Patent Publication Number: US-9429188-B2

Title: Bearing assemblies, and related methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/135,064 filed on 19 Dec. 2013, which is a continuation of U.S. application Ser. No. 13/550,825 filed on 17 Jul. 2012 (now U.S. Pat. No. 8,646,981 issued on 11 Feb. 2014), which is a continuation-in-part of U.S. application Ser. No. 13/089,725 filed on 19 Apr. 2011 (now U.S. Pat. No. 8,545,103 issued on 1 Oct. 2013), the disclosure of each of the foregoing applications is incorporated herein, in its entirety, by this reference. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present invention relate generally to bearing elements and bearing assemblies and, more particularly, to compositions, configurations, geometries and methods of manufacturing bearing components and bearing assemblies. 
     BACKGROUND 
     Bearings are well known devices that enable relative movement two or more components. A variety of different bearing types are known and utilized on a regular basis. So-called “thrust bearings” and some embodiments of radial bearings conventionally include bearing surfaces that at least partially contact and move or slide relative to one another. Such bearing surfaces are conventionally prone to wear due to their interaction with one another and, as such, are formed from appropriate wear resistant materials. For example, such bearing surfaces may include a superhard material for resisting wear during use of the bearing. In one particular example, at least one or both of the bearing surfaces may be formed of a material comprising diamond (e.g., polycrystalline diamond). 
     As noted above, bearings may be used in numerous applications. In one example, bearings may be used subterranean drilling equipment. Such equipment may include drilling motors and drill bits having multiple components that move relative to one another, such as roller cones, and may be utilized for drilling boreholes into a subterranean formation, such as for oil or gas exploration. In a conventional downhole drilling motor, the motor is suspended at the lower end of a string of drill pipe comprising a series of pipe sections connected together at joints and supported from the surface. A rotary drill bit (e.g., a fixed cutter drill bit, roller cone drill bit, a reamer, etc.) may be supported below the drilling motor (via pipe sections, drill collars, or other structural members as known in the art) or may be directly connected to the downhole motor, if desired. Drilling fluid, which is commonly known as drilling mud, is circulated through the pipe string and the motor to generate torque within the motor to cause the rotary drill bit to rotate. Bearings are conventionally used to enable efficient relative rotation of the rotary bit and other components of the drill string. 
     Many types of bearings may be used in such a drill string assembly, including the bearings that may be employed by a rotary drill bit. One particular example includes radial bearings. In one embodiment, an inner and outer race are each provided with a plurality of superhard bearing elements (e.g., polycrystalline diamond elements). The races are positioned adjacent one another so that the bearing surfaces of the bearing elements contact one another during starting and stopping or overload conditions. In fluid bearings, the surfaces of the races do not contact during normal operation but, instead, are separated by a fluid film. As may be appreciated, geometry and configuration of the bearing elements of the races may be an important factor influencing the performance and life of such a bearing structure. Examples of some conventional radial bearing apparatuses are disclosed by U.S. Pat. Nos. 4,662,348, 4,729,440, 4,738,322, 4,756,631, and 4,764,036, the disclosures of each of which are incorporated, in their entireties, by this reference. Another example of a bearing used in drill string assembly includes a thrust bearing. A thrust bearing enables rotation between two adjacent components while also supporting a high level of axial thrust. Some examples of a thrust bearing assemblies are set forth in U.S. Pat. Nos. 7,552,782 and 7,870,913, the disclosures of each of which are incorporated, in their entireties, by this reference. 
     It is a continued desire within the industry to provide improved bearing elements and apparatuses including such elements. 
     SUMMARY 
     Embodiments of the present invention are directed to various bearing elements, bearing assemblies and related methods. In accordance with one embodiment of the invention, a bearing assembly is provided. The bearing assembly includes a first tilting pad bearing assembly comprising a body and plurality of tilting pad bearings. Each tilting pad bearing includes a polycrystalline diamond (PCD) layer attached to a base layer. The plurality of tilting pad bearings being circumferentially spaced about the body defining a first collective bearing surface. The bearing assembly also includes a runner bearing comprising a PCD layer having a plurality of PCD elements coupled to a base layer defining a second collective bearing surface. The first tilting pad bearing assembly and the runner bearing are positioned and configured to move relative to each other with the first collective bearing surface being in contact with the second collective bearing surface. 
     In one embodiment, each of the plurality PCD elements of the runner bearing is contiguous with an adjacent one of the plurality of PCD elements to define a substantially continuous surface. The PCD elements of the runner bearing may exhibit an annular sector geometry in one embodiment. In another embodiment, at least some of the plurality of PCD elements may include a surface exhibiting a substantially square geometry. 
     In another embodiment, the plurality of PCD elements of the runner bearing are spaced apart from one another such that there is a gap between adjacent PCD elements. One or more of the PCD elements of the runner bearing may exhibit a substantially cylindrical geometry. 
     Additionally, in one embodiment, the PCD layer of at least one tilting pad bearing includes a plurality of PCD elements. In such an embodiment, each of the plurality PCD elements of the tilting pad bearing may be positioned to be contiguous or in direct contact with one or more adjacent PCD elements of the tilting pad bearing to define a substantially continuous surface. In another embodiment, the PCD elements may be spaced apart from one another such that there is a gap between adjacent PCD elements. The PCD elements may exhibit a variety of geometries. 
     In one embodiment, the runner bearing further comprises a second PCD layer comprising another plurality of PCD elements coupled to the base layer defining a third collective bearing surface. Additionally, the bearing assembly may include a second tilting pad bearing assembly having a body and plurality of tilting pad bearings, each tilting pad bearing of the second assembly comprising a polycrystalline diamond (PCD) layer attached to a base layer, the plurality of tilting pad bearings of the second assembly being circumferentially spaced about the body of the second assembly and defining a fourth collective bearing surface. The second tilting pad bearing assembly and the runner bearing may be positioned and configured to move relative to each other with the third collective bearing surface being in contact with the fourth collective bearing surface. 
     In accordance with another embodiment of the present invention, a bearing element is provided. The bearing element includes a base layer and a polycrystalline diamond (PCD) layer. The PCD layer includes a plurality of PCD elements coupled with the base layer with each PCD element comprising a substrate and a diamond table. 
     In one particular embodiment, each of the plurality PCD elements is contiguous with an adjacent one of the plurality of PCD elements to define a substantially continuous surface. The substantially continuous surface may exhibit various geometries. For example, in one embodiment the substantially continuous surface is shaped as an annular sector. In another embodiment the substantially continuous surface exhibits a substantially circular geometry. 
     In another embodiment, the plurality of PCD elements are spaced apart from one another such that there is a gap between adjacent PCD elements. 
     The PCD elements may also exhibit various geometries. Such geometries may include providing a diamond table surface that is substantially square, rectangular circular or other geometries. 
     In one embodiment, the base layer of the bearing element may comprise tungsten carbide. In such an embodiment, the substrate may likewise comprise tungsten carbide. In another embodiment, the base layer may comprise steel. 
     In one embodiment, the bearing element may be formed as a tilting pad bearing element. In such a case, a projection may be formed on the base layer to enable the bearing element to rock relative to other components within a bearing assembly. In another embodiment, when formed as a tilting pad bearing, the base layer may be formed to exhibit an arcuate surface. 
     In accordance with another embodiment to the present invention, a method is provided for manufacturing a bearing element. The method includes forming at least one polycrystalline diamond compact (PDC) having a diamond table and a substrate under high-pressure, high-temperature conditions. The at least one PDC is attached to a base layer. In one embodiment, forming at least one PDC includes forming a plurality of PDCs and attaching them to the base layer. The method may further include arranging the plurality of PDCs to form a substantially continuous bearing surface. In another embodiment, the method may include spacing the plurality of PDCs from each other such that a gap exists between adjacent PDCs. 
     Attaching the PDC(s) to the base layer may include a brazing process in one embodiment. In another embodiment, attaching the PDC(s) to the base layer may include an e-beam welding process. In yet another embodiment, attaching the PDC(s) to the base layer may include clamping the PDC(s) using one or more clamps or other fastening mechanisms. 
