Photo 227 -- harvest, probably stepaneks
I posted this on Facebook and asked what the device was. Julie filled me in:
I think they are baling loose hay to square bales. The horse goes around the turnbuckle and the drive shaft runs the baler that the middle man is standing by.
So the horse walks round and round, stepping on the connection to the bailer as he goes.
tim nord adds information
The Historical Society's copy of this photograph does not identify the men. When I posted this on Facebook, Historical Society member Tim Nord recognized them as Stepaneks. He is the son-in-law of Lawrence and Nettie Stehlik, and Nettie had this same photograph in her collection.