By changing commutator
By reversing direction
By shifting the brush position
By changing armature
Reduce armature reaction
To produce flux
To reduce humming
To reduce friction
To improve commutation
To reduce magnetic locking
To reduce vibration
Micro Neutral Axis
Minimum Neutral Axis
Miniature Neutral Axis
Magnetic Neutral Axis
Series
Parallel
Series - Parallel
Between armature and field