What makes planetary gearboxes so amazing?
ฝัง
- เผยแพร่เมื่อ 28 เม.ย. 2024
- I knew planetary gearboxes were fascinating before making this video, but I didn't realize how amazing they actually are. My mind was blown when researching information for this video. In this video I use a 3d printed gearbox to demonstrate just a few of the reasons why planetary gearboxes are so useful.
Learn to design your own things using Fusion 360:
50% off my Fusion 360 course: mmf.io/fusion3603dpaftxex
I recommend this 3d printer for all skill levels:
amzn.to/3HCBXQT
Creality Ender 3 Pro^
UNIQUE DESIGNS: / 3dprinteracademy
Or join this channel to get access to perks:
/ @3dprinteracademy
#3dprinted #gearbox #planetarygears #ender3pro #gearratio
The red lid you took off the superglue, there’s a sharp point inside the top of it - use that to pierce the new superglue rather than the metal tool you used.
That jumped out at me too
Was going to say the same. I'd say it would be quite common to not realise this feature exists.
That's not all.. the superglue he is using is using a duo-screw cap, meaning he would've opened the sealing by just screwing the lower part of the cap tighter...
@@sisisisi1111 that'd what he is talking about
@@ditto9300 yeah, i realized it after reading the comment again.. **shame**
I love how natural you presented the process, including (1) sliiight size mistake, (2) superglue getting on your fingers (3) oops should've used gloves (4) oops should've sanded _before_ mounting (5) okay this is not turning smoothly as I wanted (6) some things are dropping/disassembling themselves. Dang.
It's clear you're One of Us 😄
Great video 👍🏼
It's what makes him so gooodddd
he is truly mortal
Repent to Jesus Christ
“But he was pierced for our transgressions, he was crushed for our iniquities; the punishment that brought us peace was on him, and by his wounds we are healed.”
Isaiah 53:5 NIV
U
I guess you can call it natural, I would call it padding, this was defo informative but it just feels like he was trying to extend the video timelength to qualify for a extra ad. Not uncommon to do this but usually more information will be added to the video rather than just drawing out what you have already got.
@@anguskeenan4932 this is literally what I was just thinking. Same as demonstration of all "6" gear ratios.... which are just 3 gear ratios and then showing them used in the opposite ratio....
The ring gear is also known as an annulus gear.
Anus gear, also known as "ring" gear
Someday I will be mature enough tp read this without laughing...
@@ambiguoustvreference835 or a ring piece.
Remove L from annulus and read it loud
@@nicerknifes9465 no, you won't. Me neither haha
Monster trucks use these inside the wheels so the planet carrier is fixed, the sun gear is attached to the axle, and the ring gear is bolted to the wheel since it puts so much stress on the engine to rotate the huge tires.
Wow
My man! Remember watching this on Modern Marvels when HC didn't go full reality.
First time I learned about it.
My dad's 4 wheel drive Versatile tractor had that setup too.
@@deviljon not surprising since monster truck axles are adapted from heavy equipment axles. Monster trucks also have inboard disc brakes at the differential.
Bulldozers do the same with the drive
This is a wild coincidence. I've been having issues with my automatic transmission that I rebuilt. To wrap my head around how it's really working and what the problem is, I've been modeling it to 3D print a small replica. I've got two of the planetary sets done, but I need to figure out a one way clutch and how to manipulate the regular clutches. It's a big project, but will be awesome fully printed. (well somewhat small). A U140e transmission (plagued with problems).
Keep me posted if you are able to finish the project! You can use the "contact me" page on my website, I'd love to see if you can pull it off!
@@3DPrinterAcademy Printing parts as I go. The first gear planetary fits good so far. There's a lot of parts to it. I did get a one way clutch to sort of work, but more testing is needed. Still thinking about the clutch packs though.
@@squishy312 replying cause this sounds cool and I want updates.
I used dual clutch transmission instead. If you go the Lesics TH-cam Channel, you'll know how it works.
My grandfather taught me how to rebuild a 3 gear longitudinal automatic transmission and it looked crazy but the planetary gears weren't the complicated part. The valve body seemed insanely complicated some type of a mechanical computer
I think the table is misleading. Those ratios only work for a planetary gear systems with the same number of teeth on each gear.