     Other features, aspects and embodiments are set forth herein as will become apparent upon review of the detailed description. It is noted that features of one described embodiment herein may be combined with features of other described embodiments without limitation. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The foregoing and other advantages of embodiments of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1A  shows a perspective view of an embodiment of a bearing assembly according to the present invention; 
         FIG. 1B  shows an exploded view of the assembly shown in  FIG. 1A ; 
         FIG. 1C  shows a partial cross-sectional view of the assembly shown in  FIG. 1A ; 
         FIG. 2A  shows a top view and  FIGS. 2B and 2C  show respective side views of embodiments of bearing elements that may be used in a bearing assembly such as shown in  FIGS. 1A-1C ; 
         FIG. 3A  shows a top view and  FIGS. 3B and 3C  show respective side views of further embodiments of bearing elements that may be used in a bearing assembly such as shown in  FIGS. 1A-1C ; 
         FIG. 4  shows a side view of certain components of the bearing assembly shown in  FIGS. 1A-1C ; 
         FIGS. 5A and 5B  show perspective views of different embodiments of bearing elements that may be used in various bearing assemblies of the present invention; 
         FIGS. 6A and 6B  show perspective views of different embodiments of another bearing component of the bearing assembly shown in  FIGS. 1A-1C ; 
         FIGS. 7A and 7B  show a perspective views of bearing components according to other embodiments; 
         FIGS. 8A and 8B  show respective top and cross-sectional views of a bearing component according to another embodiment; 
         FIG. 8C  is an enlarged, cross-sectional view a PCD component; 
         FIG. 9A  shows a top view and  FIGS. 9B-9D  show respective cross-sectional views of a bearing component according to a further embodiment 
         FIGS. 10A and 10B  show respective top views of various embodiments of bearing elements; 
         FIG. 11  shows a top view of a component of a bearing assembly; 
         FIG. 12  shows a top view of a component of a bearing assembly; 
         FIGS. 13A-13E  show respective side views of various embodiments of bearing elements; 
         FIGS. 14A and 14B  show side views of additional embodiments of bearing elements; 
         FIG. 15A  shows a top view of a bearing element component; 
         FIG. 15B  shows a cross-sectional view of the bearing element component of  FIG. 15A ; 
         FIG. 15C  shows a partial cross-sectional view of the bearing element component of  FIGS. 15A and 15B  assembled with a backing member; 
         FIGS. 16A-16D  show a top and various cross-sectional views, respectively, of bearing components; 
         FIG. 17  shows a perspective view of a bearing assembly; 
         FIG. 18A  shows a perspective view of various components of the bearing assembly shown in  FIG. 10 ; 
         FIG. 18B  shows an exploded view of the components shown in  FIG. 18A ; 
         FIG. 18C  shows a partial side view of the components shown in  FIGS. 18A and 11B ; 
         FIGS. 19A and 19B  show end and perspective views, respectively, of a bearing element; 
         FIG. 20  shows a plan view of a fabrication component used in forming bearing elements that may be used in the bearing assemblies of the present invention; 
         FIGS. 21A and 21B  show perspective and partial cross-sectional views, respectively, of a component of a bearing assembly; 
         FIGS. 22A and 22B  show end and perspective views, respectively, of a bearing element; 
         FIGS. 23A and 23B  show front and cross-sectional views, respectively, of a component of a bearing assembly; 
         FIGS. 24A and 24B  show front and cross-sectional views, respectively, of a component of a bearing assembly; 
         FIGS. 25A and 25B  show front and cross-sectional views, respectively, of a component of a bearing assembly; 
         FIG. 26  is a perspective view of a bearing component for a bearing assembly; 
         FIG. 27  is a perspective view of a bearing component for a bearing assembly; 
         FIG. 28  shows a side view of a component of a bearing assembly; and 
         FIG. 29  is a partial cross-sectional view of a pump incorporating various bearing assemblies. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention relates generally to bearing elements and apparatuses that may include bearing surfaces comprising superhard materials. “Superhard,” as used herein, refers to any material having a hardness that is at least equal to or exceeds a hardness of tungsten carbide (e.g., without limitation, polycrystalline diamond, boron nitride, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, titanium diboride, yttrium oxide, boron carbide and mixtures of the foregoing). For example, in one embodiment, a polycrystalline diamond compact (PDC), or multiple PDCs, may be used to form a bearing surface in the bearing elements and apparatuses of the presently disclosed invention. In another embodiment, polycrystalline diamond may include nanodiamond (i.e., ultra-dispersed diamond), if desired. In yet another example, the bearing surface may include a silicon carbide and diamond composite material such as is disclosed in U.S. Pat. No. 7,060,641, the disclosure of which is incorporated herein, in its entirety, by this reference. A variety of other superhard materials may be utilized in forming a superhard bearing in accordance with the presently disclosed invention as will be appreciated by those of ordinary skill in the art. 
     Considering the example of a PDC, a PDC is conventionally fabricated by placing a cemented carbide substrate into a container or cartridge with a layer of diamond crystals or grains positioned adjacent one surface of a substrate. A number of such cartridges may be typically loaded into an ultra-high pressure press. The substrates and adjacent diamond crystal layers are then sintered under ultra-high temperature and ultra-high pressure (“HPHT”) conditions. The ultra-high pressure and ultra-high temperature conditions cause the diamond crystals or grains to bond to one another to form polycrystalline diamond with diamond-to-diamond bonds. Additionally, as known in the art, a catalyst may be employed for facilitating formation of polycrystalline diamond. In one example, a so-called “solvent catalyst” may be employed for facilitating the formation of polycrystalline diamond. For example, cobalt, nickel, and iron are some non-limiting examples of solvent catalysts that may be used in forming polycrystalline diamond. 
     In one configuration, during sintering, the solvent catalyst may include the substrate body (e.g., cobalt from a cobalt-cemented tungsten carbide substrate). In such a case, the solvent catalyst from the substrate becomes liquid and sweeps from the region adjacent to the diamond powder and into the diamond grains. In another embodiment, a solvent catalyst may be mixed with the diamond powder prior to sintering, either in lieu of, or in addition to, the existence of a solvent catalyst in the substrate. Thus, diamond grains become mutually bonded to form a polycrystalline diamond table upon the substrate. A conventional process for forming polycrystalline diamond structures is disclosed in U.S. Pat. No. 3,745,623 to Wentorf, Jr. et al., the disclosure of which is incorporated, in its entirety, by this reference. 
     The solvent catalyst may remain in the polycrystalline diamond layer within the interstitial pores between the diamond grains or may be at least partially removed to a desired depth, such as by leaching (e.g., exposing at least a portion of the diamond table to an acid) or by any other suitable method. Removal of the catalyst may enhance the thermal stability of the PDC material. Optionally, another material may replace the solvent catalyst that has been at least partially removed from the polycrystalline diamond. 
     In one embodiment, a bearing apparatus may include polycrystalline diamond (or other superhard) inserts or compacts that define a plurality of bearing surfaces that move relative to one another. Such bearing apparatuses may encompass so-called thrust bearings, radial bearings, or other bearing apparatuses having bearing surfaces that move in relation to one another. Bearing apparatuses described herein may include tilting pad bearings. Tilting pad bearings are generally used in high speed machinery operating under medium to high loads (e.g., turbines, pumps, turbocompressors and high speed gearboxes). They offer the optimum solution to any particular requirement because of their utility to automatically adjust to varying conditions. Various bearing element constructions, bearing assemblies and related methods of manufacturing and operating such components are described herein. 
