This type of CVT is used in the Enviolo step-less bicycle gear shift. I have one on my ebike, and it's so convenient to adjust my gear ratio on the fly to my liking while applying constant torque to the pedals.
This is a great design and it's awesome you released the file for everybody, but my favorite part is just the joy it brings you using it. It's infectious.
Hi, I like the principle of this design in getting a variable transmission. But I think there may have been a mistake with the motion of the intermediate balls that change the gear ratio in your model. The levers moved in different directions because they were attached to the parallelogram of the change mechanism (one lever moved towards the input shaft and the other away). This however is wrong, both levers should move in the same relative direction - either towards the input shaft or away from it. This would mean that the balls maintain the Sam relative angle to each of the rings and thus the same gearing.
That's what I was thinking too. To mirror the rotation, the parallelogram could be a figure 8 over two levels, or just a Z as a single bar would be strong enough in this situation.
@@VeniceInventors Or it could be a simple push/pull yoke attached to the ball axle. An especially useful configuration if you want to use a fly-ball regulator to control the output speed. Attach the yoke to a sleeve around the output axle, connect the regulator so that it pulls the sleeve towards the discs as the output accelerates.
In following all your 3D printed projects you seem to have inspired a lot of people to learn to use a CAD program. I think that is wonderful. Hats off to you Rob! CAD drawing is such a useful and satisfying skill to have
I don't think I will EVER be able to stop watching your videos. Even though I think I have a reasonably good understanding of physics and engineering I'm continuously learning something new from you - as well as being entertained! Thanks as ever, Rob - please keep doing what you're doing! 🙂
Hi We used to use these back in the 70s before inverter motor controllers were available they were called kopp variators the tool I used the most was a marine cylinder hone with a 3kW motor there were 7 50mm steel balls in the variator. In some respects I might still prefer to use one of these over an inverter as some motor-inverter combinations can be noisy Always love your excited enthusiasm Keep up the good work
this style of transmission is used in millions of bicycles, an special oil is used which locally solidifies from the pressure so that there is no contact of the metal parts (preventing wear)
That is a great design! There is a very similar type of CVT in common use on petrol-powered snow throwers. The engine drives a steel disk upon which a rubber-tired ring is pressed at 90 degrees. By sliding the ring close to the outer edge of the disk or toward the center of the disk it changes the ratio of input/output RPM. It's very robust and fairly efficient from the perspective of power lost to friction.
Laboratory overhead stirrers from IKA use a very similar system. The motor has a steel cone with a shallow dish, the motor sits on a rail allowing it to move in and out relative to the hard rubber contact ring and thus vary the speed
I just wanted to say that I enjoy your videos so much. I can’t stop smiling during your entire presentation because of the joy I receive in the information you provide. Thank you and please continue creating your wonderful videos.
Thank you for the video, Robert! Initially I was thinking that such a mechanism would require a ball on an axel that moves in and out of the center of a spinning disc, perpendicular to it. But this does seem more practically useful! Thanks again!
Excellent project. It would also have many uses in a waterwheel system. For instance, if you had a waterwheel powering a trip hammer, you could use it to control the duration between the hammer strokes.
@@ThinkingandTinkering With a slight modification (to allow the balls to be moved out of contact with the rings), you could even use it to stop the hammer altogether.
traditionally they would change (dwell) duration between strikes by selecting different numbers of trip cams on the driveshaft. "Ancient power-hammers and the city that put steel in the world" by Lindybeige.
I believe that the more balls you add the more friction will be generated, if you were using it for something (bicycle or a wind turbine as suggested) with a limited power output you would lose a great deal of the input energy. It’d also become really complex to control all of the balls unless they’re simply idlers - ie ones to hold the plates at a consistent distance. It’s a very interesting idea and the most dead simple CVT I’ve seen, to scale it up you’d want really solid metal circular plates for the input and output that won’t flex and solid bearing blocks and yokes to further minimize losses. While fascinating, I don’t think this is something that could really be used in a real world application but it’s definitely a cool concept.
@@sjsomething4936 Anything you add will increase friction. That is beside the point. I would have no problem cycling it with a dozen drive balls on it, but it would slip with only 2 of them because the power to traction/friction ratio would be too small. Just like adding fatter tires to a race car add rolling resistance, but without them, the car would just sit in one place and burn the tires off. All mechanisms have tradeoffs. Also, one need not have an actual whole sphere on these, a hemispherical roller would save on total machine mass, while also allowing the tilting mechanism to be closer to the center of both axis of said hemispherical roller at the same time [which offers some real advantages relating to strength of the mechanism and total mass and volume of the whole transmission]. To hold the plate at a fixed distance can be performed with some external thrust bearings, so that would not be such a big deal, and, depending on how much power one was applying to said device, might prove critical to keeping it rigidly in place under a load. So far as making the main wheels [either partially, or entirely] out of metal, that would be fine, but if you want strength without a lot of mass, setting up a hardened steel set of races on the outside with something like magnesium or composite material for the most of the drive plates would make more sense than a heavy steel one. I could see making something that safely conveys more than 50 BHP that weighs less than 10 Kg and takes up less than 1/10 of a cubic meter in volume. Compare that to most 'infinitely variable' transmissions, and that is rather light. I have an infinitely variable hydraulic transmission which is rated for 50 BHP and while it is about 1/10 of a cubic meter in volume, it weighs about 35 Kg, as it is made mostly from cast iron, machined steel, and some machined brass parts.
