Talk:Continuously variable transmission/Archive 1

Infinigear-CVT
I was concerned about the former Infinigear entry, which as someone flagged, looked like an advertisement. Fair enough, if they describe how it works, but neither the entry nor the site referenced does. An encyclopedia entry should, if nothing else, be informative. The reference to my own CVT, directly above Infinigear's, gives full details on the referenced site and reasonable detail in the short entry. The same with Larry Anderson's CVT site - you can see exactly how it works, indeed he even has a video. What is the policy on this? I emailed Infinigear for information on their device, but though they replied pleasantly enough were unwilling to disclose details at this stage. -- ChrisYonge 15:55 PST, 3 October 2006

Someone's deleted their entire entry. Extreme but effective. I would be happy to see it remain - with the advertising verbiage reduced - if they just showed how the thing works on their site. Secrecy always implies something to hide. If it's not protected they shouldn't be talking about it. If it is protected then they shouldn't be doing anything except talking about it. -- ChrisYonge 20:25 PST, 3 October 2006

ICE acronym not defined in E-CVT section
What does it mean? It just appears.

ICE = Internal Combustion Engine

this seems more commentary
"CVT control computers often emulate the traditional abrupt gear changes, especially at low speeds, because most drivers expect the sudden jerks and will reject a perfectly smooth transmission as lacking in apparent power."

Without proper referencing the above sentence seems more of a predictive or commentary nature rather than informative. As such it should be relegated to the discussion page or another suitable section. Origen

Garbled
Did anybody try to read the complete page? It is written withou any structure.

Bits about the use and history and the different types of CVT: fine. It start of with the use in small tractors whereas I would expect small city cars. The whole listing after that with the different types is ok, but I would think history would be more appropriate. The history section is crap. It says that the DAF Variomatic with rubber belts was unreliable. It drove the London-Sydney rally, resulting in a "Marathon" special. This is a common fairytale that keeps popping up: The belt drive being supposedly unreliable. The system was robust thanks to it's simpel design and the belts actually made catched some of the vibrations from the drive train.

The Variomatic was used in "heavy" applications like the DAF Pony, DAF F3 car, and was certainly useable for heavier cars, as the Volvo 440 was no lightweight.

Copyright Violations
I added the attention flag.

The bit in the History section about the Renault/Williams car with the V10 and CVT is lifted directly from this site. This makes me question how legitimate the other bits are. That part ought to be reprased or rewritten, but the writing is so clear, I can't think of a much better way of saying it. -- Huddlebum 20:32, 12 February 2006 (UTC)

I agree - it's almost a direct duplicate of the forix text - be bold - so it's history - and so is the attention flag. If whoever originally inserted it has better text to offer - or can offer an explanation for the near identical phrasing...you know what to do. SteveBaker 03:10, 4 April 2006 (UTC)

Variator
Link to Variator is not useful, as that entry is way too vague. Should it be expanded, or should there be a specialized article, e.g. "Variator (automatic continuously variable transmission)" --Nil0lab 21:19, 4 April 2006 (UTC)

BMW/Rover CVT
Lever positions: CVT does have PARK - (where the transmission is physically locked), - NEUTRAL where the engine is disengaged from the drive and the handbrake should be on. Engine could be revved as a normal gearbox. The German Sachs-ZF as fitted to BMW's and Rovers has six preset ratios in the software for manual 'sequential' changing, has a steel laminated oil-cooled belt (seperate oil cooler)and two 'wet' motorcycle style multiplate clutches (one for forward,one for reverse). The clutches work on oil pressure from an engine-driven pump, therefore as the rpm increases, oil pressure pushes the clutch plates together to provide a smooth pull away. Much better than the inefficient fluid flywheel of conventional automatics. To hold the car in low gear it simply has to be in manual position (in the case of the ZF this is with the lever to one side. It also has a 'sport' mode which simply lowers the ratio of the continuously variable range.                                                  In my bitter experience (I have driven more than 60,000 miles with one), whilst really smooth and relaxing to drive, the 'belt drive' type has to stand up to transmitting the torque of an engine of more than say, 100bhp despite claims that technology has now pushed through this limit.  One problem is that the laminated steel belts have a tendency to overheat despite an external  air cooler. Cabinscooter 21:15, 7 June 2006 (UTC)

Lever Positions
See BMW/Rover CVT Cabinscooter 21:30, 7 June 2006 (UTC)

Blonde2max 18:54, 26 March 2006 (UTC) I just wondered if CVT cars had lever positions like proper automatics? For example do they have

PARK - Where the transmittion is actually locked, and even removing the handbreak wont cause the car to roll NEUTRAL - Where the "Gearbox" and engine are completely disengadged; ie you can press the accelerator and let it rev to 5000RPM without anything exploding (assuming it's petrol) Something to hold the car in low gear/switch off overdrive?

