The top foil of a hydrodynamic fluid film thrust bearing is formed from a single flat annular disk with radial depressions extending from the outer diameter to the inner diameter of the disk that protrude toward the foil plate and define between adjacent depressions a working surface that is configured to complement the foil bumpers attached to the foil plate. The bump foils of the upper foil plate and the bump foils of the lower foil plates can be either in axial alignment or can be displaced relative to each other. When the two sets of bump foils are displaced, the leading edge of the upper bump foils are disposed upstream (relative to the direction of the air stream entering the bump foils) of the leading edge of the lower bump foils.

A method of forming an underspring for a foil thrust bearing from a uniform thickness sheet. The underspring is formed by chemically etching a plurality of slots in the disk and then stamping the tabs formed by the slots.

A hydrodynamic process or gas bearing is disclosed which includes an integral thrust disk defining a plurality of foil elements, the radially outer edge of the disk being displaced from the major bearing surface to form a circumferential step having a varying height profile. The integral thrust disk may in the alternative or in addition, include a plurality of radially outwardly extending tabs to locally increase the flexural rigidity of the disk.

A compliant foil fluid film bearing having individual fluid film foils formed as arcuate segments by an inner circumferential slot, an outer circumferential slot and a transverse therebetween. The transverse slot may be radial, slightly displaced from radial or tapered with one radial edge.

A spring cluster disc (14) for a foil thrust bearing (10) is provided with a plurality of sets (52) of springs (62,64,66). The springs are configured to provide varying spring force and thus varying stiffness in radial and circumferential directions.