Sleeve bearings are a simple and economic design with wide application in rotating machinery. These fixed geometry bearings come in several configurations to handle varying application needs for load capacity, rotating load, stiffness, damping, and rotordynamic stability (resistance to whirl).
Design variables to optimize performance include lobe geometry, number of lobes, bearing material, and lubrication. Lubrication may be pressure fed or self-lubrication, the latter typically with an oil ring
- Plain sleeve bearings – Cylindrical bearings, typically horizontally split and with the lubricant supplied through axial grooves located at the horizontal joint.
- Multi-lobe bearings – Typically used in high-speed machinery with light rotors. Most designs have three or four lobes, which can be centered for bi-directional rotation or offset for uni-directional rotation. Specialized designs may also have plain segments in the loaded region and tapered segments in the remaining areas. The multi-lobe bearing provides increased stability over plain sleeve bearings.
- Lemon bore bearings – A specific kind of multi-lobe bearing, with two large lobes offset about the center, giving them an elliptical shape. The vertical clearance is slightly smaller than the horizontal clearance. The design suppresses oil whirl with a vertical preload and can improve stiffness and damping over a plain sleeve bearing.
- Pressure dam bearings – One of the most stable fixed geometry bearings available. The design has a characteristic relief track, machined into the upper (unloaded) half, that comes to an abrupt end (pressure dam) to create an artificial load on the journal. This artificial load forces the shaft into a more eccentric position, resulting in greater stability.
- Offset half bearings – The upper and lower halves are displaced transverse to the shafts axis for greater stability than plain sleeve bearings.