I think they are quite interesting however I would never drive a CVT as it is still an automatic and they are evil =(

(PLease sign your comments by typing for tilde characters at the end of your posts ( ~ ).

The CVT MINI Cooper has all of the usual automatic shifter positions - plus the ability to push the shifter sideways to force an up-shift or a down-shift. However, since the transmission doesn't really have discrete shift points, this is merely simulated in software. I also strongly dislike driving automatics - but I recognise that for some people they are a very good idea indeed. SteveBaker 20:19, 26 March 2006 (UTC)


 * The CVT used in the Ford Five Hundred also has all the same positions as a traditional/geared automatic, so I would assume that most if not all modern CVTs use the standard positions. --SodiumBenzoate 03:09, 25 August 2006 (UTC)

The Rudge "Multi" motorcycle used a "DAF" type CVT from 1912 until the 1920s, including some racing success. So this predated the DAF by about 45 years! There were a few other older vehicles that also used one type of CVT or another, such as the Ner-a-car which used a CVT based on a mechanical integrator.

sorry i always put the ~ at the start. I am new at wiki - sorry peepole. thanks for your replys.Blonde2max 20:59, 30 April 2006 (UTC)

Yonge CVT
Biased towards the advantages and uniqueness. Needs a re-write that doesn't sound like a patent application or investment brochure. 66.183.181.9 22:10, 2 December 2006 (UTC)

E-CVT?
Is it appropriate to use "E-CVT," which is basically a Toyota marketing term, as a generic descriptor of a type of transmission?

1. The term "ECVT" was used by Subaru to describe its Justy in 1989.review So, the term isn't exclusive to Toyota even in the marketing arena.

2. If the term "E-CVT" means "electronically controlled continuously variable transmission," that's an accurate description of many pulley designs manufactured today. The term is too generic to be meaningful, especially when every other section title is an accurate descriptor of a subclass within the CVT class; again, it seems like a Toyota attempt to make a simple coupling seem more technically advanced than it is.

3. The article itself states: "Although sold as a CVT it is in fact not such a device." So, why is it in the article at all? We're right back to Toyota's marketing being reported as fact. It goes on to say: "The response of the complete system (under computer control) is similar in feel to a CVT in that the ICE speed is relatively low and constant under low power or high and constant under high power." I will abstain from a rude analogy which explains that things which feel like they may belong in a class may not, in fact, belong to that class.

This transmission is a planetary gearset. It may give a CVT-like experience as part of a broader system, but the gearbox itself is clearly not a CVT and doesn't belong in this article. Maybe the way to handle it is to simply call the whole Toyota-style hybrid system a type of CVT, because if you take out any component of that system, even the CVT-like behavior of this gearset would disappear.

One more argument for deletion of the E-CVT section: the CVT article defines a CVT as an "automatic transmission." The automatic transmission article says: "An automatic transmission is an automobile gearbox that can change gear ratios automatically as the car or truck moves, thus freeing the driver from having to shift gears manually." The Toyota system has, according to the CVT article, a "fixed gear ratio." So, by that definition, the Toyota piece is not only not a CVT, it's not even an automatic, because it can't change gear ratios at all.

I'm reluctant to edit without getting other perspectives, so thanks in advance for any thoughts on this.Meersman 17:08, 8 December 2006 (UTC)

IVT (Infinitely Variable Transmission)
The following definition for IVT is misleading:

'An extension to CVT design, sometimes known as the Infinitely Variable Transmission (IVT), allows the transmission to drive a vehicle backwards as well as forwards. Transmission input is connected to the engine, then it is split into 2 shafts with one connected to an epicyclic gear set. The output from the CVT shaft is connected to another shaft that connects to a different set of gears in the epicyclic. The gear that does not draw power from engine or CVT transfers torque to the transmission output. The gear set acts as a mechanical adding machine to subtract one speed from the other, allowing the car to go forwards, backwards, or neutral.'

