@@JSFofWT I presume you know the insides of that clutch, is there a image of the inside somewhere on the internet? If not, is it some type of compliant centrifugal clutch?
i have built a gearbox-less lego rc car that goes about 20 mph using purely legos no glue, no tape, no 3d printed/metal legos.. what i notice is the wear and tear of driving the car on cement at such speeds... The tires are blading, the servo motors die (even lego official servo motors), and parts constantly wear out and need to be replaced... i am working to upgrade to buwizz 3.0 take advantage of the new steering system my conclusion is some lego pieces especially the gears are not rigid enough to constantly handle 2000 RPMs for extended duration and even if you can come up with a design that can handle such a load the lego pieces usually melt under the friction caused by 4 buggy motors maintain 2000 RPMs my 2 cents..
Multiple differentials with power added in here and there are also the basis of tank transmissions. You don't want to put a brake on one part to make another part go faster, e.g. for steering, because that's wasteful of power, so instead you can use another diff as an input to vary things.
You are basically doing what Toyota is doing in their CVT cars. They use a planetary gear with 1 output free spinning until you want to accelerate. At the point you want to accelerate they apply a force to the free spinning gears causing the energy to redirect into the wheels. Now you could use a clutch for this but Toyota was like nah lets use an electric generator motor for that. So they take away energy from the gears which is used to power the electric motor. (And stuff like the AC.) Since a planetary gear is solid metal the transmission basically never has to be replaced. And since they don't use a clutch the amount of force is never really that big. You can activate reverse while still driving forwards and nothing will break.
It is slipping only when there is high load on the output. Of course there is some energy loss. Maybe thanks to big ratio difference between two speeds the lost energy in friction clutch is still not so big to stop the car.
There are similar-funtioning parts in some cars that do that called torque converters. There was an old car made in the 50s that had no gears and only used the torque converter which would keep slipping up until max speed. That car was infamous for being horrendously bad on gas mileage, down to only 5mpg or something. A big use for them is in drag racing where they'll rev the engine up to optimal torque/horsepower while the car remains stationary and when they launch that torque converter prevents the engine from detonating the transmission, and this is done to maximize launch potential. Bad for gas mileage but those types of cars aren't meant to be efficient, just fun lol
This is way better than the idea I came up with as a kid. Mine shifted from 3:1 up to 1:3 via a centrifugal governor and just ground the gears until it built up the speed to shift. Seems to me I messed around with differentials too but that first one stick in my mind because I remember that once it got going it could actually outrun me. Good times.
I imagine there's a range where the resisting torque on the output is high enough to cause the clutch to slip, but low enough that it allows the clutch gear to still rotate, effectively giving a range of variance in the output ratios. I think that this may actually be a CVT
I think so :) Although it has two distinct ratios at each 'end', the 'middle bit' has some variability... So it's a 2-speed gearbox with a smooth transition between ratios. Good call, well spotted :)
It is not only using 1:1 and 2,33:1 speed ratio but a large fork between both (we can see in a slomo white geer turning sometime). Very clever and compact. I cannot wait to see it on a train. Thank you for sharing.
It is also not actually 2.33 to begin with. Gear ratios when it comes to transmissions are a ratio of input/output. 2.33 would actually be a slower gear. Look up ratios of a manual transmission found in a car or truck (or even an automatic) and see how 1st gear is usally 3.xx or 2.xx or similiar.
this looked like a video were a well known design was claimed to be revolutionary, but this was actually really well made, and well explained, this video actually wowed me.
Really cool concept and it seems to also have a small cvt component. However, transmission ratios are input divided by output. 2.33 would describe a gear requiring 2.33 input rotations for 1 output rotation. Likely just done backwards but in the automotive and industrial world its backwards which leads to a little confusion. Awesome concept and it would be cool to see more gears added in this way.
This could be an excellent concept for a practical CVT in a car if: 1) a hydraulic torque converter is used instead of a clutch, and 2) a reverse gear is included.
i don't understand 4:10 if the friction cluch weren't there the motor will rotate the red gear and nothing will remain for the output shaft or in other words what is stoping the red gear and don't let it to rotate in other direction?
Very cool idea. I just wonder if that is kind of a magical illusion that looks right, but it works only because the car would also successfully climb the hill also without the transmission. Isn't there simply the extra force coming from the higher gear ratio "destroyed" by the friction in the clutch?
Hi Tobias, I have to say that this is very good question, I spent so many hours by tuning this transmission up that I even did not tried it. But I still have the car built so I just tried to climb some obstacles like small stairs (like 3-5cm tall), even climbing the car to vertical wall. Then I changed the friction clutch gear with a normal gear and the car was not able to pass some obstacles. The motor just stopped. So it really works well. Try to build it.
My first thought was also that instead of actually switching gears it just slows down and the rest of the energy gets lost to the slip gear. But if you say it works then it might be interesting to do the physics calculations behind it. The biggest problem is that there is nothing really to hold the slip gear, so if there is enough resistance at the wheels it should just backdrive. While it wouldn't be perfectly efficient, the efficiency could definitely be increased by lowering the slip gear friction and adding a backdrive prevention mechanism.
