Is it possible to have an infinite number of gear ratios?

Planetary gearboxes are incredibly satisfying. This 3d printed planetary gearbox shows how in combination with a standard combustion engine it is possible to create an infinite number of "gear ratios / transmission speeds".
Enjoy!
-Steven
Designs and STL files available for my Patrons supporters:
/ 3dprinteracademy
Electric Motors and Speed Controller:
- two electric motors: amzn.to/36S7fGH
- one speed controller: amzn.to/3ET7A8y
Thanks!
#3dprinted #gearbox #cvt #planetgears #satisfying

[@themeek351]

I'm curious to know what the torque loads would be on the ring gear and electric motor during peak power demands!

[@mantisgaming]

Yeah as soon as i heard how it works, i thought "wouldn't that put some backdrive on the electric motor?"

[@Thephotonguy]

Yeah not a wide range of ratios, and lots of backdrive and power demand from the electric motor to hold from backdriving. Innefeicient

[@mantisgaming]

@@Thephotonguy When it's set to revers, the electric motor is literally counteracting the main motor and powering the shaft isn't it? XD

[@Thephotonguy]

@@mantisgaming exactly. In reverse, all your power is coming from the electric motor. Not smart

[@wayland7150]

I have a manual screw driver that works like this. It creates greater torque if turned by the handle or greater speed if the ring gear is held or turned in the opposite direction.

[@AstonishingStudios]

Learning that there can be infinite gear ratios just unlocked human superintelligence for me.

[@dimzyx4K]

First comment🗿

[@precisionleadthrowing4628]

don't worry, it's not infinite, it's not that great and it didn't affected your intelligence (clearly) It's just added complexity + dependence + cost at no real benefit to the user

[@somerand0mpers0n]

@@precisionleadthrowing4628 real

[@monad_tcp]

@@precisionleadthrowing4628 well, it made the user mode lazy because now he doesn't have to match the engine speed to road speed anymore. I miss having to manually change gears. It was fun. And soon I'll miss having internal combustion engines. Unless I buy an antique muscle car.

[@ohytheawesome4357]

D-CVT (Direct-Shift Continuously Variable Transmission) has infinite gear ratios too, but uses belts instead for variable transmission and can switch to manual transmission for lower gears.

[@bobfredricks9567]

Yeah was wondering how long it would take for someone to mention that transmission

[@bensonboys6609]

The downside with those is they have a lot of moving parts as well as having wear items (the belt). They also have a tendency to slip. This is able to achieve infinite ratios with meshing gears. Electric motors are easy to control and cheap. With this model though, I don’t see how the torque is transmitted preferentially to the driveshaft and not the motor. When operating in reverse, I don’t see how any of the engine torque would be going to the driveshaft.

[@Fisustin]

@@bensonboys6609 In this case it's actually sharing the torque between the driveshaft and the motor driving the ring gear. So it's rather combining the power from the two different engines. So it's meant for a different use-case than CVTs like the one with belts are for. This kind of mechanisms are normally used to combine the power of electric as well as gasoline engine in some hybrid cars like the Toyota Prius' HSD.

[@matpidrums7006]

this is actually a really cool way of making a cvt that i hadn't considered. traditional belt driven cvt's have the potential to slip which is not good to say the least, and this gets rid of the problem by using gears and i think it's really cool

[@nikolatesla811]

Look at how the toyota hybrid transmissions work. It's very similar to this.

[@Sentinel851]

You can nearly always substitute a belt for a chain and get a near zero amount of slippage, but you tend to reduce the efficiency of the system, but if we're ending up with a more optimal system than before, it could be worth it

[@tigerxra8515]

Yeah, planetary gear is a key to hybrid cars, tractor cvt's (like Fendt Vario). This gear can add two different a speed and torque engines to a single output shaft, without a conflict. I had a class about transmissions and planetary gear blew my mind. It has such a great potential.

[@Hogger280]

Yes, used in Prius - engine connected to the ring gear, wheels to the planet carrier and motor/generator/starter connected to the sun gear.

[@thrashard96]

Weber Auto has videos about Priuses, the ICE is connected to the planet carrier, and two electric motors/generators are connected to the sun gear and the ring gear. The ring gear also drives the wheels.

[@Hogger280]

@@thrashard96 Yup, I got the ring gear and planet carrier switched.