The IVT is a subset of CVT's because it is a special case CVT. Most (if not all) IVT's result from the combination of a CVT with an epicyclic gear system (which is also known as a planetary gear system) that facilitates the aforementioned subtraction of one speed from another speed. This subtraction only needs to result in an infinite range of positive, non-backwards 'gear ratios' because reversal of output direction is trivial, in practice; the IVT definition should only include continuous output variability from zero output to any finite positive maximum output ratio because the maximum output ratio can be arbitrarily chosen (from infinite practical possibilities) through input or output gear, pulley or sprocket sizes without affecting the zero output or the continuity. Importantly, the IVT is distinguished as being 'infinite' in its bandgap, or range; high gear is infinite times higher than low gear.

Although it is true that an epicyclic gear system can produce positive and reverse (backward) output from a CVT, this is impractical because near-zero output (at the pos/neg transition) will produce exceedingly high torque values within any traction-based CVT, and will produce extreme vibration with any 'ratcheting' CVT. Practical constraints should exclude reverse operation from the IVT definition. —The preceding unsigned comment was added by 71.198.223.13 (talk) 02:15, 26 January 2007 (UTC).

IVT (infinitely Variable Transmission)
02:35, 26 January 2007 (UTC)71.198.223.13The following definition for IVT is misleading:

'An extension to CVT design, sometimes known as the Infinitely Variable Transmission (IVT), allows the transmission to drive a vehicle backwards as well as forwards. Transmission input is connected to the engine, then it is split into 2 shafts with one connected to an epicyclic gear set. The output from the CVT shaft is connected to another shaft that connects to a different set of gears in the epicyclic. The gear that does not draw power from engine or CVT transfers torque to the transmission output. The gear set acts as a mechanical adding machine to subtract one speed from the other, allowing the car to go forwards, backwards, or neutral.'

The IVT is a subset of CVT's because it is a special case CVT. Most (if not all) IVT's result from the combination of a CVT with an epicyclic gear system (which is also known as a planetary gear system) that facilitates the aforementioned subtraction of one speed from another speed. This subtraction only needs to result in an infinite range of positive, non-backwards 'gear ratios' because reversal of output direction is trivial, in practice; the IVT definition should only include continuous output variability from zero output to any finite positive maximum output ratio because the maximum output ratio can be arbitrarily chosen (from infinite practical possibilities) through input or output gear, pulley or sprocket sizes without affecting the zero output or the continuity. Importantly, the IVT is distinguished as being 'infinite' in its bandgap, or range; high gear is infinite times higher than low gear.

Although it is true that an epicyclic gear system can produce positive and reverse (backward) output from a CVT, this is impractical because near-zero output (at the pos/neg transition) will produce exceedingly high torque values within any traction-based CVT, and will produce extreme vibration with any 'ratcheting' CVT. Practical constraints should exclude reverse operation from the IVT definition. 71.198.223.13 02:35, 26 January 2007 (UTC)

Prius CVT
The Toyota Prius is perhaps incorrectly listed here as having a CVT. The Prius and other Hybrid Synergy Drive equipped cars do not have a CVT in the conventional sense of the term. They do not have a mechanical transmission with variable ratio. Rather, they use a combination of 2 motors generators and a planetary gearset to achieve the same effect.


 * I've added explicit discussion of the Prius' system here. It's still a CVT in the sense that the ratio of engine-to-wheel speed is continuously variable. Toyota themselves call it an E-CVT (electronically-controlled CVT). --KJBracey 09:21, 13 November 2005 (UTC)

I agree with the following statement (shown above): 'The Toyota Prius is perhaps incorrectly listed here as having a CVT. The Prius and other Hybrid Synergy Drive equipped cars do not have a CVT in the conventional sense of the term. They do not have a mechanical transmission with variable ratio. Rather, they use a combination of 2 motors generators and a planetary gearset to achieve the same effect.'

The Toyota Prius drive system should be termed 'Power Split System' as opposed to CVT. The term 'CVT' should be narrowly defined as a stand-alone device with only one input and only one output.

The CVT is a transmission in which the ratio of the rotational speeds of two shafts, as the input shaft and output shaft of a vehicle or other machine, can be varied continuously within a given range, providing an infinite number of possible ratios. The Prius drive does not fit this definition because it uses more than one input shaft.

