🔍 Key Concepts

• Brush alignment on a DC commutator so that each brush spans several bars but the positive and negative groups are separated by 180 electrical degrees • Equal current sharing between parallel paths (each row of commutator segments should be covered the same way by the + and – brushes) • Avoiding short‑circuits and sparking (a single bar should not be under both + and – brush sets at the same time)

💭 Think About

• Look at how the + brush rows and – brush rows are positioned relative to the commutator bars: in which diagram are they directly opposite each other with uniform spacing? • In which diagram does every commutator bar see only one polarity of brush at a time, while the opposite polarity is exactly across the commutator? • Which pattern would let you rotate the armature slightly and still keep roughly the same overlap between brushes and bars, helping to reduce sparking?

✅ Before You Answer

• Verify that positive and negative brush sets are 180 electrical degrees apart around the commutator (directly opposite each other). • Check that each commutator bar is covered in the same way by the brush pattern (no bar should be favored or left out). • Confirm that no bar is simultaneously under both + and – brush groups, which would create a direct short and heavy sparking.