     Various systems and assemblies using the described bearing apparatuses are contemplated, including, for example, various components associated with drilling strings and down hole drilling tools. For example, a radial bearing according to the present invention may be included within a motor or turbine. Generally, such a downhole drilling motor assembly may be located at the end of a series of pipe sections comprising a drill string. The housing of downhole drilling motor assembly may remain stationary as a rotary drill bit coupled thereto rotates. Thus, an output shaft of a downhole drilling motor assembly may be coupled to a rotary drill bit and drilling fluid (i.e., drilling mud) may cause torque to be applied to the output shaft to cause a rotary drill bit to rotate. Thus, such a downhole drilling motor or turbine assembly may include one or more radial bearing apparatuses. Of course, the bearing components and assemblies described herein are not limited to use in subterranean drilling equipment and applications. Rather, the described components and assemblies may be used in various mechanical systems and applications. 
     The use of polycrystalline diamond (PCD) in assemblies that include, for example, tilting pad bearings and shaft rotors have several advantages (as compared to conventional tilting pad bearings using babbit or polymer pad surfaces with steel runners). For example, PCD tilting pads and PCD rotors exhibit less wear due to the inherent wear resistance of PCD. Wear in tilting pad bearings normally occurs during starting and stopping of the machine rotating parts. Additionally, a bearing that places one PCD bearing surface against another bearing PCD surface tends to not gall or wipe as typical metal bearing surfaces. Rather, such surfaces tend to polish with the result of improving the bearing surface characteristics. It is also believed that, with an exceptionally high thermal conductivity, PCD bearing pads should also remove more heat from the bearing surface which may, in turn, increase the viscosity of the fluid and increase the film thickness during hydrodynamic operation—an important parameter in tilting pad bearing performance and design. The high thermal conductivity will also remove heat from the contacting surfaces during starting and stopping, which will help to keep the contacting surfaces from overheating. As noted above, and as will be appreciated by those of ordinary skill in the art, bearing surfaces in a tilting pad design may conventionally be separated by a fluid film during normal operation so that surface wear and frictional forces are substantially reduced. Among other things, the fluid film helps to distribute forces among the pads or shoes of the bearing assembly. Additionally, such a bearing configuration provides superior shock absorbing and damping characteristics. 
     While specific examples of bearing elements, bearing assemblies and manufacturing processes are described herein, a variety of other techniques, features and processes may be utilized in association with the described embodiments. For example, various types of bearing elements are described in U.S. Pat. Nos. 7,635,035, 7,866,418 and 8,146,687, as well as in U.S. patent application Ser. Nos. 11/545,929, 12/495,986, 13/070,636 and 13/087,775, the disclosures of each of which are incorporated by reference herein in their entireties. Additionally, various bearing ring designs and manufacturing processes are described in U.S. Pat. Nos. 7,533,739, 7,901,137 and 7,942,218 as well as in U.S. patent application Ser. Nos. 12/425,304 and 12/761,535, the disclosures of each of which are incorporated by reference herein in their entireties. 
     Referring to  FIGS. 1A-1C , various views are shown of a bearing assembly  100  in accordance with an embodiment of the present invention. In the presently described embodiment, the bearing assembly  100  is configured as a thrust bearing. However, as will become apparent below, various features and aspects of the present invention are applicable to a number of other types of bearings as well. 
     The bearing assembly  100  includes a pair of tilting pad assemblies  102 A and  102 B with a bearing runner  104  disposed therebetween. While the tilting pad assemblies  102 A and  102 B may be configured differently from each other, in the present embodiment they are configured to be substantially identical to one another. As such, similar (although, perhaps not identical) components in the tilting pad assemblies  102 A and  102 B will be identified with common references numerals. 
     The tilting pad assemblies  102 A and  102 B each include a body  106  configured in a generally ring-shaped or toroid-shaped configuration and may define an aperture  108  which may be generally centered about a longitudinal axis  110 . An annulus  112  or an annular channel may be formed in the body  106  to house some of the components of the pad assembly  102 . For example, a plurality of components that form a leveling mechanism  114  as will be described in further detail below. A plurality of individual bearing elements, also referred to as tilting bearing pads  116  (or tilting shoes), are positioned above the leveling mechanism and may be partially disposed in the annulus  112  of the body  106 . 
     Referring to  FIGS. 2A and 2B  in conjunction with  FIGS. 1A-1C , each tilting bearing pad  116  may be formed to include one or more polycrystalline diamond (PCD) layers  118  formed on a base layer  120 . The PCD layer  118  may include a substrate  122  and a diamond table  124  and may be formed, for example, using high-temperature, high-pressure sintering processes such as set forth above. In one particular embodiment, the substrate  122  may comprise tungsten carbide, although other materials may be utilized. In other embodiments, the substrate  122  may be optionally omitted. The base layer  120  of the tilting bearing pad  116  may be formed of a variety of materials including, for example various metals, metal alloys or carbide materials. In one example, the base layer  120  may comprise a steel material. In another example, the base layer  120  may comprise a tungsten carbide material (e.g., a cemented tungsten carbide material, such as, for example, cobalt-cements tungsten carbide). The use of a tungsten carbide material to form both the base layer  120  and the substrate of the PCD layer  118  may help to reduce or eliminate residual stresses in the tilting pad bearing pad  116  after fabrication due to fact that such components would exhibit suitably similar rates of thermal expansion. In other embodiments, as will be described below, a material with a relatively higher rate of thermal expansion may be used for the base layer  120  in order to correct or take advantage of any warping tin the PCD layer  118  during brazing. 
     In one embodiment, the PCD layer  118  may be formed as a PCD compact (e.g., a 19 millimeter or a 13 millimeter diameter PCD compact) that is shaped, such as by machining or otherwise shaping the sides (e.g., grinding or wire electro discharge machining), to a desired geometry. For example, a conventional round-shaped PCD compact (represented by dashed lines in  FIG. 2A ) may cut or machined to exhibit a substantially wedge- or annular sector-shaped geometry as shown in  FIG. 2A ). 
     The tilting pad bearings  116  also include a protrusion or button  126  along a portion of the base layer  120 . The button  126  engages a portion of the leveling mechanism  114  and enables the tilting pad bearing  116  to tilt, pivot or rock relative to the leveling mechanism  114  as well as the body  106  within a defined range of motion. For example, as seen in  FIG. 1C , the button  126  may be configured to abut a portion of the leveling mechanism  114  such that there is a gap or a space between the base layer  120  of the tilting pad bearing  116  and the adjacent components of the leveling mechanism  114  (as well as between the base layer  120  of the tilting pad bearing  116  and adjacent portions of the body  106 ) so that the tilting pad bearing  116  can rock relative to such components. In one example, such as illustrated by  FIG. 2B , the button  126  is substantially centered relative to the radial edges of the tilting pad bearing  116 . However, in other embodiments, such as shown in  FIG. 2C , the button  126  may be slightly off center relative to the radial edges of the tilting pad bearing  116 . In one particular embodiment, the center of the button  126  may be placed at a location that is approximately 60% of circumferential distance away from the leading edge of the tilting pad bearing  116  (the circumferential distance being shown as length L extending from one radial edge to the other radial edge). The button  126  may also be centered between inner and outer circumferential edges, or it may be displaced toward one of the circumferential edges if desired. 
     Referring to  FIGS. 3A and 3B , another embodiment of a tilting pad bearing  116  is illustrated. As with the embodiments described with respect to  FIGS. 2A-2C , each tilting bearing pad  116  may be formed to include one or more polycrystalline diamond (PCD) layers  118  formed on a base layer  120 . The PCD layer  118  may include a substrate  122  and a diamond table  124  and may be formed, for example, using high-temperature, high-pressure sintering processes such as set forth above. In one particular embodiment, the substrate  122  may comprise tungsten carbide, although other materials may be utilized. In other embodiments, the substrate  122  may be optionally omitted or the substrate  122  may form the portion shown as base layer  120  (i.e., base layer  120  may be optionally omitted). The base layer  120  of the tilting bearing pad  116  may be formed of a variety of materials including, for example various metals, metal alloys or carbide materials. In one example, the base layer  120  may comprise a steel material. In another example, the base layer  120  may comprise a tungsten carbide material (e.g., a cemented tungsten carbide material, such as, for example, cobalt-cemented tungsten carbide). The tilting pad  116  bearing may be formed from substantially similar materials, and using substantially similar processes, as those described with respect to other embodiments described above. However, it is noted that the tilting pad  116  exhibits a substantially cylindrical geometry rather than being shaped like some other embodiments described herein. Thus, the tilting pad  116  may be formed from, for example, a conventional PCD compact, such as a 13 mm or a 19 mm diameter compact. Of course, the tilting pad  116  may exhibit other sizes, or may be cut from a tool blank or otherwise formed if desired. 
