🔍 Key Concepts
• Typical causes of gear tooth scratching, scuffing, and galling in marine reduction gears
• What “pitting” indicates about contact stress, lubrication film, and surface fatigue on gear teeth
• Relationship between lubrication quality, contamination, and overload on tooth surface damage
💭 Think About
• Think about what happens to the tooth surface if hard particles get into the oil versus when there is simply not enough oil film present.
• Consider which condition (scratching, scuffing, pitting, galling) is most closely related to surface fatigue from repeated loading rather than a single overload event.
• Match each damage type with whether it is more likely caused by misalignment/overload, contaminated lubricant, or poor lubrication film strength alone.
✅ Before You Answer
• For each damage word, ask: is this mainly from surface fatigue, abrasive wear, or adhesive/seizure-type wear?
• Verify that the described cause for pitting correctly reflects it as a form of surface fatigue and material removal at high contact stress, not just cosmetic wear.
• Check that the described cause for galling matches an adhesive/seizure-type failure with metal transfer or plastic flow, usually along the pitch line.