I made a clock with a planetary gear system and the sun to plant ratio (with the ring stationary) is a 6:1 ratio
yeah it depends on the number of teeth on each gear
I wouldn't say misleading. He did say that was a factor.
@seth polevoi ur misunderstanding might be that the table at the end is just for the planetary gear system he 3d printed in the video. Different planetary gear ratios will depend on number of teeth and sizing for sure, so that's why your clock one is different 👍
He did admit right after that it also depends on teeth number, and I’m pretty sure he was talking about that specific one because it is downloadable and to explain it better.
Is it possible to get a 1 to -1 ratio?
The leaking superglue was a plot twist i did not see coming. Out of left field. Really threw me for a loop. This is great cinematic storytelling. Nice little subplot to the overarching narrative.
When I was an automatic transmission tech back in the 90's, I thought (and still do) that the coolest transmission was the 700r4 (the same gearsets used in the 4T60, 4T60E and 4T65E). Using only two planetary gearsets, it achieved 4 forward speeds (4th as overdrive) and reverse, and was the most compact 4 speed transmission of the 90's.
That was the one the third gen f bodies used, from the 80's
4l60, 4l60e, 4l65e. But yeah the 4t60 is just the front wheel drive version.
I think its rather nice that the dodge 4 speeds used an extra planetary gear-set. They only have 4 clutch packs, rather than the 7-9 clutch packs of a 4l40 or 4l60 series trans.
They also achieve 4 speeds with only two sprag clutches, rather than the 2-3 in the gm trannies.
Its crazy how both sides went on achieving 4speeds. Ford and GM made trannies from scratch, while Chrysler, really Dodge, expanded on their existing 3 speed by adding a 3rd planetary. Imagine if GM did this with a 3 speed powerglide.
No one ever talks about the 4L30E transmissions
@@moto083c Maybe there's a reason for that?
This a cool project, but I still have a couple of questions...
How did super-gluing my gloves to my hands assist the gears?
How do I remove the gloves now? (You did that bit off-camera!)
Super glue is removable with nail polish remover, cheap and easy. Be careful though, it damages some plastics!
All plastics*
@@danielthecake8617 it's in a plastic container though
It doesn't dissolve plastic, it softens the bonds to other molecules, meaning higher
density plastics are almost unaffected.
@@dane7961 They use a specific plastic built not to break apart.
On heavy truck in the UK this gearing is used in the drive axle hubs, we call them double reduction hubs, it reduces the size of the crown wheel and pinion, thus giving the axle a higher ground clearance. 🇬🇧
I think making inner handles' ends longer than the outer ones would make it more comfortable to rotate.
But the ring gear is on the outside? Like you could do it but it's not as easy as just make the rotor longer than the sun gears
@@gavinsreid They meant the parts you hold that are horizontal.
Adding electric motors to the gearbox effectively turns it into a cvt.
A thing toyota made in their hybrids.
It works by spinning two of the 3 components in various directions and ratios to acheive infinitely variable gears.
It is also probably the most reliable transmission ever created, as there is no friction material, nor a torque converter, just gears and electric motors.
That's how geared hubs for ebikes are. The weakest link are the blue gears in this video, those are made of nylon in most motors. Those have a 5000+ km lifespan.
Wouldn't that need variable input speeds to work?
@@revimfadli4666 that is what the electeic motors are for. One sits on the input shaft of the engine, and can rotate faster, slower or in reverse for lower gears. It is capable of generating electricity from the engine when needed.
The other sits on the output shaft and varies the rotation as well as acts as a generator when breaking. There are many videos explaining this in a much more concise way.
I though cvt used a belt situated between to cone shaped gears.
@@fredtaylor9792 a CVT means infinitely variable gear ratios, and there are more then one method to acheive that.
Those are called belt driven CVTs. This is an electric CVT or eCVT.
When John Deere came out with their power shift on the tractors, the 6 to 7 or 7 to 8 shift was very harsh. The dealer advised that was because one of the planetary gears, had to switch its direction of rotation, to complete the shift. Now it all makes more sense.
Just one? Interesting because what you say means that at least one planetary gear is independant from the rest somehow. Id love to see that gearbox.
The thing that people don’t understand about the gear wars is it really was never about the gears
It was about Rick 😂
This is by far the best planetary gear system explanation I've ever seen
What clearance are you using for the things to rotate when printing? Like how much gap is there between the pins in the planet carrier and the inside of the planet gears for them to spin freely without much friction?
