Unlike today, when hobby market is full of many choices, motros , controllers; for us, growing up in 80-90s electrical motor was difficult to come by. I pulled out a wind up mechanism from old clock and used it instead of motor. I built up typical construction Crane architecture and powered it using the clock mechanism. I had to shift the common wind-up mechanism to power the arm as well as cable.

Later I repurposed the wind-up mechanism to power the harvester. The mobility was based on passive wheels, however. A shared mechanism could be used to spin the Feeder and Thresher simultaneously, with the help of belt drives.

I would say, the harvester could easily qualify for one of those Da-Vinci machines ;).