It's a Porcupine Thresher!

Horses were attached to the big end, and the small end was attached to a free-turning post. The pegs acted as flails to thresh out grain on the threshing floor. It was used around 1820 in New York's Mohawk Valley.

The Porcupine Thresher is just one of many fascinating machines in the agricultural collection at the Henry Ford Museum in Dearborn, Michigan.