Fixed Profile Journal Bearings
Waukesha Bearings supplies medium and thick wall journal bearings specifically designed for turbomachinery. Several configurations are available to handle application needs for load capacity, rotating load, stiffness, damping, and rotordynamic stability.
The addition of grooves to fixed profile bearings can reduce destabilizing effects due to fluid rotation, while alterations to the circular geometry provide additional stability gains.
Performance can also be optimized through bearing material and lubrication method. Lubrication may be pressure fed or self-lubrication, the latter typically with an oil ring. Polymer linings can be used to extend performance limits or withstand high ambient temperatures. Hydrostatic jacking is recommended for machines with high start-up loads.
Sleeve Bearing Geometries
Plain sleeve bearings are cylindrical bearings, typically horizontally split and with the lubricant supplied through axial grooves located at the horizontal joint.
Most multi-lobe bearing 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. They are typically used in high-speed machinery with light rotors.
A specific kind of multi-lobe bearing, the lemon bore bearing has 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.
One of the most stable fixed geometry bearings available, the pressure dam bearing 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.
The upper and lower halves of an offset half bearing are displaced transverse to the shafts axis for greater stability than plain sleeve bearings.
Tilt Pad Bearing in the Space of a Sleeve Bearing
Flexure Pivot® tilt pad journal bearings offer the performance of a tilt pad bearing with the simplicity of a sleeve bearing. Available with a low-profile, Flexure Pivot bearings can sometimes replace sleeve bearings without housing modifications.