     The tilting pad bearings  116  may also include a protrusion or button  126  along a portion of the base layer  120 . As shown in  FIG. 3B , the button  126  may be integrally formed with, for example, the base layer  120 . In other embodiments, the button  126  may be a separate component adhered, coupled or affixed to, for example, the base layer  120 . As seen in  FIG. 3C , in another embodiment, a lower surface of the base layer  120  may be rounded to exhibit a substantially spherical (or a portion of a sphere) to act as the button  126 . 
     Referring briefly to  FIG. 4 , an example is shown of the tilting pad bearings  116  disposed on components of the leveling mechanism  114  with the body  106  and other components of the tilting pad bearing assembly  102 A (or  102 B) being absent in order to provide a better view of the leveling mechanism  114 . The leveling mechanism  114  includes a plurality of lower components  127 A and a plurality of upper components  127 B that engage one another in a generally conformal or mating relationship, with upper and lower components alternating as they circumferentially extend about the annulus  112  in which they are disposed (see e.g.,  FIG. 1C ). It is noted that the terms “upper” and “lower” are used for convenience and are used as relative terms with respect to the view shown in  FIG. 4 . The buttons  126  of the tilting pad bearings  116  each rest on a corresponding upper component  127 B and may tilt or rock relative thereto. In some embodiments, the leveling mechanism  114  may be omitted. 
     Referring back to  FIGS. 1A-1C , the body  106  may be configured to limit the movement of the tilting pad bearings  116  in various directions (within defined limits or tolerances) relative to the body  106 . For example, notches or recesses  128  may be formed in the body  106  to engage shoulder portions or other surfaces of the tilting pad bearings  116 . The recesses  128  help to maintain the tilting bearing pads  116  at a desired position relative to the body  106  and limit the tilting pad bearings  116  from moving in a circumferential direction relative to the body  106  during operation of the assembly  100 . 
     When assembled, retaining devices  130  such as fasteners (or other structures or mechanisms) may be associated with the body  106  to engage a portion of the leveling mechanism  114  (e.g., a slot  131  or other feature in, for example, the upper components  127 B) to retain the leveling mechanism in a desired position (within desired tolerances or specifications) within the annulus  112  (e.g., see  FIG. 1C ). Another plurality of retaining devices  132  such as fasteners (or other structures or mechanisms) may also be associated with the body  106 . In one embodiment, the retaining devices  132  include fasteners located along a face that is generally opposite the face where the tilting pad bearings  116  are located. Each retaining device  132  may engage a portion of the leveling mechanism  114  (e.g., a lower component  127 A) to prevent the leveling mechanism  114  from moving in the circumferential direction, or at least limit its circumferential movement within desired tolerances or specifications. The use of a leveling mechanism  114  may help compensate for differences in manufacturing tolerances of the numerous components that make up the bearing assembly  100 . 
     Still referring to  FIGS. 1A-1C , the runner  104  of the bearing assembly includes a base layer  140 , a first PCD layer  142 A on the base layer forming a first bearing face  144 A, and a second PCD layer  142 B on the base layer  140  forming a second bearing face  144 B or surface, the two bearing faces being on opposite sides of the base layer  140 . Each of the PCD layers  142 A and  142 B may include a substrate  146  and a diamond table  148  and may be formed, for example, using high-temperature, high-pressure sintering processes. In one particular embodiment, the substrate  146  may comprise tungsten carbide, although other materials may be utilized. The base layer  140  of the runner  104  may be formed of a variety of materials including, for example various metals, metal alloys or carbide materials. In one example, the base layer  140  may comprise a steel material. In another example, the base layer  140  may comprise a tungsten carbide material. 
     As perhaps best seen in  FIG. 1B , the runner  104  may be configured as a substantially annular or ring shaped body defining an opening  150  which may be generally centered about a longitudinal axis  110 . A recess  152  may be formed, for example, in an inner surface of the runner that defines the opening  150 . The recess  152  may be configured as a keyway to enable coupling of the runner  104  to a shaft (not shown) or other structure extending through the various openings  108  and  150 . The coupling of the runner  104  with a shaft or other structure will help enable relative rotation of the runner  104  and the tilting bearing pad assemblies  102 A and  102 B. 
     The runner  104  is disposed between the tilting pad assemblies  102 A and  102 B such that the first bearing face  144 A engages the collective bearing surface  134 A of one tilting pad bearing assembly  102 A and the second bearing face  144 B engages the collective bearing surface  134 B of the other tilting pad bearing assembly  102 B. As noted above, the bearing assembly  100  is configured so that a shaft may pass through the openings and, for example, be coupled with the runner  104  and be rotated about the longitudinal axis relative to the tilting pad bearing assemblies  102 A and  102 B. In this configuration, the runner  104  may be considered a rotor while the tilting pad assemblies  102 A and  102 B may remain in a substantially fixed position relative to the runner  104  and be considered to be stators. In other embodiments, the runner  104  may be configured as a stator while the tilting bearing pad assemblies  102 A and  102 B may be configured as rotors. Other potential embodiments are also considered, including any or all of tilting bearing pad assemblies  102 A and  102 B and the runner  104  being configured to rotate, but at different rotational rates, or in different directions, relative to adjacent components or assemblies. 
     It is noted that implementing PCD materials into tilting pad geometries pose various challenges. For example, forming relatively large bearing surfaces (e.g., the bearing surface of a tilting pad bearing  116  or the bearing face  144 A of a runner  104 ) can be challenging due to conventional PCD manufacturing processes. For example, a tilting pad bearing  116  may be sized to be less than an inch in length and/or width in one embodiment and may be as large as a few feet in length and/or width in another embodiment. If the tilting pad bearing  116  is to exhibit a bearing surface that is substantially similar to the size of a conventional PCD compact, then a single PCD compact may be used to form the bearing pad  116 . However, when the tilting pad bearing  116 , or the bearing face of the runner  104 , is larger than a conventional PCD compact, then other approaches need to be utilized. 
     Referring briefly to  FIG. 5A , a tilting pad bearing  116  is shown in accordance with one embodiment of the present invention. The tilting pad bearing  116  includes a PCD material layer  118  and a base layer  120 . The PCD layer  118  includes a PCD table  124  formed on a substrate  122  such as described above. The PCD layer  118  is formed from a plurality of individual PCD compacts that have been cut or formed into a desired shaped segments (e.g., square or rectangular) and placed together to form the PCD layer  118 . For example, in an assembly  100  that exhibits an outer diameter of roughly 11 inches, the surface of the tilting bearing pad  116  may be 2 inches in length and in width or greater. Thus, several PCD compacts (PDCs) exhibiting, for example, a ¾ inch diameter may be cut (e.g., using a laser or an electro discharge machine (EDM) process) into individual squares, rectangles or other desired shapes  160 . The cut shapes  160  may then be fitted together on the base layer  120  and bonded therewith. 
     In another embodiment, referring to  FIG. 5B , the PCD layer  118  may be formed as a single, integral component. For example, the PCD layer  118  may be cut from a PCD cutting-tool blank that exhibits a sufficiently large size. In one example, a PCD cutting-tool blank having a diameter of approximately 2 to 3 inches may be cut (e.g., using laser, grinding, and/or EDM processes) to the desired shape of the tilting pad bearing  116 . 
