How does the power transfer unit in the A320 work? As far as i know the function of a PTU is to power one hydraulic system (either green or yellow) that is experiencing low pressure driven by pressure from the other system which still has the normal 3000 psi, where no fluid transfer happens. I have read (correct me if im wrong) that this happens with the help of hydraulic pumps, but how exactly does the "power" transfer happen?
The PTU consist of a hydraulic motor that drives a hydraulic pump.

The motor is driven by one hydraulic system, the shaft of the motor is connected to the pump and the pump powers the other hydraulic system.