How Does a CVT Work?

How Does a CVT Work?

Automatic transmissions are HUGELY popular in North America. Europe is still a strong hold for the manual gearbox but on this side of the Atlantic self-shifters account for at least 90 percent of new-vehicle sales; the standard trans lost the market-share race decades ago and in spectacular fashion.

Jatco-CVT8Despite their dominance the automatic is not a unified adversary, a single threat. There are several major kinds slush-box ranging from the traditional planetary-gear, stepped-ratio unit, to dual-clutch models to the controversial CVT, which of course is shorthand for continuously variable transmission.

And that final option is the one that raises the ire of true automotive enthusiasts like nothing else this side of hybrids. If these folks don’t have three pedals and a mechanical ratio-selector to play with they just aren’t satisfied.

CVTs are a relatively new trend on the market; they promise better fuel economy and smoother driving, but how do they actually work?  How can they change ratios without traditional gears? Is this automotive witchcraft or just common-sense engineering?


Surprisingly there is a wide variety of different CVT designs out there, but for automotive applications many of them just aren’t practical. Pierre Loing, vice president of product, advanced planning and strategy at Nissan North America said “For us there is basically one system, which we use in different sizes and executions… for transversely mounted applications.”

Of all the automakers in North America Nissan has probably been the most aggressive in pushing CVTs. The technology has proliferated throughout their lineup in recent years and you can get one in vehicles ranging from the tiny Versa Note hatchback all the way up to the hefty Pathfinder crossover.

Nissan-Versa-PathfinderThe layout used by Nissan and other companies consists of a few major components including a pair of variable-diameter pulleys as well a special belt that connects them. Jim Paris, director of business development, Continental business unit transmissions NAFTA region summed things up succinctly. He said “By varying their dimensions the belt itself rides higher or lower on the pulleys and changes the ratio between the drive and the driven pulley.”

In short one pulley gets bigger and the other smaller. This movement changes the ratio between the two; it’s a brilliantly simple and effective idea that always provides the driver with the proper “gear.”

CVT-ChainsCuriously Continental, a tire-one supplier company, doesn’t actually build any CVTs. Instead they focus on controllers. Paris said “We’re actually the largest maker of transmission electronics on the globe.” This includes things like sensors, actuators and mechatronic modules. They work intimately with OEMs on all kinds of automatic transmissions from conventional planetary models to dual-clutch units to CVTs and beyond.

Now, one of the most complicated parts of a CVT is actually the belt, probably more appropriately referred to as a chain. Paris said “The belts themselves have a lot of work to do, transferring a multiplication of engine torque through the driveline.” He also touched on their cost and complexity, noting that they’re difficult to build and require very tight manufacturing tolerances, something that makes them quite expensive.

These belts are often constructed of a series of metallic segments joined together by metal bands. This design allows the belt to flex yet still transfer torque without ripping apart. Still other CVT designs use chains that consist of innumerable metal links to form a sturdy yet flexible loop. Keeping things simple, some CVTs push while others pull.Nissan-Extroid-CVT-01In addition to automobiles CVTs are used in all kinds of applications from snowmobiles to stationary machinery. In these lighter-duty applications the transmissions often feature rubber belts instead of chains or bands.

Nissan-Extroid-CVT-02Beyond the variable-diameter pulley style, Nissan also experimented with another CVT configuration. The toroidal design is completely different and has no belts. Instead it features rollers and disks that vary the ratio between input and output. Loing said “Nissan looked at this technical challenge,” building one in the 1990s. He noted that “it was an exceptional transmission,” comparing it to an expensive watch, though that was its Achilles’ heel; it was just too costly for mass-market vehicles.

Nissan-Extroid-CVT-03A third option is called the E-CVT, a design used in the popular Toyota Prius and its Hybrid Synergy Drive system. This setup features a planetary gearset like a conventional automatic transmission but with a twist… literally. “Suns, planets and rings are each attached to a torque-producing device” Paris said. “They have two electric machines and the engine” he continued. Varying the torque applied to different parts of the gearset changes the ratio, just like a variable-diameter pulley CVT.


CVTs continue to gain more and more traction in the marketplace. Nissan and to a lesser extent Audi were pretty much on the forefront of this movement but other automakers are jumping on the “belt-wagon” so to speak. Loing said that with their latest models “Toyota and Honda [are] coming to CVT as well.”

