Reading a bit more on it, it's starting to sound less practical to me. Almost more like a differential, in that you have to supply a variable speed to one shaf

Reading a bit more on it, it's starting to sound less practical to me. Almost more like a differential, in that you have to supply a variable speed to one shaft to change the ratio. Now that's easy enough with an electric motor, but if that auxiliary input requires significant torque, it's not so useful anymore. Several people have commented that it sounds very much like some of the hydrostatic drives used in the Agri industries. But hey, it's still a neat demonstration, if not entirely practical.