This is how the NuVinci/Enviolo CVT works; I'm in the process of building a rear wheel for my bike with one. I've seen the videos dozens of times but I've never quite translated it to the workbench...thanks for the insights and inspiration.
Your videos are awesome, they expose me (and many others) to knowledge and information I didn't see anywhere else, and inspire new ideas and creative thinking. Thank you for your work and for sharing it with the world so freely and generously.
I do have one question regarding this video in particular... Intuitively, it seems that turning the two balls in *opposite* directions ("/\" or "\/") would make both of them touch the wheels with the same circumference for each wheel, while turning them in the *same* direction ("//" or "\\") would make them work *against* each other. Looking at the way Kopp variators work, (thank you @TheBlibo), my intuition seems correct, yet when you've tested your device it worked... can you explain what's happening here? One way this can happen is slippage. And again, intuitively the ball with the larger circumference contact at the input side has some torque and angle advantages over the other side, which means the other side should be the one slipping. If that's the case, the output wheel should slow down, no matter which way the balls are tilted. ...But I don't want to make any assumptions since I haven't tried it myself (yet:), so I would appreciate an explanation.
Like every CVT, this ball-version relies on friction too. Friction however has the disadvantage of losses, since the material, that bulges in front of a wheel (or ball) does not release all its energy back, but creates heat. The effect is called inner friction. Additionally, there is wear and tear, since the contact area is very small. Of course, losses can be minimized, by e.g. using toroids and balls from hardened steel, however, this decreases the available torque.
There seems to be one problem with the model, rather than using a parallelogram you'd want to be using something that would shift the shafts of the balls all towards one wheel. It gets noticeably louder when you turn the handle, likely due to one of the balls having more friction on it than the other one.
@@ThinkingandTinkering With a single ball the mechanism works as you've described. But with the parallelogram one of the balls has the small radius on the red wheel and the other has the large radius on the red wheel. When in reality for a reduction you'd want both small radii on the red wheel and both large radii on the blue wheel. It becomes more apparent as you add balls around the circumference of the wheels.
I think the parallelogram isn't the right movement, the control rod needs to cross the centre point, so the the inner axis' of the balls point in the same direction, not opposite, the two ball posts should turn in opposite rotations, i.e. one clockwise, the other anti-clockwise. Is there a way I can send you a drawing to explain better?
it doesn't seem to matter - i tried it both ways and it made no difference so I went for the easiest mechanism - where the ball touches the ring might change that but for what i did - it seems ether is good - and the control rod does cross the centre of rotation that's why the offset cage
@@ThinkingandTinkeringOne of the balls is generating friction then, and you'll probably only get the slower output due to the greater torque vs friction of the ball that is angled away from the output, if they have crossed members you could get the output to spin faster than the input too, though likely with a little more elbow work.
I saw a bicycle transmission like this. The axis of the planetary balls was aligned with the axis of the drive and driven wheels so that the same effect could be achieved without reversing the rotation of power input compared to the output.
Ooh! Nice. Amazing demonstraion of a simple principle that's certainly in the "i'd never have thought of that" category. But wait a sec... Shouldn't the two balls be rotating _antiparallel?_ I mean, when one ball's axis of rotation is tilted towards the red wheel, say, the other ball's axis should also be tilted _towards_ the red wheel, yes? Not _away_ from it?
it doesn't seem to matter - i tried it both ways and it made no difference so I went for the easiest mechanism - where the ball touches the ring might change that but for what i did - it seems ether is good
You forgot to show it pulled toward you showing the speedup of the structure. Now I'm going to have to build it to be able to see that. This is a fabulous DIY energy adjustment device and can be made with other rubber parts also. This design is excellent for a hydro unit to adjust the speed as the water flow changes by the hour as it rains and then gets dry out again. It can be set to precisely keep speed at the mains frequency or a fixed voltage for a solar charger inverter.
Please forgive my ignorance, hence my question. Wouldn't the parallelogram as implemented here, make one of the balls be positioned in the slow-to-fast position and the other ball in the fast-to-slow position simultaneously? If that's the case then the slowing down was in part due to friction, not just a ratio. To settle or answer this question we need to see demonstrated the opposite of it slowing down: speeding up. You do a great job at explaining and demonstrating, thanks.
One benefit of this type of transmission I could see is that if the output side seizes up for some reason, the transmission will slip instead up continuing to turn and could prevent further damage on the output side.
if you used this with a windmill, you could probably use and actuator to maintain a stable voltage on the output. By sampling the output voltage , shift the gear back and forth for the desired output. almost like a voltage regulator
@@Xayuap you wouldn't want this on a generator, the flywheel effect steals power from the generator constantly trying to maintain speed. his device already controls the speed
great idea - as always. Disappointed that there were no "yee ha's" during the C&W musak! :) I can only imagine what you were like with mecanno! LOL Keep up those great ideas....
Great video Robert. Looks like my idea for a centifugal brake for my wind turbine has just been thrown out of the window after watchng this video. Generator constant velocity is a theme which i have been looking at recently, whether it be mechanical or electical. Many thanks.
Just the sort of thing I've been looking for! Not exactly as shown, mind you, but if you mirror the mechanism into two transmissions with a central driving wheel, and have their transmission levers on one bar, you'll have two outgoing wheels with a fixed sum of transmissions, which is necessary if you've got a box-trike that needs to be able to turn tight corners...
Very cool concept, but there is a flaw. Both balls should have rotated toward you. The way you have it, one ball rotated away from you, and one ball rotated toward you. The transmission design was fighting itself, which is why it was squeaking. Make the connector bars connect to opposite sides of the lever, so that when you pull the lever, both balls rotate towards you, or away. But at any rate, a very cool design.
