🔍 Key Concepts

• Lubrication of roller bearings in marine machinery • Effect of over-packing vs under-packing a bearing with grease • Role of heat dissipation and grease expansion inside a bearing housing

💭 Think About

• Think about what happens to the grease and temperature inside a bearing when it is spinning at normal operating speed if it is packed too full. • Consider why manufacturers often leave space inside a bearing housing instead of completely filling it with grease. • Ask yourself which answer range would best allow both lubrication AND room for grease to move and for heat to escape.

✅ Before You Answer

• Verify how over-filling a roller bearing can lead to excess friction, churning, and overheating. • Consider that the correct percentage should provide a continuous film of grease on the rolling elements without hydraulic lock or churning. • Eliminate any choice that would likely cause excess churning of grease at operating RPMs.