Ken,
One of my hobbies is collecting and playing with vintage John Deere garden tractors. My collection dates from Kohler powered 1963 round fenders with manual Peerless transaxles to a 1985 diesel powered garden tractor with a hydrostatic transmission and a turbo added by yours truly. NOT all garden tractors are created equal… Most of the stuff available are simply toys IMO, these are manufactured by a couple of OEM’s and are rebranded with specific names we all recognize. This is true of Craftsman, Toro, Cub Cadet, John Deere, and others. The retail market stuff you get from Home Depot and the like fall into this category and are not built or designed to last or perform as well the products sold by a John Deere dealer as an example.
The hydrostats in these retail tractors are entirely different, said retail mowers/tractors hydrostats are not robust, are diminutive and sized to run a lawn mower with out additional loads. I’d suggest your hydrostatic transmission comments pertains to these types of tractors. Small to Full size tractors utilize hydrostats and they have proven to be highly desired and to work well for many years.
I can offer that anyone of my John Deere hydrostat garden tractors could pull your kids train until the cows come home! They are designed to pull plows, discs and other implements. Tractor sizes range from the aforementioned retail stuff to slightly larger. While these tractors cost more than the retail stuff when new, they work and last for years.
Some of the John Deere garden tractors that I’m talking about are; later 110-140 series, 300-332 series and 400-455 series. These are all older models.
If you find the need, I’m akin to helping you out herein. For instance we could start with a used JD-140 w/hydro, refit with a modern overhead cam, fuel efficient and quiet two cylinder engine (in lieu of the tired 14/16hp single Kohler’s) service, tires, seat and paint. Been there and done that, makes a great inexpensive work horse IMO. Cost maybe $3,000.00 or so, including a used 140. I’d even donate one of my 140’s in need of restoration to your wonderful cause.
Michael