yes sir, that's why i am not 100% sure, but there are design that also uses carbon brushes, these are those tha does not have permanent magnet in the rotating field.
Quote Originally Posted by jick.cejoco View Post
it doesn't have a carbon brush that needs to be replaced



the pair of carbon brushes are the only means of connecting the rotating field coil to the power source, the voltage regulator and the ground. over time, they wear out as a result of constant friction between the slip rings and the brushes. if the rotor is stuck, usually it is the bearing or in some cases rust building up between the claw poles of the rotor and the stator laminated core.