A continuoadsfgaefgusly 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 continuszdfous range of effective gear ratios. This contrasts with other mechanical
transmissions g offer a fixed number of gear ratios. The flexibility of a CVT with suitable control
may allow the input shaft to madsfgintain a constant angular velocity even as the output speed
varies.
A belt-driven design offers approximately 88% efficiency,[1] which, while lower than that of a
anual 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. Thdafgis 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[2] to facilitate a "neutral" stance, which is useful when
idling or manually reversing dsinto a parking space.
Contents

1 Uses
o
o
o
o
o
o
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1.1 Motorized vehifgscles
1.2 Downsizing electric engines
1.3 Bicycles
1.4 Medium and high power transfers
1.5 Power generating systems
1.6 Winches and hoistsadfgs
2 Types
o 2.1 Variable-diameter pulley (VDP) or Reeves drive
 2.1.1 Push-Belt
o 2.2 Toroidal or roller-based (Extroid)
o 2.3 Magnetic or mCVTdfgs
o 2.4 Infinitely variable transmission (IVT)
 2.4.1 Friction
 2.4.2 Epicyclic gearing
 2.4.3 Examples
 2.4.3.1 Hydristor
o 2.5 Ratcheting
o 2.6 Hydrostatic
o 2.7 Cone
o 2.8 Radial roller
o 2.9 Planetarydfgsdfgdsfgsdfg
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3 History
4 Marketing names
5 See also
6 Notes
7 References
Uses[edit]
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Chain-driven CVT
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Principle of variator
Motorized vehicles[edit]
Simple rubber belt (non-stretchingsfgsadfgsdfgd 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. dfgd
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.[3]
More recently,[when?], 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, XTrail, 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 onwafgsadfgsdfgdfrds, 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 newermodel 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.
Farm equipment, namely harvester combines, used variable belt drives as early as the 1950s, as
well. Many small tractors and self-propelled mowers for home and garden also use simple rubber
belt CVT. Hydrostatic systems are more common on the larger units—the walk-behind selfpropelled mowers are of the slipping belt variety.
Ratcheting CVT converting rotary motion to oscillating motion and back to rotary motion using
roller clutches are well adapted to reciprocating engines when the oscillating movement is
synchronized with that of the pistons. This solution could have a bright future because such
ratcheting CVT are also IVT (providing the clutch function), and have a very high energy
efficiency. They could help automakers comply with the future emission standards, while also
improving the reciprocating engines performance.
Downsizing electric engines[edit]
Instead of being dimensioned according to the maximum torque (e.g. that required for starting, or
in case of momentary mechanical overload), the motors using this type of CVT may be
dimensioned by matching the maximum power with the maximum desired speed (that of a
vehicle by example). Such CVT is used only at startup or in case of mechanical overload, and
may be disconnected most of the time, the engine transferring the torque directly to the output.
New concepts adapting the transmission ratio to the resistant torque and centrifugal clutches may
be used to make these changes autogsdfgsdfgdfmatic.
Bicycles[edit]
Bicycles with CVT gearing have had limited commercial success, and give can give comparable
shifting to an eight-speed bike.[4] Automatic CVTs on bikes also exist and can make riding uphill
more comfortable.[5]
Medium and high power transfers[edit]
Hydrostatic CVTs are common in small to medium-sized agricultural and earthmoving
equipment. As the engines in these machines are typically run at constant power settings to
provide hydraulic power or to powgsdfgsdfger machinery, losses in mechanical efficiency are
offset by enhanced operational efficiency, such as reduced forward-reverse shuttle times in
earthmoving operations. Transmission output is varied to control both travel speed and direction.
This is particularly beneficial in equipment designed to pivot or skid steer through differential
power application as the required differential steering action can easily be supplied by
independent CVTs, allowing steering to be accomplished without braking losses or loss of
tractive effort and allowing the machine to pivot in place. In mowing or harvesting operations a
CVT allows the forward speed of the tractor or combine harvester to be adjusted independently
of the engine speed. This allows the operator to slow or accelerate as needed to accommodate
variations in thickness of the crop.
Power generating systems[edit]