1) Grinder 2) Grinding mill 3) Mill 4) Tread-wheel 5) Treadmill 
A treadwheel or treadmill is a form of engine typically powered by humans. It may resemble a water wheel in appearance, and can be worked either by a human treading paddles set into its circumference (treadmill), or by a human or animal standing inside it (treadwheel). These devices are no longer used for power or punishment, and the term `treadm....
• (n.) A wheel turned by persons or animals, by treading, climbing, or pushing with the feet, upon its periphery or face. See Treadmill.
a penal appliance introduced in 1818 by the British engineer Sir William Cubitt (1785–1861) as a means of usefully employing convicts. Designed in ...
A wooden wheel turned by the feet of people, used to power mills or other machinery.