Considering the savings involved in building transmissions with only three shifting parts, you’ll understand why car companies have become very interested in CVTs lately.
All of this may sound complicated, nonetheless it isn’t. In theory, a CVT is far less complex than a normal automated transmission. A planetary gear automatic transmission – marketed in the tens of millions this past year – has Variable Speed Transmission hundreds of finely machined moving parts. It offers wearable friction bands and elaborate electronic and hydraulic settings. A CVT like the one referred to above has three simple moving parts: the belt and both pulleys.
There’s another benefit: The cheapest and maximum ratios are also additional apart than they would be in a conventional step-gear transmission, giving the transmitting a greater “ratio spread” This means it is even more flexible.
The engine can always run at the optimum speed for power or for fuel economy, regardless of the wheel speed, which means no revving up or down with each gear change, and just the right rpm for the proper speed on a regular basis.
As a result, instead of five or six ratios, you get an infinite number of ratios between the lowest (smallest-diameter pulley environment) and highest (largest-diameter pulley environment).
Here’s a good example: When you begin from a stop, the control computer de-clamps the input pulley so the belt turns the tiniest diameter while the result pulley 
(which goes to the tires) clamps tighter to help make the belt turn its largest diameter. This produces the cheapest gear ratio (say, 3.0-to-1) for the quickest acceleration. As quickness builds, the pc varies the pulley diameters, as conditions dictate, to get the best balance of fuel economic climate and power.