[@dutchsailor6620]

Since action is reaction, you would need a lot of energy from the electric motor to get a decent amount of energy on the output shaft. The outer "stationary" (I know its not in this model) gear has to counteract the the forces applied by the planetary gears. The more torque you need on the output shaft, the more power the electric motor has to deliver.

[@ajayamirtharaj3016]

yeah that's what i thought. you need a motor equal in power to that of the engine which makes no practical sense cuz the efficiency is completely zero when the motor speed and engine speed matches cuz the output speed is zero. Well it's better than those free energy videos i guess.

[@GoldenAura32]

You really wouldn't use a system like this all the time. In an ideal setting you could run the motor in reverse to assist with acceleration up to some speed, then forward to assist with deceleration or sudden engine load spikes from say offroad conditions. In both cases you would draw from the alternator the excess power after the battery has reached peak voltage.

[@4lines633]

​@@ajayamirtharaj3016when the output speed is zero, the Electric motor is actually "helping" the engine to idle, or "helping" the planetary gear set to be in motion, it's not going against anything, the power lost is coming from the planetary gear and converting the engine power to electric for the motor (minimal energy if we consider idling)

[@Alxium]

This whole system seems like it is wasting an enormous amount of energy to just stand still. The engine is running at peak performance at thousands of RPMs while the electric motor is spinning the gear to keep the axle stationary. It would make more sense to just drive the wheels with the electric motor and power that with batteries that can be charged by the grid or an onboard ICE. To be 100% honest, taking an ICE out of the equation would increase energy efficiency by a lot as there is so much energy loss in all the moving components vs a direct or close to direct drive electric motor.

[@tomsko863]

Generally, you are correct. What the video creator said is to assume that the "engine" was working at "peak efficiency", then you will be using its energy (synonymous to "losing energy") to power the motor to get to the correct output speed (so you are no longer at "peak efficiency" are you?). There is no way to tell, with just this model, if you get *better* efficiency doing it this way rather than not running the engine at this theoretical "peak efficiently" state. I highly, highly, HIGHLY doubt it. If there are any advantages it would be patented by now and attempted However, since I am an engineer, I will say that this is an interesting idea but show me some data. Like always: Data or STFU. No real data? Then STFU.

[@dontosaw]

Well in real world applications they use two motors, one to change the effective gear ratio and the other to apply power, along with the engine. kzbin.info/www/bejne/hWeUiJyegreXoK8si=ZeeKDI0cw3hqtki_

[@MrT------5743]

It seems to me, having an internal combustion engine only keeping batteries charged and having an electric motor driving the vehicle would be simpler and the motor would only need to run when the batteries are discharged and needs recharging. You wouldn't need any transmission at all or an engine big enough to drive the car, just enough to keep the batteries charged. The system in the video, as you sit at a stop light waiting to go, the engine would be running at its optimal speed (thousands of RPM's potentially) and your not moving. Sitting there burning a lot more gas than traditional engines would be doing at idle.

[@polarisbear7468]

Yes, they are called hybrids

[@protoborg]

@@polarisbear7468 Nope. That's not how hybrids work at all. The ICE does NOT just charge the battery. It passes power through a combination transmission to the wheels. During high speed or high acceleration, the ICE kicks in to provide additional power. It also extends the range of the vehicle without needing a larger battery. Until the battery needs to charge or you need to accelerate quickly or travel above a certain speed the engine is completely off. It does NOT constantly charge the battery.

[@aud1gen]

That’s like a diesel locomotive, although I don’t think diesels have a battery, which is why the engine always has to be running to spin the generator.

[@nicholaslau3194]

@@protoborg There are many kinds of hybrid cars and how each of them charges is programmed differently. You cant use a blanket statement to claim all hybrids work than way

[@aiacfrosti1772]

@@protoborg This is how Toyota programs its hybrids. Other companies have variations of this

[@daarshg]

I am a huge fan of your videos. Precise and clear, very informative , and still no information overload !!

[@yngndrw.]

I believe a mechanism like this is used in some tanks, although the electric motor is used to control the difference in speed between the left and right treads rather than the overall speed.

[@Himechinachae]

M47 patton

[@omarmartinez2806]

Very underrated channel you should have way more subscribers your videos and models are very comprehensive yet presented in a clear and concise way. Good job on the videos and keep them coming!!