You definitely lose some of the motor power to the clutch gear. Can't avoid that with this kind of setup, which is why you won't see this exact setup on cars. (Something similar is used to switch gears in automatic gearbox, though.) But we care about output torque here, not the efficiency of power use. This setup won't produce as much torque at the same speed as a fixed gear would have, but it's still way more torque than you were getting out of high gear ratio setup, so it still works.
I’d imagine torque would be multiplied for the lower gear. If you think about it, the high gear is overdrive and when the clutch slips the ratio drops to 1:1, increasing the torque
I see you've experimented with big trends in the past, but please stick with lego engineering videos! If they are as good as this, I'm sure your channel can grow.
I am impressed. Thanks for sharing this amazing automatic transmission idea. I will definitely use this design and will pray for you when having fun. Awesome :)
Well done. I thought of something similar decades ago, but the Lego parts I needed to build it didn't exist yet; by the time the parts I needed did exist, I had moved on to other hobbies. Nowadays I wrench on purpose-built RC cars with tiny engines.
1:35 Minor correction: even when one of the outputs of an open differential is stationary, it still splits *torque* evenly. It's the power that goes to the other output.
Yes you are right in splits the power 50:50 all the time. But the rotation goes to one output only. that is important to understand that you can even combine inputs, not only split.
This is a fantastic idea! It would be rad if they made a small self contained torque converter with a stator. It would be insane torque multiplication.
normally i would think of "auto transmission" as say first gear max is 60 mph, when i get to 60 mph the gearbox would automaticly switch to second gear, etc etc till last gear. but this is a good enough model :D good job!
That's just awesome! So simple yet so ingenious. Should put one of these on an input shaft, speed it up or slow it down with gearing, then put another one. Should be able to get 3-4 speeds out of it with with different torque thresholds.
There are iron plates pushing on plastic, I thin it will last some days, but of course it is just a toy. Important for me was to demonstrate that this way can work.
@@CrusaderSports250 I made one one time with model team hubs and fan blades inside. It was filled with low viscosity corn syrup. Lol I was 16 and a lil whack with inventions.
Such a simple mechanism and better than every other automatic gearbox I've seen made with Lego. And you know what the best part is? Every other solution I've seen involves gears grinding at least some of the time, this *JUST* works.
Thank you Tangent. Exactly this was my intention. Make something absolutely simple and working. Funny thing is, that many people dont believe that it really works... they thing that the car can pass the obstackles even on high speed and switching down is just illusion.. Because of them I made another video showing how it works. I made simple switch which disables friction clutch to show how the gearbox works only on high speed. Here. m.ua-cam.com/video/QBS1XcSwk_g/v-deo.html
This is the basic principle of the Voith DIWA automatic gearboxes mainly used in city buses. While stationary and at the beginning of acceleration, the engine's torque is fully transferred through the (internal, it's not seperate as with most gearboxes) torque converter and the lower the speed difference between engine and gearbox output the more this shifts towards the parallely operating fully mechanical 1st gear. At a certain speed difference the torque converter will then become almost completely needless and the fully mechanic 2nd gear is engaged. With this gearbox type, the torque converter is only functional in 1st gear and is disabled from 2nd (of the 2, 3 or 4 gears) onwards, but is used as a retarder, just to have mentioned this.
This obviously works, nice gearing, but my understanding from tests and logic says: *there cannot be two fixed gear ratios in one closed gear system* So if it slips, every rotation of the output axle is possible. Obviously this burns some energy as it doesn't use torque to shift, but force x rotation = power. But your great accomplisment: You modelled a local (higher) output torque maximum into the slip range. However, increase the breaking force on the output, it can always completely stop rotating, no matter how high the motor force is. Still kind of a good overload protection for the motor.
Yes you are right. It is also motor protection. And in extra high loading the clutch oscilates and it helps to overcome some high obstacles. Its interesting concept and after many tests I realized that it is great mechanism. Especially for its small dimensions.
From one frontier its a true automatic gearbox, but the target of gearbox is with decreasing rotation speed increase strong of rotation. The white gear is getting part of the rotation moment. That means, that you simply decreasing rotation speed, without chanching rotation strong. P. S. sorry for my english and commas. I am from Russia
This looks really, really cool, but I wonder if it actually works as a proper transmission (exchanging speed for torque). You should do a test showing a scenario when the same motor that has same gearing as your fast speed can't climb a slope, and then show that your gearbox can climb it. I've seen a lot of various gearbox ideas that do indeed change the speed, but do so by wasting energy in various ways. In your configuration it seems you may be just wasting energy on white clutch gear slipping.
