Thanks so much for sharing this! This really simplifies it as opposed to other explanations. This makes planetary gears far less daunting. Thanks Justin!!!
WHAT? You're not going to first make my eyeballs bleed with 30 minutes of riveting footage defining angular velocity? Thanks for the quick and easy explanation! I appreciate it!
THANK YOU Justin! Absolutely fantastic educational video! Straight forward, and to the point! Extremely easy to follow..... and thanks to your Working Examples...... extremely easy to calculate & apply!
Cool explanation ! Quick questions : how does the operator select which gear is the driver then? How do I know the efficiency of the transmission? (there must be some energy loss) How do I use this is real life applications? (say I want to move a 100kg load on a small platform with 2 or 4 wheels. How do I work out the torque required?) Thanks!
Awesome Video, Perfectly informative. What is this Specific Planetary out of? I need this type of Planitary to make a Planitary Hub for a racing application, thanks!
thank you. this helps me so much. how do you calculate the ratio with different amount of planetary gears? does it even matter? some have different size planetary gears in them.
thank you! what i didn't understand though, is why you said we don't count the teeth of the planetary carrier. Why not? Certainly there are in fact a fixed number of teeth on one of those planetary carrier gears
Hi, this video was very helpful, thanks a ton. I have a few doubts though. 1. If the number of teeth on planetary gear is calculated by the sum of the teeth on ring and the sun, how do we calculate the teeth on each planet gear? 2. does this depend on the number of planets we have? thanks again
1. The planet gear has to be the right size to fill the gap between the sun and ring gears, so in this case it needs to have 30 teeth as the radius of a gear is proportional to the number of teeth (For a given gear module - which is a fancy way of saying tooth size). The diameter of the ring gear is equal to 2 x planet gears + 1 x sun gear, the sun gear has 30 teeth, the ring has 90, so 90 = 30 + 2 (Planet gear teeth), which solves to give 30 for the planet gears. 2. Only one tooth at a time usually carries the entire load between when 2 gears when they mesh, so the more planets, the more teeth are available to carry the load, so the higher the torque that can be carried by the ringset. The number of planet gears has no effect on the ratio. Keep in mind that for most applications nobody cares what speed the planet gear turns at, it's the planet gear carrier that's working as an input or output. The speed the planet carrier turns at depends on the difference in speed between the ring gear and the sun gear.
What about when the planet carrier is always held still, and the ring is the drive and the sun is the driven, I need help on what I’m trying to make with ratios
May I ask you a question? You said that: Planet Carrier = Sun + Ring. In this case, we have 3 planet gears. But what if we only have 2 planet gears connect to the carrier? Is this formula still true?
It would be since it isn’t based on the amount of planetary pinion gears are in the carrier, but on the circumference of the carrier which the pinion gears make up. Think of it like drawing a circle and putting two points on either side of the circle. It’s still the same circumference, even if you double, triple, quadruple, etc. the amount of points, it’s just more areas of contact.
Justin, can you please tell me where you got the planetary gear set in the video? I am looking for an off-the-shelf planetary gear for a project and it appears that what you have would be about perfect. Thanks!
It's just an idea! The idea is that: One to three is a completely balanced gear ratio for one link of a coaxial gearbox. This, for example, is optimal for a wind turbine, where the loads change by about two orders of magnitude - this is 100 times! Switches must be made between these links. And so: 1:3:9:27:81:243 Six-speed transmission. The wind speed acting on the entire washed area of the fan - this theoretical perspective windmill, varies from 2 m / s to 32 m / s! And the power removed from this electric generator varies from 2 kW to 200 kW! That's why you need such a reducer. I mean - It's a crazy idea to use a wind generator for hurricane winds. And, at the same time, - for very quiet winds - almost calm! For small autonomous settlements or even for separate remote buildings. The coaxial gearbox has an advantage both in terms of the weight of the metal, and in terms of the efficiency of the interaction of gears, and, probably, in other parameters. Perhaps the same gearbox is suitable for other technical objects, just need to think about which ones. Considering the remarkable parameters of the coaxial transmission scheme of the mechanical moment.
Then for the planet gears / pinions, we just estimate the number of teeth on the ring and sun gears, and add them up - or if desired, count the number of teeth exactly, and use the result to do the calculations ? Isn't there a precise formula that would be used for this ? There must be, or engineers would just be guessing when they make their designs.
So if I had a sun gear with 12 teeth, a ring gear with 60 teeth, and the planet gears had 24 teeth each, I would add the s12+r60 = 72 and the p24 x 3 = 72 because I have three planet gears that would be a 6:1 gear ratio?
