Carbon Brushes for DC Motors and Generators

by Terry Taylor, Senior Consultant, IDCON INC

Brush grades are usually classified according to the manufacturing processes and the types of carbons, graphites and other ingredients used. The 4 main brush grade families are –

  • Carbon-graphitesCarbon graphite brushes
  • Electrographitics
  • Graphites
  • Metal-graphites

Carbon-Graphite Brushes made their entrance early in the brush industry.  These are generally limited to lower current densities (45 amps/ and are used in older, slower speed motors with a maximum surface speed of 4000 ft./min. These are high friction brushes that make them very unattractive for present day use on commutators.

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