The Coolest Transmission You've Never Heard Of... The Ratcheting CVT

[Music] sometimes my ideas of a cool machine are a bit eccentric and this idea was no exception you see when I was 16 years old I'd come up with an idea that I thought would revolutionize the automobile industry what if there is a way to build a continuously variable transmission and avoid using rubber or other weak materials as mechanical interfaces what if there was a way to do it with good old American gears and get positive engagement that wouldn't slip or wear out is torque increased well I ended up building my invention by welding together a bunch of old push rods that I cut up and assembled it with a couple of D wrenches some ready rod a homemade crankshaft Springs and brake cables from a bicycle the final product looked like something that MacGyver would build to get off of Gilligan's Island at the time I was really proud of my invention and it actually did work I had invented the world's first continuously variable transmission that used a positive engagement mechanism instead of a belt or a fluid or so I thought I did you see the CVT that I thought I had invented had actually been patented as early as 1994 when I was just 2 years old it became obvious to me that I wasn't the first person to come up with this idea after learning that I realized the idea wasn't gonna make me rich and I ended up throwing away the one that I had built so many years ago it just got lost in the matrix but then I got a 3d printer and this youtube channel and I remembered that one thing that I made that one time and decided that I really wanted to make another version that I can 3d print so I could share the idea with you guys and here it is admittedly I did actually change how the machine works my first machine like this did not have a variable crankshaft and instead varied the output by changing its point of attachment to the ratcheting mechanism so it was changing the height at which the the crankshaft attached to the ratchet but this newer design is much more advanced because it has the addition of a neutral ratio I do plan to show you guys how this thing works but not yet hold up first off if you're not familiar with what a CVT is don't worry I'm gonna go over that and I'm also gonna go over some reasons why you would use a CVT some reasons why you wouldn't and I'll go over the specifics of how this CBT works which is known as a ratcheting CVT and then as always I'll pull out my cordless drill and demonstrate this thing flailing around like the idiotic invention that it really is so a CVT is a really cool kind of transmission that's used in some cars but it's also extensively used in recreational vehicles like snowmobiles and four-wheelers but why well the answer to that question is because those things use gasoline engines you see gasoline engines have a range of rpms where the engine is most efficient usually at the lower end of the scale and also a range of rpms where the engine can output the most power but here stands the problem when you want to accelerate that vehicle that four-wheeler or that snowmobile you want to be able to harness the power of that engine as much as possible so that you can use a smaller and lighter engine to reduce the weight of the vehicle and in order to do that with a multi ratio transmission you would need to have a lot of gears and shift solenoids so that you can always keep the engine in its power bath but that would increase the weight to the transmission the weight to the vehicle and decrease the total power to weight ratio slowing you down enter CVTs the answer to the problem the reason that these are called cvts is because for any given input rpm with the correct design considerations you could achieve an infinite number of ratios between the lower and the upper limit in order to keep your engine load at the perfect amount so that you could hold the throttle wide open while keeping the engine within the power band so why don't all cars use these CVT things right I mean they're so great you could harness the full power of the engine to crease the weight and components or make the engine run in its power band or its efficiency band I mean why not well there are two reasons and this second one is a little disappointing number one so along with being known for their simplicity lightweight design power conversion abilities they're also really well known for their frequent failures since they don't have any locked-in ratios you can't really design one with gear mechanisms thus they completely rely on having the necessary amount of sliding friction to work properly once that friction material wears down the transmission can no longer transfer energy which is the entire purpose of having a transmission you'll understand what I mean if you've ever owned a snowmobile the belts burn out quite commonly a problem that's not acceptable in motor vehicles of course there's a ton of other designs that have addressed these problems but there is no perfect solution number two this is the kind of Reason where I lose a little bit of faith in humanity a lot of consumers don't understand cvts don't understand why they're important or why they would want one in their car because of that when cvts first came out a lot of them were programmed to act just like a normal transmission that way the consumer could hear their engine revving up and down like it's supposed to that's right they made a transmission with an infinite number of ratios and they programmed it to use like five or six of them just to make the consumers happy it's like buying a supercomputer and using it to play solitaire it bothers me let's talk about how this thing works first it takes the rotational motion from the input shaft and if the Kamloops are somewhat offset it turns that motion into a linear back and forth motion by moving this rod in and out and these ratchets take that linear ish motion and rectify it into one direction of rotational motion this design has three phases and the reason for that is to smooth out the output velocity which would never be able to actually move at a perfectly consistent velocity because of the way it is if it only had one phase or one of these wheels that could just as well be a rapid trap and if it only had two phases the backlash and the ratcheting mechanisms would cause significant stopping points I assume that adding more than three phases would have diminishing returns now before we get to the drill I want to talk about this adjustment mechanism for the cam offset because this is really really cool this is something that I had to think about for a couple of hours trying to figure out a figure to even be done and here's why imagine that this adjustment cap is directly attached to a smaller shaft inside here and that shaft has a pinion gear for each dam and each camp has a rack of gears that mate with that pinion gear in this example turning the crank shafts without simultaneously rotating this adjustment at the same speed would adjust the height to the camps which isn't really ideal you would only be able to rotate the machine a quarter of a turn so this seems a little bit off-topic but when you think about a tank like a military tank how do you assume that the steering works do they have two engines one for each wheel well maybe but some tanks use a system called dual differential steering allowing for one large engine to drive the tank forward and backwards and one smaller motor that only needs to offset the output to the left and the right tracks since steering does not need to be as fast as driving you could use an even smaller geared motor for the steering this is what inspired me to create the gearing mechanism that's hidden underneath this cover what's underneath this cover is a gearing mechanism that is derived from the dual differential setup that most tanks use with the drive input removed turn into an idler and I folded up the whole thing into a nice little package of two planetary gear sets with the input shaft locked to one planetary carrier the inside shaft flocked to the other planetary carrier the the Sun gear as a composite gear as an idler one ring gear is locked directly to the frame and the other ring gear is attached to this adjustment cover turning the adjustment causes a speed differential between the two planetary carriers thus creating a speed differential between the inner and the outer shafts while say that word three times anyway anyways let's let's spin this thing let's just make it go real fast and see if it blows up so I got this removable handle take that off so I'm gonna go ahead and mister this spinning it with a drill in neutral and as I turn this cap this way you'll see these cams come out and then it will start to increase the gear ratio for your reference the output the output from this machine is is this weirdly shaped shaft right here that is the output shaft this is the shaft and this is the adjustment mechanism so let's get started that's not a good start dang it now I have to fix my machine [Music] [Music] what do you think pretty cool huh and finally there's something inherent to this design that makes it kind of hard to classify it as a full-blown CVT as a matter of fact it just might be an impostor to find out why subscribe and come back next week maybe I'll make a video on it in the next couple weeks I'm gonna be releasing the fusion 360 files and the STL files to build this machine so you could 3d print your own I'll be releasing them on Thingiverse and when it is released you'll find a link in the description I'm probably also gonna make an assembly video because this is a very complex machine that's very hard to assemble and very hard to print hey don't forget to follow me on Twitter and subscribe and if you have any questions or suggestions for me leave a comment below if you'd like to help my CVTs reach a broader audience then hit that like button share this video with your friends and if you'd like to become a patron I would really really appreciate that hey thanks for watching for those of you who stuck around this long I figured I'd show you this gearing mechanism right I'm completely in love with this gearing mechanism well you guys know I have some weird fascination with years already but so this is all it is this is the whole thing so it is a carrier carrier ooh it's a good thing I took that apart because this was gonna be welded together I might have got a little wild with that so all it is is two planetary gear sets joined by a Sun gear that's the only gear their share in common one of these ring gears is attached to the frame the these little grooves around here the other ring gear is attached to this cover with those grooves and yeah each carrier well first off the two shafts and here one of them is the inner shaft that does the cam on the gears the outside shaft is just has a little index mark on it I'm gonna put this back together off video because yeah but anyways thank you for watching [Music] [Music] [Music]

