Considering the cost savings involved with building transmissions with just three shifting parts, you’ll understand why car companies have grown to be very thinking about 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 equipment automatic transmission – offered in the tens of millions this past year – has hundreds of finely machined moving parts. It provides wearable friction bands and elaborate electronic and hydraulic regulates. A CVT just like the one explained above has three fundamental shifting parts: the belt and both pulleys.
There’s another benefit: The lowest and highest ratios are also further apart than they might be in a conventional step-gear transmission, giving the transmission a larger “ratio spread” This means it is even more flexible.
The 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 constantly.
As a result, rather than five or six ratios, you get thousands of ratios between your lowest (smallest-diameter Variable Speed Transmission pulley environment) and highest (largest-diameter pulley environment).
Here’s an example: When you start from a stop, the control computer de-clamps the input pulley so the belt turns the smallest diameter while the result pulley (which goes to the tires) clamps tighter to help make the belt convert its largest diameter. This produces the lowest gear ratio (say, 3.0-to-1) for the quickest acceleration. As velocity builds, the computer varies the pulley diameters, as conditions dictate, to get the best balance of fuel economic climate and power.