How CVTs Work

The sophisticated mechanisms that help a car run smoothly have always been an important element in a car’s description. A transmission is a mechanism that allows a power source to send power to a drive mechanism. This means that the power generated by the engine is transformed into torque. Torque is the force that is applied to rotating items. In a car, a transmission converts the speed of an engine into torque. There are various types of transmissions and each have their pros and cons. Today we are going to explain how CVTs work.

CVT is the abbreviation for a continuously variable transmission. This is the oldest type of transmission. The concept was invented by Leonardo Da Vinci over 500 years ago. One might think that by now it would have been replaced by newer technologies. However the inner workings of this system are so well thought that they can even be applied to modern cars. Over the years the transmission has suffered some transformations and improvements but the basic principle remained the same.

If you want to understand how CVTs work the best thing is to do is to analyze them in comparison with the automatic versions. An automatic transmission has actual gears that change the speed ratio between the engine and the wheels. The planetary gears are combined together in order to create the proper gear ratio. On the other hand a continuously variable transmission doesn’t use a gear system. Instead it can can be based on pulleys, it can be toroidal or hydrostatic.

A pulley system is the most encountered type of CTV. It allows infinite variability between the extreme ratios that don’t have discrete steps. You will notice that despite the fact that none of the continuously variable system use gears, the word is still used in their description in order to refer to the ratio of the shaft to drive shaft speed. The pulleys have different diameters and have a metal belt running between them. The input shaft is represented by the pulley connected to the engine while the output shaft is the pulley connected to the drive wheel. The pulleys have moveable halves. As the halves come together the belt rides higher thus increasing the pulley’s diameter which varies the ratio. When the input pulley is small and the output one is enlarged a low ratio is created which is optimal for low-speed acceleration.

In order to better understand how CVTs work you need to think in terms ratio variability. Both conventional transmissions( manual or automatic) focus on lowering the engine speed as the speed of the car increases. However a continuously variable transmission doesn’t change the ratio in stages but it varies it continuously.