An air-operated double diaphragm pump, wherein the pump (40) is disposed with a shaft (30) and a bushing (28). The shaft (30) includes a plurality of indentations which allow passage of air and the bushing (28) is adapted to receive the shaft (30) and be in sliding engagement with the shaft (30). The bushing (28) includes vents (22) formed on the bushing and a hole (24) formed at each respective terminal portion of the bushing (28) to allow passage of air. The bushing (28) also includes ribs (26) protruding radially outwards from inner surface of the bushing (28) toward the shaft (30). The indentations (34) disposed along the shaft (30) and hole (24) formed at each terminal portion of the bushing (28) are alignable to create a path for air to travel.

Embodiments of a gas bearing for aircraft engines are provided herein. In some embodiments, a gas bearing may include a first shaft; a second shaft disposed concentrically about the first shaft; and a protrusion extending from at least one of an inner surface of the first shaft or the outer surface of the second shaft to form a gap between the first shaft and the second shaft.

A foil bearing includes an outer member (11), and a plurality of foils (13) that are mounted to an inner circumferential surface (11a) of the outer member (11) and directly face the inner circumferential surface (11a) of the outer member (11) in a radial direction without interposition of another member (such as back foils). The foils (13) each include: holding portions (13a, 13b) that are formed at both circumferential ends and held while in contact with the outer member (11); and a body portion (13c) that is formed circumferentially between the holding portions (13a, 13b) and has a bearing surface (A). At least an end portion on one side in a circumferential direction of the body portion (13c) is raised radially inward with respect to the inner circumferential surface (11a) of the outer member (11).

Provided is a foil bearing, an air film is formed in a radial bearing gap between a first bearing surface arranged on a top foil and a second bearing surface along with rotation of a shaft, and the shaft is supported with a pressure of the air film. Lubricating powder is interposed between the bearing surfaces. The top foil is partially elastically deformed in a width direction of the radial bearing gap in accordance with the pressure of the air film generated in the radial bearing gap, thereby being alternately shifted between a first state in which a retaining portion capable of retaining the lubricating powder is formed and a second state in which the retaining portion substantially disappears, and shifted from the second state to the first state along with an increase in the pressure of the air film.