[@kotelypiesely1268]

Fendt's Vario heavy-duty transmission, used in tractors, ditches the electric motor and substitutes it with a variable angle hydraulic pumps

[@equinox9077]

I have 0 knowledge about engines or gears but the way you explained it actually made sense, thanks you for this video it was very entertaining 💪🏽🗿

[@danielcimanes2794]

From all the videos I found online so far, this is THE most easily understanding demonstration of how planetary gears work.

[@dnorby6990]

The thing is that the electric motor has to be the same power as the internal combustion one because has to hold the double ring gear spinning to keep spining the output and thats hard to make small and compact so it s intresting but does not make that much sense. because its very difficult.

[@QualityDoggo]

Same power or just reach the same speeds?

[@aaskuei]

@@QualityDoggo same power or the whole thing will free spin with the output shaft not able to move the wheels

[@bendyhouse9473]

@DNorby If you rewatch the video, you will see that the electric motor only has to have the same power when 0 rpm output is needed. The output is equal to the engine when the motor is not turning

[@Skyra_0]

Hey, really awesome vid! You explained the concept really well 👍. I can’t wait to use this idea for a project I’m working on.

[@itchytrack]

don't use this, it does not work. it actually puts a ton of torque on the moto. you might just use the motor instead of the engine

[@wizrom3046]

This concept has been around for a long time. The BIG problem is that at low speeds the electric motor has to ABSORB power, so (for example) if the main engine is making 100 hp and you want a slow RPM 10 hp at the wheels the electric motor needs to absorb 90 hp and dissipate it as heat (or maybe charge a battery). So yes, you can create a speed differential but it also causes a power differential. It can still be useful for some specialty super-low RPM tasks like cranes and tractors but it is poor for cars compared to something like a conventional gearbox.

[@TheRealKoolguy007]

Or just use the power to turn another motor connected directly to the differential, AKA, the Toyota Synergy Drive.

[@yankeedoodle7693]

Can you give an example of when the engine would be producing 100 horsepower and the car only calling for 10 at the wheels?

[@wizrom3046]

@@yankeedoodle7693 it is not like that. The mechanics of the dual motor/planetary system is that the power output at low rpms is the differential of the 2 motors. The gearing is provided by the differential of the 2 motor speeds, the torque is equal to the motor torques so the output power is motorA power - motorB power so that to get low speeds at the outout it is very inefficient because motorA has to provide more power than is needed, and motorB has to absorb the excess power. I just used those figures to make a point.

[@yankeedoodle7693]

@@wizrom3046 what you're thinking of is counter torque. There are examples of your theory in the prius power split. Two elements of the planetary are mechanically coupled, so by design they share the load of the third element.

[@wizrom3046]

@@yankeedoodle7693 exactly, it can be a useful way to share the load like in a power split, but it is very problematic when used as a gearing system to provide a large gear ratio (as would be used in a car).

[@nicolasonoufriou5439]

Wow! This is the most informative and demonstrative explanation I have seen so far regarding an ecvt system of gears! 🙏

[@robthomas8895]

Thank you for a great explanation and demonstration. I spent a sleepless night thinking about this. I plan to print this model.

[@QualityDoggo]

very cool stuff. combines the common/dense/simple fuel-powered-engine with electronically controlled motors, without actually driving the car using a motor. Wonder how the efficiency compares to regular and "hybrid" cars. Of course... these days another option for "no abrupt changes" is a full-electric system... assuming the car has enough battery power onboard.

[@itchytrack]

there is one problem with this, it actually puts a ton of torque on the moto. you might just use the motor instead of the engine

[@dashcamvids]

very nicely done!! great job!!

[@ericgolub8589]

If I’m not mistaken, won’t the torque of the output be reduced when the motor and the engine are rotating against each other?

[@GodofGHz]

Yes it would, which is why CVTs dont work this way

[@gmeast]

The planetary set must handle.John Deer uses this arrangement using a hydraulic motor including Dynamic Neutral. Textile equipment used differentials (both cycloidal gears and/or ring & pinion-axle-gears-cage-spiider gears) to control equipment speed via a power take-off from a single dynamo-driven common shaft running the length of the factory ... late 1800's - early 1900's. The individual drives on each machine were called Mechanical Amplifiers. Then came the rise of the small electric motor which allowed for the elimination of the common drive. Very old technology, but fun to play with.

