Hydrodynamic Bearing Requirements
Hydrodynamic bearings require three elements to generate the hydrodynamic film:
- Viscous fluid (the lubricant)
- Relative motion (the sliding action of one surface relative to another)
- Converging geometry
In journal bearings, the converging geometry is provided by the slight difference in diameters of the shaft and the bore of the bearing. For improved static and dynamic performance, a defined profile can be machined into the bearing. Tilt pads are often used if stability is an issue, if varying conditions must be accommodated or if other bearing performance parameters require optimization.
In thrust bearings, the converging geometry is either machined into the face of a fixed plate or provided by the tilting action of tilt pad thrust bearings. A fixed geometry is designed for a specific condition, while tilt pad bearings are often used to accommodate changing conditions.