There are a couple reasons for this “shift” (no pun intended) in transmission preference. Loing said “the biggest one is fuel economy, the other one is smoothness.” With no preset ratios like a typical planetary-gear automatic he said “[there’s] no torque cut” meaning the power flows in one steady stream as you accelerate – it doesn’t get interrupted by gear changes.

Nissan-Tachometer“I think in general the smoothness is valued” Loing noted, though not by all drivers. “[Some] customers tend to like to have some of those torque cuts.” In response Nissan can actually simulate traditional upshifts in several of its new CVTs to make them mimic a conventional automatic gearbox.

Loing said the reason a CVT is more efficient than a conventional automatic is because “it has the engine operate between the maximum torque and maximum power. By doing this the engine always operates in the optimal RPM zone.”

Additionally Paris said that compared to a typical planetary-gearset transmission “the number of mechanical parts is much lower.” He also said “It’s odd, in a way CVTs are a less efficient design than other transmission types.” According to Paris they have “higher internal friction,” but since they “allow the engine to operate in a narrower rev band” they’re more efficient overall.

Paris said that friction is something companies like Jatco, a leader in the CVT market one of Nissan’s major partners, have been ruthlessly working to reduce. According to Jatco their new CVT 8 model features a best-in-class ratio spread and significantly lower friction compared to previous CVT models.


Of course everything has its advantages and disadvantages; CVTs are no exception. One of the biggest drawbacks has to do with how much torque they can handle. Loing said they’re typically limited to between 300 and 350 Newton meters of twist. In ‘Murican figures that works out to between roughly 220 and 260 lb-ft of torque.

2014 Nissan MaximaHowever, in recent years manufacturers have been able to increase how much CVTs can handle. “The improvement of the belt has made this torque increase possible” Loing said.

Another potential disadvantage is mass. Even though they have fewer internal parts Paris said “CVTs tend to be the heaviest of the transmission types.” He also said that due to low adoption rates in the past “[They’ve] been very expensive to replace.”

But what about reliability? Do CVTs have more issues than conventional automatic transmissions? Paris said absolutely yes, noting that there have been a number of class-action lawsuits associated with past units.

But automakers have certainly made strides in improving reliability over the years. In fact Loing said drivers shouldn’t have any issues with CVTs, noting that Nissan backs them up with the same warranty you’d get with a conventional automatic transmission. “There’s no reason why it should be different” he said.

Another downside to CVTs has to do with NVH, that’s noise, vibration and harshness. Due to their limited torque capacity they’re often paired with small, four-cylinder engines. During acceleration CVTs will typically hold a powerplant at a specific RPM, which can create a droning sound and lots of driver irritation.


Going forward CVTs are practically guaranteed to continue gaining traction in markets around the world as automakers work to improve fuel efficiency. Japanese OEMs led by Nissan are really pushing them. Loing said “It’s our best selling transmission in North America” noting that “It’s something that’s here to stay with us.”

Nissan is even starting to expand its CVT offerings in the Old World, a market that’s still dominated by manual gearboxes. “We see now even in Europe CVTs coming in the Nissan lineup and associated with diesel” Loing said, noting that the new generation of the company’s Qashqai compact crossover features an oil-burner paired with a CVT.

Nissan-Qashqai-01One area of future improvement could be the adoption of dry clutches instead of torque converters. Paris said “That could take some money out of CVTs,” which according to him tend to be expensive.

As it stands today continuously variable transmissions will probably continue their growth in the marketplace. Love them for efficiency and smoothness or loathe them because of droning NVH and possible durability issues they’re not going anywhere.

  • Jonny_Vancouver

    Yay! keep them coming! I can’t wait till the CVT reaches it’s full potential! I really like the duel clutch trans too (namely the one VW uses), but there just seems to be more headway being made with CVT’s and I think they’re more practical for most people, at least for now … Great article!

  • Richard Joash Tan

    you forgot to mention that Subaru has regular and high torque CVTs

  • bagger

    Awful droning and the internal friction with pricey belt, sounds expensive. I’ve heard they are usually replaced rather than repaired, not sure if that’s true. So far, I’d just keep it in the snowmobile….

  • Cory Ray

    Planetary automatics are often replaced instead of repaired too. It takes specialized knowledge and tools to rebuild one. Dealerships usually outsource the work to specialist shops.

