🔍 Key Concepts

• Journal bearing lubrication and how a fluid film supports the shaft • Meaning of hydrodynamic film thickness and what property of a liquid controls its ability to flow under shear • Difference between lubricant properties: pour point, fluidity/viscosity, dielectric strength, interfacial tension

💭 Think About

• Which property of the lubricant most directly affects how easily it can flow and maintain a separating film between metal surfaces at a given speed and load? • Think about which property marine engineers use when selecting oils for bearings that operate at different temperatures and speeds. • Which listed properties are mainly electrical or surface phenomena, and which is a bulk-flow/mechanical behavior property?

✅ Before You Answer

• Make sure you can define viscosity/fluidity in your own words and relate it to film thickness. • Eliminate any properties that relate mostly to low-temperature solidification or electrical insulation, since those are not primary factors in hydrodynamic film thickness. • Confirm which option is the inverse concept of viscosity, commonly used in bearing design calculations.