No, that isn't correct. You don't ever count or use the number of teeth on the planet gear when determining the ratio. The planet gears are idler gears and their speed is always going to be a result of the speeds of the sun and ring gears. To figure out your ratio, you need to determine which of the three components are acting as the input and output gears, and then divide the number of teeth on the output gear by the number of teeth on the input gear. If the planetary carrier happens to be either the input or output gear in your scenario, you should not count the teeth, but use the sum of the number of teeth on the sun and ring gears for your number. I hope that helps!
So is the sun gear turning the planetary carrier, or is the carrier turning the sun gear? If the sun gear is the "drive" gear and the carrier is the "driven" gear, your ration would be p72/s12 = 6:1, just like you said, but it is not because of the number of teeth on the planet gears--that is just coincidence that they add up to 72. You could easily have a fourth planetary gear in your carrier, and it would add 12 more teeth to the mix, but it would not change the gear ratio.
Hi, I would like to know that gear you are using for education belong to which vehicle? Really important for me the information Thanks With Regards Sam Australia 🇦🇺
shouldnt your ring be the sum of 2x the planet carrier + the sun gear??? so when your sun gear is 30 en your ring is 90 your carriers would be 60 together
The actual physical number of teeth on the carrier gears have no bearing on the gear ratio. The speed and torque of the carrier are the result of the number of teeth on the ring and sun gear.
There are two ways to get a 1:1 ratio from a planetary gear set: You can lock the entire assembly together and turn them as one unit, or you can spin the third member of the gear set in the opposite direction at exactly the right speed so that both the input and the output gears are turning at the same speed.
Justin Miller So the second one is what I'm talking about (I don't think the first one really counts), if the only way to get a one to one ratio in a planetary set is to run the same number of gear teeth on the sun and ring gear how would a one to one ratio be possible when the ring gear will always be a larger circumference than the sun gear?
Beach&BoardFan...You can do that with sprag bearings or one way bearings on the planetary gears and carrier such that when the sun gear rotates in one direction, carrier locks & planets spin, you would get the gear reduction of say 3:1 or whatever ratio you have sun to ring... and when you rotate the sun gear in the other direction, the planet gears would lock while the carrier would unlock & spin with the sun gear driving the ring gear directly @ 1:1... done
@@beachboardfan9544 Locking the assembly up is a legitimate use for planetary sets, and it used very often. If a 1:1 ratio is needed in addition to other ratios, it's the simplest design. For your second approach, that would require addition gearing to get the carrier to turn at the right speed, and, if you wanted more than one ratio from that gearset, then you're talking an addition brake for that extra gearset. I'm scratching my head to think of an OEM application where an engineer was able to justify the additional engineering/cost/complexity just to avoid using a simple lockup
+Okan Kurt It is because whenever the planetary carrier is acting as the input or output gear in a set (not just an idler), the carrier is effectively being turned by both the sun and the ring gear. For example, if I were to hold the ring gear still, while turning the sun gear, the carrier would be the output. Note that it is not the planetary gears that are the output, it is the carrier. The rotational speed of the carrier is determined by how the planetary gears are "rolled" between the sun gear and the ring gear. Hence, the sum of the teeth on both gears. I hope that wasn't too confusing!
Is easier to see by the next formula: (Nr+Ns)*Wp=Nr*Wr+Ns*Ws Where "Nr" is the number of Teeth of the Ring, "Ns" is the number of Teeth of the Sun, "Wp" is the angular Velocity of the Planet Carrier, "Wr" is the angular Velocity of the Ring and "Ws" is the angular Velocity of the Sun gear. So you can see that the planet carrier velocity don't depend from the number of teeth of the planet gears, instead depend from the sum of the teeth of the sun and the ring.
The number of teeth on the ring is the number of times it turns the the planets is the number of times the sun turns So if the ring has 60 teeth and the planets have 10 the sun turns 6 times because the sun can only turn the number of teeth on the ring
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Sir, 8 Years later, and this is still gold. Thank you. All these other guys make it so complicated.
I have searched the whole internet and this answered all my questions in 5 min thanks soooo much!!!
Thanks so much for sharing this! This really simplifies it as opposed to other explanations. This makes planetary gears far less daunting. Thanks Justin!!!
WHAT? You're not going to first make my eyeballs bleed with 30 minutes of riveting footage defining angular velocity? Thanks for the quick and easy explanation! I appreciate it!
So simple yet full of thought. Thank you for explaining this to us.
THANK YOU Justin!
Absolutely fantastic educational video!