Remember that any definition draws an outline around the subject of definition; description must include all relevant conditions and exclude all irrelevant conditions, much like a circled unit in a Venn diagram. The narrowest definitions allow us to describe relationships between elements of discussion in a discrete manner, as in a Venn diagram. Terms that are narrowly defined contain no implications that can confuse and obfuscate communication. Please be very careful about use of terms and definitions so that we can communicate clearly!Simbasat 20:33, 26 January 2007 (UTC)

Copied from talk:Infinitely Variable Transmission
The Infinitely Variable Transmission (IVT) is a specific type of Continuously Variable Transmission (CVT). The Wikipedia definition of the CVT is flawed, and should be corrected before the definition of the IVT is produced. As an early inventor of both a CVT and an IVT, I feel that I'm qualified to define both terms.

Note that any definition should include only essential conditions, and therefor it should not include anything else. For example, a CVT is not necessarily an automatic transmission because its ratio can be continuously adjusted manually, so it should not be defined as an automatic transmission! The CVT does not require reverse operation either. The only conditions for a CVT are that it is continuously variable in its essential control (ratio) of shaft speeds within a given range, and that it is a transmission, and nothing else. I suggest the following replacement Wikipedia definition of the CVT:

The Continuously Variable Transmission (CVT) is a transmission in which the ratio of the rotational speeds of two shafts, as the input shaft and output shaft of a vehicle or other machine, can be varied continuously within a given range, providing an infinite number of possible ratios.

The Infinitely Variable Transmission (IVT) definition is more challenging because it contains the word 'infinitely', which is sometimes confused with the infinite choice of ratios in any CVT. Prevalent usage of the term IVT refers to the infinite range of ratios with certain CVT's, as opposed to infinite choice. This distinction about infinite range is critical to the definition of the IVT because it implies either that the highest output/input ratio is infinitely higher than the lowest ratio, or conversely that the lowest output/input ratio is infinitesimal. No transmission can have an infinitely high output/input ratio, but a transmission can have an infinitesimally low (including zero) output/input ratio, so the IVT must be continuously variable in selection of ratios that include zero output. So, I offer the following Wikipedia definition of the IVT:

The Infinitely Variable Transmission (IVT) is a CVT in which the ratio of output shaft rotation speed to input shaft rotation speed can be varied continuously within a given range that includes zero.

Users of the terms CVT and IVT as defined above should not confound their discussions by misuse. CVT's and IVT's can have additional features, such as automatic operation, disengageability and reversibility. Please note that such discussions can use adjectives that preface these terms, e.g. 'Automatic CVT', 'Disengageable CVT', or 'Reversible IVT', etc.71.198.223.13 00:50, 27 January 2007 (UTC)

Van Doorne's info wrong.
Please note that when DAF Cars was bought by Volvo, it's trucks and variomatic stayed out of the deal. However a special company called VDT (Van Doorne's Transmissie) was set up, existing until today.

This company led a development for Williams F1 in 1993 for a CVT. It was banned by the FIA. 159.134.94.21 08:52, 21 June 2007 (UTC)

Anderson A+CVT
Is it me or does the section on the Anderson A+CVT seem like original research? Considering that the guy who uploaded the photo took it himself and is called Fred Anderson. In my opinion it is in breach of the No original research policy, any other opinions? Mumby 16:39, 5 March 2007 (UTC)

Hello, Mumby. I am the person who posted the photo of the Anderson A+CVT. Yes, I am related to the inventor, but that does not mean that the photo is not credible. I did not write the article that appeared on Wikipedia, nor do I know who did, although I did clarify one point that was misleading in the original text. The A+CVT is a unique and innovative type of CVT. I understand that Wikipedia is not supposed to be used for marketing purposes. However, the A+CVT is different from other CVT designs, for reasons that were explained in the text that you removed. This technology is of interest to many engineers and students, judging by the inquiries that come in through www.andersoncvt.com. I would ask that you reconsider your decision to delete this information from Wikipedia. Thank you.

72.49.52.16 21:13, 7 July 2007 (UTC)

Rearranging sections
I think that it would be a good idea to spin off the lists of old and new cars with CVTs into a separate list page. Also, I think it would be good to put the section on types of CVTs near the end of the article and move the section on examples near the top (it could also be renamed, "Uses of CVTs" perhaps). --West.Devin (talk) 06:43, 29 November 2007 (UTC)

'CVTs in production before 2005'
The comment about there not being transmissions suitable for heavy duty use strikes me as a little odd, given that I've several times been a passenger on a ~35-passenger bus around my (UK) town that gives every impression it's using a CVT. That or a conventional automatic stuck in third gear with a very loose torque converter and nitro boosted engine. Takes off with very strong acceleration (comparable with an 80s city car) with fairly high RPMs and sustains them without any dip or other gearchange telltale until cruising speed, where they fall back and vary up and down to maintain speed. This was several years ago, probably before 2000. Someone somewhere seems to have been making high-torque CVTs :) 82.46.180.56 (talk) 13:56, 12 January 2008 (UTC)