[@ChristopherBurtraw]

This is a FANTASTIC way to demonstrate how hybrid transmissions work. Well done!

[@robthomas8895]

This is a great model, thank you. One Mode you haven’t described though, is if you hold the ICE stationary and drive the output on the electric motor only. This is how CVT cars would start off from Stopped.

[@bunnygetspancake6916]

You could even get it to spin faster by reversing the direction of the electric motor

[@dancoulson6579]

The issue is that now we need two engines, and to be able to vary the speed of the second one... The second engine needs to be equally as strong as the first, or any resistance on the output shaft will simply cause the weaker force to stop or even rotate backwards. This is just the same as using a differential in reverse... By spinning both wheels in opposite directions at the same speed you can have a stationary drive shaft.

[@vivigarr]

Think of this as a compact transmission for things such a machinery. I'm thinking of the ways this could be used to control powered feed on a lathe.

[@quacxks100]

Wow. I did not understand untill the end of the video but that is amazing.

[@mesinmodbus4566]

great!, add battery / capacitor to charge and discharge and this called e-cvt, your dc motor represent the MG1, you can add extra motor as MG2 at the output shaft.

[@TylerBeckofTECHESPRESSO]

Great video!!

[@ironsidemaster3038]

This is a good demonstrration on how you can get infinite gear ratios, kind of like the HSD in the Toyota Prius!

[@Chewbacca1220]

This is very cool!

[@peteradshead2383]

The way I've seen are 2 cones and a belt between them which is what daf cars used in the 70s to make a varimatic gearbox .

[@jo-zw9eu]

thanks :) well explained

[@joshuawheeler4404]

3rd and 4th generation Toyota prius use this concept except with 2 motor/generators and 2 planetary gear sets to do this exact thing it's genius if you look at the actual mechanism it's so simple yet so complex and you can tell it is a reliable means to use

[@timucinbahsi445]

Thanks for the work u've put into this. i've been thinking about this system a lot lately but something doesn't sit right with me. By adding an electric motor, we are adding extra power to the system. Spinning and torque ratio doesn't have the same meaning anymore as the power input is different. I can't really wrap my head around it. idk.

[@SJ-co6nk]

Seems like this is essentially a mechanical comparator. E(engine) - E(Motor) = E(Output), give or take a constant here or there. You'd end up in an odd position where you're using lots of energy when you're stopped, and the faster you go the more efficient your engine is.

[@Chwibon]

No when you’re stopped, engine power is transmitted to the motor power, effectively producing current for charging the battery.

[@SJ-co6nk]

@@Chwibon Not based on this mechanism. With this mechanism, it takes energy to slow the output shaft. You'd need something else to capture energy.

[@gunnerpetrea3531]

If you spin the electric motor in reverse that would cause the output speed to increase correct?

[@hooorizooon]

This idea is implemented in oil and gas to have variable speed on pump or compressor, you can find more information on VOITH transmission company

[@dapje2002]

What a great video!

[@spinnirack3645]

Your definition of infinite is adorable

[@ShadowSausage]

This is veeeeery cool!

[@railmastergaming]

could you attach a clutch to the other end of the engine and use that clutch to alter the speed of planetary gearbox instead of using a motor? thus using the engine power for its own transmission? just a thought, also i love your videos!

[@QualityDoggo]

probably could... but it would always be various amounts of slipping right? Not sure if the components would like that. the electric motor is probably powered by the engine/alternator anyways.

[@gavinhicks7621]

Could use a secondary alternator to power the electric motor circuit

[@railmastergaming]

@@gavinhicks7621 nice 👌

[@jackykoning]

Toyota uses 2 planetary gears with 1 of them having both engines, the output goes to the second planetary gear and then what is essentially a dynamo varies the output to the wheels. If you take no energy the dynamo gear would free spin. The more energy the dynamo blocks the more output can go to the wheels.

[@Chotkos]

You can also use any differential to do the same - just connect main motor and electric engine to differential outputs. Differential input will become steerable bybelectric engine same way.

[@H34...]

This is a two in one out differential, not a variable ratio transmission. If the electric motor and ICE both spun at a constant speed, the output would also be a constant speed. The only thing with a variable speed here is the electric motor and that's controlled electronically.

[@beardymcbeardface69]

100%

[@Vlican]

That's a cool demo! I think Toyota's hybrid system works something like that...