     It is noted that the tilting pad bearings  116  shown in  FIGS. 5A and 5B  (as well as in  FIGS. 1A-1C ) are shown to include a bearing surface that may be generally described as being an annular sector (i.e., a circumferential portion of a ring), having an inner radius and an outer radius that are connected by two spaced-apart, radially extending edges. As seen in  FIG. 5B , the corners joining the various sides may be rounded or clipped. Additionally, as seen in  FIGS. 5A and 5B , the peripheral edge of the upper surface may exhibit a chamfer or a radius if desired to prevent a sharp edge from potentially chipping or breaking as it engages other surfaces during operation of the bearing assembly  100 . However, such a configuration for the tilting pad bearings  116  is merely an example and should not be considered limiting. Other shapes and configurations are also contemplated. For example, in another embodiment, the bearing surface presented by the tilting pad bearing  116  may be substantially circular rather than an annular sector. Such a configuration, depending on the size of the tilting pad bearing  116 , may be more amenable to using PCD compacts (or PCD cutting-tool blanks) and may result in less waste since less (or perhaps none) of the PCD compact will have to be trimmed before or after attaching it to the base layer  120  of the tilting pad bearing  116 . 
     Referring to  FIG. 6A , a runner  104  is shown in accordance with an embodiment of the present invention. The PCD layers  142 A and  142 B of the runner  104  may be configured of a plurality of cut shapes  162 , such as squares, rectangles or other shapes (or combinations thereof) formed from individual PCD compacts, similar to the PCD layer  118  of the tilting pad bearing  116  described with respect to  FIG. 5A  above. In another embodiment, as seen in  FIG. 6B , PCD layers  142 A and  142 B of the runner  104  may be configured of a plurality of annular sector shapes  164 , similar to the PCD layers  118  of the tilting pad bearing  116  described with respect to  FIG. 5B  above. Indeed, in one embodiment, the annular sector shapes  164  may be manufactured to be substantially identical to the PCD layers  118  of the tilting pad bearings  116 , which may reduce manufacturing costs and complexities. 
     Referring to  FIGS. 7A and 7B , a runner  104  and a base layer for the runner  104  are shown, respectively, in accordance with another embodiment of the present invention. The PCD layers  142 A and  142 B of the runner  104  may be configured of a plurality of annular sector shapes  164 , as with the embodiment illustrated in  FIG. 6B . The base layer  140  may include a plurality of alignment features  168  circumferentially spaced along each axial face of the runner so as to sit between and circumferentially align adjacent annular sector shapes  164  of the PCD layers  142 A and  142 B. Additionally, the base layer may include shouldered portion  168  on each face (only one shown in  FIGS. 7A and 7B ) about the radially inner periphery to abut and radially align the annular sector shapes  164  of the PCD layers  142 A and  142 B. Of course other features and techniques may be used to align the various components and such alignment features  166  and  168  are merely examples that may be used in various embodiments. In the embodiments described with respect to  FIGS. 6A, 6B, 7A and 7B , the PCD layers  142 A and  142 B may be attached to the base layer  140  substantially simultaneously using, for example, a brazing process. In other embodiments, each layer may be attached to the base layer in an independent process. 
     Referring to  FIGS. 8A and 8B , another embodiment of a runner  104  is illustrated. As with previously described embodiments, the PCD layers  142 A and  142 B of the runner  104  may be configured of a plurality of individual PCD components (showing, again, an annular sector  164  that may be formed from a conventional PCD compact or from a tooling blank—represented in dashed lines). While  FIGS. 8A and 8B  depict the PCD layers  142 A and  142 B as being formed using annular sectors  164 , other shapes may also be utilized such as described above. The base layer of the runner  104  may be formed from multiple components including, for example, a first base component  140 A associated with the first PCD layer  142 A and a second base component  140 B associated with the second PCD layer  142 B. The base components  140 A and  140 B may be coupled to one another, for example, by way of a plurality of fasteners  170 . The base components may be keyed or otherwise cooperatively shaped to ensure alignment with one another upon assembly. In another embodiment, the final shaping and finishing of the runner  104  may be accomplished after the assembly of the various components. 
     Referring to  FIG. 8C , an enlarged, cross-sectional view a PCD component (e.g., a PCD compact shaped for use as an annular sector  164  of a PCD layer  142 A or  142 B) is shown. Base members  172  may be brazed or otherwise attached to the PCD compact and configured for coupling with a fastener  174  (see  FIG. 8B ) to fasten the annular sector  164  (or other-shaped PCD component) to a base component  140 A or  140 B of the runner  104 . While only one base member is shown as being brazed to the annular sector  164  in  FIGS. 8B and 8C , multiple of such members may be brazed to each annular sector  164 . For example, in one particular embodiment, three distinct base members  172  may be brazed on to the annular sector  164 . In other embodiments, a single, larger base member that is substantially similar in geometry to the annular sector (e.g., also exhibiting an annular sector geometry) may be brazed to the annular sector and have threaded holes tapped in for subsequent coupling with an associated base component  140 A or  140 B. Thus, assembly of the runner  104  may be accomplished with minimal brazing (e.g., the base members  172 ) while other components may be assembled using other coupling or attaching techniques. In other embodiments, the PCD components of the PCD layers  142 A and  142 B (e.g., the annular sectors) may be brazed to their associated base components  140 A and  140 B with the base components being subsequently assembled using, for example, fasteners or other mechanical components. 
     Referring now to  FIGS. 9A-9D  another embodiment of a runner  104  is illustrated. As with previously described embodiments, the PCD layers  142 A and  142 B of the runner  104  may be configured of a plurality of individual PCD components. While the embodiment illustrated by  FIGS. 9A-9D  depict the PCD layers  142 A and  142 B as being formed using annular sectors  164 , other shapes may also be utilized such as has been described above. Each PCD layer  142 A and  142 B is associated with a base ring member  140 A and  140 B. The base ring members  140 A and  140 B may be formed, for example, of steel or of any other material suitable for attaching the annular sectors  164  of the PCD layers  142 A and  142 B. In one embodiment, the annular sectors  164  may be brazed to the base ring members  140 A and  140 B. 
     A central base component  140 C may be formed, for example, of steel or another appropriate material. Annular grooves  175 A and  175 B are formed on each axial face of the central base component  140 C. As seen best in  FIG. 9B , the base ring members  140 A and  140 B are each positioned within an associated annular groove  175 A and  175 B of the central base component  140 C. In one embodiment, the base ring members  140 A and  140 B may be secured to the central base component  140 C by way of an interference fit (such as a press fit) with their associated annular grooves  175 A and  175 B. 
     Referring briefly to  FIG. 10A , a top view of another embodiment of a tilting pad bearing  116  is shown. The tilting pad bearing  116  exhibits a substantially annular sector shape, such as has been described above, and includes a base layer  120  with a plurality of PCD elements  176  (e.g., polycrystalline diamond compacts) coupled with the base layer to form a PCD layer  118  as a bearing surface. It is noted that the plurality of PCD elements  176  are not cut, formed or otherwise shaped so that they fit tightly next to each to form a substantially continuous bearing surface (such as with the embodiment shown in  FIG. 5A ). Rather, the PCD elements  176  are generally circular in shape and there are gaps between adjacent PCD elements  176  on a given tilting pad bearing  116 . It is noted that, while such a configuration may not perform as an idealized hydrodynamic bearing, such may provide a lower cost alternative to other embodiments by enabling the use of conventional, prefabricated PCD compacts without substantial modification (e.g., through subsequent cutting or forming operations using laser or EDM processes) and by using fewer compacts to form the bearing surface. Additionally, such a configuration should provide increased cooling by virtue of the spaces between the individual PCD elements  176 . The individual PCD elements  176  may be arranged according to a particular design or geometry or may be spaced so that they exhibit a specific distances with adjacent PCD elements  176 . As shown in  FIG. 10B , another embodiment may include a tilting pad bearing  116  that exhibits a substantially round geometry (viewed from above as with  FIG. 10A ) or some other geometry instead of an annular sector. The tilting pad bearing  116  shown in  FIG. 10B  includes a base layer  120  with a plurality of PCD elements  176  coupled with the base layer to form a PCD layer  118  as a bearing surface similar to that which is described with respect to the embodiment shown in  FIG. 10A . 
