🔍 Key Concepts

• Hydrodynamic journal bearing operation at normal (steady) speed • How the shaft rotation drags oil into a converging wedge to carry the load • Where the minimum clearance (closest approach) between journal and bearing will be, relative to the direction of rotation and the load

💭 Think About

• Assume the load on the shaft is acting straight downward. As the journal turns, in which quadrant of the bearing will the oil film build up to support that load? • Look at the arrow showing direction of rotation. Should the journal be closest to the bearing metal where the surface is approaching the load, or where it is leaving the load? • Which figure shows the journal shifted off-center in the direction you’d expect once the oil film has fully developed at operating speed, not during startup or at rest?

✅ Before You Answer

• Identify which side of each sketch represents the loaded zone (where the journal is “pushing” hardest against the bearing). • Check which option shows a small clearance (journal nearest bearing) just ahead of the vertical line of centers in the direction of rotation, where the oil wedge forms. • Eliminate any figure where the journal is simply hanging straight down with no evidence of a sideways displacement due to the hydrodynamic oil film.