Mastodawn

When I was a kid, I sometimes wondered how a sprinkler "knew" how to change directions without being powered with electronics. I think it wasn't until I was in my late 30s that I came across this GIF and I realized how insanely genius a simple sprinkler really is.

EDIT: Some people have kindly pointed out that this GIF was in fact from a demonstration on how different gears function and not from an actual sprinkler as I had originally led to believe. Other people have been assholes about it.

@SKleefeld and then there is me: "what the fuck are they talking about, this thing spins CW all the ti - oh."

NormanDunbar Jul 7

@utf_7 @SKleefeld Psst. I thought that too. Then noticed the little gear.....the penny dropped! 🙂

jimkennedy Jul 7

@SKleefeld thank you for this.

Marty Fouts Jul 7

@SKleefeld and the best part is that is only one of perhaps a half dozen ways to do it mechanically that were in use when I was a kid.

@MartyFouts @SKleefeld We demand more gifs!

The Mane Six (Octo Version)Jul 7

@SKleefeld Oh, this is way more fascinating and descriptive than our previous explanation of, "I dunno, gears or somethin', innit?" Thank you for sharing!

Piiieps & Brummm Jul 7

@FurryThrowPillows
You were right. This IS a kind of gears. :-)

@SKleefeld that’s brilliant! Is it usually the small normal looking cog that runs at constant speed, so the large strange cog has two speeds and directions?

Sean Kleefeld Jul 7

@benjohn It's the large, weird gear that's constant, but because it has teeth on both the outer AND inner circumferences, that is what changes the speed and direction of the smaller, normal-looking gear.

@SKleefeld I see the direction and speed change 👍

What I'm not getting is that the little cog spins fast for many more turns than it turns slowly? This seems like it would not bring the head back to its original position?

Sean Kleefeld Jul 7

@benjohn Someone else pointed to the source of this image. It was part of a display just to showcase the principle, so this specific set of gears was not used in production.

@SKleefeld ah! I really want to see how the whole things works now. I spent a while looking last night, but didn’t find this specific kind.

Sprinklers
https://youtu.be/jKi7xGE4BEw?si=eJ9E2Oi_9k4cwAYS

The Impact Sprinkler - more clever than it seems!

YouTube

gloria dei Jul 7

@RnDanger @SKleefeld Yes, this is the standard reversing sprinkler, with a completely different mechanism (driven by the water jet).

Benjamin Braatz Jul 7

@SKleefeld Doesn't it then always turn further in one direction (when the outer teeth turn it) than in the other direction (when the fewer inner teeth turn it)?

Sean Kleefeld Jul 7

@HeptaSean Not further, just faster

Benjamin Braatz Jul 7

@SKleefeld But the small cog wheel makes a few turns clockwise, but not even one counter-clockwise each round.

@HeptaSean @SKleefeld Exactly. I doubt this is from a sprinkler, but hey, internet. Everything is true if its popular 🤷

Sean Kleefeld Jul 7

@gernot @HeptaSean Any thoughts on what it might be from then?

Sean Kleefeld Jul 7

@gernot @HeptaSean Someone else pointed out the source of the image. It comes from an engineering display/demonstration and this specific gear setup was not actually used in production.
https://www.youtube.com/watch?v=3aobPgGzB-U

gear system that changes direction

YouTube

@SKleefeld @HeptaSean I was thinking that the inner ring of teeth would want to have the same tooth count as the outer ring, but substantially more period. Here it has the same period as the outer, but many fewer teeth. The little cog would then get back to the same place that it started. The speeds would still differ though (as here). It’s a really beautiful gizmo - thank you for posting it.

@HeptaSean @SKleefeld I guess nothing stops you, with this design, to make sure that the number of teeth on the outer ring are the same as the number of teeth on the inner ring. Then the second cog would go the same distance in each direction, albeit at different speeds.

John Sturgeon Jul 8

@HeptaSean @SKleefeld

I'm thinking the same thing.. .I have no answer for that. I also don't know what’s turning the main gear if not for electricity. The whole post makes no sense.

After some digging turns out it has nothing to do with sprinklers.

Benjamin Braatz Jul 8

@johnsturgeon @SKleefeld To not be too mean: It is an interesting mechanism and oddly satisfying. And in another reply was a link to a YouTube video explaining one other type of sprinkler. So, all in all, this thread was totally worth the time.

Ari [APz] Sovijärvi Jul 7

@SKleefeld The biggest brain explosion were the "smart" sprinklers, that had a dial that selected various "programs". It was bit of a magic until I got to take one apart to discover that the dial just moved one gear up and down, selecting which center/outer gear it was interfacing with. Such a simple idea for something a modern mind would instantly use a microcontroller for.

@apzpins @SKleefeld I had a similar reaction when I read about how this toy robot arm relied on mechanical cleverness rather than a bunch of servos:

https://www.starborneworks.com/?p=22

Ari [APz] Sovijärvi Jul 7

@mirth That design actually reminds me of commercial robots, where there's multiple gears at each joint.

I worked in a large CNC facility and got to see 6 axis machines open several times, some have really funky looking gear setups inside the joints. Puzzled me so bad how they got rotating motion across the joints seeing there was no space for strong motors in the arm itself.

Efi (nap pet) 🦊💤Jul 7

@SKleefeld oooooooh, neat

Riley Labrecque🎏Jul 7

@SKleefeld I can hear this gif!

@SKleefeld that is bloody brilliant

verified_dragon

The things we can do with gears!

Engineers are magic tbh

@SKleefeld Pardon my pour English. What is it you call a sprinkler that has such gears inside ?

Pick Nick 🇨🇦Jul 7

@PH7831 @SKleefeld

Un arroseur de pelouse?