I find 0.4mm usually works great
Depends on the printer and material. I normaly get away with 0.2mm with PETG
Copied from my notes I use for my own projects:
.5 mm = 20 mils = fairly loose, some catching
.35 mm = 15 mils = tight fit, fairly easy removal
.25 mm = 10 mils = very tight, removal difficult
I use PLA in an Ender 3 Pro, which is a fairly common setup.
I've always preferred to use other adhesives like contact cement over superglue. IME superglue is *exceedingly* effective at sealing its own container shut, and it's nowhere near as good at adhering anything else.
Troo dat!
I don't know how it works in fusion 360 but in onshape there's a setting for backslash in the gear tool which makes it really easy to change the tolerances... Great video btw!
Your model and explanation are the most clear i have ever seen! I am going to show this to my children so they can understand this powerful concept
BUDDY!... I have been in automotive business my entire life and have increasingly seen this gear setup used in one more places over the years. Due to the detail and explanation in this video I can totally see why! For the first time! Brilliant! Thank you so much - so very sincerely
1:01 thanks for the information
Another amazing feature of the planetary gearbox is the amount of torque it can withstand,due to the large amount of contact of gear teeth.
Do you think the depth of the gear (thickness) of the gear also contributes to the amount of contact of gear teeth, thereby, helping to withstand the torque? Just a question that I began to have after reading your comment.
Uh.. I don’t think so.
It’s like a chain.. only as strong as its weakest link. The sun and planet gears are really no different than spur gears. It’s just the planets and ring gear that have more contact because the ring gear is an interior gear.. but more contact also means more friction.
Thank you for this video. It is informative and inspiring. For 40 years, I've wanted a special planetary gear design, made from lightweight materials. With modern technology, software and 3-D printing, maybe I can now make it myself.
Great video. I had a gear system like this in an old drill I took apart. I threw the drill away but kept the gears for ages as it was just a cool thing 😃
This is very helpful for the turbojet engine that I am designing, I need the intake fan to be spinning much slower than the compression fans. A planetary gear set is perfect for it.
I've had 5 or 6 different bicycles with different hub gears. I've also worked repairing pneumatic tools including their planetary gearboxes. This is by far the best explanation and demonstration on how they work I've ever seen! The energy flows of planetary gear boxes can be hard to understand but you made it easy. Thanks!
Planetary gearsets are very cool . I learned about them in my 4th year apprenticeship of auto mechanics . Most newer transmissions use a double planetary gearset . Very cool stuff .
Very well done! Easy to see the concept! And it's a good concept to see! This concept was deployed in many of the earliest and most successful transmissions of many early cars. Ford loved this configuration and used it with great success on the Model T.
Good design. I would try to incorporate ball bearings, and make the gear teeth helical for smoother and quiter operation.
And I would do different designs to show a better view of how 5 drives work. Neutral, Reduction, Overdrive, Reverse, and Direct Drive.
Helical gears would put an axial force on the members and complicate it further.
You have created one out of four axles on a monster truck or the back half of an automatic transmission. The part after all the fluid has done the work.
That is pretty cool I wish they had 3D printing when I was in school to help people visualize and understand things like that. Instead we had a cutaway of an old transmission😀
He created a repop concept of one of the earliest and most successful transmissions of many early cars. Ford loved this configuration and used it with great success on the Model T.
i work with alot of related gearboxes like this on electric bikes and shimano nexus, this was a really good way to explain it. deffnitly gonna get one these printed for everytime i have to try to explaine how a planetary gearbox works to someone. going to save me so much time =)
Thank you for the video. I've been watching transmission teardown videos for a while and couldn't figure out how a planetary system created the different gear ratios. Your video made it make sense for me.
Sturmey- Archer 3 speed bicycle hub is made this way. When you have it apart you can figure it out, but it's not obvious.
Nice video and explanation. Always impressed when TH-camrs just design and 3d print a model as a part of the demonstration. I thought that automatic transmissions worked with fluid dynamics? Always like a day at the library.
They do! The final drive of the shafts is similar once you get beyond the torque converter and down to the output end. He'd have been better concentrating on transmissions in general rather than confusing the issue with auto vs manual transmission as it's arbitrary.
