Although most know it as CVT and consider it a relatively new invention, the Continuously Variable Transmission has had many names since its first incarnation. It has been called single speed transmission, pulley transmission, and step-less transmission. In motorcycles, it’s called twist-and-go.
Compared to a standard automatic transmission which employs gear ratios in a fixed number, CVT changes through effective gear ratios seamlessly in a continuous range. The input shaft is therefore allowed to maintain an angular velocity that is constant. This translates to higher efficiency and better fuel economy in an ideal world scenario.
A Look Back in Time
The concept of the CVT dates to 1490 when Leonardo Da Vinci first conceptualized a step-less variant. Milton Reeves then invented one of the first variable-speed transmissions which he used in a saw milling engine back in 1879. This invention was then used in his first car which came out in 1896.
In 1886, Benz and Daimler filed in Europe for a patent of the first CVT that is based on a friction belt, then filed another one in the US for the toroidal CVT in 1935.
The CVT saw significant developments during the 1940s and the 1950s when Charles H. Miner invented the variable speed clutch pulley. He filed for US patents for this invention which were later granted. He then formed a company in Denver called the Miner Pulley which produced clutch pulleys for car manufacturers. The company was later sold to Warner Clutch.
Advancements in technology ushered in more developments for the CVT system, with Subaru releasing the Justy in Tokyo in the year 1987. This CVT system was electronically controlled and was developed by the Fuji Heavy Industries. Subaru also released the four-wheel drive version of the Justy in 1988.
Soon enough, other companies released their own variations of the CVT system. Ford and Fiat released in 1987 their steel-belted versions in their Fiesta and Uno, respectively, which became the first mainstream European cars to be equipped with the CVT system.
Nissan followed suit in 1992 by developing their own N-CVT together with Fuji Heavy Industries. This new CVT system included a torque converter which allowed higher torque, thus more power.
After these advances, the CVT has been honed to near perfection and is now the automatic transmission type of choice for most budget modern vehicles.
Advantages of CVT
Compact Design: The CVT is lighter and simpler when compared to traditional automatic transmission gear boxes. This means higher fuel efficiency.
Step-less acceleration: Because the CVT can shift seamlessly through a range of effective gear ratios, there are no jerks during the shift.
Maximum torque: The CVT can deliver maximum torque by allowing the immediate revving of the engine.
Smoother ride: CVT ‘shifts’ through the gear ratios smoothly compared to standard automatics wherein there are noticeable jerks as it changes gears. This allows for a smoother, more comfortable ride.
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