     Referring briefly to  FIG. 11 , a runner  104  is shown that includes a base layer  140  and a plurality of PCD elements  178  (such as polycrystalline diamond compacts) coupled with the base layer  140  to form a PCD layer (e.g.,  142 A or  142 B). The PCD elements  178  are arranged in a similar manner as discussed with respect to the tilting pad bearings  116  shown in  FIGS. 10A and 10B , being generally circular in cross-sectional geometry and being spaced apart from one another such that there are gaps or spaces between adjacent PCD elements  178 . The individual PCD elements  178  may be arranged according to a particular design or geometry or may be spaced so that they exhibit a specific distances from adjacent PCD elements  178 . It is noted that different embodiments of the runner  104  may be combined with different embodiments of the tilting pad bearings  116 . For example, the runner  104  shown and described with respect to  FIG. 11  may be combined in an assembly that includes tilting pad bearings shown and described with respect to  FIG. 5A or 5B . Of course other combinations of embodiments are also contemplated, without limitation. 
     Referring briefly to  FIG. 12 , another embodiment of a runner  104  is shown. The runner  104  includes a base layer  140  and a plurality of PCD elements  179  (such as polycrystalline diamond compacts) coupled with the base layer  140  to form a PCD layer (e.g.,  142 A or  142 B). The PCD elements  179  shown in  FIG. 12  are arranged in two circular rows, although a single row may be used or more rows than two may be employed. The PCD elements  179  may be formed from a cylindrical PCD compact, such as described above and as indicated again by dashed lines about one of the PCD elements  179 . Such PCD compacts may be trimmed to exhibit a substantially wedge-shaped or annular sector-shaped geometry so as to fit the various PCD elements  179  into a circular pattern with relatively small gaps, or even substantially no gaps, being present between adjacent PCD elements  179 . 
     Attaching the PCD layer to the base material (for either the tilting pad bearings  116  or the runner in  104  any of the various embodiments contemplated herein) may be accomplished a variety of processes such as, for example, by brazing, by e-beam welding, mechanical attachment or any other suitable configuration. In any case, attaching the PCD layer to the base material can provide certain challenges. 
     Referring to  FIGS. 13A-13E , some examples of techniques for attaching the PCD layer to a base material are illustrated. 
     With initial reference to  FIG. 13A , a bearing element  180  (which may be used as a tilting pad bearing or as a runner) may be formed by providing a base layer  182  and forming a pocket  184  in the base layer  182 . A PCD element  186  (e.g., a polycrystalline diamond compact that includes a diamond table  188  formed on a substrate  190 ) may be disposed in the pocket  184 . The PCD element  186  may then be joined (e.g., brazed) to the base layer  182  to fix it relative to the base layer  182 . The base layer  182  and the PCD element  186  may be held in place during joining by use of proper fixtures and/or by appropriate application of force to the components of the bearing element  180 . As previously mentioned, the base layer  182  and the substrate may be formed of substantially similar or suitable materials or of materials that exhibit suitable coefficients of thermal expansion to help reduce or prevent cracking or the induction of thermal stresses into the resulting bearing element  180 . While a single pocket  184  is shown in the base layer  182 , multiple pockets may be formed with a PCD element  186  being disposed in each pocket if desired. The pocket  184  may be shaped to correspond with the cross-sectional geometry of the compact  186 . Thus, for example, if the PCD element  186  is substantially cylindrical in shape, the pocket  184  may be substantially cylindrically shaped to receive the compact therein in a substantially mating relationship. 
     Referring to  FIG. 13B , a bearing element  180  may be formed in accordance with another embodiment by providing a pocket  184  in a base layer  182  and disposing a plurality of PCD elements  186  within the pocket  182 . In one embodiment, the PCD elements  186  may be abutted against each other so that they are in contact with each other and exhibit little or no space therebetween. The PCD elements  186  may exhibit a variety of shapes and, in one embodiment, may be configured as squares or rectangles that are combined together to provide, for example, a bearing surface similar to that described with respect to the tilting pad bearing shown in  FIG. 5A . 
     The use of a pocket to effect the joining of the base layer  182  and the PCD element  186  will help to maintain alignment of the components during any heating that may take place in the joining process. The PCD elements  186  may be joined with the base layer  182 , such as by brazing, while they are held in position within the pocket  184  by an applied force or by appropriate fixtures. The pocket  184  may be shaped to correspond with the combined cross-sectional geometry of the plurality of PCD elements  186 . Thus, for example, the plurality of compacts  186  may be shaped and combined to define a substantially annular sector shape, with the pocket being similarly shaped to receive such a combination of PCD elements  186 . Of course, other geometries and configurations are also contemplated. Once secured to the base layer  182 , the PCD elements  186  may be machined, ground or lapped to provide a substantially coplanar surface (i.e., within defined tolerances) for the resulting bearing element  118 . 
     It is noted that, while the embodiments shown and described with respect to  FIGS. 13A and 13B  are described in terms of joining the PCD elements  186  with the base material  182  through processes such as brazing, other means of attaching or coupling may also be used. In one example, the pockets  184  and the compacts  186  may be configured to effect an interference fit (i.e., a press fit or a shrink fit). For example, the pocket  184  may be configured to be slightly smaller than the PCD compact  186  that is to be disposed therein. The base layer  182  may then be heated to make it expand and/or the PCD element(s)  186  may be cooled to make it (them) contract prior to disposing the PCD element(s)  186  in the pocket  184 . After placing the PCD elements(s)  186  in the pocket  184 , which may require application of force, the two components may be brought to a common temperature causing the pocket  184  to “shrink” and/or the PCD element  186  to expand resulting in the PCD element  186  being tightly grasped by the pocket  184  of the base layer  182 . 
     Referring briefly to  FIG. 13C , in another embodiment, a bearing element  180  may be formed by placing a base layer  182  and the PCD element  186  in a fixture  192  and holding the components in alignment during brazing. In such a configuration, it is not necessarily required to have a pocket formed in the base layer  182 . Rather, the PCD element  186  may be simply abutted against a surface of the base layer  182  and maintained in that position by the fixture  192 . For example, the fixture  192  may be configured to hold the sidewalls of the compact  186  in alignment with the side walls of the base layer  182  while a brazing, bonding or some other joining process takes place. 
     Referring to  FIG. 13D , in accordance with another embodiment, a bearing element  180  may be formed by placing a PCD elements  186  on a base layer  182  and joining them together, such as by brazing. The PCD element  186  and/or the base layer  182  may be originally formed as an “oversized” component, meaning that it is larger than its final design dimensions. The excess of the base layer  182  and/or the PCD element  186  may be cut or machined to final dimensions as indicated by dotted lines  194  such that it looks as shown in  FIG. 13E . Such a process should eliminate some concerns of alignment between the PCD element  186  and the base layer  182  during the joining process. Referring specifically to  FIG. 13E , such a bearing element may also be formed by aligning the compact  186  with a similarly sized base layer  182  and E-beam welding the two components together. E-beam welding may involve less heating of the base material  182  and compact  186  and may result in less residual stress and warping of such components. 
     Referring to  FIGS. 14A and 14B , another embodiment of a bearing element  200  is shown. The bearing element  200  includes a first base layer  202  which is pre-brazed to a PCD element  204 . The PCD element  204  may include a diamond table  206  bonded to a substrate  208  such as has been described hereinabove. The first base layer  202  may be formed, for example, of steel, another metal, or a metal alloy. A threaded hole  210  may be formed in the first base layer. As seen in  FIG. 14B , a plurality of bearing elements  200  may be positioned adjacent each other and coupled with a second base layer  212 . The second base layer  212  may include a plurality of through holes  214  that align with the holes  210  of individual bearing elements  200  and threaded fasteners  216  may be used to couple the second base layer  212  with the individual bearing elements  200 . As with previously described embodiments, the bearing elements  200  may be formed to exhibit various shapes and sizes. For example, in one embodiment, the bearing elements  200  may be substantially cylindrical. In another embodiment, they may be configured to exhibit a square, rectangular or other polygonal shape. They may be spaced apart (e.g., such as shown with respect to  FIG. 10A, 10B or 11 ) or they may be placed adjacent to each other and fit together to form a substantially continuous surface (e.g., such as shown in  FIG. 5A, 6A or 6B ). Also, as with other embodiments, after assembly of the bearing elements  200  with the second base layer  212 , the bearing elements may be machined, ground, lapped or otherwise processed to obtain substantially coplanar bearing surfaces. 
