🔍 Key Concepts

• Hydrodynamic lubrication in journal (main) bearings • How viscosity, bearing pressure, and shaft speed (rpm) each affect oil film formation • Relationship between load, speed, and oil properties in maintaining separation between metal surfaces

💭 Think About

• Ask yourself: if you increase bearing load (pressure) but change nothing else, what tends to happen to the oil film thickness? • Consider what higher or lower oil viscosity does to the ability of the oil to form and hold a stable film between moving surfaces. • Think about how shaft rpm affects the ability of the bearing to "pump" oil into a wedge and sustain a film—does higher speed help or hurt film formation?

✅ Before You Answer

• Be sure you understand that the oil film in a main bearing is created by relative motion and oil wedge pressure, not just by having oil present. • Check which of the listed factors directly influences the pressure distribution and thickness of the hydrodynamic oil film between shaft and bearing. • Ask: is there only one controlling factor here, or do these variables work together to determine actual film thickness in service?