In particular range of load it behaves like gearbox. However, under the very high load: engine works, vehicle stops and clutch slips different direction. I like the solution with the clutch/friction, as it enables smooth rotation speed change depending on load. It's great! Nevertheless, I prefer the friction between "gears" (like in planetary gear), when the minimal speed (the first gear) is limited by the engine power, not by gear clutch. Regards
So, it's more like a clutch slipping than a gearbox, since a gearbox is supposed to increase torque wile on lower gears, not the opposite like here where power is getting lost at lower speeds...still, interesting solution to avoid stalling the motor
For a basic automatic transmission made from lego, it is wonderful. I'm a little surprised that the lego makers didnt come up with it. Ir they haven't taken your idea and used it
The point of real gearbox is to not simply go slower when there's load but to have more torque when it's in low gear. Here the slow spinning is achieved by slipping the clutch so I don't see how it will have more torque than in high gear. Correct me if I'm wrong. Also would be nice to see a comparison between this and a fixed gearbox with high gear only. Which one would be able to pull harder. In any case I have to say this is a very interesting setup to think of in terms of doing the proper physics calculations.
I have almost done my next video where exactly this will be compared, you are not the only one who ask for this. But it really increase the output torque. The friction clutch somehow consumes the power of motor in low speed, but output rotation goes down not because of clutch brakes the motor but clutch seems to disconnect the faster rotation way, which is fast but not strong. Detail calculations of torques are not simple but if you take it as one closed system you can easily get the result. Torque goes high. Also real simulations show it.
This is pretty much how a car automatic gearbox works. The differentials look different and there are multiple clutches to change the ratios as needed, but the main principle is the same.
This is a super cool design and is actually a fairly similar idea the Toyota Hybrid system uses (except obviously much more complex, being motor-generators rather than gearboxes and they can adjust to act like a CVT instead of a 2-speed gearbox)
You should test it "side by side" with the transmission, without transmission but low gear, without transmission high gear. test uphill speed, flat level take off speed, down hill speed, and over a course of up and down hill timed. my hypothesis is you are sacrificing torque by using this since the friction plate is acting as a brake for one input. I suspect you are getting whatever the resistance of the friction plate is subtracted from the low gear power.
I really appreciated the simplicity of the solution, much better than other solutions that require more pieces. I have actually applied your solution to one of my MOCs, my red station wagon, which is equipped with two L motors. But unfortunately the friction clutches (one for each motor) spin the opposite direction it should when stressed, probably due to the MOC's weight (850g)... I believe in my case each motor should get two friction clutches, but there's no room for this upgrade. Anyways, just sharing the experience, I'll apply it to a lighter model instead. Cheers!
Amazing job, truly a brilliant idea. However, I have noticed one issue that may come up. As explained, enough resistance will cause the gearbox to go into low gear, as it should, but if this resistance becomes strong enough, the differential in the gear box will begin to spin backwards (same direction as the input), because the output (wheels) could be stopped fully or pushed backwards (via the resistance). This would in turn cause the outer section of the clutch gear to spin in the opposite direction as the input. This would also lead to a situation none of the power put into the gearbox gets transferred to the output (wheels) and is instead wasted. I still find this design to be awesome nonetheless
in this situation the friction gear would provide a similar effect to the clutch in a limited slip differential, that is that whatever torque is required to cause the gear to slip is the amount of torque that would continue to be delivered to the wheels. Obviously not enough, but still not zero. It would be interesting to see another variation with two more differentials and a ratchet set up so that when the friction gear turns the "wrong way," i.e. the gearbox is stalled out, a low gear kicks in.
The first differential would block power output from the low gear using the ratchet when the friction gear is going the right way, that way the two gear sets aren't fighting each other. The second one would be used to branch in the power from the low gear onto the output shaft.
@@arkel_77 If I put this gearbox in a large and heavy lego car, would it cause the gearbox to stay in low gear constantly because of the weight of a large car?
how would a 2.33:1 ratio be faster than a 1:1? The number on the left is the amount of times the input must rotate for the output to rotate the amount of times shown on the right (usually once). ex. a 3:1 ratio means that it requires 3 rotations of the input for the output to rotate once. So a 1:1 ratio would go faster than a 2.33:1 ratio.
You can achieve that function in a better way, with a magnetic clutch, that way there's wear. You could also cascade it to make it 3 or 4 speed or whatever you want.
I am curious about the torque numbers on each gear. I would imagine that there is quite some power loss from that friction clutch, so it would be nice to see how much more torque the low gear produces compared to the high gear.
I will post new video soon, where this will be compared. Fixed high speed gear VS automatic gear with friction clutch. The clutch has friction drag around 5Ncm.
How much power does clutch consume when it's slipping? If the power dissipated by the clutch is half then there's no advantage in torque just half the speed.
I’d love to see a multi speed transmission. Imagine something that could go into a semi truck that can have high torque but then have enough gears to get to higher speeds
I believe the high speed ratio is actually 1:2.33. one turn of the motor outputs 2.33 turns of the shaft. Additionally, unlike a conventional trans, you're not getting any torque amplification through gear ratios, as 1:1 sucks for this. Pretty neat project though.
i am puzzled, i suppose heat dispersion and friction are minimal, but yet isn't friction less efficent than say lowering tension input of the motor to make it turn slower? my main concern is battery duration, by reducing waste heat to 0. also i learned that by stressing a motor with friction while it is trying to push at its max can have terrible effects on the motors working capabilities, so it leaves me questioning how could the design be more efficent
The friction present at the low speed having to turn against the clutch is kind of a drag, I also know that lego clutches dont have a long life expectancy, If you made a manual version with a gear that engages and disengages using the collar lego makes for that very purpose you could eliminate both issues but I guess it would not be automatic any more.
