Froment Motor, or Revolving Armature Engine


Froment Motor, or Revolving Armature Engine


Electric Motors


In 1844 Froment devised an electric motor that was one of the first used for industrial purposes. In his design, electromagnets are energized to attract iron bars mounted on a revolving cage. Once the iron bar is level with the electromagnet, the current to the electromagnet is cut off until the next iron bar is in range. A commutator is used to complete and then break the current to the electromagnet. This Froment-type motor was probably made in the second half of the 19th century.


Property of the W&L Physics & Engineering Department



“Froment Motor, or Revolving Armature Engine,” Digital Exhibits at Washington and Lee University Library, accessed May 26, 2018,