Continuously variable transmission

A continuously variable transmission (CVT), also known as a shiftless transmission, single-speed transmission, stepless transmission, pulley transmission, or, in case of motorcycles, a 'twist-and-go', is an automatic transmission that can change seamlessly through a continuous range of effective gear ratios. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. The flexibility of a CVT with suitable control may allow the input shaft to maintain a constant angular velocity even as the output speed varies. A belt-driven design offers approximately 88% efficiency, which, while lower than that of a manual transmission, can be offset by lower production cost and by enabling the engine to run at its most efficient speed for a range of output speeds. When power is more important than economy, the ratio of the CVT can be changed to allow the engine to turn at the RPM at which it produces greatest power. This is typically higher than the RPM that achieves peak efficiency. In low-mass low-torque applications (such as motor scooters) a belt-driven CVT also offers ease of use and mechanical simplicity. A CVT does not strictly require the presence of a clutch. Nevertheless, in some vehicles (e.g. motorcycles), a centrifugal clutch is added to facilitate a 'neutral' stance, which is useful when idling or manually reversing into a parking space. Simple rubber belt (non-stretching fixed circumference manufactured using various highly durable and flexible materials) CVTs are commonly used in small motorized vehicles, where their mechanical simplicity and ease of use outweigh their comparative inefficiency. Nearly all snowmobiles, utility vehicles, golf carts and motor scooters use CVTs, typically the rubber belt or variable pulley variety. CVTs, along with several other electronic systems and driver aids were prohibited from Formula 1 in 1994 due to concerns over escalating research and development costs, and maintaining a specific level of driver involvement with the vehicles. More recently,, CVT systems have been developed for go-karts and have proven to increase performance and engine life expectancy. The Tomcar range of off-road vehicles also utilizes the CVT system. Some vehicles that offer CVT are the Chrysler Pacifica hybrid, the Ford C-MAX hybrid, the Mitsubishi Lancer, the Dodge Caliber, the Toyota Corolla, the Scion iQ, the Honda Insight, Fit, CR-Z hybrid, CR-V, Capa, Honda Civic, Honda Accord, the Nissan Tiida/Versa (SL, SV, and Note S Plus or higher models), Cube, Juke, Sentra, Altima, Maxima, 2013 1.2 Note, Rogue, X-Trail, Murano, Pathfinder, Sunny and the non-Mexican Micra, the Jeep Patriot and Compass, the Suzuki SX4 S-Cross, and the Subaru Forester, Impreza, Legacy, Outback and Crosstrek, Suzuki Kizashi, Toyota Allion 2009 onwards, Toyota Premio 2009 onwards, Toyota Avalon, Toyota Mark X, etc. CVTs should be distinguished from power-sharing transmissions (PSTs), as used in newer hybrid cars, such as the Toyota Prius, Highlander and Camry, the Nissan Altima, and newer-model Ford Escape Hybrid SUVs. CVT technology uses only one input from a prime mover and delivers variable output speeds and torque, whereas PST technology uses two prime mover inputs and varies the ratio of their contributions to output speed and power. These transmissions are fundamentally different.