     Referring to  FIGS. 15A-15C , another embodiment of a bearing element  230  is shown.  FIGS. 15A and 15B  depict a PCD element  232  having a diamond layer  234  bonded with a substrate  236 . A pair of shoulders  238  are formed in the PCD element  232  at diametrically opposing sides. As shown in  FIG. 15C , the PCD element  232  is placed on a base layer  240  which has a plurality of threaded blind holes  242  formed therein. Clamps  244  may be coupled to the base layer  240  by way of threaded fasteners  246 . The clamps  244  include an extension or projection  246  that engages a shoulder  238  of the PCD element  230  to hold the element  230  securely against the base layer  240 . It is noted that the shoulders formed in the PCD element  232  need not be two in number, or necessarily diametrically opposed in location. Rather, other quantities and arrangements of shoulders, tapered geometries, or other suitable engagement features are contemplated. In one embodiment, a shoulder may be formed about the entire periphery of the compact  232  so that alignment issues with respect to the clamp locations are negated. Also, any number of clamps  246  may be utilized, including a single ring clamp that extends about at least a portion of the periphery of the compact  232 . 
     Referring to  FIGS. 16A-16D , another embodiment is shown for attaching a PCD element  260  to a base member  262 .  FIGS. 16A and 16B  show a base member  262  that includes a recessed surface  264  exhibiting an arcuate surface. For example, the recessed surface  264  may exhibit a substantially spherical geometry (such as a portion of a sphere).  FIG. 16C  shows a PCD element  260  being attached to the base member  262  by way of a layer of brazing material  266 . The PCD element  262  and brazing material  266  may substantially conform to the recessed surface  264  of the base member  262  while such materials are at elevated temperatures during the brazing process. However, due to the pairing of materials based on coefficients of thermal expansion (e.g., selecting materials with a desired differential in their respective coefficients of thermal expansion), the base member  262  may warp or deform upon cooling to atmospheric temperatures from the elevated brazing process temperatures. The PCD element  260  now exhibits a substantially flat or planar surface while the bottom or lower surface of base member  262  may be arcuate or non-planar. 
     Following the manufacture of the bearing elements, regardless of the manufacturing process used, the bearing elements may be incorporated into an assembly to form, for example, a bearing surface on a runner or a collective bearing surface in a tilting pad bearing assembly. Again, the bearing surfaces of such assemblies may be lapped, machined or ground to defined a substantially coplanar bearing surface. 
     Referring now to  FIG. 17  a radial bearing assembly  300  is shown. In one embodiment, the bearing assembly  300  includes a first bearing  302  configured as a rotor and a second bearing ring  304  configured as a stator. In other embodiments, the first bearing ring  302  may be configured as a stator and the second bearing ring  304  may be configured as a rotor. The second bearing ring  304  defines an opening  306  that is substantially centered about an axis  308  and the first bearing ring  304  extends through the opening  306 . Whichever bearing ring is configured as a rotor is configured to rotate generally about the axis  308 . 
     Referring to  FIGS. 18A-18C , the second bearing ring  304  includes a body  310  having an outer radial surface  312  and an inner radial surface  314  that defines, in large part, the opening  306 . A plurality of tilting pad bearings  316  are positioned against the inner radial surface  314  at circumferentially spaced locations. The tilting pad bearings  316  may be held in place within the body  310  by a pair of plates  318  coupled with opposing axial sides of the body  310 . As best seen in  FIG. 18C , each tilting pad bearing  316  includes a diamond layer  320  (or other superabrasive layer) attached to a base layer  322 . The diamond layer may include a plurality of PCD elements  326  disposed next to each other and collectively defining a substantially arcuate surface  328 . The PCD elements  326  may each be configured to include a diamond table and a substrate such as has been described hereinabove. The plurality of tilting pad bearings  316  collectively define a bearing surface which engages a bearing surface  330  of the first bearing ring  302 , separated by a fluid film which may develop into a fluid film wedge  331  during relative rotation of the first bearing ring  302  and the second bearing ring  304  as will be appreciated as will be appreciated by those of ordinary skill in the art. In one embodiment, it is noted that the base layer  322  of the tilting pad bearings  316  exhibits a radius that is smaller than the radius of the inner radial surface  314  of the body such that the tilting pad bearings  316  may rock relative to the body  310 . 
     As seen in  FIGS. 19A and 19B , in one embodiment the bearing elements  326  may be configured to exhibit a substantially trapezoidal cross-sectional geometry with a narrower upper portion (i.e., across the upper surface of the diamond layer  356 ) and a wider lower portion (i.e., across the lower surface of the substrate  354 ). Such a configuration enables a plurality of bearing elements  326  to be arranged with sidewalls  358  of one bearing element  326  being positionable adjacent the sidewalls  358  of other bearing elements  326  such that the diamond layers of the plurality of bearing elements  326  collectively define a portion of a substantially cylindrical bearing surface. In one embodiment, the upper surface of the individual bearing elements  326  may be arcuate (i.e., concave, as shown) to define a portion of a cylindrical bearing surface. The arcuate profile may be machined on each PCD compact individually prior to assembly or the entire assembly may be machined to define the arcuate bearing surface after the bearing elements  326  are otherwise assembled. In another embodiment, the upper surface of each bearing element  326  may be substantially planar such that the resulting bearing surface is (at least initially, prior to wear) approximated as a portion of a cylindrical surface. In one embodiment, one or more chamfers  360  may be formed between the upper surface of the diamond layer  356  and a side wall  358  of the bearing element  326 , as indicated in  FIG. 19A  by dashed lines. In other embodiments, other edge treatments may be used, such as the forming of a radius between the upper surface of the diamond layer  356  and a side wall  358  of the bearing element. In other embodiments, one or more chamfers may be combined with one or more radii along the transition edge of two such surfaces. 
     Referring briefly to  FIG. 20 , in one embodiment, PCD elements  326  (or other PCD elements such as PCD elements  352  described with respect to  FIGS. 22A and 22B  below) may be formed from a PCD cutting tool blank  340 . In one particular example, a cutting tool blank  340  having a diameter of approximately 2.36 inches may be cut into six individual PCD elements  326  and  352  each having a length of approximately 1.6 inches and a width of approximately 0.3 inch. Of course other sizes and geometries are contemplated and such an example should not be considered limiting. 
     Referring to  FIGS. 21A and 21B , the first bearing ring  302  includes a body portion  350  that serves as a base layer and a plurality of bearing elements  352  coupled with the body portion  350  to define the bearing surface  330  of the first bearing ring  302 . Each of the bearing elements  352  may be configured as PCD elements including a substrate  354  and a diamond layer  356  such as has been previously described. As seen in  FIGS. 22A and 22B , in one embodiment the bearing elements  352  may be configured to exhibit a substantially trapezoidal cross-sectional geometry with a wider upper portion (i.e., across the upper surface of the diamond layer  356 ) and a narrower lower portion (i.e., across the lower surface of the substrate  352 ). Such a configuration enables a plurality of bearing elements  352  to be arranged with the sidewalls  358  of one bearing element  352  being positioned adjacent the sidewalls  358  of other bearing elements  352  such that the diamond layers of the plurality of bearing elements  352  collectively define a substantially cylindrical bearing surface  330  ( FIG. 21A ). 