Cone CVT Section
Does anyone know where the original Japanese language article is? I would like to see it in order to check my edit of the existing rough translation. Thanks!--BudgieBirdChan0211 (talk) 01:36, 9 April 2008 (UTC)

Nutating cone transmission
Sometime in the 80's Popular Science ran an article on a nutating cone transmission. It had two steel cones arranged base to base, set at an angle in a cylinder so that the sides of the cones were parallel to and projecting through the side of the cylinder on opposite sides and ends. For shifting it used a pair of rings around the cylinder, pressing against the sides of the cones. Speed changing was done by changing the distance between the rings. I could do a 3D model of those parts from memory, but I don't remember how the power input and output was connected. —Preceding unsigned comment added by Bizzybody (talk • contribs) 07:18, 16 June 2008 (UTC)

Continuously Variable Planetary drive
Does anybody know more about these things? Could someone with more knowledge please explain them. I have a link http://www.fallbrooktech.com/03_Bicycle.asp —Preceding unsigned comment added by 137.219.252.169 (talk) 10:44, 28 April 2009 (UTC)

Wikipedia currently has a page-in-progress on the NuVinci Continuously Variable Planetary Transmission. Currently, it needs a bit of TLC, including a shorter name, however it still provides sufficient information. Currently, I am in the process of un-orphaning the page. —Preceding unsigned comment added by Kevandegrift (talk • contribs) 02:14, 12 November 2009 (UTC)

No, a planetary drive gear is just another gear and cannot be continuously variable. If its a planetary drive being driven by friction, then its just another Continuously variable friction surface.

Also see the paragraph about the chain driven by cog with varying number of teeth. This also not infinitely variable, as teeth can only be added or subtracted one at a time... And the chain  must be made of rubber and lasts only a little longer than ...what, like 5  seconds.

Illustrations Needed
Might be easy for you guys to visualize what's going on, but we need more illustrations for the rest of us! --Nil0lab 21:14, 4 April 2006 (UTC)

I agree 82.133.107.231 23:33, 14 October 2007 (UTC)

I added an image from another article to the examples section.--West.Devin (talk) 06:35, 29 November 2007 (UTC)

Nice article... for a serious nerd. Please... someone draw us something to illustrate what those 'preaching' (or whatever) means. We're not the inventors. CrB 16:31, 21 July 2009 (UTC) —Preceding unsigned comment added by ADouBTor (talk • contribs)

I added a self made image of a toroidal CVT. Faraday&#39;s Cage (talk) 22:48, 24 January 2010 (UTC)

IVT weasel words and obfuscatio
the paragraph on IVT tries to present as a perfect :Continuously variable transmission IVT is either yet another friction device, OR its a gear box ...

thats all just weasel words .. it says "almost infinite" .. 9 is infinity now ???

Prius drive is really just a gear box. and is not a continously variable transmission.

Its not the perfect "infinitely variable gearbox". with gears being wheels with teeth.

article also fails to mention there can be no "infinitely variable gearbox" since the number of teeth cannot be fractional.

202.92.40.8 (talk) 16:45, 8 April 2010 (UTC)


 * So fix it! – ukexpat (talk) 17:29, 8 April 2010 (UTC)

Audi CVT
"Audi has, since 2000, offered a chain-type CVT (Multitronic) as an option on some of its larger-engine models, for example the A4 3.0 L V6."

This implies that only some models of Audi's lineup are available with CVT. It is also available on "smaller" engine models, such as the A4 2.0T (which I actually own) (98.66.27.37 (talk) 03:35, 3 May 2010 (UTC))

The D-Drive is a model of a proposed CVT, not a CVT
My anonymous edits to the recently-added last paragraph on the D-Drive have just been summarily reverted by Favonian. Perhaps my intent was unclear: I am trying to introduce neutrality into that paragraph (though perhaps I overbalanced it with clumsy, faux-sympathetic folksy-ism). My point, which I will soon make in another, simpler edit (not a double-reversion), is that the D-Drive is a model. It is unproven. It cannot be presented in Wikipedia as if it was a known, working variant of CVT. Personally, for what little it's worth, I don't think that the D-Drive works in practice, though the model is very cool. —Preceding unsigned comment added by 76.126.219.236 (talk) 11:25, 15 May 2010 (UTC)


