Self-propelled loaders

First production model of Melroe "Self-Propelled Loader" at the West Fargo, North Dakota, stockyards. Late 1958

The first Melroe Self Propelled Loader, M60, “complete with 9.2 HP engine” sold for $1,390 with four available attachments including a utility scoop, manure fork, rotary snow plow and sweeper. The Keller brothers received $15 royalty on each machine sale until about 1980 when the duration of the patent ended, said Joe Keller.

https://ironsolutions.com/agriculture-equipment-value-guides/the-first-skid-steer/

1958: Cyril and Louis Keller make a deal with Melroe Manufacturing Co. for production of their small, three wheel loader. Melroe began marketing the M 60 self propelled loader, essentially launching the compact equipment industry.

1959: The Melroe loader is redesigned as the M 200.

https://undergroundinfrastructure.com