Quinn Comendant Jul 7

@PH7831 @SKleefeld There are no sprinklers with gears inside like this. The best guess is use in laundry machines or ice makers.

The gears in the GIF here are nonfunctional; they're part of an engineering exhibition, see here: https://www.youtube.com/watch?v=3aobPgGzB-U

gear system that changes direction

YouTube

Sean Kleefeld Jul 7

@com @PH7831 Oh, fantastic! I've seen the GIF for years but never knew the source! Thanks!

autistic plushies Jul 7

@SKleefeld this is so cool

there are minecraft mods that add gear blocks, that behave somewhat like gears. create and crossroads

in create, alternating directions regularly i think would need either some redstone and some precise timing or a magical block that turns input rotation into arbitrary sequences. and the former would need precise timing because instead of jamming, create components break when exposed to contradictory forces.

in crossroads, you can get a bit closer to this; you can have two gears that rotate a third gear in opposite direction, and have exactly one of them have gears (and thus connect to the output gear) at a given time. still sort of magic-y, though.

in nodecore, which is not a minecraft mod but rather a completely different game, you could probably build, not quite this since gears have a fixed size, but something similar. because the gears there are made up of fungible components, you can actually customize them yourself instead of relying on built-in special cases.

notsoloud Jul 7

@SKleefeld
A different type moves by the force of the water swinging a small spring loaded hammer, that knocks the nozzle a little to one side. At some point the nozzle gets to a device that makes the hammer move the nozzle more quickly in the opposite direction. You can know them by the sound: tchou gah tchou gah tchou gah tjk tjk tjk tjk tjk tjk tjk tjk.

They are powered solely by water pressure and very neat, because you can set the angle they cover by small metal loops.

John Wilson Jul 7

@notsoloud @SKleefeld

Out here in a life irrigated …

https://youtu.be/IFIN1faED_s

Nelson SR200 Big Gun High Volume Sprinkler

YouTube

@notsoloud @SKleefeld @TechConnectify made a great video on them https://www.youtube.com/watch?v=jKi7xGE4BEw

The Impact Sprinkler - more clever than it seems!

YouTube

Femme Malheureuse Jul 7

@notsoloud @SKleefeld You're referring to an impact sprinkler.

See the adjustments beginning at 1:12 in this video: https://youtu.be/7MdnOfgtm5c?feature=shared

This is even more simple than a gear/cam setup and doesn't use plastic components.

Dramm ColorStorm Impulse Sprinkler: How to Adjust & Use It | The Gardening Products Review

YouTube

Eh Eye Ate Dub Yah ✡︎

Reminds me of how a rotary dialer works, too.

Doppellhelix Jul 7

@SKleefeld
Genius

@SKleefeld This day I have also been enlightened.

Axel ⌨🐧🐪🚴😷 | R.I.P Natenom Jul 7

@SKleefeld: I imagined it to work like the clicky top of a ballpoint pen or a push-button light switch. So thanks for that insight.

johngough Jul 7

@SKleefeld there’s something insanely satisfying in this. “Ah would you look at that” kind of thing. Nice

シナモンエノーラ

celeste_hearts_catgender

@SKleefeld You'll love this video about basic mechanical "patterns"

https://youtu.be/mAOCiyUV83I

Mechanical Principles - 1930

YouTube

Sean Kleefeld Jul 7

@cinnamon Amazing what a small change to a simple gear can make!

WildRikku Jul 7

@SKleefeld Cool! I never had one of those, but I did have a switch that had one input and six outputs and every time water stopped it would switch to the next output. That way I could cheat and use a cheaper 2-program water "computer" (timed valve) but really have 6 fields. The switch actually used the water pressure drop to switch, no power needed, I loved that.

@SKleefeld I spent a lot of time as a kid thumbing through this old book called "507 Mechanical Movements" trying to figure the diagrams out. It's full of exactly this stuff.

Anyway I just had to go check to see if this one is in there, yep, #216. It describes the mechanism as only "The external and internal mutilated cog-wheels work alternately into the pinion, and give it slow forward and quick reverse motion."

Lydia Trivia Jul 7

@SKleefeld the sprinklers that I wondered about as a kid were the ones that go chh-chh-chh-chh t-t-t-t, which have a more complicated mechanism to go back and forth

https://www.youtube.com/watch?v=jKi7xGE4BEw

The Impact Sprinkler - more clever than it seems!

YouTube

Paul McO'Smith III Jul 7

@SKleefeld i hate science.

cedill-yap yap Jul 7

@SKleefeld
I suggest, the best website ever
https://507movements.com/mm_216.html

EDIT : found the right number (216)

507 Mechanical Movements, 216

Mechanical Movement 216

Roy -- the dull one Jul 8

@cedilla @SKleefeld

A very interesting website, indeed - thanks!

MegatronicThronBanks Jul 7

@SKleefeld The 3-piece bonnet-catch (that's 'hood' for our US friends) on old Toyota Corollas and Coronas is still the single cleverest mechanical device I've ever seen.

John Sturgeon Jul 8

@SKleefeld @milgrim
Nope. It's not a sprinkler mechanism. Let's keep Mastodon free from this stuff shall we?

@SKleefeld
What movement pattern does this sprinkler follow?

I see the little cog spends half its time going anticlockwise slowly, and half going clockwise quickly. So the sprinkler wouldn't just be going back and forth on one arc??

Or is this just an example, and a real device would have an equal number of teeth on the inner and outer rings?

@SKleefeld If You're thinking of the sprinklers that make that trademark "Pfff Click click click click" noise as they rewind, that's a different mechanism. A more clever one, I think.

https://m.youtube.com/watch?v=jKi7xGE4BEw

The Impact Sprinkler - more clever than it seems!

YouTube