Considering the financial savings involved in building transmissions with just three moving parts, you’ll realize why car companies have become very interested in CVTs lately.
All of this may sound complicated, but it isn’t. Theoretically, a CVT is far less complex when compared to a normal automated transmission. A planetary equipment automatic transmission – offered in the tens of millions last year – has a huge selection of finely machined moving parts. It provides wearable friction bands and elaborate digital and hydraulic settings. A CVT like the one defined above has three fundamental shifting parts: the belt and the two pulleys.
There’s another advantage: The cheapest and greatest ratios are also additional apart than they might be in a typical step-gear tranny, giving the tranny a greater “ratio spread” This means it is a lot more flexible.
The Variable Speed Transmission engine can always run at the optimum speed for power or for fuel economy, whatever the wheel speed, which means no revving up or down with each gear change, and just the right rpm 
for the right speed on a regular basis.
As a result, instead of five or six ratios, you get thousands of ratios between the lowest (smallest-diameter pulley establishing) and highest (largest-diameter pulley environment).
Here’s a good example: When you start from a stop, the control computer de-clamps the input pulley so the belt turns the smallest diameter while the output pulley (which goes to the tires) clamps tighter to make the belt change its largest diameter. This generates the lowest gear ratio (say, 3.0-to-1) for the quickest acceleration. As rate builds, the computer varies the pulley diameters, as conditions dictate, to find the best balance of fuel economy and power.