Adjusting speed

Adjusting armature resistance

By stopping the generator

Adjusting excitation

Continuity of supply

Reduce cost

Easy operation

Easy connection

Over loading

Insufficient brush tension

Excessive brush pressure

Insufficient brush spring pressure

Unbalanced armature

Foreign material in air gap

More current in armature

Incorrect grade of bearing grease

Oily commutator surface

Defective alignment

Defective bearing

Wrong alignment