I have a CVT transmission, which consists of a metal belt and four circular toroid discs, that form two pulleys. I need to be able to move the two toroids further and closer together. This movement has to be separate for the two pulleys, so when the drive toroids (connected to the engine) get further apart, decreasing the diameter, the driven toroids (connected to the driveshaft) have to get closer together as to tense the belt. This all has to be controlled by a raspberry pi. I thought about maybe using a hydraulic piston, but I'm not very familiar with hydraulics.
How should I design the system to move the toroids closer and further apart?