[@erikschmidt2571]

Incredible!

[@rashadrali]

Is the torque at the output shaft constant regardless of the output shaft speed, or does torque depend on the speed of the output shaft like how regular gear ratios work?

[@jespermller6956]

But how much power do you need for the electric motor compared to the internal combustion engine? What does the graph look like but this setup?

[@theshuman100]

pretty sure this is how tanks steer and they have two seperate engines because of that

[@kestiz2077]

@@theshuman100 most cases no, there is clutch for both tracks, and to turn you let one to slip to slow that track. And in most simple ones there is just differential and brakes, where you just brake one side of differential to turn.

[@Danny-3688]

This system is very similar to the CVT transmissions used in some Case IH tractors.

[@fretfarm]

In agriculture we already have this type of cvt but we more commonly use hydraulic motors instead of electronic

[@thomashanson6603]

Very interesting. I suppose if you turned the electric motor in reverse you could add to the output power?

[@Tuppoo94]

This is sort of how a Toyota hybrid system works. However, in those the engine drives the planet carrier, and the sun gear and ring gear are powered by electric motors. The ring gear is the output to the wheels. This system allows the car to be driven on electricity alone, with the engine switched off, or on a combination of engine and electric motor.

[@neusgames321]

Not really unlimited gear ratio’s though this gearbox is just adding or subtracting the rpm of the combustion engine fron the electrical engine in a certain ratio. That said the plannatary gears setup are used in cars with a automatic gearbox. Then the multiple plannetary gear setups (like shown in the video) are placed in series. If the setups are connect in a smart way, a lot of gear ratio’s can be achieved with relative little gears but saddly not infinite. For infinite gears a CVT uses a pulley that can increase and dercrease in diameter, but this system slips often so is not very efficiënt.

[@fridolinfeuerbach1441]

Nice what you can do with 3d printing

[@LiteomGamingChannel]

But if the motor is spinning really fast, doesn't the motor for the outer gear have to spin at a relatively equivalent speed to counteract or "change gears" ? Wouldn't that mean that the power required is also high ? (Just curious)

[@fi2ks]

Please do a 18 speed “semi” gear box? Accounting for speed differences (road, rpm etc)???

[@EazymoneyBicch]

Aye man, love ur videos but i was wondering if i can buy that somewhere?? I dont have a 3D printer but i would love to have something like this. Do u sell ur creations and if so, where??

[@bobfredricks9567]

Question is, does reducing the speed of the output shaft against the input shaft increase torque?

[@itchytrack]

well this doesn't actually work because the motor is doing all the work when not going at a base speed

[@gamingbuildingandcubing5644]

CVT (continuous variable transmission) technicaly also has an infinite number /amount of gear ratios

[@pranavsreedhar1402]

an infinite thanks for this!

[@dontosaw]

I had to watch this a couple of times to see what was going on. The crankshaft is tied to the sun gear and the output shaft is the planet carrier.

[@theredstormer8078]

This is just a fancy differential, not a transmission. Any amount of force on that output shaft would backdrive a motor any weaker than the engine!

[@jjptech]

Basically this is a oversimplify version of the Toyota's e-CVT transmissions mounted on their Hybrids like the Prius or Rav4

[@dmytroi5456]

Yeah, we can have any RPM if we control speed of electric motor. We can even remove gearbox and combustion engine to reduce the weight)

[@bendyhouse9473]

True, but then you need a much larger battery which would add more weight than the engine

[@Gboyrides]

is there a place where we can get the STL file for this little mini planetary motor engine

[@tabd3277]

If you reversed the direction of the electric motor, would it cause the carrier shaft to spin even faster than when the electric motor is stopped?

[@Erowens98]

Yes.

[@itchytrack]

yeah, but this doesn't actually work because the motor is doing all the work when not going at a base speed

[@madeenahardwareandplumbing]

Hi brother would you please, teach us how to make a gear ⚙️ , and this engin model

[@AndrewAHayes]

My Nissan Juke has Continuous Variable Transmission combined with digital throttle profiles, Eco Standard and Sport

[@MyHandleIsGood]

I believe that would use a belt driven CVT, which is a bit more complex than this eCVT, but it is really interesting, and especially useful for fuel economy purposes. Most car enthusiasts don't like them though since they don't have the same feeling as a more conventional gearbox.

