Considering the financial savings involved with building transmissions with only three shifting parts, you’ll understand why car companies have grown to be very interested in CVTs lately.
All of this may sound complicated, but it isn’t. Theoretically, a CVT is much less complex when compared to a normal automatic transmission. A planetary equipment automatic transmission – marketed in the tens of millions last year – has hundreds of finely machined moving parts. It provides wearable friction bands and elaborate electronic and hydraulic controls. A CVT just like the one explained above has three basic moving parts: the belt and the two pulleys.
There’s another benefit: The cheapest and best ratios are also further apart than they might be in a typical step-gear transmitting, giving the transmitting a greater “ratio spread” This means it is a lot 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 the ideal rpm for the proper speed all the time.
As a result, rather than five or six ratios, you get an infinite number of 
ratios between the lowest (smallest-diameter pulley environment) and highest (largest-diameter pulley establishing).
Here’s a good example: When you begin from a stop, the control computer de-clamps the input pulley therefore the belt turns the tiniest diameter while the result pulley (which would go to the tires) clamps tighter to help make the belt switch its largest diameter. This creates the lowest gear ratio (say, 3.0-to-1) for the quickest acceleration. As Variable Speed Transmission swiftness builds, the pc varies the pulley diameters, as conditions dictate, to find the best balance of fuel economic climate and power.