     In one embodiment, the upper surface of the individual bearing elements  352  may be arcuate (i.e., convex, as shown) to define the cylindrical bearing surface  330 . The arcuate profile may be machined on each PCD compact individually prior to assembly or the entire assembly may be machined to define the arcuate bearing surface  330  after the bearing elements  352  otherwise assembled. In another embodiment, the upper surface of each bearing element  352  may be substantially planar such that the resulting bearing surface  330  is (at least initially, prior to wear) approximated as a cylindrical surface. In one embodiment, one or more chamfers  360  may be formed between the upper surface of the diamond layer  356  and a side wall  358  of the bearing element  352 , as indicated in  FIG. 22A  by dashed lines. In other embodiments, other edge treatments may be used, such as the forming of a radius between the upper surface of the diamond layer  356  and a side wall  358  of the bearing element. In other embodiments, one or more chamfers may be combined with one or more radii along the transition edge of two such surfaces. 
     Referring now to  FIGS. 23A and 23B , a tilting pad bearing  316  for use in the second bearing ring  304  is shown in accordance with another embodiment. The tilting pad bearing  316  includes a base layer  322  and a plurality of PCD elements  326 . The PCD elements  326  may each be configured to include a diamond table and a substrate such as has been described hereinabove. However, rather than exhibiting a geometry that is elongated with a substantially square or rectangular cross-section (with an optional arcuate bearing) such as described with respect to the embodiment shown in  FIGS. 18A-18C , the PCD elements  326  are substantially cylindrical and arranged in an array of rows and columns to define a collective bearing surface. In one embodiment, such PCD elements  326  may comprise conventional PCD compacts which are subsequently attached to the base layer  322  (e.g., by brazing or other appropriate processes). 
     Referring to  FIGS. 24A and 24B , a tilting pad bearing  316  for use in the second bearing ring  304  is shown in accordance with yet another embodiment. The tilting pad bearing  316  includes a base layer  322  and a single PCD element  326 . The PCD element  326  may be configured to include a diamond table and a substrate such as has been described hereinabove. In one embodiment, the PCD element  326  may be formed of a single cutting tool blank which is subsequently bonded to the base layer  322 . It is noted that in such an embodiment, the thickness of the diamond layer in the PCD element  326  will need to be of sufficient thickness to account for the concave bearing surface that will be formed (either through various fabrication processes prior to assembly, or to account for the formation of such a surface due to wear). 
     Referring to  FIGS. 25A and 25B , a bearing ring  302  is shown in accordance with another embodiment. The bearing ring  302  includes a body  350  forming a base layer and a plurality of bearing elements  352  that are formed as individual PCD elements. The PCD elements may each be configured to include a diamond table and a substrate such as has been described hereinabove. However, rather than exhibiting a geometry that is elongated with a substantially trapezoidal cross-section (with an optional arcuate bearing) such as described with respect to the embodiment shown in  FIGS. 21A and 21B , the PCD elements are substantially cylindrical and arranged in a plurality of rows extending axially along the body  350  to define a collective bearing surface. In one embodiment, such bearing elements  352  may comprise conventional PCD compacts which are subsequently bonded with the body  350 . 
     Referring to  FIG. 26  a bearing ring  302  is shown in accordance with another embodiment. The bearing ring  302  includes a body  350  forming a base layer and a plurality of bearing elements  352  that are formed as individual PCD elements. The PCD elements may each be configured to include a diamond table and a substrate such as has been described hereinabove. However, rather than exhibiting a geometry that is elongated with a substantially trapezoidal cross-section (with an optional arcuate bearing) such as described with respect to the embodiment shown in  FIGS. 21A and 21B , the PCD elements may be formed from conventional cylindrical PCD compacts (e.g., a 19 mm or a 13 mm diameter PCD compact) which is shaped to include two opposing substantially linear side surfaces. A linear (or planar) side surface of one PCD element may abut a linear (or planar) side surface of another, adjacent PCD element. The bearing elements  352  may exhibit a substantially trapezoidal cross-sectional geometry such that they may be arranged along the body  350  to define a collective bearing surface (e.g., such as described with respect to  FIGS. 21A, 21B, 22A and 22B ). 
     Referring to  FIG. 27  another bearing ring  380  is shown in accordance with another embodiment. The bearing ring  380  may be used, for example as the second bearing ring in the assembly  300  depicted in  FIG. 17 . However, the bearing ring  380  is not configured with tilting pad bearings as is the previously described bearing ring  304  associated with the bearing assembly  300 . The bearing ring  380  includes a body  382  forming a base layer and a plurality of bearing elements  384  that are formed as individual PCD elements. The PCD elements may each be configured to include a diamond table and a substrate such as has been described hereinabove. The PCD element may be formed from conventional cylindrical PCD compacts (e.g., a 19 mm or a 13 mm diameter PCD compact) which is shaped to include two opposing substantially linear side surfaces. A linear (or planar) side surface of one PCD element may abut a linear (or planar) side surface of another, adjacent PCD element. The bearing elements  384  may exhibit a substantially trapezoidal cross-sectional geometry such that they may be arranged along n interior radial surface of the body  382  to define a collective bearing surface. Of course, PCD elements  384  exhibiting similar geometries may be used to form tilting pad bearings if desired and used in an assembly similar to the second bearing ring  304  described hereinabove. 
     Referring briefly to  FIG. 28 , another bearing assembly  400  is shown. The bearing assembly  400  is configured as a radial bearing and may include a first bearing ring  402  (shown in dashed lines) and a second bearing ring  404 . The first bearing ring  402  may be configured such as one of the previously described embodiments. The second bearing ring  404  is configured as a multi-lobe bearing and includes a body  406  and a plurality of bearing sets  408 , each including a plurality of bearing elements  410 . Each bearing element may be configured, for example, similar to the PCD elements  326  described above with respect to  FIGS. 18A-18C and 12 . Each bearing set  408  is configured such that the radius of curvature of its collective bearing surface is greater than the radius of the bearing surface of the first bearing ring  402 . Thus, a fluid film may form a wedge  412  that causes separation between the first bearing ring  402  and the second bearing ring  404  as will be appreciated by those of ordinary skill in the art and as illustrated in  FIG. 28  (and as also illustrated in  FIG. 18C  with regard to other embodiments). 
     As mentioned above, the bearing apparatuses and assemblies disclosed above may be incorporated into any suitable mechanical system including any suitable rotary drill bit, motor, pump or drilling tool that may include a radial bearing apparatus or thrust bearing apparatus, without limitation. One example of such a mechanical system, without limitation, is shown in  FIG. 29  which illustrates a pump  450 . The pump  450  includes a housing  452  defining an inlet  454 , and outlet  456  and a fluid flow path  458  between the inlet  454  and the outlet  456 . A pump shaft  460  is disposed within the housing  452  and configured to rotate about an axis  462  relative to the housing. Impeller structures  464  are coupled with the pump shaft  460  and configured to convey fluid along the flow path  458  from the inlet  454  to the outlet  458  upon rotation of the pump shaft  460 . 
     Various bearings may be used to maintain the position of the pump shaft  460  relative to the housing  452  along the axis  462  while enabling it to rotate about the axis  462 . For example, a pair of radial bearings or journal bearings  470 , one near each end of the pump shaft  460 , may be used to enable relative rotation of the pump shaft  460  and the housing  452  while keeping the pump shaft substantially centered about the axis  462 . A thrust bearing  472  may also be incorporated into the pump. For example, a thrust bearing  472  may be disposed near one end of the pump shaft  460  and configured to substantially limit or constrain displacement of the pump shaft  460  along the axis  462  while still enabling rotation of the pump shaft  460  about the axis  462  relative to the pump housing  452 . 
     The radial or journal bearings  470  may be configured, for example, as the bearing assembly  300  described with respect to  FIG. 17 . The thrust bearing  472  may be configured, for example, as the bearing assembly  100  described with respect to  FIG. 1A-1C . Of course, the bearings  470  and  472  may be configured according to other embodiments or include other features described herein as desired. 
     While certain embodiments and details have been included herein for purposes of illustrating aspects of the instant disclosure, it will be apparent to those skilled in the art that various changes in the systems, apparatuses, and methods disclosed herein may be made without departing from the scope of the instant disclosure, which is defined, in part, in the appended claims. It is additionally noted that features or aspects of any embodiment described herein may be combined with other features or aspects of any other embodiment without limitation.