In your examples of alternative possibilities, you suggest a 2 engine input, 1 output combination. This does not work. If you combine 2 inputs with 1 output it will work at the strength of 1 input, since if one input cant overcome the torque, it will simply stall and become an output. I suggest you try it. 2 same speed engines in, 1 output. Then test if this increases torque compared to 1 engine. I strongly think it wont.
Why do you think that two engines together will not increase the power of whole system? I have already tested a lot of similar solutions, many of them without success. But if there are two engines, I am sure the output power will be combination of both motors. Like hybrid cars, one petrol engine, one electric engine. Total power of the car is sum of both minus some energy loss. And we use here differential, it means if one input is stationary, the gearbox still works. It is not blocked because of one engine is stalled.
Interesting concept. Obviously not efficient at all with using a slip clutch. I’d be really interesting in seeing a similar setup with a clutching gear instead of a slip clutch gear. Nice job.
Thanks. In reality it works. The output torque in slow speed is higher than in high speed even there is a friction clutch, everything is about the gear ratio. I am preparing another video to show that the car can overcome some obstacles with this gearbox, which is not able to overcome on fixed high speed.
Just watched this and can't help but wonder if this can be put into the 42099 X-treme Off-Roader?!??! ..because if you own this excellent set you likely know about the simple but needed rear gear swap to change speed for torque.
Cool engineering. But to see if it accomplishes anything, really need to test it. see if the car can climb a steeper incline with or without the transmission (keep weight the same) and see if it’s faster on flat ground with or without the transmission.
Friction clutch just means it makes the wheel spin slower under load, because of the energy loss there's no mechanical advantage, you can see how much it struggles under load.
Finally a gearbox that doesn't need springs or elastic bands
Aren't the springs just inside the clutch? That does make it really compact.
@@voxelfusion9894 its just a friction type clutch
@@JSFofWT I presume you know the insides of that clutch, is there a image of the inside somewhere on the internet? If not, is it some type of compliant centrifugal clutch?
@@Positroni no it's just a bushing held in place with friction
@@JSFofWT well, bushing is kind of like a rubber band in this case
I’m simply amazed at what can be built using LEGO and also so impressed with the way an engineer’s mind works! This is very cool.
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
Engineering is the best job on earth.
@@kaseycrooks5080yes
i have built a gearbox-less lego rc car that goes about 20 mph using purely legos no glue, no tape, no 3d printed/metal legos.. what i notice is the wear and tear of driving the car on cement at such speeds...
The tires are blading, the servo motors die (even lego official servo motors), and parts constantly wear out and need to be replaced... i am working to upgrade to buwizz 3.0 take advantage of the new steering system
my conclusion is some lego pieces especially the gears are not rigid enough to constantly handle 2000 RPMs for extended duration and even if you can come up with a design that can handle such a load the lego pieces usually melt under the friction caused by 4 buggy motors maintain 2000 RPMs
my 2 cents..
@@kaseycrooks5080 40% of billionaires are engineers
i am speechless about this auto-gearbox its... unbelivable simple
2:28 you broke my mind because its so ingenious but so simple. awesome concept!
Multiple differentials with power added in here and there are also the basis of tank transmissions. You don't want to put a brake on one part to make another part go faster, e.g. for steering, because that's wasteful of power, so instead you can use another diff as an input to vary things.
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
You are basically doing what Toyota is doing in their CVT cars.
They use a planetary gear with 1 output free spinning until you want to accelerate. At the point you want to accelerate they apply a force to the free spinning gears causing the energy to redirect into the wheels. Now you could use a clutch for this but Toyota was like nah lets use an electric generator motor for that. So they take away energy from the gears which is used to power the electric motor. (And stuff like the AC.)
Since a planetary gear is solid metal the transmission basically never has to be replaced. And since they don't use a clutch the amount of force is never really that big. You can activate reverse while still driving forwards and nothing will break.
GREAT explaining. I really learned something today. Never thought this would interest me, but it was soo captivating!
Thank you :)
Thanks for the detailed breakdown. One question, since the slipping gear is always slipping, do you sacrifice a lot of engine power?
It is slipping only when there is high load on the output. Of course there is some energy loss. Maybe thanks to big ratio difference between two speeds the lost energy in friction clutch is still not so big to stop the car.
nice job, could be done with planetary gears
There are similar-funtioning parts in some cars that do that called torque converters. There was an old car made in the 50s that had no gears and only used the torque converter which would keep slipping up until max speed. That car was infamous for being horrendously bad on gas mileage, down to only 5mpg or something. A big use for them is in drag racing where they'll rev the engine up to optimal torque/horsepower while the car remains stationary and when they launch that torque converter prevents the engine from detonating the transmission, and this is done to maximize launch potential. Bad for gas mileage but those types of cars aren't meant to be efficient, just fun lol
@@maebae5350 hydrodinamics ones, ¿right?