I hope you save all these fantastic design projects somewhere! Then we can set up the RMS museum of fantastical devices - and visitors can then go home and build it themselves. I say this because, while the web is a great motivational tool, as a kid I remember being memerized whenever my folks took me to places with these sorts of devices, and this lead to adventures and jobs and careers in all things technecial. I would have been over the moon if I could have gone home and 3D printed my own!
Fascinating mechanism, but shouldnt the balls turn together to point in the same direction so both slow ends are on the same wheel, rotational symetry ? Great video.
6 minutes ago!! Edit: as with so many of these videos, my mind is blown by how simple and compact it is! I was hoping to see the opposite ratio, making the output faster. I wonder about the ability to adhere the transmission wheels to the control ball though, especially if the input velocity is much higher than the desired output velocity
@RobertMurraySmith Shouldn't the two balls have had their axes turned in opposite directions? Turning them in the same direction, the rings have opposite ratios on each ball, i.e: 1:3 on one side 3:1 on the other. You need to turn them the same angle towards the same ring, don't you?
You could redo the parallelograms long sides as sliding crossbars that have a slot to pass through each other along the sides to fix this. then each end turns the same angle towards the same axle.
Remember the idea i said earlier for the galaxy drive and the gravity battery with the fan blades that can seal. I was thinking that we could fill the tube for the gravity battery with water, and have a series of blades that wil open and turn as the weight drops, but as you put energy back into the system, it closes the fan blades automatically and also draws the water up, as added weight. Im thinking this might be useful for an under a pond or lake or under the ocean type application? Perhaps reverse it maybe, so that theres a vacume under the fanblade seal that causes a vacume as the weight is pulled back out of the hole while sealed off...
Great😊😊😊RESPEKT😊😊😊zašto se takav mjenjač u automobilima i u drugim strojevima ne korist ? ..,..tebi: Puno poštovanje gospodine, i hvala ti zato što otvoreno govoriš o tim jednostavnim rješenjima, i volim da te inžinjeri raznih struka više poslušaju i poštuju tvoj rad GREAT.
Brilliant I don’t have a 3 d printer but nothing stopping someone building this say out of another material Wood metal etc as a model thanks for showing this
Robert, this is very cute. But I believe it might have some usefulness beyond that of a transmission. Specifically, it looks quite suitable for getting two plates or rings to counterrotate. That would be a nice way to set up counterrotating magnets on stationary coils (if that's a thing), or, if one wanted to deal with the hassles of power transmission, to have dual sets of coils counterrotating over the magnets. Or even just coils on one and magnets on the other.
It looks like crab steering not Chinese puzzle as I would expect, the bar on the top should be a cross linkage not straight. Top down view would make it clearer.
it doesn't seem to matter - i tried it both ways and it made no difference so I went for the easiest mechanism - where the ball touches the ring might change that but for what i did - it seems ether is good
What if you amplified the out put from the coil and magnets by a telsa pancake coil with magnet disc driven by a wind turbine. The inductance into the primary gets amplified in the secondary by a thin plate of non magnetized paramagnetic alloy.
Hmmm, my first attempt would have been to have kept both slower or both faster rotations of the small transfer balls to the same disc. First glance tells me that one ball slips , I wonder why... interesting, And weird. Guess I'll have a think about it later after I've had coffee.
One ball does slip because the parallel bars should have been crossing bars. As it is built one ball is fighting the other when not centered. I think that is why we were not shown the driven disc spinning faster than the drive disc. On this channel a video per day is a priority over accurate useful information, but it does keep guys like us thinking.
For a second, I thought this was going to be another variable transmission, were the balls would be between the two wheels and balls would be pushed closer to the center to speed up and closer to the edges to slow down. This one is new to me and could be made as an auto speed controller, just what a windmill needs, and perhaps if wind gets way to fast, could also activate a disc brake system.
Yep - torotrack... maintaining contact pressure is key (to inefficiency too_ +/- 90 degrees for infinite +/- rotational conversion (don't ask about efficiency at the extremes)- mononum of 3 balls is logical (3 is "self orienting in plane" allowing cv joints to be used on the disks - freely orienting...).
Are u planning on making a feedback loop for the constant secondary "gear" speed? If so are u gonna use arduino or a raspberry or will u make your own feedback driver? I would love to see it this could dramically lower the cost of diy wind turbines since u can use a asyncronous motor as a generator straight on the grid
The defeciencies of this transmision is the ratio controlled manually, i got an idea to monitor the motor current with sense resistor feed to microcintroller using opamp. The microcontroller control a small servo motor to control the ratio through the lever. The decision using microcontroller is that the ratio could be altered to be non linear using non linear function or to speed up the algorithm by using lookup table. The microcontroller i choose is esp-12f for the price. By the way for the wind collector, i think it is better and easier to use the blade like in boat impeller reversed stacked in upward spiral. It will direct the air straight upward for higher speed and to catch air current that slips away. I also planned to paint it black doff to heat up the air inside the "chamber" so that it generate slightly more speed on hotter days using air convection. Will this works? It is only as per my understanding, i only formally learn chemistry, finance and economics studies.😅
...or you could use a simple mechanical centrifugal regulator (a-la steam engine) to control the ball angle and ratio. This avoids the fun of programming your microproceser of course, so probably defeats the object of your exercise!