Channel: Gear Down For What?

Views: 1,949,910

Rating: 4.5941362 out of 5

Keywords: 3D, Printed, CVT, Ratcheting, Invention, IVT, Plastic, Drill, Infinite, Ratio

Id: G9-N-nIqc4g

Length: 15min 8sec (908 seconds)

Published: Mon Mar 05 2018

Reddit Comments

[u/DuckDuckBoson]

Very cool. Had to stop watching when I realized he was stalling for time. Getting real sick of youtubers artificially extending content.

[u/SirDigbyChknCaesar]

Continuously Variable Transmission, not "consistently"

But that guy has a lot of practical knowledge about gears and transmissions.

[u/drive2fast]

The reason you don’t see this is that the ratchet mechanism would rip itself apart with any real torque application, regardless of materials.

[u/ss0889]

thats a nice idea but wouldnt the ratcheting mechanism wear out very quickly and sound like shit the whole time till it finally wore out? Seems like the springs that keep the ratcheting mechanism would need to be excellent (though i guess that exists since its already used for engine valves) and the ratchet part would undergo severe wear.

[u/rossreed88]

I made one of these out of lego many years ago. I also thought I invented it but of course i didnt lol... I had a hard time making a reliable ratchet.

[u/jizzymane]

Aka the movement isn’t fluid and will wear and tear away too quickly

[u/Sparkyman12345678]

Hey guys, this is my video, and now I can see all the bad things that you've said about it 😈

[u/theoracleiam]

I have a CVT in my Nissan. There are a few makes & models out there that have them.

[u/geek_on_two_wheels]

Continuously 3D printed variable transmission