That 2:3 ratio you were getting is actually how the Ravigneaux gear set gives the 33% Overdrive on the Ford AOD transmission...It's a very simple design and works really well if maintained properly.
Awesome demonstration and well explained! Thanks so much for sharing this with us! I found that you cut 24 Teeth into the Sun Gear and 48 Teeth into the Ring Gear. Take the sum of the Sun and Ring Gear to use as the value for the Planet Carrier (72 Teeth). The Ratios are easy to figure after that.
I've always found it hard to understand planetary gears, but this video helped me!
Wonderful experience and thanks you 😊
Your experiment is priceless
it misses some on the actual benefit of such gears
Genius.
I am infatuated with Unimog trucks and for 15 years I've wondered how their drive train works.
And now I understand about 75% more than I did
Thank you
Made a set of these at work not to long ago but had no idea how they were applied. Nice work
We have all had things go wrong when building something. What matters most is the end result and yours is amazing!
Simple but looks amazing
Consider using dichloromethane (DCM) instead of superglue for PLA or acetone for ABS. This gives a much stronger and more reliable bond
Good explanation and well demonstrated. Also I liked that you do not edit out your errors or sticky finger problems.
A very impressive demonstration. Thank you!
Working in the automotive field it ain't pretty when these fail. Mostly because of not changing the transmission oil at service intervals or neutral drop shift.
The "Power Split Device" in a Toyota Hybrid Synergy Drive E-CVT transmission, is a planetary gear set, just like depicted in this video. In the Toyota Prius, the original application for HSD, The Sun Gear is splined to a 30hp, 3-phase synchronous motor called MG1. The Planet Gear Carrier is splined to the gasoline engine, and the Ring Gear connects two ways, to the front wheels and via the Differential gear set, and to a 70 hp synchronus motor, MG2. The genius in this system is provided by the software that controls the overall flow of power to and from the gasoline engine and the two motor generators. MG1, the smaller, 30 hp unit, has two jobs: to reclaim kinetic energy when the vehicle needs to slow down, via "regenerative braking", and to control and limit the speed of the gasoline engine. At any given vehicle speed, the computer can adjust power flow to MG1, and thus control how fast the sun gear is spinning, or even make it spin backwards, and this indirectly controls how fast the gasoline engine is spinning. The computer is programmed to try and keep the gasoline engine running within it's most fuel efficient range of rotation speeds (1,000 to 2,500 rpm), and to limit the maximum speed of the engine to about 4,200 rpm. While the gasoline engine is being controlled by the computer via MG1's spin on the Sun gear, the computer is simultaneously controlling power supply to the 70hp MG2 motor. How much power can be delivered by this motor is influenced by the state of charge in the traction battery, temperature and power limitations in the inverter and motor stator, the power demand by the driver or cruise controll, steepness of the terrain, altitude and oxygen supply in the air intake to the gas engine, and several other factors. The computer makes thousands of decisions every second, and is programmed to optimize all of the components in the power train to deliver the maximum fuel efficiency, and minimize tailpipe emissions to keep the Government happy. It's not just Toyota, of course: many manufacturers sell Hybrid cars, and most of them use technology similar to the Toyota HSD, in which a planetary gear device is central to marrying one or more electric motors, a large battery, and a gas or diesel combustion engine in a unified powertrain that uses electricity from the battery to propel the car whenever possible, and use as little fossil fuel as possible.
Awesome explanation! Nissan licensed Toyota's Synergy Drive so they used the same PSD. Honda and most other did not and instead mated an electric motor to either a standard automatic or CVT transmission which was nowhere near as efficient or reliable. The PSD is an ancient concept that was tailor made for hybrids.
After taking apart and reassembling several automatic transmissions, I didn't know some stuff from this video. Nicely done.
When I was training to be a helicopter mechanic at Fort Rucker in Alabama, I had the opportunity to see the planetary gearbox of the UH-1 helicopter. It was a beautiful thing to behold. The intricately machined parts fit inside each other with incredible precision.
Humans can make amazing things...
Only to destroy everything later.
That's why Aliens don't visit us.
Great demo! Thanks, it's helped me understand how planetary gears work.
I also see its not just me who gets themselves in somewhat of a mess with superglue.
I would've somehow got myself stuck to the inside of the glove too!
it misses some on the actual benefit of using such gears
Has anyone ever used superglue without a drop somehow getting on your finger?
yes
Has anyone noticed there’s a sharp point inside the cap the superglue to pierce the silver seal on the new superglue.