This makes me look at the normal derailer in a bicycle as obsolete! I wonder how involved it would be to adapt😊1 this to a chain drive for such an application?
Um , the wind very seldom holds a steady speed , that would be your power source . But he said the speed is variable at the output end too . That’s puzzling to me . How do you handle torq ? In the C V T s I’ve seen , there is a belt that handles the torq , but the friction is what destroys the belt . In a car transmission , they are metal . In old toys with gas engines they are rubber mixed with Kevlar . But on a wind turbine ? Talk about a maintenance problem ! There has to be a better way .
Some sort of centrifugal lever on the input side that pushes and pulls that lever to maintain a more stable input RPM while automatically increasing the output RPM would be interesting.
I've been wanting to build such a thing for 2 bicycle wheels to explore the rotational inertia of counterrotating flywheels and what happens to the precessional forces. One theory is that the opposite vectors would simply cancel out. I'm thinking that the axle bending forces of the counteracting precessions would be detected.
They would cancel out as a whole but definitely still have local force imbalances. Granted it is easier to control but it still doesn't disappear in the system. Mechanical energy transfer happens fast but not instantly and that creates a problematic imbalance itself at high RPMs for any object. Like anything naively manufactured spinning at 10k RPM gets problematic in that.
@KaiserTom Yes, yes, the tendency to precess, as a whole, would disappear. But assuming that both were counterrotating about the Z axis, I'm not convinced that the moment of inertia about X, or Y, would remain unaffected. The differences between the static moment of rotational inertia about X, and the spinning moment about X is what I've been wondering about. I does not make sense that it would be the same, although the simplistic math would say that it might. The bending force on the axle, of both gyros trying to precess in opposite directions should have some equal reaction resistant to that motion.
Compared to the friction disc design, this one is definitely a little less complex. But I expect it would not be as durable. The friction against the balls would be almost constantly abrasive when not configured in a 1:1 position. Same can be said for fricrion disc designs. However; the latter experiences abrasion against only 1 point of contact, while the ball design is experiencing it from 2 points. And I think that the differential will amplify that abrasion. That's only speculation. I've never seen this design hands-on. But the friction disc design is common in lawn tractors here in the US, and are usually very reliable; high longevity. I'm rather surprised that automotive CVTs did not employ the same design.
Maybe a very fool question (according to what we know about "gears and transmission") but does it feel harder / easier to spin it when You change the ratio of in / output?
Theoretically it's single point contact which means it's unable to transmit much more than a hand crank force,. Reality is, it's not single point, resulting in friction and wear.
This type of CVT is used in the Enviolo step-less bicycle gear shift. I have one on my ebike, and it's so convenient to adjust my gear ratio on the fly to my liking while applying constant torque to the pedals.
Yep.just like the Schimano from 1958. 10 speeds, shift on the fly while pedaling.
I have a servo actuated version of it, Nuvinci Harmony. Automatic cvt . Infinit pleasure :-}
This is a great design and it's awesome you released the file for everybody, but my favorite part is just the joy it brings you using it. It's infectious.
lol - cheers mate
Hi, I like the principle of this design in getting a variable transmission. But I think there may have been a mistake with the motion of the intermediate balls that change the gear ratio in your model. The levers moved in different directions because they were attached to the parallelogram of the change mechanism (one lever moved towards the input shaft and the other away). This however is wrong, both levers should move in the same relative direction - either towards the input shaft or away from it. This would mean that the balls maintain the Sam relative angle to each of the rings and thus the same gearing.
That's what I was thinking too. To mirror the rotation, the parallelogram could be a figure 8 over two levels, or just a Z as a single bar would be strong enough in this situation.
@@VeniceInventors Or it could be a simple push/pull yoke attached to the ball axle. An especially useful configuration if you want to use a fly-ball regulator to control the output speed.
Attach the yoke to a sleeve around the output axle, connect the regulator so that it pulls the sleeve towards the discs as the output accelerates.
I actually commented the same, because I was surprised no one else caught it, then I post and see this.
I came into the comments to say exactly the same thing.
I noticed the same. That is why the balls were squeaking, the intermediate balls were working at opposition.
In following all your 3D printed projects you seem to have inspired a lot of people to learn to use a CAD program. I think that is wonderful. Hats off to you Rob! CAD drawing is such a useful and satisfying skill to have
Nothing's more useful than a drawing, whether to catch your own flawed thinking or to show people just what you've dreamed up 🙂
I don't think I will EVER be able to stop watching your videos.
Even though I think I have a reasonably good understanding of physics and engineering I'm continuously learning something new from you - as well as being entertained!
Thanks as ever, Rob - please keep doing what you're doing! 🙂
Hi
We used to use these back in the 70s before inverter motor controllers were available they were called kopp variators the tool I used the most was a marine cylinder hone with a 3kW motor there were 7 50mm steel balls in the variator.
In some respects I might still prefer to use one of these over an inverter as some motor-inverter combinations can be noisy
Always love your excited enthusiasm
Keep up the good work
this style of transmission is used in millions of bicycles, an special oil is used which locally solidifies from the pressure so that there is no contact of the metal parts (preventing wear)
Non-Newtonian shear is TIGHT!
I enjoy watching you enjoy these inventions almost as much as the inventions themselves. Thanks as always.
That is a great design! There is a very similar type of CVT in common use on petrol-powered snow throwers. The engine drives a steel disk upon which a rubber-tired ring is pressed at 90 degrees. By sliding the ring close to the outer edge of the disk or toward the center of the disk it changes the ratio of input/output RPM. It's very robust and fairly efficient from the perspective of power lost to friction.
