I just came across this:
The claim is that it is a kind of analogue computer. But I don't see any moving parts. How does it work?
EDIT: If someone could draw lines on the diagram to illustrate, that would be great.
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Fluid flows in the channels and steel balls and solenoids are used to block, or open, relevant channels.
Used in many automatic gearboxes, the balls can be solenoid controlled or spring loaded depending what needs to happen to control gear changes and a "soft" or "hard" aka "slow" or "fast" response.
Fluid valves are regulated by pressure and velocity as the engine and transmission ratio along with acceleration and velocity of the vehicle, choose the optimal gear by torque and power available with engine RPM.