page_title: Mouse mill motor
section_title: Construction
hierarchical_section_title: Mouse mill motor / Construction
caption_attribution_description: Mouse mill motor, rotor and coils (Rankin Kennedy, Electrical Installations, Vol V, 1903).jpg
context_page_description: Froment's "mouse mill" motor was an early form of electric motor, also known as the Revolving Armature Engine. It has similarities to both the synchronous motor and the contemporary stepper motor.
  As the mouse mill motor was simple to construct and its speed could easily be governed, it was later used to drive automatic recorders in telegraphy.
  The name derives from the rotor's resemblance to a small treadmill. Their usual size was more to the scale of a hamster than a mouse, but rodents were more common at the time as domestic pests, not domestic pets.
context_section_description: The motor consists of a freely rotating rotor, surrounded by a number of electromagnets. The rotor is made of a light brass wheel, with a number of soft iron bars or "attractors" mounted around its rim and parallel to the axis. There may be one, two or four electromagnets mounted on the frame of the motor, together with a cam-operated switch for each magnet. Many of the early motors were made by the scientific instrument maker Daniel Davis of Boston,  who sold them as the "Revolving Armature Engine".
caption: Coils and rotor of a motor
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