I have an old (like 70's or so) lawnmore that used the same design. An idler 'tire' lol
Laboratory overhead stirrers from IKA use a very similar system. The motor has a steel cone with a shallow dish, the motor sits on a rail allowing it to move in and out relative to the hard rubber contact ring and thus vary the speed
I just wanted to say that I enjoy your videos so much. I can’t stop smiling during your entire presentation because of the joy I receive in the information you provide. Thank you and please continue creating your wonderful videos.
Thank you for the video, Robert! Initially I was thinking that such a mechanism would require a ball on an axel that moves in and out of the center of a spinning disc, perpendicular to it. But this does seem more practically useful! Thanks again!
It could be that both methods could both be combined together for a higher level of control!
Glad it helped
Take something simple, make something complicated and crazy and absolutely wonderful out of it.
You’re a genius and an entertainer man!
Never seen this mechanism before. That is brilliant, such an elegant solution.
Your getting good at making 3D printed parts Robert, I love how you make them so everything just clips together. Thanks for sharing.
Thanks for the knowledge and joy from the satisfaction of the functionality. Unity in knowledge ✌🏼
The best explanation and demonstration of this type of drive I have seen!😊
Wow, thanks!
Excellent project. It would also have many uses in a waterwheel system. For instance, if you had a waterwheel powering a trip hammer, you could use it to control the duration between the hammer strokes.
oh - that's clever - nice one mate
@@ThinkingandTinkering With a slight modification (to allow the balls to be moved out of contact with the rings), you could even use it to stop the hammer altogether.
This is similar to the transmission in a snow blower.
@@rayg436 Is it used to control the speed of the snowblower?
traditionally they would change (dwell) duration between strikes by selecting different numbers of trip cams on the driveshaft. "Ancient power-hammers and the city that put steel in the world" by Lindybeige.
I would use as many balls as I could get around the edges so as to make sure power is securely transferred without slippage and without part damage.
I believe that the more balls you add the more friction will be generated, if you were using it for something (bicycle or a wind turbine as suggested) with a limited power output you would lose a great deal of the input energy. It’d also become really complex to control all of the balls unless they’re simply idlers - ie ones to hold the plates at a consistent distance. It’s a very interesting idea and the most dead simple CVT I’ve seen, to scale it up you’d want really solid metal circular plates for the input and output that won’t flex and solid bearing blocks and yokes to further minimize losses. While fascinating, I don’t think this is something that could really be used in a real world application but it’s definitely a cool concept.
@@sjsomething4936 Anything you add will increase friction. That is beside the point.
I would have no problem cycling it with a dozen drive balls on it, but it would slip with only 2 of them because the power to traction/friction ratio would be too small.
Just like adding fatter tires to a race car add rolling resistance, but without them, the car would just sit in one place and burn the tires off.
All mechanisms have tradeoffs.
Also, one need not have an actual whole sphere on these, a hemispherical roller would save on total machine mass, while also allowing the tilting mechanism to be closer to the center of both axis of said hemispherical roller at the same time [which offers some real advantages relating to strength of the mechanism and total mass and volume of the whole transmission].
To hold the plate at a fixed distance can be performed with some external thrust bearings, so that would not be such a big deal, and, depending on how much power one was applying to said device, might prove critical to keeping it rigidly in place under a load.
So far as making the main wheels [either partially, or entirely] out of metal, that would be fine, but if you want strength without a lot of mass, setting up a hardened steel set of races on the outside with something like magnesium or composite material for the most of the drive plates would make more sense than a heavy steel one.
I could see making something that safely conveys more than 50 BHP that weighs less than 10 Kg and takes up less than 1/10 of a cubic meter in volume.
Compare that to most 'infinitely variable' transmissions, and that is rather light.
I have an infinitely variable hydraulic transmission which is rated for 50 BHP and while it is about 1/10 of a cubic meter in volume, it weighs about 35 Kg, as it is made mostly from cast iron, machined steel, and some machined brass parts.
love to see this channel hit a million subs
lol - that would be cool!
This is how the NuVinci/Enviolo CVT works; I'm in the process of building a rear wheel for my bike with one.
I've seen the videos dozens of times but I've never quite translated it to the workbench...thanks for the insights and inspiration.
Your videos are awesome, they expose me (and many others) to knowledge and information I didn't see anywhere else, and inspire new ideas and creative thinking.
Thank you for your work and for sharing it with the world so freely and generously.
I do have one question regarding this video in particular... Intuitively, it seems that turning the two balls in *opposite* directions ("/\" or "\/") would make both of them touch the wheels with the same circumference for each wheel, while turning them in the *same* direction ("//" or "\\") would make them work *against* each other.
Looking at the way Kopp variators work, (thank you @TheBlibo), my intuition seems correct, yet when you've tested your device it worked... can you explain what's happening here?
One way this can happen is slippage.
And again, intuitively the ball with the larger circumference contact at the input side has some torque and angle advantages over the other side, which means the other side should be the one slipping.
If that's the case, the output wheel should slow down, no matter which way the balls are tilted.
...But I don't want to make any assumptions since I haven't tried it myself (yet:), so I would appreciate an explanation.
You've made a differential. Same concept. Love your attitude towards your creations.
Subscriber for life 😊
What a unique idea for a simple mechanism. Well done!
Never seen that system before, outstanding. Thanks Rob.
