Abstract: A foil journal bearing with a dual stiffness spring comprises a housing, a shaft arranged for relative coaxial rotation with respect to the housing, and a single spring layer surrounding the shaft. The single spring layer may have a first linear spring rate and a second linear spring rate wherein the first linear spring rate is formed by first pitch corrugations along a length of the single spring layer and the second linear spring rate is formed by second pitch corrugations along a length of the single spring layer. In an aspect of the invention, the foil journal bearing provides a top foil having first and second ends positioned in a notch in the housing. In an aspect of the invention, the single spring layer maintains a ratio of three of the second pitch corrugations to each of the first pitch corrugations.

Abstract: A journal foil bearing comprising a retaining member having an inner surface which defines a shaft opening within which a rotatable shaft is receivable for rotation; and a foil assembly affixed to and lining the inner surface and comprising a plurality of foil sub-assemblies each subtending a circumferential segment, of the inner surface.

Abstract: A hydrodynamic bearing set, for use with a thrust disk disposed between planar surfaces of a housing, includes first and second topfoils disposed adjacent first and second thrust disk axial bearing surfaces and removably secured to the housing. An underspring is secured between each planar housing surface and the corresponding topfoil. Dual-leaf spring pairs attached to at least one topfoil periphery function to urge the topfoils away from the thrust disk axial bearing surfaces by applying a force against a planar housing surface, another topfoil, or a spacer washer secured between adjacent topfoil dual-leaf pairs or frictionally retained within the housing. Alternatively, a wavy washer, a conical spring, a Belleville washer, or a coil spring can be substituted for the dual-leaf spring pairs.