 * I may have been a bit drastic in my reaction to your rather over-the-top contribution. Feel free to add information, as long as it is neutral in tone and based on reliable sources.  Favonian (talk) 11:36, 15 May 2010 (UTC)

A little research reveals -- on Durnin's own web site -- an independent analysis by Gilmore Engineers, dated August 21, 2008: http://infinitelyvariabletransmission.com.au/wp-content/uploads/2010/05/dDrive-Transmission-Report.pdf which concludes, on p. 19 "The Durnin transmission is strictly an element of an Infinitely Variable Transmission.... The Durnin transmission requires some external means of varying the speed of the Control shaft (and providing power through that shaft) to serve as a true IVT.  This variable-speed Control shaft could be powered by an additional 'variator' component (a component capable of a continuously varying transmission ratio), for example a CVT." Since the Durnin mechanism is not a CVT (and, in fact, requires the equivalent of an associated CVT for operation), I am removing its material from the article. —Preceding unsigned comment added by 76.126.219.236 (talk) 09:55, 16 May 2010 (UTC)

CVT .1929, 1935
This reference: http://austinmemories.co.uk/page139/page139.html from the Austin Memories website (English automobile) refers to an American CVT from 1929 and the vehicle into which it was installed from 1935. I mention this since the illustration shows a type not mentioned in the Wikipedia article. Following is an exempt from Austin Memories.

"It all began in America when a Frank Anderson Hayes who lived in Middletown, Monmouth, New Jersey USA. began experimenting with a method of transmitting power at a variable speed, but at the maximum torque. He filed no less than six patents in America under the heading Hayes Variable Speed Power Transmission on the 7 May 1929, and then in the UK on the 2 September 1929. Two years later he again applied for further Patents, this time under the heading, Improvements in or Relating to Variable Speed Power Transmission." ```` —Preceding unsigned comment added by 99.147.161.75 (talk) 23:53, 13 February 2011 (UTC)

Naudic Incremental CVT (iCVT)
I pulled the entire section on the Naudic Incremental CVT (iCVT) for the same reason as the Anderson system. It had basically turned into an advert for the naudic system; it is not neutral and I think it is in breach of wikipedia's policies on advertising and original research. Consider this: the Naudic CVT was invented by a guy called Dr. J. Naude, and all the info is being added by a user called JNaude. The article should describe the difffernt types of CVT, not the different brands. Mumby 17:37, 22 March 2007 (UTC)

Most of it seems to have returned, only without a heading. It seems to me to be a different type, hence worthy of attention even though it's written like an advert. I restored the heading and will rewrite the section for style. Benet Allen (talk) 12:32, 1 July 2011 (UTC)

Advantages and drawbacks section
This section appears to be pro-CVT in that in lists all the advantages over the disadvantages, anyone care to clean this section up? and make it more of a list format?

This section lists the smooth operation as a drawback. Surely smoother operation is an advantage, not a drawback. So why would any intelligent person bother to design an electronic system to put a jerk into a smooth motion. I may be mildly infringing the neutral opinion code by suggesting that anyone who wants a jerk in the transmission already has one in the car! Molnek142 (talk) 06:29, 16 June 2008 (UTC)

This is also nonsense. "The original Ford Fiesta 1.1 CTX, for example, used 8.2 percent more gasoline than the manual transmission version in city driving." City driving consumption only 8.2 percent worse than a manual is exceptional for an automatic transmission. Advantages and drawbacks of CVT are obviously measured against conventional automatic transmissions. —Preceding unsigned comment added by 80.246.148.73 (talk) 12:33, 8 August 2008 (UTC)

"Very few problems have been reported with the CVT transmission, lowering the cost of ownership." WHAT?! Second hand Audi multitronics are very expensive - because they have 200 or 300k km resource and then it's gone, and, unlike tiptronic, multitronic can be only replaced - gearbox and work may cost, let's say, 5k euros. —Preceding unsigned comment added by Mshathlonxp (talk • contribs) 23:17, 5 September 2008 (UTC)
 * The DAF CVT and th Push-system lik ein the Justy was certainly lower in cost of ownership. One example does not mean commonplace. If the guys at Audi did not destroy the idea of CVT (smooth operation for one) we would see less trouble with their CVT.