Straight forward, and to the point!
Extremely easy to follow.....
and thanks to your Working Examples......
extremely easy to calculate & apply!
I love the use of a real gear and your quick review of basics
Straight to the point simple and covered everything. Thank you very much
Awesome video. makes calculating ratios so simple, thank you
Plain and simple, and easy to understand. No "fancy" calculations that leave my head spinning
Thank you very much, I have also searched the internet for this information. This was simplified and just great! Thank you!
Thank you! It's one thing to have the knowledge and a completely different thing to be able to convey it. You seem to posess both. Good job!
thank you for this video, cos all the other videos i found were just a demonstration of how the gear set works rather than finding the ratio.
Thanks for explaining it in a very simple manner.
Thanks a lot 👌
Cool explanation !
Quick questions : how does the operator select which gear is the driver then?
How do I know the efficiency of the transmission? (there must be some energy loss)
How do I use this is real life applications? (say I want to move a 100kg load on a small platform with 2 or 4 wheels. How do I work out the torque required?)
Thanks!
your explanation is so good I give you a comment and upvote after 1:20 mins.
You're a great teatcher. Thank you. That's precisely what I was looking for.
Simplest and best explanation I've seen!!
Excellent, just what I wanted to know, thanks for posting.
Thank you .. I loved your content and the neat explanation!! Please keep making videos like this!!!😊
@Justin Miller This finally begins to make some sense to me, thank you. Very good explanation and video.
great vid! you cleared up a lot of confusion.
finally, you explained this very nice and simple. thanks so much bud.
Quite simple explanation solved the puzzle. Thanks a lot
thankyou!! is this the same for offset epicyclic gearing?
Hi man! how do you calculate when planets are fixed/held what you call a star set?
Awesome Video, Perfectly informative. What is this Specific Planetary out of? I need this type of Planitary to make a Planitary Hub for a racing application, thanks!
Thank you so much for sharing this video, really appreciate
Just the answer I've been looking for. That's easy once it has been explained in a simple way
Thank you so much.that was a neat presentation
Finally a clear explanation! Thank you...👍
Thanks, that was a great explanation!!
thank you. this helps me so much. how do you calculate the ratio with different amount of planetary gears? does it even matter? some have different size planetary gears in them.
Thank you. very well explained
This video was of great help. !!
Sir can you please explain how to decide the number of planet gears and no.of teeth.?
Thanks a lot.
Thanks. Very helpful and description.
Thank you, as stated by others, well presented, easy to follow and started with the definition for a gear ratio. Really nice to see this.
bro plz make a video which explains the whole calculation to design this planetary gear box for a vehicle with final drive ratios
Where can we reference that the planet carrier has R+S teeth? Need a reference for a project.
Awesome!! Great instruction Thank you
well explained......thanks miller
Magnificent video greetings from Córdoba Veracruz México
Thank you! Exactly what I wanted!
Very good teaching about calculate Planetary gear ratio sir
This give better under stand, thank you
Great video.
its help me alot..thanks for the video..
Good video.
Is 120 teeth on the planetary gear sum of all the teeth on three planet gears?
Awsome explaination.....thankyou very much
thank you! what i didn't understand though, is why you said we don't count the teeth of the planetary carrier. Why not? Certainly there are in fact a fixed number of teeth on one of those planetary carrier gears
Thank you teacher!😀
Good explanation
Is there any way to achieve a 2:1 /1:2 ratio with the sun gear being the drive, planetary carrier being driven?
Nice explanation
I'll request if u can show the calculation by vector diagram plotting on graph paper to find out gear ratio , rpm and final speed of vehicle
So great! Thanks
Hi, this video was very helpful, thanks a ton.
I have a few doubts though.
1. If the number of teeth on planetary gear is calculated by the sum of the teeth on ring and the sun, how do we calculate the teeth on each planet gear?
2. does this depend on the number of planets we have?
thanks again
1. The planet gear has to be the right size to fill the gap between the sun and ring gears, so in this case it needs to have 30 teeth as the radius of a gear is proportional to the number of teeth (For a given gear module - which is a fancy way of saying tooth size). The diameter of the ring gear is equal to 2 x planet gears + 1 x sun gear, the sun gear has 30 teeth, the ring has 90, so 90 = 30 + 2 (Planet gear teeth), which solves to give 30 for the planet gears.
2. Only one tooth at a time usually carries the entire load between when 2 gears when they mesh, so the more planets, the more teeth are available to carry the load, so the higher the torque that can be carried by the ringset. The number of planet gears has no effect on the ratio. Keep in mind that for most applications nobody cares what speed the planet gear turns at, it's the planet gear carrier that's working as an input or output. The speed the planet carrier turns at depends on the difference in speed between the ring gear and the sun gear.