@@tomstech4390 Still better than anything I could come up with
Finally a video as simple and educational as the old chevrolet videos
This is way better than the idea I came up with as a kid. Mine shifted from 3:1 up to 1:3 via a centrifugal governor and just ground the gears until it built up the speed to shift. Seems to me I messed around with differentials too but that first one stick in my mind because I remember that once it got going it could actually outrun me. Good times.
I imagine there's a range where the resisting torque on the output is high enough to cause the clutch to slip, but low enough that it allows the clutch gear to still rotate, effectively giving a range of variance in the output ratios. I think that this may actually be a CVT
I think so :)
Although it has two distinct ratios at each 'end', the 'middle bit' has some variability... So it's a 2-speed gearbox with a smooth transition between ratios.
Good call, well spotted :)
Replace the friction clutch with a magnetic clutch, and you could sell this in regular cars as a sealed CVT
Sadly this transmission doesnt work. You can get the same result using only the slip gear
@@adamkovarcik914 not really. Depending on the load, the slip gear on its own will just stop moving the driveshaft
If you stack several of this design, I think the gradual nature of each module would make it effectively a CVT with noticeably higher top speed
It is not only using 1:1 and 2,33:1 speed ratio but a large fork between both (we can see in a slomo white geer turning sometime). Very clever and compact. I cannot wait to see it on a train.
Thank you for sharing.
It is also not actually 2.33 to begin with. Gear ratios when it comes to transmissions are a ratio of input/output. 2.33 would actually be a slower gear. Look up ratios of a manual transmission found in a car or truck (or even an automatic) and see how 1st gear is usally 3.xx or 2.xx or similiar.
this looked like a video were a well known design was claimed to be revolutionary, but this was actually really well made, and well explained, this video actually wowed me.
Thank you :). Incredibe things are possible to be made of lego.
Really cool concept and it seems to also have a small cvt component. However, transmission ratios are input divided by output. 2.33 would describe a gear requiring 2.33 input rotations for 1 output rotation. Likely just done backwards but in the automotive and industrial world its backwards which leads to a little confusion. Awesome concept and it would be cool to see more gears added in this way.
This could be an excellent concept for a practical CVT in a car if: 1) a hydraulic torque converter is used instead of a clutch, and 2) a reverse gear is included.
i don't understand 4:10 if the friction cluch weren't there the motor will rotate the red gear and nothing will remain for the output shaft or in other words what is stoping the red gear and don't let it to rotate in other direction?
Very cool idea. I just wonder if that is kind of a magical illusion that looks right, but it works only because the car would also successfully climb the hill also without the transmission. Isn't there simply the extra force coming from the higher gear ratio "destroyed" by the friction in the clutch?
Hi Tobias, I have to say that this is very good question, I spent so many hours by tuning this transmission up that I even did not tried it. But I still have the car built so I just tried to climb some obstacles like small stairs (like 3-5cm tall), even climbing the car to vertical wall. Then I changed the friction clutch gear with a normal gear and the car was not able to pass some obstacles. The motor just stopped. So it really works well. Try to build it.
@@ferdoreznik Thanks for your answer, so all I have to say: well done ;-)
My first thought was also that instead of actually switching gears it just slows down and the rest of the energy gets lost to the slip gear. But if you say it works then it might be interesting to do the physics calculations behind it.
The biggest problem is that there is nothing really to hold the slip gear, so if there is enough resistance at the wheels it should just backdrive.
While it wouldn't be perfectly efficient, the efficiency could definitely be increased by lowering the slip gear friction and adding a backdrive prevention mechanism.
You definitely lose some of the motor power to the clutch gear. Can't avoid that with this kind of setup, which is why you won't see this exact setup on cars. (Something similar is used to switch gears in automatic gearbox, though.) But we care about output torque here, not the efficiency of power use. This setup won't produce as much torque at the same speed as a fixed gear would have, but it's still way more torque than you were getting out of high gear ratio setup, so it still works.
I’d imagine torque would be multiplied for the lower gear. If you think about it, the high gear is overdrive and when the clutch slips the ratio drops to 1:1, increasing the torque
Excellent, best video explaining a Lego auto transmission.
Thank you Kenneth 😀 !
I see you've experimented with big trends in the past, but please stick with lego engineering videos! If they are as good as this, I'm sure your channel can grow.
I like how you repurposed a differential to use as a transmission! Very cool outside the box thinking!
Thank you Josiah...
I am impressed. Thanks for sharing this amazing automatic transmission idea. I will definitely use this design and will pray for you when having fun. Awesome :)
I never realized what the white gear was for until now
Well done. I thought of something similar decades ago, but the Lego parts I needed to build it didn't exist yet; by the time the parts I needed did exist, I had moved on to other hobbies. Nowadays I wrench on purpose-built RC cars with tiny engines.