Of course, smooth operation highly important and in my experience is the biggest advantage of CVT. What I don't think is emphasised enough is that CVT is only really suitable for lower torque levels for durability. I would recommend that 1.4 litres is the absolute maximum engine size if you want reasonable life from the transmission. I know this from experience ! Cabinscooter (talk) 08:36, 18 July 2011 (UTC)

Single tooth cone cvt
This section reads like an advert/spam. The "most promising" cvt? says who? Eigenbanana (talk) 21:10, 4 March 2011 (UTC)


 * So, fix it! – ukexpat (talk) 21:13, 4 March 2011 (UTC)


 * I agree with deleting it. It's just an idea an inventor had, and he put up a website hoping to attract investors. Not encyclopedic, not independently sourced. See WP:CRYSTAL and WP:UNDUE. --Dennis Bratland (talk) 19:21, 1 November 2011 (UTC)

There are several problems with this page
"The V-belt needs to be very stiff in the pulley's axial direction in order to make only short radial movements while sliding in and out of the pulleys. This can be achieved by a chain and not by homogeneous rubber." Somebody had better tell Kawasaki that the system (which uses a rubber belt) they use on their Mule ATV vehicles will not work! by the way Kawasaki is just an example, every cvt system I have seen on a groundscare machine uses a belt.

"This type of transmission, most commonly manufactured by Hydro-Gear" No, Hydro-Gear is just one of many different manufacturers.

"Many versions of riding lawn mowers and garden tractors propelled by a hydrostatic transmission are capable of pulling a reverse tine tiller and even a single bladed plow." Well, yes they will, but it is not recommended to use any ground engaging equipment with hydrostatic drive, it leads to damage in the unit.

"Hydro-Gear, created the first cost-effective integrated hydrostatic transaxle suitable for propelling consumer zero turning radius mowers." Care to share with us just which zero-turn mower uses this trans-axle? The only machine that I can think of that uses this type of axle is the Kubota GR range of ride-ons, they are sold as glide-steer not zero-turn. They will not zero turn but will turn extremely tightly. — Preceding unsigned comment added by Hortimech (talk • contribs) 09:42, 5 October 2011 (UTC)


 * PatheticCopyEditor (talk) 23:04, 23 February 2012 (UTC)

Improved New Toothed CVT
I added this section for informative purposes. People can learn from it and improve it. — Preceding unsigned comment added by Cvtreserach (talk • contribs) 00:28, 18 March 2012 (UTC)
 * See WP:SELFPUBLISH. The information was obviously self-promotional advertising, and not based on independent sources. Please find citations that come from independent, third-party, reliable sources such as books, magazines, and newspapers. Also, be sure you're familiar with the advice in Conflict of interest. A much more enjoyable and productive way to contribute to Wikipedia would be to work on subjects that interest you, but do not involve any professional conflicts of interest, like this new invention you are attempting to sell or attract investment for. --Dennis Bratland (talk) 01:01, 18 March 2012 (UTC)

FES CVT
Flywheels have also been proposed for use in continuously variable transmissions. Punch Powertrain is currently working on such a device. — Preceding unsigned comment added by 91.182.91.212 (talk) 11:24, 13 September 2012 (UTC)

Bosch systems
Car cvt : 2 systems: 1) pushbelt ( DAF/VDT/ BOSCH TRANSMISSION TECHNOLOGY bv, ). 2) :  pullchain ( AUDI LuK )

1). In this system, metal plates are grabbed by the drivepully and pushed together thus forming a pushrod, held together by the two steel belts, and pushing the drivenpully to turn. The metal plates are selected by computer so the total lenght fits the steel belts without play.

2) this system uses a more or less normal chainbelt, which is grabbed by the drivepully and pulls the drivenpully.

In 1985 VDT, the successor of DAF intoduced the patented pushbelt-CVT for cars named TRANSMATIC. Many carmakers were interested but would not buy complete transmissions and making there own production plants redundant. So VDT delivers the hart of allmost all CVT's, the belt, to most carmakers. Up to now they produced 25 000 000 belts.

