What are the advantages of using brushed DC motors?

[jackwyatt]

A Brushed DC Motors is an internally modified electric motor designed to operate from a direct current power source and to use electric brushes for contact. Brushed motors were the first commercially significant use of electric power to drive mechanical energy, and DC distribution systems were used to drive motors in commercial and industrial buildings for more than 100 years. Brushed DC motors can be varied in speed by changing the operating voltage or magnetic field strength.