Theoretically, could you stack 2 of these for a wider range of speed? I'm assuming it would become slower but stronger
Cvt with legos
Technically yes
1:35 Minor correction: even when one of the outputs of an open differential is stationary, it still splits *torque* evenly. It's the power that goes to the other output.
Yes you are right in splits the power 50:50 all the time. But the rotation goes to one output only. that is important to understand that you can even combine inputs, not only split.
This is a fantastic idea! It would be rad if they made a small self contained torque converter with a stator. It would be insane torque multiplication.
Very nice explanations. This is the first time I have ever understood how a CVT works.
normally i would think of "auto transmission" as
say first gear max is 60 mph, when i get to 60 mph the gearbox would automaticly switch to second gear, etc etc till last gear.
but this is a good enough model :D good job!
That's just awesome! So simple yet so ingenious.
Should put one of these on an input shaft, speed it up or slow it down with gearing, then put another one. Should be able to get 3-4 speeds out of it with with different torque thresholds.
Really clever! Nice and compact, simple, efficient. You can put more than one in a row as well.
Lego has come a long way since I was a kid.
Very simple and functional.
Thanks for this cool video and the time you spent on explaining. Question: Does/ doesn't the friction gear wear out quickly in this construction?
There are iron plates pushing on plastic, I thin it will last some days, but of course it is just a toy. Important for me was to demonstrate that this way can work.
Good if replaced for a fluid clutch aka torque converter.
@@Bassotronics unfortunately Lego doesn't do one.☺.
@@CrusaderSports250
I made one one time with model team hubs and fan blades inside. It was filled with low viscosity corn syrup. Lol
I was 16 and a lil whack with inventions.
That amazing explanation of transmission system
Hats of you 👍👍👍🙏
Such a simple mechanism and better than every other automatic gearbox I've seen made with Lego.
And you know what the best part is? Every other solution I've seen involves gears grinding at least some of the time, this *JUST* works.
Thank you Tangent. Exactly this was my intention. Make something absolutely simple and working. Funny thing is, that many people dont believe that it really works... they thing that the car can pass the obstackles even on high speed and switching down is just illusion.. Because of them I made another video showing how it works. I made simple switch which disables friction clutch to show how the gearbox works only on high speed. Here.
m.ua-cam.com/video/QBS1XcSwk_g/v-deo.html
stack 2 of them to get 3 speed levels please :D
It would have a couple of redundant gears so you’d be better off building a standard 3 speed transmission I think
i mean it's technically variable
This is the basic principle of the Voith DIWA automatic gearboxes mainly used in city buses. While stationary and at the beginning of acceleration, the engine's torque is fully transferred through the (internal, it's not seperate as with most gearboxes) torque converter and the lower the speed difference between engine and gearbox output the more this shifts towards the parallely operating fully mechanical 1st gear. At a certain speed difference the torque converter will then become almost completely needless and the fully mechanic 2nd gear is engaged. With this gearbox type, the torque converter is only functional in 1st gear and is disabled from 2nd (of the 2, 3 or 4 gears) onwards, but is used as a retarder, just to have mentioned this.
I've always wonder if can be done this with helical gears instead of clutch
Simple, but does the job perfectly
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
Would there be a way to “stack” them in a way to get multiple ratios?
Yes just add one on the output
If that is your goal then just add a cvt
I was thinking along the same lines, but as I did couldn't help but think "isn't that just a planetary transmission then"
James Vann it is, but Lego doesnt have Planetary gears so, we have to use differentials, which are very similar to Planetary gears...
@@Pitstopcomponents fair enough was mainly noting the similarity, and contemplating how one could theoretically have inspired the othere
Thats a beautiful and smart creation
This obviously works, nice gearing, but my understanding from tests and logic says: *there cannot be two fixed gear ratios in one closed gear system* So if it slips, every rotation of the output axle is possible. Obviously this burns some energy as it doesn't use torque to shift, but force x rotation = power.
But your great accomplisment: You modelled a local (higher) output torque maximum into the slip range. However, increase the breaking force on the output, it can always completely stop rotating, no matter how high the motor force is. Still kind of a good overload protection for the motor.
Yes you are right. It is also motor protection. And in extra high loading the clutch oscilates and it helps to overcome some high obstacles. Its interesting concept and after many tests I realized that it is great mechanism. Especially for its small dimensions.
From one frontier its a true automatic gearbox, but the target of gearbox is with decreasing rotation speed increase strong of rotation. The white gear is getting part of the rotation moment. That means, that you simply decreasing rotation speed, without chanching rotation strong.
P. S. sorry for my english and commas. I am from Russia
This looks really, really cool, but I wonder if it actually works as a proper transmission (exchanging speed for torque). You should do a test showing a scenario when the same motor that has same gearing as your fast speed can't climb a slope, and then show that your gearbox can climb it. I've seen a lot of various gearbox ideas that do indeed change the speed, but do so by wasting energy in various ways. In your configuration it seems you may be just wasting energy on white clutch gear slipping.