STAALWATER (talk) 15:37, 3 August 2013 (UTC)

Leonardo da Vinci
The page indicates that "Leonardo da Vinci, in 1490, conceptualized a stepless continuously variable transmission" and has two external links immediately after that. However, neither of those links provides any substantive information about Leonardo, much less about that particular conceptualization. I have not found any evidence for this assertion; in fact, everything I've found (via Google, etc.) uses an almost identical phrase, with no additional information nor evidence. Unless someone can produce a valid reference, this should be removed from the page. 152.17.54.23 01:56, 1 April 2007 (UTC)

I can produce a reference from Scientific American and will do so in the next few days. --West.Devin (talk) 06:16, 29 November 2007 (UTC)

As per the first item in this discussion, the current reference provides no evidence of this claim. Search results for "da vinci" "continuously variable transmission" all produce the same diagram of a stepped transmission drawn by Da Vinci. With no other evidence than this image, it's dubious whether Da Vinci made the significant conceptual step between a gear cluster and a cone. Simonmckenzie (talk) 00:20, 14 August 2013 (UTC)


 * There is another well-known drawing that does show a stepless conical gear . However it's part of a gear train with another stepped three-step gear. I suspect that it's another source of some of these claims (although Gibbs-Smith doesn't fall for it). As with so much of Da Vinci, it doesn't work - there's no way to select which of the three is in mesh. Now Da Vinci was aware (and drew) the fusee and the effects of varying diameter on speed and torque; he understood how a conical lantern wheel could act as a multi-diameter gear. In the 1490 drawing that's at root of the main CVT claim, he shows an axially-sliding stepped gear with the use of a long pinion to permit the movement. What he doesn't appear to have known (AFAIK) is a mechanism to either selectively engage individual gears (such as a floating ring or belt between smooth pulleys) or else the notion of one movable pulley with varying shaft spacing, or to have coupled his long pinion to a conical (rather than stepped) gear. Without at least one of these, I see no way to claim that he invented or even "conceptualized" the CVT.
 * I'd support removing this claim in the direct form it is here. It might be better though to comment on such claims (as there certainly are the claims) and to describe just how far he demonstrably did get, and what was still missing from making that a CVT. Andy Dingley (talk) 01:19, 14 August 2013 (UTC)

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Variable-diameter pulley = Friction CVT ?
Is the Variable-diameter pulley equal to the Friction CVT ? See http://cvt.com.sapo.pt/why/why_cvt.htm and http://www.gizmology.net/cvt.htm

Also, the first image says "A Chain-driven CVT", change this by "Variable-diameter pulley", also place the image at the appropriate section (types), and places the Types above the Use section 91.182.79.197 (talk) 14:56, 14 December 2010 (UTC)


 * No. Once again, you haven't the first clue what you're dealing with. There is no such single thing as "the variable diameter pulley CVT" or "the Friction CVT". They are two operating principles, there are countless examples of different CVT designs using either of these principles. It is very wrong (and will yet again, be reverted on sight) for you to start applying yet another of your inane over-simplifications or ex cathedra re-explanations of existing and well-known devices according to your fanciful inventions. Andy Dingley (talk) 15:36, 14 December 2010 (UTC)


 * OK, these may not be good names, but one has to make a distinction somewhere to keep the article a bit clear and readable. Also, if these names aren't suitable, I don't think "Chain-driven CVT" is suitable either, and not to mention confusing. The swapping of the article sections also shouldn't hurt. In addition, I found an image at http://wikicars.org/en/Continuously_Variable_Transmission#Variable-diameter_pulley_.28VDP.29 which can be added (I'm guessing there's no copyright on this image)


 * Finally, some extra manufacturers of CVT's (which are allot more useful than simply "models"/car manufacturers:

91.182.53.128 (talk) 12:05, 16 December 2010 (UTC)
 * ZF Sachs
 * Hi-Lo Manufacturing
 * http://infinitelyvariabletransmission.com.au/ivt/the-technology/ (-->IVT)

Under the variable diameter pulley CVT it states as a fact that a variable diameter pulley CVT requires a metal chain. I have a chinese-built scooter with a variable diameter pulley CVT, and it uses a rubber V-belt, not a metal chain. I propose this information be changed.--Tzalumen (talk) 21:19, 6 January 2011 (UTC)
 * A low-powered vehicle can get by with a nylon reinforced V-belt, but more power requires more reinforcement. A high-powered scooter will require Kevlar reinforcement; a 100hp car will need steel reinforcement in the belt. Steel belts will eventually eat up the pulleys, creating expensive maintenance problems.  There is no free lunch.Santamoly (talk) 20:13, 21 July 2016 (UTC)

Justy was not first in US
The page (as do several others) say that the Subaru Justy was the first production car to offer a CVT in the US, though I don't believe this is correct. According to the Standard Catalog of Imported Cars, DAF imported the 600 with the Variomatic transmission into the US starting in 1959, and DAF continued offering CVT-equipped cars in the US until 1973. Autonerd (talk) 17:31, 8 September 2016 (UTC)

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