How Does a Hydrostatic Transmission Work?

I've driven many hydrostatic mowers and lawn tractors - but I've never taken one apart until today! The basic job of this transmission (and the concept of Hydrostatic power) is converting constant velocity power through a hydraulic pump into a matching hydraulic motor with a variable speed. But to see the process and the parts... That's a whole new level of understanding. Here is a link that was shown to me with an excellent animation of the fluid flow process since it's impossible to operate with the transmission disassembled -   • Hydrostatic Transmission  . Enjoy!