Yes. Exactly that's my next video. Already working on it and it looks that it really works. Please wait for that.
Very simple but awesome solution to a big question.
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
In particular range of load it behaves like gearbox. However, under the very high load: engine works, vehicle stops and clutch slips different direction.
I like the solution with the clutch/friction, as it enables smooth rotation speed change depending on load. It's great! Nevertheless, I prefer the friction between "gears" (like in planetary gear), when the minimal speed (the first gear) is limited by the engine power, not by gear clutch. Regards
Btw the way you use the differential (and explain it) is similar to the concept of "power split device" used in every hybrid gearbox from toyota
i rewatched this several times. It’s genius.
Thanks. 🙂
So, it's more like a clutch slipping than a gearbox, since a gearbox is supposed to increase torque wile on lower gears, not the opposite like here where power is getting lost at lower speeds...still, interesting solution to avoid stalling the motor
For a basic automatic transmission made from lego, it is wonderful. I'm a little surprised that the lego makers didnt come up with it. Ir they haven't taken your idea and used it
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
Awesome thanks for the Auto Transmission
The point of real gearbox is to not simply go slower when there's load but to have more torque when it's in low gear. Here the slow spinning is achieved by slipping the clutch so I don't see how it will have more torque than in high gear. Correct me if I'm wrong.
Also would be nice to see a comparison between this and a fixed gearbox with high gear only. Which one would be able to pull harder.
In any case I have to say this is a very interesting setup to think of in terms of doing the proper physics calculations.
I have almost done my next video where exactly this will be compared, you are not the only one who ask for this. But it really increase the output torque. The friction clutch somehow consumes the power of motor in low speed, but output rotation goes down not because of clutch brakes the motor but clutch seems to disconnect the faster rotation way, which is fast but not strong. Detail calculations of torques are not simple but if you take it as one closed system you can easily get the result. Torque goes high. Also real simulations show it.
Ingenious! Can you share instructions for the compact version please? Not very clear from the video
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
This is pretty much how a car automatic gearbox works. The differentials look different and there are multiple clutches to change the ratios as needed, but the main principle is the same.
This is a super cool design and is actually a fairly similar idea the Toyota Hybrid system uses (except obviously much more complex, being motor-generators rather than gearboxes and they can adjust to act like a CVT instead of a 2-speed gearbox)
I pass the smallest transmission medal to you. Good job!
Freaking awesome 😲👌🏼
Very good explanation!
this video is brilliant
You should test it "side by side" with the transmission, without transmission but low gear, without transmission high gear. test uphill speed, flat level take off speed, down hill speed, and over a course of up and down hill timed. my hypothesis is you are sacrificing torque by using this since the friction plate is acting as a brake for one input. I suspect you are getting whatever the resistance of the friction plate is subtracted from the low gear power.
Some seriously clever engineering here for a fun Lego project!
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
I really appreciated the simplicity of the solution, much better than other solutions that require more pieces. I have actually applied your solution to one of my MOCs, my red station wagon, which is equipped with two L motors. But unfortunately the friction clutches (one for each motor) spin the opposite direction it should when stressed, probably due to the MOC's weight (850g)... I believe in my case each motor should get two friction clutches, but there's no room for this upgrade. Anyways, just sharing the experience, I'll apply it to a lighter model instead. Cheers!
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
Amazing job, truly a brilliant idea. However, I have noticed one issue that may come up. As explained, enough resistance will cause the gearbox to go into low gear, as it should, but if this resistance becomes strong enough, the differential in the gear box will begin to spin backwards (same direction as the input), because the output (wheels) could be stopped fully or pushed backwards (via the resistance). This would in turn cause the outer section of the clutch gear to spin in the opposite direction as the input. This would also lead to a situation none of the power put into the gearbox gets transferred to the output (wheels) and is instead wasted. I still find this design to be awesome nonetheless
in this situation the friction gear would provide a similar effect to the clutch in a limited slip differential, that is that whatever torque is required to cause the gear to slip is the amount of torque that would continue to be delivered to the wheels. Obviously not enough, but still not zero. It would be interesting to see another variation with two more differentials and a ratchet set up so that when the friction gear turns the "wrong way," i.e. the gearbox is stalled out, a low gear kicks in.
The first differential would block power output from the low gear using the ratchet when the friction gear is going the right way, that way the two gear sets aren't fighting each other. The second one would be used to branch in the power from the low gear onto the output shaft.
@@arkel_77 If I put this gearbox in a large and heavy lego car, would it cause the gearbox to stay in low gear constantly because of the weight of a large car?
how would a 2.33:1 ratio be faster than a 1:1?
The number on the left is the amount of times the input must rotate for the output to rotate the amount of times shown on the right (usually once).
ex. a 3:1 ratio means that it requires 3 rotations of the input for the output to rotate once.
So a 1:1 ratio would go faster than a 2.33:1 ratio.
Good idea and design, though.
If you want you can swap the numbers to make you happy. Dont worry it works...