Like every CVT, this ball-version relies on friction too. Friction however has the disadvantage of losses, since the material, that bulges in front of a wheel (or ball) does not release all its energy back, but creates heat. The effect is called inner friction. Additionally, there is wear and tear, since the contact area is very small. Of course, losses can be minimized, by e.g. using toroids and balls from hardened steel, however, this decreases the available torque.
Wow! That's awesome Rob. Keep up the flow of knowledge. You are truly appreciated.
There seems to be one problem with the model, rather than using a parallelogram you'd want to be using something that would shift the shafts of the balls all towards one wheel. It gets noticeably louder when you turn the handle, likely due to one of the balls having more friction on it than the other one.
that doesn't seem right mate - and basically you saw it working - so I am not sure what you mean
@@ThinkingandTinkering With a single ball the mechanism works as you've described. But with the parallelogram one of the balls has the small radius on the red wheel and the other has the large radius on the red wheel. When in reality for a reduction you'd want both small radii on the red wheel and both large radii on the blue wheel.
It becomes more apparent as you add balls around the circumference of the wheels.
@@inventor121 i was about to say the same :) you are absolutely right
Replace the parallel bars with crossing bars and it will become self evident. @@ThinkingandTinkering
I think the parallelogram isn't the right movement, the control rod needs to cross the centre point, so the the inner axis' of the balls point in the same direction, not opposite, the two ball posts should turn in opposite rotations, i.e. one clockwise, the other anti-clockwise.
Is there a way I can send you a drawing to explain better?
it doesn't seem to matter - i tried it both ways and it made no difference so I went for the easiest mechanism - where the ball touches the ring might change that but for what i did - it seems ether is good - and the control rod does cross the centre of rotation that's why the offset cage
Crossing control rods are the right way to go for this build.
@@danedmiston9673 Agreed
@@ThinkingandTinkeringOne of the balls is generating friction then, and you'll probably only get the slower output due to the greater torque vs friction of the ball that is angled away from the output, if they have crossed members you could get the output to spin faster than the input too, though likely with a little more elbow work.
I saw a bicycle transmission like this. The axis of the planetary balls was aligned with the axis of the drive and driven wheels so that the same effect could be achieved without reversing the rotation of power input compared to the output.
Ooh! Nice. Amazing demonstraion of a simple principle that's certainly in the "i'd never have thought of that" category.
But wait a sec... Shouldn't the two balls be rotating _antiparallel?_ I mean, when one ball's axis of rotation is tilted towards the red wheel, say, the other ball's axis should also be tilted _towards_ the red wheel, yes? Not _away_ from it?
it doesn't seem to matter - i tried it both ways and it made no difference so I went for the easiest mechanism - where the ball touches the ring might change that but for what i did - it seems ether is good
Correct, one of the balls was slipping and not contributing anything to the output rotation.
You make cool and inspiring video's thank you!
Glad you like them!
You forgot to show it pulled toward you showing the speedup of the structure.
Now I'm going to have to build it to be able to see that. This is a fabulous DIY energy adjustment device and can be made with other rubber parts also.
This design is excellent for a hydro unit to adjust the speed as the water flow changes by the hour as it rains and then gets dry out again.
It can be set to precisely keep speed at the mains frequency or a fixed voltage for a solar charger inverter.
You have an awesome way of explaining things. Always love watching your stuff from Oklahoma!
Awesome! Thank you!
Please forgive my ignorance, hence my question. Wouldn't the parallelogram as implemented here, make one of the balls be positioned in the slow-to-fast position and the other ball in the fast-to-slow position simultaneously? If that's the case then the slowing down was in part due to friction, not just a ratio. To settle or answer this question we need to see demonstrated the opposite of it slowing down: speeding up. You do a great job at explaining and demonstrating, thanks.
One benefit of this type of transmission I could see is that if the output side seizes up for some reason, the transmission will slip instead up continuing to turn and could prevent further damage on the output side.
This is done with a different mechanism in piston airplanes where the propeller speed remains constant while the power can vary.
if you used this with a windmill, you could probably use and actuator to maintain a stable voltage on the output. By sampling the output voltage , shift the gear back and forth for the desired output. almost like a voltage regulator
a mechanical centrifugal governor would do
@@Xayuap thats gonna be hard if you are not using steam
there are automatic bicycles shifting mechanisms that use small mechanical centrifugal governors to keep pedaling speed uniform
@@Xayuap you wouldn't want this on a generator, the flywheel effect steals power from the generator constantly trying to maintain speed. his device already controls the speed
that makes sense,
electronically maybe it is just less power.
but information wise, both devices can be made arbitrarily smaller.
great idea - as always. Disappointed that there were no "yee ha's" during the C&W musak! :) I can only imagine what you were like with mecanno! LOL Keep up those great ideas....
Love it. Really must get a 3d printer
Great video Robert. Looks like my idea for a centifugal brake for my wind turbine has just been thrown out of the window after watchng this video.
Generator constant velocity is a theme which i have been looking at recently, whether it be mechanical or electical. Many thanks.
That's genius! I wish I'd had a bicycle with a continuously variable gear change like that when I was still able to cycle! :-)
Ne znam koju si škoku završio?,🤣🤣🤣🤣🤣ali puno sam za nekoliko godina od tebe naučio i radujem se tvom novom videu, Great.
RM-S and a 3D printer, a match made in heaven I think.
Just the sort of thing I've been looking for! Not exactly as shown, mind you, but if you mirror the mechanism into two transmissions with a central driving wheel, and have their transmission levers on one bar, you'll have two outgoing wheels with a fixed sum of transmissions, which is necessary if you've got a box-trike that needs to be able to turn tight corners...