What about when the planet carrier is always held still, and the ring is the drive and the sun is the driven, I need help on what I’m trying to make with ratios
Thank you explain this . 🙏
Great explanations ! The actual planetary gear you have is used in what application ? What brand and model is it ? Thanks
Found in in older answers, GM 700-R transmission
Thank you so much!
Well said.
But sir can you please explain , how to find gear ratio with two inputs and one output ( no component is held stationary)
May I ask you a question? You said that: Planet Carrier = Sun + Ring. In this case, we have 3 planet gears. But what if we only have 2 planet gears connect to the carrier? Is this formula still true?
It would be since it isn’t based on the amount of planetary pinion gears are in the carrier, but on the circumference of the carrier which the pinion gears make up. Think of it like drawing a circle and putting two points on either side of the circle. It’s still the same circumference, even if you double, triple, quadruple, etc. the amount of points, it’s just more areas of contact.
thanks soo much this has helped
Thank you very much :D
Justin, can you please tell me where you got the planetary gear set in the video? I am looking for an off-the-shelf planetary gear for a project and it appears that what you have would be about perfect. Thanks!
I think it is out of a GM 700-R transmission, but I can't tell you for sure. I found it laying around.
How do you calculate a compound planetary gear set ratio or more than one set of planetary gears?
It's just an idea!
The idea is that:
One to three is a completely balanced gear ratio for one link of a coaxial gearbox.
This, for example, is optimal for a wind turbine, where the loads change by about two orders of magnitude - this is 100 times!
Switches must be made between these links.
And so: 1:3:9:27:81:243
Six-speed transmission.
The wind speed acting on the entire washed area of the fan - this theoretical perspective windmill, varies from 2 m / s to 32 m / s!
And the power removed from this electric generator varies from 2 kW to 200 kW!
That's why you need such a reducer.
I mean - It's a crazy idea to use a wind generator for hurricane winds.
And, at the same time, - for very quiet winds - almost calm!
For small autonomous settlements or even for separate remote buildings.
The coaxial gearbox has an advantage both in terms of the weight of the metal, and in terms of the efficiency of the interaction of gears, and, probably, in other parameters.
Perhaps the same gearbox is suitable for other technical objects, just need to think about which ones.
Considering the remarkable parameters of the coaxial transmission scheme of the mechanical moment.
can you tell me the dimensions of this.....and what is the DP
Thank you.
Then for the planet gears / pinions, we just estimate the number of teeth on the ring and sun gears, and add them up - or if desired, count the number of teeth exactly, and use the result to do the calculations ? Isn't there a precise formula that would be used for this ? There must be, or engineers would just be guessing when they make their designs.
thank you.
What happens on 2 stage planatery gear
if I have a one to four ratio does that mean the small gear is going four times faster?
Yes. That is correct.
Damn this would’ve been useful like two months ago. Took me a while to figure it out.
Thank you
Awesome explanation ...... thanks for this ...... but one thing i share with u that sun gear has 28 teeth not 30 ..... ur guess around near .....
Thanks!
HI WHERE THE PLANETART CAME FROM , WHERE DO WE GET IT
Great video sir! Thank you!
So if I had a sun gear with 12 teeth, a ring gear with 60 teeth, and the planet gears had 24 teeth each, I would add the s12+r60 = 72 and the p24 x 3 = 72 because I have three planet gears that would be a 6:1 gear ratio?
No, that isn't correct. You don't ever count or use the number of teeth on the planet gear when determining the ratio. The planet gears are idler gears and their speed is always going to be a result of the speeds of the sun and ring gears. To figure out your ratio, you need to determine which of the three components are acting as the input and output gears, and then divide the number of teeth on the output gear by the number of teeth on the input gear. If the planetary carrier happens to be either the input or output gear in your scenario, you should not count the teeth, but use the sum of the number of teeth on the sun and ring gears for your number. I hope that helps!
The ring gear is stationary and the planetary carrier is able to rotate
So is the sun gear turning the planetary carrier, or is the carrier turning the sun gear? If the sun gear is the "drive" gear and the carrier is the "driven" gear, your ration would be p72/s12 = 6:1, just like you said, but it is not because of the number of teeth on the planet gears--that is just coincidence that they add up to 72. You could easily have a fourth planetary gear in your carrier, and it would add 12 more teeth to the mix, but it would not change the gear ratio.
