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Efficient Transmission Designs



  • Continuously Variable Transmission (CVT) - CVTs in currently available vehicles utilize a pair of variable-diameter pulleys connected by a belt or chain that can produce an infinite number of engine/wheel speed ratios. This system has several advantages over conventional transmission designs: Seamless acceleration without the jerk or jolt from changing gears; No frequent downshifting or "gear hunting" on hills; Fuel efficiency Improvement: 6% ; Savings Over Vehicle Lifetime: $1,600.


  • Antonov - This company has existed for ages, with a ready to implement, hyperefficient atomatic transmission. Though not a CVT, very efficient and pleasant in driving (good old excelerating feeling). Beats me why never implemented. See nice animated explanations.
  • Torotrak’s new generation transmission is good gear - The continuously variable transmissions and infinitely variable transmissions by the UK-based engineering company, Torotrak, utilize a traction drive ‘toroidal variator’, which incorporates smooth, saucer-shaped discs and circular rollers. This variator allows the transmission to deliver a stepless range of ratios to meet all driving conditions.. (GizMag; Sept. 3, 2009)
  • Torotrak - Full toroidal Infinitely Variable Transmission (IVT) optimises engine efficiency without the torque limitation of a continuously variable transmission (CVT). Tests show a fuel economy improvement of 20% compared to a 4-speed automatic and 10% compared to a 6-speed automatic, with significant emission reductions. When applied to a hybrid the IVT improves efficiency in steady state cruise conditions.
  • Hydristor to convert vehicles into green hybrids - This infinitely variable vane hydraulic pump/motor is basically a simplified automatic transmission with no gears, with regenerative storage capability. Aiming to retrofit existing vehicles, it is projected to double or even triple mileage, while drastically cutting emissions (to 1/4) and boosting performance.
  • Van Cor Transmission - Symbiotic Drive runs both the gas engine and an electric motor at the same time in varied proportions to produce continuously variable output, an energy efficient process called “torque amplification?. The two power sources are combined through a planetary system in which the electric motor can become an output generator when the gas engine is idling or when the vehicle is decelerating.
  • Torvec - Infinitely Variable Transmission (IVT™) combines hydraulic pump technology with gearing and valving resulting in fuel economy improvement of 38% in city driving conditions and reduced emissions. The transmission can bolt into existing drive trains with no redesign of the automobile. There are over 70% fewer parts to fail and all key wear parts operate in hydraulic fluid containment.
  • SuperDrive - Continuously variable transmission (CVT) capable of heavy torque loads and high speeds with improved fuel economy and reduced emissions. A CVT is a totally automatic transmission that does not shift from one gear to another as the vehicle accelerates, but provides constant, smooth acceleration. See also Department of Energy (pdf file) - Hydraulic transmission system improves fuel efficiency 20-25% in heavy duty diesel trucks and 50-55% in light duty trucks.
  • NuVinci CVP Transmission by Fallbrook Technologies - Continuously variable gear technology is introduced in a bicycle hub application, from there to then be applied elsewhere. Provides an infinite number of gear ratios. Allows shifting while at a stop, using simple controls.
  • CVET Power - Continuously Variable Electronic Transmission could dramatically increase automobile mileage and performance. The CVET design makes it possible to operate a motor (whether gas or electric) at its peak efficiency of operation, at highway speeds or in start/stop city driving. The CVET does not rely on the external application of mechanical forces to control the output speed, eliminating the major sources of efficiency loss.
  • Artemis Intelligent Power - HEDDAT (High Efficiency Digital Displacement™ Automotive Transmission) series hydraulic transmissions for automotive applications can offer impressive fuel savings, performance enhancement and cost savings over conventional transmissions. Benefits: Part load efficiency; Infinitely variable transmission ratio; Regenerative braking with accumulator storage; Engine off operation.
  • Two-Mode Hybrid Transmission - Sized similarly to a conventional automatic transmission, this full hybrid can operate in infinitely variable gear ratios or one of four fixed ratios, with existing internal combustion engines. It can use electric motors for power boosting and regenerative braking, and is capable of towing heavy loads. The Two-Mode will boost fuel economy of big SUVs and large luxury cars by at least 25 percent, providing an all-electric launch and drive capability.
  • Gyro Energy - GyroTorque, also known as GVT (Gyroscopic Variable Transmission) is an infinitely variable transmission that facilitates greater capture and control of input energy from wind & wave resources to reduce the cost of power generation.
  • CVT Systems - New, different concept of a cvt. It is simple and uses many off the shelf components. No pulleys, belts, hydraulics, electronics or friction components are used in the ratio change section. For use in all types of automobiles, automobile accessory drives, machine tools, tractors, constant frequency electrical power generation, electric vehicles, winches, bicycles.
A+CVT prototype (dual cone version)
A+CVT prototype (dual cone version)
  • Anderson CVT - Reduces fuel consumption by enabling automobile engines to function at their optimum speed. The A+CVT is a variation on the principal of two parallel cones positioned with the larger end of each one alongside the smaller end of the other. What's different about the A+CVT is an innovative component called floating sprocket bars (FSBs.).
  • VeriTran - Infinitran™ continuously variable transmissions are based on controlled epicyclic gear trains. Continuous output from forward, to neutral, and to reverse in a single device with no clutch. Novel traction arrangements and gearing lead to high efficiency without the torque converters that competing designs often require.