[@Fisustin]

Is that actually an iCVT (continuously variable transmission, with infinite gear ratios as you can reach also 0), or just a way to combine the power from two different motors? Since resistance on output shaft would also cause significant torque applied to the motor driving the ring gear.

[@gamesandmore3252]

would this also work with magnetic (no friction) gears , i am curious at higher speeds, would the outter ring gear have the same effect on the planetary gear?

[@Pawel25683]

But what with power of the electric motor? If it must be stronger or almost as strong as the main engine, there is no sense to mount the combustion engine.

[@l5-cs.]

attach a drill / impact wrench to a gear box see how fast it spins

[@mrmuffin9626]

I recommend that you check your audio files next time you upload to KZbin background noise is almost as loud as the “Voiceover”

[@dakkyun4095]

You know, a planetary gear set is a differential turned sideways

[@ethanebang8902]

I mean there is the belt driven CVT and it was made years ago AND ITS USED IN CARS Plus this isn’t a cvt, it’s just using a motor for the second input which is the ring gear

[@mynamisis]

So is the output shaft able to support a load?

[@hey_how_are_ya]

Is this model available for download? I would love to print it.

[@TuLowProd.]

Fancy CVT!

[@tfmzero5964]

Can you make a manual car transmission with the planetary gear box

[@calvingoodall2065]

Oh, oops. Took a wrong turn looking for CBT stuff. Cool mechanism, but not really what I'm looking for. I'll be on my way.

[@demp11]

Really really cool thought CVT transmission was the only solution for infinite gear ratios to a point.

[@boringjoe3927]

One word to answer the question of the video. CVT

[@Kram1032]

So obviously electro motors work differently. But might there be an advantage to doing this with two electro motors as well?

[@magnuswright5572]

"And is this mechanism used in real life?" Boy I sure hope so, I came up with something similar to drive two outputs at different speeds (and potentially in different directions) using a large power motor and a small "steering" motor and it would make me sad if it doesn't end up working

[@mariebcfhs9491]

This is a mechanical computer to find the difference between engine speed and electric motor, there isn't any change in gear ratio. The entire point of a transmission is to give the engine a gearing advantage when starting from a stop or when you need to accelerate quickly, or to allow a low engine rpm at high speeds to save fuel when cruising.

[@beardymcbeardface69]

There is a very light sprinkling in the comments section here, of people who actually understand what is being shown in this video, and you are one of those few people. It seems that very few understand that the only mechanism providing infinite variability in this demonstration, is the electric motor (and associated electrical circuitry). The other thing which demonstrations like this never show, is that beyond just demonstrating speed, when a load is placed on the output and thus a significant amount of torque comes into play, that little electric motor can then unwittingly become THE LOAD! If the _intended_ load is too high and the ICE is stronger than the electric motor, the ICE will drive the electric motor, instead of the intended load. LOL

[@davidcerven5072]

So as I unerstand correctly, if you want to get the output speed to be equal or faster than the input, the electric motor will need to spin in reverse to the input (engine) ?

[@arunshiva2008]

Awesome

[@neuron888]

The ring gear must be really big to fit the sun & planets inside it.

[@vdel9036]

So, you need a second engine, or electric motor (in your model), with a variable speed control, to make the thing work. If the problem is only replaced on this auxiliary power, the question remains the same : how will it be able to produce a variable speed ?

[@carultch]

Electric motors are much more versatile in their ability to adapt to speeds, than gasoline engines.

[@3ch0_17]

CVTs help counteract this semi decently

[@planktonfun1]

nice and portable

[@mattturner6017]

I am rather uneducated in the mechanical workings of automobiles, but it seems what you have there is a piston engine and an electric motor working against one another, if only slightly. I say that because one of the settings has both active power sources running the output shaft at zero rotation. All that work to make the shaft stand still? We can do that without expending energy through a fancy transmission.

[@jakobmitchell1568]

Wouldn't it be better to have the electric motor driving a worm gear / other mom reverse drivable gear system? Seems like the torque from the main driver would overpower it under load

[@laforetsolaire6978]

Yeah good idea

[@thegrandestbazaar4800]

Very good

[@Jb33124]

I believe that there was one Formula 1 car tested which had a system which had only one gear at the perfect rpm for every corner or movement on track with a system like this (someone correct me if I'm wrong or I missed something!)