The sun gear is the drive gear and the carrier is the driven gear
Smart ♥
how you have found 120 by Plant carrier ?
its the sum of three planet gear~
From which mobil is this gear set?
Hi, I would like to know that
gear you are using for education belong to which vehicle?
Really important for me the information
Thanks
With Regards
Sam Australia 🇦🇺
Very well explained! Thank you so much for this video!! Da boss!
shouldnt your ring be the sum of 2x the planet carrier + the sun gear??? so when your sun gear is 30 en your ring is 90 your carriers would be 60 together
The actual physical number of teeth on the carrier gears have no bearing on the gear ratio. The speed and torque of the carrier are the result of the number of teeth on the ring and sun gear.
correct
So can there be a planetary gear set with a 1:1 ratio where the input and output are matched in speed?
There are two ways to get a 1:1 ratio from a planetary gear set: You can lock the entire assembly together and turn them as one unit, or you can spin the third member of the gear set in the opposite direction at exactly the right speed so that both the input and the output gears are turning at the same speed.
Justin Miller
So the second one is what I'm talking about (I don't think the first one really counts), if the only way to get a one to one ratio in a planetary set is to run the same number of gear teeth on the sun and ring gear how would a one to one ratio be possible when the ring gear will always be a larger circumference than the sun gear?
Beach&BoardFan...You can do that with sprag bearings or one way bearings on the planetary gears and carrier such that when the sun gear rotates in one direction, carrier locks & planets spin, you would get the gear reduction of say 3:1 or whatever ratio you have sun to ring... and when you rotate the sun gear in the other direction, the planet gears would lock while the carrier would unlock & spin with the sun gear driving the ring gear directly @ 1:1... done
Beach&BoardFan Why does the first one not count? Isn’t that how a 1:1 ratio is obtained on an Allison automatic transmission?
@@beachboardfan9544 Locking the assembly up is a legitimate use for planetary sets, and it used very often. If a 1:1 ratio is needed in addition to other ratios, it's the simplest design. For your second approach, that would require addition gearing to get the carrier to turn at the right speed, and, if you wanted more than one ratio from that gearset, then you're talking an addition brake for that extra gearset. I'm scratching my head to think of an OEM application where an engineer was able to justify the additional engineering/cost/complexity just to avoid using a simple lockup
Fitter happier more productive
can any one or engineer tell me wether a planetary gearbox can operate on reversed rotation
+Belle Sylvio It can
Thanks
i just learned something
How could the planetary gear have 120 teeth whereas it is smaller than the sun gear ⚙ consisting of 30 teeth?
Why do we say the planet gear has the sum of the gears of the sun and the ring?
+Okan Kurt It is because whenever the planetary carrier is acting as the input or output gear in a set (not just an idler), the carrier is effectively being turned by both the sun and the ring gear. For example, if I were to hold the ring gear still, while turning the sun gear, the carrier would be the output. Note that it is not the planetary gears that are the output, it is the carrier. The rotational speed of the carrier is determined by how the planetary gears are "rolled" between the sun gear and the ring gear. Hence, the sum of the teeth on both gears. I hope that wasn't too confusing!
Is easier to see by the next formula:
(Nr+Ns)*Wp=Nr*Wr+Ns*Ws
Where "Nr" is the number of Teeth of the Ring, "Ns" is the number of Teeth of the Sun, "Wp" is the angular Velocity of the Planet Carrier, "Wr" is the angular Velocity of the Ring and "Ws" is the angular Velocity of the Sun gear.
So you can see that the planet carrier velocity don't depend from the number of teeth of the planet gears, instead depend from the sum of the teeth of the sun and the ring.
IN GENERAL HOW MUCH TORQUE WILL INCREASE
The torque is multiplied by the gear ratio. For example, if the gear ration is 3:1, then the torque would be multiplied by 3.
@@JustinMillerAutomotive THANKS FOR THE CLARIFICATION
To find the number of teeth on the planetary gears, do we divide the number of teeth of the carrier by the number of planets?
Please reply:
Is it possible to keep the ring gear stationary, not by holding it, but by rotating the Sun and the carrier at certain speeds?
Thanks
Justin, can you explain how its done if the ring, sun, planets, and carrier are all rotating?
Have a look at my replies to Front Me and Rayan Wave further up the comments.
well done explanation
Came here after a dizzing spell of velocities and arrows in videos.
The number of teeth on the ring is the number of times it turns the the planets is the number of times the sun turns
So if the ring has 60 teeth and the planets have 10 the sun turns 6 times because the sun can only turn the number of teeth on the ring