  • Jonno

    What no mention of DAF the inventor of CVT

  • Doug Martin

    Finally? No more designing cars to be most efficient at 55mph and inefficient at just about any other speed due to fixed transmission ratios? Can’t wait to actually ‘cruise’ again at 70

  • Bluegrallis

    E= mc squared, says no vehicle will ever be as efficient at 70 as it is at 55.

  • lostjr

    The discussion about Nissan CVT leaves out the fact that there is a planetary gear set on the output (after the CV mechanism) that provides a high and low range.

  • ScottS

    I have owned a Toyota Prius C hybrid with an E-CVT since May 2013. It is described in this article, but the illustration to the right of the description is something else, not an E-CVT. It is a remarkably clever design and, apparently, is pretty efficient. Reliability statistics for the car, overall, are very good. I am aware of no common transmission problems. Because it uses two electric motor/generator units instead of belts or clutches, my guess is that it would not be practical to use except in a hybrid. I have been very happy with it. I don’t think mine is optimized for hard acceleration, but I haven’t really put it to the test. I would buy another.

« Back
SWEEPSTAKES – OFFICIAL RULES, TERMS AND CONDITIONS’s Monthly Overlay Newsletter Signup – By subscribing to our email newsletter, Entrants are eligible to win one (1) Gift Card (value of $100.00 USD). One (1) winner will be chosen every month at random and contacted by VerticalScope Inc.’s staff. * is not a sponsor of this promotion. Except as required by law, Gift Cards ("GCs") cannot be transferred for value or redeemed for cash. GCs may be used only for purchases of eligible goods at or certain of its affiliated websites. For complete terms and conditions, see GCs are issued by ACI Gift Cards, Inc., a Washington corporation. All Amazon ®, ™ & © are IP of, Inc. or its affiliates. No expiration date or service fees.


2. PRIZE: One (1) Winner will be randomly selected every month to each receive: one (1) $100.00 Gift Card (the “Prize Supplier”). Total approximate retail value of all prizes is approximately $100.00 USD. Prizes are not transferable and no cash or prize substitution is allowed. Prize package is awarded "as is" with no warranty or guarantee, either express or implied.

3. ELIGIBILITY: From the time of entry through the final date of prize fulfillment, each contest entrant and selected entrant must be a permanent lawful citizen and resident residing in the 50 United States or the District of Columbia or in Canada, and be twenty one (21) years of age or older. VOID IN PUERTO RICO, THE U.S. VIRGIN ISLANDS, IN ALL FOREIGN COUNTRIES OUTSIDE OF THE UNITED STATES, AND ALL OTHER U.S. TERRITORIES OR CANADA AND POSSESSIONS AND WHERE PROHIBITED OR RESTRICTED BY LAW. Employees, officers, directors, agents and representatives, of the Sponsor and the Prize Supplier and each of their respective parent companies, affiliates, subsidiaries, advertising and promotion agencies, promotion partners and any entity involved in the development, production, implementation, administration or fulfillment of this Sweepstakes, and the immediate family members (e.g., spouse, mother, father, sister, brother, uncle, aunt, nephew, niece, grandparent, in-law, daughter and son, regardless of where they live) and persons living in the same household (whether or not related) of such individuals are not eligible to participate or win. Only one selected entrant per household. All decisions of the Sponsor with respect to this sweepstakes are final. The Sponsor shall have the right at any time to require proof of identity and failure to provide such proof may result in disqualification from the Sweepstakes.

4. ENTER BY INTERNET: You may enter this sweepstakes via the Internet by logging onto and subscribing to our email newsletter via the pop-up overlay.

5. SELECTION OF WINNER: One (1) Entrant will be selected by random selection who have subscribed to our email newsletter. The winner may be announced publicly on and will be contacted by VerticalScope Inc.’s staff. The winner will be required to provide a mailing address (that is not a P.O. box) to receive the prize which will be shipped free of charge.