Very cool concept, but there is a flaw. Both balls should have rotated toward you. The way you have it, one ball rotated away from you, and one ball rotated toward you. The transmission design was fighting itself, which is why it was squeaking. Make the connector bars connect to opposite sides of the lever, so that when you pull the lever, both balls rotate towards you, or away. But at any rate, a very cool design.
I hope you save all these fantastic design projects somewhere! Then we can set up the RMS museum of fantastical devices - and visitors can then go home and build it themselves. I say this because, while the web is a great motivational tool, as a kid I remember being memerized whenever my folks took me to places with these sorts of devices, and this lead to adventures and jobs and careers in all things technecial. I would have been over the moon if I could have gone home and 3D printed my own!
really wonderful design rob
Fascinating mechanism, but shouldnt the balls turn together to point in the same direction so both slow ends are on the same wheel, rotational symetry ? Great video.
Superb. I wonder where it will wear first and how one can make it longer lasting.
6 minutes ago!!
Edit: as with so many of these videos, my mind is blown by how simple and compact it is! I was hoping to see the opposite ratio, making the output faster. I wonder about the ability to adhere the transmission wheels to the control ball though, especially if the input velocity is much higher than the desired output velocity
Fantastic! Thank you and your furry friend for such an elegant concept!
@RobertMurraySmith Shouldn't the two balls have had their axes turned in opposite directions? Turning them in the same direction, the rings have opposite ratios on each ball, i.e: 1:3 on one side 3:1 on the other. You need to turn them the same angle towards the same ring, don't you?
You could redo the parallelograms long sides as sliding crossbars that have a slot to pass through each other along the sides to fix this. then each end turns the same angle towards the same axle.
Remember the idea i said earlier for the galaxy drive and the gravity battery with the fan blades that can seal. I was thinking that we could fill the tube for the gravity battery with water, and have a series of blades that wil open and turn as the weight drops, but as you put energy back into the system, it closes the fan blades automatically and also draws the water up, as added weight. Im thinking this might be useful for an under a pond or lake or under the ocean type application? Perhaps reverse it maybe, so that theres a vacume under the fanblade seal that causes a vacume as the weight is pulled back out of the hole while sealed off...
Great😊😊😊RESPEKT😊😊😊zašto se takav mjenjač u automobilima i u drugim strojevima ne korist ? ..,..tebi:
Puno poštovanje gospodine, i hvala ti zato što otvoreno govoriš o tim jednostavnim rješenjima, i volim da te inžinjeri raznih struka više poslušaju i poštuju tvoj rad GREAT.
Cmon you're doing the cVT now. Don't tell us fibs Rob, you're just trying to 3d print a twizy, aren't you... lololol. Great work mate!
A brilliant bit of engineering! What are the maximum and minimum ratios that can be achieved with this design?
You are a genius Rob
Brilliant I don’t have a 3 d printer but nothing stopping someone building this say out of another material Wood metal etc as a model thanks for showing this
Robert, this is very cute. But I believe it might have some usefulness beyond that of a transmission.
Specifically, it looks quite suitable for getting two plates or rings to counterrotate.
That would be a nice way to set up counterrotating magnets on stationary coils (if that's a thing), or, if one wanted to deal with the hassles of power transmission, to have dual sets of coils counterrotating over the magnets. Or even just coils on one and magnets on the other.
Excellent video…can you tell us what the min and max speed ratios are vs the angle of the control mechanism
It looks like crab steering not Chinese puzzle as I would expect, the bar on the top should be a cross linkage not straight. Top down view would make it clearer.
it doesn't seem to matter - i tried it both ways and it made no difference so I went for the easiest mechanism - where the ball touches the ring might change that but for what i did - it seems ether is good
Would've been nice to see a close up of the apparatus in motion...🤔
What if you amplified the out put from the coil and magnets by a telsa pancake coil with magnet disc driven by a wind turbine. The inductance into the primary gets amplified in the secondary by a thin plate of non magnetized paramagnetic alloy.
Hmmm, my first attempt would have been to have kept both slower or both faster rotations of the small transfer balls to the same disc.
First glance tells me that one ball slips , I wonder why... interesting, And weird.
Guess I'll have a think about it later after I've had coffee.
One ball does slip because the parallel bars should have been crossing bars. As it is built one ball is fighting the other when not centered. I think that is why we were not shown the driven disc spinning faster than the drive disc. On this channel a video per day is a priority over accurate useful information, but it does keep guys like us thinking.
Could be an interesting base for a wimshurst too. I wonder how the rubber would affect that 🤔
Love this ... But is there a way that this or your other variable transmission can adjust based on the rotation speed of, say your wind turbine?
I was pondering a governor mate
very clever design!
doesn’t this also gear up?
Great video Robert. New topic - AEROmine wind turbine - ever seen this set up? Based in Texas
Simply BRILLIANT !!!!!
Nissan used to have these types of CVTs attached to their V6 powerplants.
For a second, I thought this was going to be another variable transmission, were the balls would be between the two wheels and balls would be pushed closer to the center to speed up and closer to the edges to slow down. This one is new to me and could be made as an auto speed controller, just what a windmill needs, and perhaps if wind gets way to fast, could also activate a disc brake system.
Perhaps mount it vertical and put an airfoil of some sort on the control arm to get consistent power mechanically.
