Rex;
Much of the equipment you have pictured(pulled by horses but operated by stationery engine) are in use by Amish farmers, I see those various combinations in use regularly. The lowest photo in your first post shows a rig we called a "buck rake"
When I was but a lad and on our own farm, I observed and felt the transition from horse to tractor power. During the 1940s-1950s horse drawn equipment including ground drive units were often adapted to tractors, simply by cutting the poles short and putting a new pintle hitch on. Many mowers, rakes, spreaders and grain drills running around with shortened poles.
I handled loose hay and baled hay..and as a teenager, tossed around those 100lb wire bales from a New Holland #76 baler. I started on the tough end of a "misery whip".. (two man crosscut), before graduating to chainsaws. I have logged with horses, and dodgrd "widow makers" before I was of age to leave behind a widow. Milked cows by hand and machine..and hoisted the cans onto the truck.
Yes, our first tractor, a Farmall "C" was heartily welcomed and unlike a horse, did not need a lengthy training period before use and if well cared for, may yet be running today. My dad then sold one farm and bought another, which included a Farmall "H"..a larger, more powerful tractor..that's when we started acquiring some implements designed for tractors...the labor difference was huge.
Also in the mix was a homemade tractor, usually built from something like a Model A Ford with a truck differential & rear tires. We called these things "doodlebugs".
My dad also worked in a local factory and I attended school while running his farm, so we had to get up at 3:30 AM to be able to get everything accomplished. So, when I entered the Army at 18, fresh from the farm, while others moaned ove 5 AM reville..I was enjoying an extra 1&1/2 hours of sleep !
One would tend to think farming by horses would not work any longer...but the Amish do it and are prospering. The farms not being bought up in my area by large, conglomerate farms are being bought most often by the Amish.
Hope you guys didn't mind..just fun for an old man to reminisce