Brush pressure that is too what is the single most common cause of commutator problems?

• A. Moderate
• B. Heavy
• C. Light
• D. Very light

Answer: (D)

The main idea is that good, consistent contact between the brushes and the rotating commutator is essential for smooth current transfer. When brush pressure is too light, the brush isn’t pressed firmly against the commutator as it turns. This leads to intermittent contact, higher contact resistance, and sparking as each segment passes under the brush. The sparking pits and grooves the commutator surface and causes uneven wear, which can quickly degrade performance and lead to more serious damage to the windings and insulation over time. Because many commutator problems originate from insufficient contact, very light pressure is the most common root cause.

Moderate pressure generally maintains adequate contact, and heavy pressure tends to cause mechanical wear and overheating. Those conditions produce different telltale symptoms and are less frequently the primary cause of commutator problems.