6. ODDS OF WINNING: Odds of winning a prize are determined by the total number of eligible entries received.

7. RESTRICTIONS: The prize package consists of one (1) Gift Card with an approximate value of $100.00 USD. If prize cannot be awarded due to circumstances beyond the control of the Sponsor or Prize Supplier, no substitute prize will be awarded due to the unique nature of the prize. Sponsor and Prize Supplier shall not be liable to the winner or any person claiming through winner for failure to supply the prize or any part thereof, by reason of any acts of God, any action(s), regulation(s), order(s) or request(s) by any governmental or quasi-governmental entity (whether or not the action(s), regulations(s), order(s) or request(s) prove(s) to be invalid), equipment failure, utility failure, internet failure, terrorist acts, threatened terrorist acts, air raid, blackout, act of public enemy, earthquake, war (declared or undeclared), fire, flood, epidemic, explosion, unusually severe weather, hurricane, embargo, labor dispute or strike (whether legal or illegal) labor or material shortage, transportation interruption of any kind, work slow-down, civil disturbance, insurrection, riot, or any other cause beyond Sponsor's or Prize Supplier's control (collectively, "Force Majeure Event"). Sponsor shall not be responsible for any cancellations, delays, diversions or substitutions or any act or omissions whatsoever by the performers/events, other transportation companies or any other persons providing any of these services and accommodations to passengers including any results thereof such as changes in services or accommodations necessitated by same.

8. CONDITIONS: By entering the Sweepstakes, entrants agree to be bound by the Official Rules, Terms and Conditions and that Sponsor has the irrevocable right to use in perpetuity entrants' names, user names, likenesses, photographs, voices, home mailing address, biographical and prize information, and entry materials, without notice to entrants and without compensation or obligation, in any and all media now or hereafter known throughout the world, in any manner whatsoever, to advertise and promote Sponsor, its products and services, the Sweepstakes, and for any other purpose except where prohibited by law. Entrant waives the right to assert as a cost of winning a prize any and all costs of verification and redemption or travel to redeem said prize and any liability which might arise from redeeming or seeking to redeem said prize. Sponsor is not responsible for fraudulent calls or emails made to entrants not by the Sponsor. If the Sweepstakes is not capable of running as planned by reason of damage by computer viruses, worms or bugs, tampering, unauthorized intervention, fraud, technical limitations or failures, any Force Majeure Event or any other cause which, in the sole opinion of Sponsor, could corrupt, compromise, undermine or otherwise affect the administration, security, fairness, integrity, viability or proper conduct of the Sweepstakes, Sponsor reserves the right, in its sole and absolute discretion, to cancel, terminate, modify or suspend all or any part of the Sweepstakes, and to select a winner from among all eligible entries received by Sponsor up until the time of such cancellation, termination, modification or suspension, as applicable. Sponsor reserves the right in its sole discretion to disqualify any individual that (i) tampers or attempts to tamper with the entry process or the operations of this Sweepstakes in any manner, (ii) violates the Official Rules, Terms and Conditions or (iii) acts in an unsportsmanlike or disruptive manner, or with intent to annoy, abuse, threaten or harass any other person. CAUTION: ANY ATTEMPT BY AN ENTRANT OR ANY OTHER INDIVIDUAL TO DELIBERATELY DAMAGE OR UNDERMINE THE LEGITIMATE OPERATION OF THIS SWEEPSTAKES IS A VIOLATION OF CRIMINAL AND CIVIL LAWS. SHOULD SUCH AN ATTEMPT BE MADE, SPONSOR RESERVES THE RIGHT TO SEEK CIVIL AND/OR CRIMINAL PROSECUTION AND/OR DAMAGES FROM ANY SUCH PERSON TO THE FULLEST EXTENT PERMITTED BY LAW. Any expenses and receipt and use of the prize and federal, state and local taxes and fees applicable in connection with the prize awarded are the sole responsibility of the winner. An IRS Form 1099 will be issued in the name of the winner for the actual value of the prize received. This Sweepstakes is subject to all federal, state and local laws of the United States. VOID WHERE PROHIBITED. Sponsor, Prize Supplier, and their respective officers, directors, parent companies, affiliates, subsidiaries and advertising and promotion agencies, employees, representatives and agents are not responsible for and shall not be liable for (i) any injuries, losses or damages of any kind caused by a prize resulting from acceptance, possession or usage of the prize, or (ii) printing, distribution or production errors. Sponsor or its affiliates may rescind any promotion found to contain such errors without liability at its or their sole discretion.

9. SPONSOR: The Sponsor of this contest is VerticalScope Inc. (the owner and operator of, 111 Peter Street, Suite 700, Toronto, Ontario, M5V 2H1.

Subscribe to our email newsletter and automatically be entered to win.
*Restrictions apply. See offer for details

Get Breaking Automotive News, Reviews and Video in your Facebook Feed!

Already Liked