They are terribly inefficient and who is going to be servicing all these hydraulics in the 3rd world? Every farming town in the USA has someone who can make custom hydro lines quickly. How many of those shops in Africa?
Petrol engines are inefficient. Solar panels are inefficient. Your and my metabolisms are inefficient. Suitability to purpose matters more in my humble opinion. Alongside modularity and reusability.
Please contribute anything you know about custom hydraulic lines to https://wiki.replimat.org/wiki/Main_Page - I will approve accounts for any hackernews folk who request one.
Go look at an old farmall or ford tractor and understand how they solved these problems 70+ years ago. Be careful thinking you are smarter than those engineers.
Great example. Compare the traction of your machine to an 8N. That engine will outlast 4-5 briggs engines easy (10K vs 2K hrs). They have an efficient gear drive as opposed to hydrostatic. Lots less maintenance and no need for gallons of hydro fluid. They have a robust 3pt hitch with an excellent PTO drive. They will drag your tractor up and down the field all day long. I really mean to be constructive, sorry if I am not sugar coating it.
I appreciate your enthusiasm. First of all, the design originates with Open Source Ecology, a sister project. I'm involved with Replimat. There's also Gridbeam, XYZ Cargo, Precious Plastic, and about a dozen other groups actively developing around the system(s).
I appreciate all your points about the sort of tractor best suited to your unique circumstances. I don't see anything about our communities designs which prevent you from constructing such a machine using our parts and techniques. I think it'd be a neat design to have among all the others which can be built this way!
Hydraulic motors with PTO splined shafts are widely available like this: https://www.surpluscenter.com/Hydraulics/Hydraulic-Motors/Ag...