Naudic iCVT prototype
Naudic iCVT prototype
  • Barloworld CVT Technologies - The Naudic iCVT is the only positively driven CVT in the world, eliminating the shortcomings of conventional CVTs. The Naudic CVT concept is therefore capable of exceeding the fuel savings of 18% currently being quoted for conventional CVTs. A prototype of the Naudic iCVT (Incremental Continuously Variable Transmission) has been tested to 600 N.m input torque in a Porsche 924 turbo. The transmission, which features 64 ratios that shift under load without any clutch action, is positively driven at all times.This is the world's first CVT-type transmission to accomplish a positive drive even when shifting and the first time a prototype of such a gearbox has been successfully tested in an actual vehicle.

  • NexxtDrive - DualDrive Transmission combines the functionality of a continuously variable automatic gearbox with that of an efficient hybrid electric drive, for the automotive, off-road, light electric vehicle, wind generation and other industrial applications.
  • Transmission Technologies Corporation - The TTC - IVT (Infinitely Variable Transmission) is the latest version of a technology meant to improve fuel economy and reduce emissions. Our design is a toroidal traction-drive transmission. TTC's Automated Mechanical Transmission provides all the benefits of a manual transmission with the best features of an automatic transmission, improving efficiency in a wide variety of stop-and-go operations.
  • Neptunus Transmission - Based on a ingenious solution where a planetary gear is made to be stepless. Major fuel consumption savings are due to the combustion engine optimization!
  • Zero Inertia - An extremely simple modification of a continuoulsy variable transmission (CVT) is able to eliminate the well known compromise between fuel economy and driveability. The modification comprises the augmentation of the CVT with a few gears, a planetary gearset and a compact steel flywheel.
  • Ratio Disc - World's most efficient CVT at 98% efficiency solves the problems of CVTs. Advantages: Capable of large engine power: Responds rapidly to torque changes; Accommodates misalignments; Uses simple to manufacture parts; Has high power to weight ratio
  • Differential Dynamics - The DDMotion Infinitely Variable Transmission requires no clutch, belts or hydraulics. It mechanically offers optimal power transfer similar to how a transistor electronically modulates electrical signals.
  • John Deere - Agricultural tractor Infinitely Variable Transmission automatically maximizes fuel efficiency in medium and light load conditions, with constant vehicle speed at reduced engine rpm levels. And because of the lowered engine speed, in-tractor noise levels are reduced and long-term durability is greatly enhanced.
  • Van Cor Transmission - Allows changes in gear ratios without interruption of torque based on conic gears. For automotive applications, the VCT would improve fuel economy compared to stepped-gear-ratio transmissions.

  • Warko CVT - A new revolutionary cone CVT, presented in Berlin at the 6th International CTI Symposium of Innovative Automotive Transmissions, on 3-7 December 2007.A particular characteristic of the Warko is absence of a clutch: the engine is always connected to the wheels, and the rear drive is obtained by means of an epicyclic system in output.This system, named “power split?, allows the condition of geared neutral or "zero Dynamic".

In the News

  • IVT Improves Bus Fuel Economy 19% - Torotrak achieved a 19% improvement in fuel economy by replacing the standard 5-speed automatic transmission with a prototype Infinitely Variable Transmission (IVT). By operating the engine at the most efficient point the IVT may enable downsizing of the engine leading to further efficiency and fuel economy improvements. (Green Car Congress; Oct. 2, 2007)
  • F1 tech for road cars - Xtrac will exploit Torotrak’s full-toroidal traction drive to develop highly efficient CVTs for use in the new kinetic energy recovery systems (KERS) proposed for F1 motor racing. The system holds promise for use in road cars, storing kinetic energy in a flywheel, boosting fuel economy without complex electrical-battery hybrid architectures. (Gizmag; Jun. 6, 2007)
  • ZF 8-Speed Automatic Transmission - ZF has designed a new 8-speed automatic transmission for passenger cars based on a new transmission concept featuring four planetary gearsets and five shift elements. It enables fuel savings of approximately 6% compared to 6-speed transmissions and 14% compared to a 5-speed. (Green Car Congress; May 2, 2007)
  • CVTs for Hydraulic Hybrids - Folsom Technologies has developed a line of hydromechanical continuously variable transmissions (CVT) that are configurable as a component of a hydraulic hybrid system. For operating duty cycles that have frequent start/stops (such as NYC taxis, school buses, garbage haulers, etc.) the fuel savings can be greater than 50%. (Green Car Congress; Apr. 13, 2007)
  • Zeroshift Automated Manual Transmission - Zeroshift has developed a way of replacing synchromesh in a manual gearbox with a reliable, cheap-to-manufacture mechanism that allows completely seamless gearchanges. The AMT changes gear faster and provides improved acceleration, economy and emissions in any vehicle to which it is applied. (Gizmag; Feb. 9, 2007)

  • Currie to build LEVs using Fallbrook’s NuVinci™ CVP - Currie Technologies will expand its IZIP™ product line to include hybrid electric bicycles and electric scooters combining the Currie Electro-Drive™ with the NuVinci CVP continuously variable planetary transmission . As a result, a new vehicle category will be created – a family of light electric vehicles whose enhanced performance makes them a practical alternative to gas-powered vehicles. (Fallbrook Technologies; September 12, 2006)
  • Eco-friendly transmission improves efficiency - 82-year-old Salt Lake City inventor has accomplished his lifelong dream with a super-efficient transmission that could increase mileage in a car from 20 mpg to 30 mpg. Can go in bikes, cars, helicopters and anything that has a motor. 23 foreign patents filed. (Deseret News; Feb. 3, 2006)


  • Featured: Humor / Fuel Efficiency > Transmissions >
    The one and only Turboencabulator - The Turboencabulator or turbo-encabulator (and its later incarnation, the retroencabulator or retro-encabulator) is a fictional machine whose alleged existence became an in-joke and subject of professional humor among electrical engineers. A must see video if you've not seen it before. Hillarious. (PESWiki; Mar. 12, 2010)

See also






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