A hydrodynamic bearing in the form of a flex pad bearing includes configurations structured to change a bearing characteristic. One form of the bearing includes a nonlinear back wall that includes a circular arc and a transition, where the back wall extends radially outward of a ligament. The bearing can include an opening for the deposit of a weighted mass, wherein the opening can threadingly receive a threaded weighted mass. In one form a sidewall that includes the back wall segment can have an average outer radius which determines a thickness of the flex pads. A ratio of the pad between the thickness and diameter of a central passage can be set to achieve the change in bearing characteristic.

A split double row spherical roller bearing comprising an outer ring including an outer race, an inner ring within the outer ring including an inner race, a cage mounted between the inner and outer races, the cage mounting rollers which engage the inner and outer races, the inner ring, inner race, outer ring, outer race, and cage each comprising two generally semicircular parts engageable together to form a circular component via respective radially extending contact surfaces, and characterized in that the contact surfaces of at least the outer ring comprise a saw-tooth arrangement in which the angle of each saw tooth joint is between 25 and 40 degrees.

A bearing sleeve element comprising a thin sheet of metal like bronze or brass with “dog bone” shaped pattern cut out through metal sheet in combination with a thin sheet of Teflon compressed and trapped inside “dog bone” shaped cavities of metal sheet in order to serve as a low friction bearing between two sliding surfaces.

A hydrodynamic bearing in the form of a flex pad bearing includes configurations structured to change a bearing characteristic. One form of the bearing includes a nonlinear back wall that includes a circular arc and a transition, where the back wall extends radially outward of a ligament. The bearing can include an opening for the deposit of a weighted mass, wherein the opening can threadingly receive a threaded weighted mass. In one form a sidewall that includes the back wall segment can have an average outer radius which determines a thickness of the flex pads. A ratio of the pad between the thickness and diameter of a central passage can be set to achieve the change in bearing characteristic.

Interfacing surfaces of adjacent tiles in a downhole tool may combine to form a tortuous path therebetween. In various embodiments, this tortuous path may run generally parallel and/or perpendicular to a top surface of the tiles. One example of such a tortuous path may be created by a protrusion extending from an interfacing surface of one of the tiles that may fit snugly within a cavity receding into an interfacing surface of another of the tiles.

A split double row spherical roller bearing comprising an outer ring including an outer race, an inner ring within the outer ring including an inner race, a cage mounted between the inner and outer races, the cage mounting rollers which engage the inner and outer races, the inner ring, inner race, outer ring, outer race, and cage each comprising two generally semicircular parts engageable together to form a circular component via respective radially extending contact surfaces, and characterized in that the contact surfaces of at least the outer ring comprise a saw-tooth arrangement in which the angle of each saw tooth joint is between 25 and 40 degrees.

A hydrodynamic bearing in the form of a flex pad bearing includes configurations structured to change a bearing characteristic. One form of the bearing includes a nonlinear back wall that includes a circular arc and a transition, where the back wall extends radially outward of a ligament. The bearing can include an opening for the deposit of a weighted mass, wherein the opening can threadingly receive a threaded weighted mass. In one form a sidewall that includes the back wall segment can have an average outer radius which determines a thickness of the flex pads.

There are provided a sealing device and a hub bearing that can reduce torque. Pear-skin-like projections and depressions are provided on each of a sliding surface in a lip for foreign object (a side lip 121a and a middle lip 121b) and a sliding surface in a lip for grease 122. Roughness of the pear-skin-like projections and depressions provided on the sliding surface of the lip for grease 122 is larger than roughness of the pear-skin-like projections and depressions provided on the sliding surface of the lip for foreign object.

A wing foil bearing may include one or more wing or tab foil layers. A tab foil layer may comprise a thin material with a two-dimensional array of tab shapes. A tab shape may be defined by a boundary of material separated from the thin material and having an integral edge and a free edge. Tab shapes may include one or more free-state bends relative to the thin material, forming a two-dimensional array of cantilever wings or tabs. Tab arrays may be one or more of various types or two-dimensional arrays, and a tab foil layer may include additional tab arrays and tabs. One or more tab foil layers may be engaged with a mounting surface layer and a counter-surface layer to form a wing foil bearing. Tab foil layers may be stacked and or nested, including partial nesting and complete nesting.

A hub seal seals a gap between an outer race member and an inner race member of a hub bearing. The hub seal includes: an annular base; and a seal member attached to the base and including an annular elastic material. The seal member includes a side lip extending toward an outer side and an intermediate lip extending toward the outer side on an inner periphery side relative to the side lip. A sliding surface of the side lip that comes into contact to seal the gap between the outer race member and the inner race member is rougher than a sliding surface of the intermediate lip that comes into contact to seal the gap between the outer race member and the inner race member.