@@darktherapy r/wooosh
when the stars aline sure. for every other time I prefer latex gloves
I know this is a 1 yo post, but I have something to share. I got a couple of small cuts on my hands whilst repairing my dishwasher some time ago. I wanted to glue them so that I could go back to work. The problem is I dropped the damn thing and managed to step in the glue afterwards... So my Birkenstock got glued to the floor 😢
I had thought that no glue got on the floor while I inspected it.
Now this is satifying to watch it can also give a perfect explanation on how time itself works
Wonderful explanation of something that I have never totally understood until now and I’ve worked on them in hydraulic winches and only had a vague understanding of them until now
The latest example of using a planetary gearset is in the design of a Toyota/Lexus hybrid transmission. It's nothing more than the internal combustion engine (ICE) driving one of the planetary cranks and an beefy electric motor driving another crank, with the third crank tied to the wheels. Either the ICE or the motor or both can spin to drive the wheels, and by using a computer and a gigantic 600v battery the motor can actually spin backwards, as needed, in order to match the desired ICE rpms to the wheel rpms. The whole thing is brilliant and totally transparent to the driver, and since it's nothing more than just a planetary gearset it's indestructible. And no "shifting" per se--instead, the computer just directs different motor and ICE rpms to meet the wheel rpm needs. Toyota calls it a Continuously-Variable Transmission (CVT) but it has nothing in common with the old-fashioned CVTs that used cone-shaped pulleys and a steel drive belt that would eventually fail.
The worst thing about this design is how they have to protect it in low traction surfaces. If you get snow and have hills they are terrible because they can’t allow a spinning wheel to suddenly gain traction or parts break. You can have your foot planted and the car will just slowly come to a stop in the middle of the hill. I think they have a ton of room for improvement.
This is basically the Toyota Hybrid transmission. The car's wheels and large electric traction motor are attached to one shaft, the gas engine to a second, and a smaller electric motor is attached to the third shaft. It's much simpler and more durable than using a belted CVT and it allows lots of different modes of operation. The gas engine can idle at a stoplight to charge the battery or provide cabin heat, or the transmission can allow the car to be driven by the electric traction motor while the gas engine is off. Mechanically, the system is simple and robust, but it takes a lot of advanced high-power electronics and computers to make it run smoothly.
this was the best video for explaining planetary gears that I've seen.
Boy did this bring back memories... a VERY long time ago when I was a young teenager I taught myself how to rebuild Ford(1949-1954) 3-speed transmissions with a Borg-Warner overdrive. An interesting fact about those overdrive units is... when the O/D was manually selected, but not engaged you would be in a 'free-wheeling' situation so when you let up on the gas the engine would simply go to idle. When you got up to around 30mph and let off the gas momentarily, a solenoid would engage the O/D. The free-wheeling was necessary when you were running down the road so there was no load on the O/D gears during the shift. The really interesting part was... (lets say you wanted to pass) when you floored the gas pedal it would depress a switch mounted under the gas pedal. That would actually short out the engine coil (just like you turned the ignition off), which would in turn remove any load on the gears, then the unit would shift out of O/D. If you did not want the O/D to engage at all (town driving) you would manual select 'no O/.D'. That would lock up the planetaries on the sun gear. Fun memories I have not thought about for a very long time.
Last year I’ve learn the formulas and calculations to know the gear ratios depending on the number of gears and which handle you turns. It’s quite a mess but a nice mess in the end.
The gear ratios don't depend on the number of teeth on the planetary gears. Just the sun gear and ring gear.
I know that your ring gear has 2x as many teeth as your sun gear because it produces a 2:1 ratio when the planetary gears are held still.
Great model and explanation. Thank you, brilliant work! 👍
The Ford Model T had this simple gearbox as well. The Model T didn't have the standard pedal layout we know today, it had one pedal for first and second gear, a pedal in the middle for the reverse, and another pedal for brakes c:
I hope that's right.
Excellent video, very good information density per unit time.
Can you model a v8 engine block with pistons and crankshaft?
Holy schnikey's that's insane! I knew the basics of how a planetary gearbox created reduction but I had no idea you could get multiple ratios out of one set of gears like that
that large black sheet you were working on looks like what came with my Ender 3. And its what I put down on the table when I superglue as well!
