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Related to Horse power: torque
A machine that allows walking horses to power rotating machinery. One, two, three, or more equally spaced sweep arms several feet long to which horses were hitched radiated from a hub. Ahead of each sweep was an additional light arm (lead pole) to which the horses’ bridles were attached in order to constrain the horses to walk in a circular path. The horses pulled the sweep(s) around and caused the hub to rotate. The hub was connected by gears to a drive shaft (Tumbling rod) which ran close enough to the ground for the horses to step over it each time they came around. Once outside the horses’ path, the shaft could either be directly coupled or belted to the machine to be powered. Most horse powers were portable and mounted on either skids or wheels, but fixed installations were sometimes built inside barns.