Yep - torotrack...
maintaining contact pressure is key (to inefficiency too_ +/- 90 degrees for infinite +/- rotational conversion (don't ask about efficiency at the extremes)- mononum of 3 balls is logical (3 is "self orienting in plane" allowing cv joints to be used on the disks - freely orienting...).
Are u planning on making a feedback loop for the constant secondary "gear" speed?
If so are u gonna use arduino or a raspberry or will u make your own feedback driver?
I would love to see it this could dramically lower the cost of diy wind turbines since u can use a asyncronous motor as a generator straight on the grid
You could do this with an old school ball governor. Give it a Google. Quite ingenuous.
There must be countless variations on this mechanism.
My old 1980's Snapper lawn mower used a similar style of transmission.
Are you going to install a similar transmission in a wind turbine? Then we'd have a governor
We don't out grow making things. We just invent bigger and better ways to do it. I bet you were a Lego's fan. Love your work Rob
lol - yes i was lol
The defeciencies of this transmision is the ratio controlled manually, i got an idea to monitor the motor current with sense resistor feed to microcintroller using opamp. The microcontroller control a small servo motor to control the ratio through the lever.
The decision using microcontroller is that the ratio could be altered to be non linear using non linear function or to speed up the algorithm by using lookup table. The microcontroller i choose is esp-12f for the price.
By the way for the wind collector, i think it is better and easier to use the blade like in boat impeller reversed stacked in upward spiral. It will direct the air straight upward for higher speed and to catch air current that slips away. I also planned to paint it black doff to heat up the air inside the "chamber" so that it generate slightly more speed on hotter days using air convection. Will this works? It is only as per my understanding, i only formally learn chemistry, finance and economics studies.😅
...or you could use a simple mechanical centrifugal regulator (a-la steam engine) to control the ball angle and ratio. This avoids the fun of programming your microproceser of course, so probably defeats the object of your exercise!
This makes me look at the normal derailer in a bicycle as obsolete! I wonder how involved it would be to adapt😊1 this to a chain drive for such an application?
Look up Enviolo, they have almost the same design CVT for bikes.
Explosion of joy was marvelous :D
Um , the wind very seldom holds a steady speed , that would be your power source . But he said the speed is variable at the output end too . That’s puzzling to me . How do you handle torq ? In the C V T s I’ve seen , there is a belt that handles the torq , but the friction is what destroys the belt . In a car transmission , they are metal . In old toys with gas engines they are rubber mixed with Kevlar .
But on a wind turbine ? Talk about a maintenance problem !
There has to be a better way .
Fantastic work Rob. I'm glad you didn't use dogs' balls.
Loved your variable tran.
You sir, are a genius, and I really enjoyed this video. Thank you so much.
Glad you enjoyed it!
Some sort of centrifugal lever on the input side that pushes and pulls that lever to maintain a more stable input RPM while automatically increasing the output RPM would be interesting.
I was pondering a governor mate
I've been wanting to build such a thing for 2 bicycle wheels to explore the rotational inertia of counterrotating flywheels and what happens to the precessional forces. One theory is that the opposite vectors would simply cancel out. I'm thinking that the axle bending forces of the counteracting precessions would be detected.
They would cancel out as a whole but definitely still have local force imbalances. Granted it is easier to control but it still doesn't disappear in the system. Mechanical energy transfer happens fast but not instantly and that creates a problematic imbalance itself at high RPMs for any object. Like anything naively manufactured spinning at 10k RPM gets problematic in that.
@KaiserTom
Yes, yes, the tendency to precess, as a whole, would disappear. But assuming that both were counterrotating about the Z axis, I'm not convinced that the moment of inertia about X, or Y, would remain unaffected. The differences between the static moment of rotational inertia about X, and the spinning moment about X is what I've been wondering about. I does not make sense that it would be the same, although the simplistic math would say that it might. The bending force on the axle, of both gyros trying to precess in opposite directions should have some equal reaction resistant to that motion.
Amazing. Such a clever idea.
Lijepi pozdrav i respekt iz Croatia, imam patent za vjetroturbine i ovaj dio je luda stvar, ako ju upotrijebim. 😍😍😍😍😍hvala ti, i volim vjetroturbine!
Compared to the friction disc design, this one is definitely a little less complex. But I expect it would not be as durable. The friction against the balls would be almost constantly abrasive when not configured in a 1:1 position. Same can be said for fricrion disc designs. However; the latter experiences abrasion against only 1 point of contact, while the ball design is experiencing it from 2 points. And I think that the differential will amplify that abrasion.
That's only speculation. I've never seen this design hands-on. But the friction disc design is common in lawn tractors here in the US, and are usually very reliable; high longevity. I'm rather surprised that automotive CVTs did not employ the same design.
I love it!!!!! Thanks Rob. /Mikael
Is the friction loss due to scrubbing of the balls significant
Your a genius, I don't understand why you don't go into production with your ideas
prefer to give them away mate
Another brilliant idea 👏 Thanks for sharing ✌️
Isn't this the basis of the enviola bike transmission? Other than the friction, it works great.
yeah it is basically exactly that - just a version you can make easily at home
Maybe a very fool question (according to what we know about "gears and transmission") but does it feel harder / easier to spin it when You change the ratio of in / output?
yes it does
Why does the title say 2014, but this was only uploaded 6 hours ago? 🤔
Theoretically it's single point contact which means it's unable to transmit much more than a hand crank force,. Reality is, it's not single point, resulting in friction and wear.
Yes, you can still work with only one ball, but it's best to have two.
Think it would take longer to learn how to write the program for each shape than to physically machine them.