Final a great design with even a greater explanation
I really bike that you built a rig to show the gears working and it holds camera so you can you see it perfectly close up
I tried it few times. Not working. There must be maybe different clutch resistance.
For a while I couldn't understand how automatic transmissions work, only after seeing a lego one I understand xD
Genius, SUPER GENIUS, greetings from Lima Peru
i wonder, is it possible to chain these gearboxes with gearing reduction, so that you can have a three, even four speed automatic?
Really nice man good job
Thank you for explaining and not just showing it.
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
I am so excited i saw diffential drive shaft in my lego insruction ,thats why i did test run
Thanks!!!!!! Now i can make an offroader that won't constantly go slow
You can achieve that function in a better way, with a magnetic clutch, that way there's wear. You could also cascade it to make it 3 or 4 speed or whatever you want.
Best innovation you can change the world good luck
Thanks 🙂
I am curious about the torque numbers on each gear. I would imagine that there is quite some power loss from that friction clutch, so it would be nice to see how much more torque the low gear produces compared to the high gear.
I will post new video soon, where this will be compared. Fixed high speed gear VS automatic gear with friction clutch. The clutch has friction drag around 5Ncm.
This is fantastic! Great video!
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
Very well explained!
Yes this is the right approach when you try to use a differential like a gear box, (in the lego world)
that's a really cool little device, might have to build one now
Very impressive. You could add something like a rachet to stop feedback under heavy load. Although I barely saw that happen in the testing you showed.
My friend made one of these when we were kids. He chained 3 together in series to have more gear ratios.
How much power does clutch consume when it's slipping? If the power dissipated by the clutch is half then there's no advantage in torque just half the speed.
Hi, check my next video there you can see even some simple calculation..
Very well explained! Thanks!
I’d love to see a multi speed transmission. Imagine something that could go into a semi truck that can have high torque but then have enough gears to get to higher speeds
Maybe you could daisy-chain these and have a reduction gear at the beginning to increase the torque.
You should build a freewheel and some kind of suspension. I think I remember some lego technique springless suspension.
Toyota eCVT principle?
I believe the high speed ratio is actually 1:2.33. one turn of the motor outputs 2.33 turns of the shaft.
Additionally, unlike a conventional trans, you're not getting any torque amplification through gear ratios, as 1:1 sucks for this.
Pretty neat project though.
i am puzzled, i suppose heat dispersion and friction are minimal, but yet isn't friction less efficent than say lowering tension input of the motor to make it turn slower? my main concern is battery duration, by reducing waste heat to 0. also i learned that by stressing a motor with friction while it is trying to push at its max can have terrible effects on the motors working capabilities, so it leaves me questioning how could the design be more efficent
Some old cars had an "overdrive" cruising gear that worked on a principle similar to this
The friction present at the low speed having to turn against the clutch is kind of a drag, I also know that lego clutches dont have a long life expectancy, If you made a manual version with a gear that engages and disengages using the collar lego makes for that very purpose you could eliminate both issues but I guess it would not be automatic any more.
I have been looking for this so long
In your examples of alternative possibilities, you suggest a 2 engine input, 1 output combination. This does not work. If you combine 2 inputs with 1 output it will work at the strength of 1 input, since if one input cant overcome the torque, it will simply stall and become an output. I suggest you try it. 2 same speed engines in, 1 output. Then test if this increases torque compared to 1 engine. I strongly think it wont.
Why do you think that two engines together will not increase the power of whole system? I have already tested a lot of similar solutions, many of them without success. But if there are two engines, I am sure the output power will be combination of both motors. Like hybrid cars, one petrol engine, one electric engine. Total power of the car is sum of both minus some energy loss. And we use here differential, it means if one input is stationary, the gearbox still works. It is not blocked because of one engine is stalled.
Interesting concept. Obviously not efficient at all with using a slip clutch. I’d be really interesting in seeing a similar setup with a clutching gear instead of a slip clutch gear. Nice job.
Thanks. In reality it works. The output torque in slow speed is higher than in high speed even there is a friction clutch, everything is about the gear ratio. I am preparing another video to show that the car can overcome some obstacles with this gearbox, which is not able to overcome on fixed high speed.
It's a nice concept but in the long term that slip gear is going to get looser
Yes, that's right. 🙂
solid design wonder if you could make the bottom 1 2x1 instead of 1 1x1 and 1 bushing
Just watched this and can't help but wonder if this can be put into the 42099 X-treme Off-Roader?!??! ..because if you own this excellent set you likely know about the simple but needed rear gear swap to change speed for torque.
Excellent video with a great explanation and demonstration of how it works!
I have build a even smaller automatic gearbox if you want you can check it out on my channel...
This is tge beat gearbox I've ever seen like how did you vome up with this its so genius
Cool engineering. But to see if it accomplishes anything, really need to test it. see if the car can climb a steeper incline with or without the transmission (keep weight the same) and see if it’s faster on flat ground with or without the transmission.
Friction clutch just means it makes the wheel spin slower under load, because of the energy loss there's no mechanical advantage, you can see how much it struggles under load.