Brush dynamo

Charles F. brush assembled his first dynamo in the summer of 1876 using a horse-drawn treadmill to power it. U.S. Patent #189997 "Improvement in Magneto-Electric Machines" was issued April 24, 1877. Brush started with the basic Gramme design where the wire on the sides and interior of the ring were outside the effective zone of the field and too much heat was retained. To improve upon this design, his ring armature was shaped like a disc rather than the cylinder shape of the Gramme armature. The field electromagnets were positioned on the sides of the armature disc rather than around the circumference. There were four electromagnets, two with north pole shoes and two with south pole shoes. The like poles opposed each other, one on each side of the disc armature.