Always wondered exactly how the ratios were achieved. Now I have to find something else to always wonder about.
Can we see it being use with some kind of motor?
My sincere compliments for including your whoopsies, instead of pretending you're a flawless god by leaving them out. This was a lovely, educative watch! Thanks!
I love the gearing on the champion hand crank forge blower. One turn of the handle, turned the about 60 revolutions.
When I'm printing parts that will fit together I generally print the outer part with a 101 or 102% scale. It fits better without losing it's properties.
Can you please make a tutorial about modelling this planetary gear in Fusion 360 for 3d printing like you did?
*Everyone who agrees with me leave a like.
Thank you for the video! I was curious how my excavator planetary drives work and I think this satisfies it!
Needed this for a reminder on how gas turbines achieve counter-rotating blades in designs where turbines rotate at a different ratio (and different direction) to compressor blades.
If you vary the speed of individual handles you get a continuously variable gear ratio. This is what Toyota uses for their hybrid transmissions.
That's not how CVTs work. They usually use belts on tapered discs, or other friction based mechanism that can produce arbitrary changes between drive and driven axles.
@@batlin belt or chain driven is the most common but there are more ways to achieve a CVT. The Toyota hybrids use a planetary gearset for example.
Engineers will save the world. No idea who came up with the automatic transmission, but thanks to them, the whole world can drive instead of shifting through their own gears.
Some people will never be able to learn manual transmissions. Even guys.
And they should not be able to drive then
Sometimes I like shifting through gears
@@NICKCAMP04 I'm just more concerned how these people can survive, when they cant understand simple thing. Slow releasing of clutch. That's all it takes
7:00 the beat drop was lit
I'm super early for this one. 😁😁
It's why I prefer internal gear hubs for my bicycles. Everything critical is enclosed. If you make sure the shift cable is properly adjusted and give them some oil now and then they run almost forever with very few problems.
The ZF 8hp transmission utilizes this design. Absolutely love the trans, 8hp75, in our Wrangler rubicon ecodiesel.
OMW. Yt algorithm wins again. Coming from eskate boards this is so relevant as gear drives are now being used as an alternative to belt drives and direct drives.
Also need to learn how to 3D print components for my boards so this video is excellent. Great presentation and easily accessible. Thanks so much.
Tip: the end of the glue tube cap can be used to pierce the new tube. In fact, the cap is designed to do so. Great job with the gears.
Nicely done. Makes a lot easier to watch and understand. Thanks.
it misses some on the actual benefit of using such gears
Thank you I have been asking for a planetary gearbox thank you 😊
This was priceless...
PRICELESS.
YOU ROCK..
THANKSA TON
Very nice how complex ,and self-contained.
Man, reduction gearbox in a T-56 has a planetary gear system with 5 planetary gears. Was one of the coolest things to study in tech school.
Thank you for making an interesting and informative video!
@3dprinteracademy Which orientation is best to print the ring gear? I am having difficulty with supports
Is it a setup like this that enables rotating radar antennas to maintain power without twisting the wires that feed them?
In the process of rebuilding the transmission in my car, this 3 pinion planetary gear set is also in Chrysler A727 transmissions, later transmissions had a 4 pinion planetary gears.
Gear reduction ratio in first gear is very similar to this model of 2.23:1
very educative. Thank you regards
I got to learn a little bit about these when helping fix a crane at work. There's what's called a planetary gearbox that uses hydraulics to spin the gear and make the crane rotate. I had to disassemble and clean it up. It was a Linkbelt crane. All together, I'd say it weighed 300 pounds.
wow nice demonstration it's very clear to me now, they always used to confused me. This is so cool I never know what to make, guess I'll start making one for the kids for next Christmas! I better start now or I'll never finish in time lol.
it misses some on the actual benefit of using such gears
Very nicely done. The rotation is very cool. Was there a special reason to print the white base in 2 parts?
Loved watching you put on gloves. Best part
I first knew about the planetary gear in a motorcycle supercharger.
Cool stuff
That was a very nice video!! Thanks for the upload
Superb simplified explanation 👌
tell a combination in such a way that, regardless of the direction of the input, the output should always be in one direction
Thanks alot, I've been trying to understand how planetary gears work, this video certainly did that. Its much harder to understand on google
This is the cutest form of gears!