mechanism, only the forces aren't a big deal for us. but it is exactly that.

[@jeffclark9918]

The mechanism even looks like a Motorola Razr

[@Dylan1313]

thank you, i had the exact thought. how do people not remember that flip phones existed. the Razr is a perfect example. or even the gameboy sp/ds

[@eastermind7141]

Click or Snapping beetles are a good example of the elator mechanism

[@pugofwarbr]

it was the first thing i thought when he showed the mechanism

[@lglb]

Your mechanism is common to latches and latching switches. A pressure switch on a water system or an air compressor uses the same mechanics (using a spring vs. a rubber band). Lots of switches, latches, hinges.