CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US 62/859,965 filed 11 June 2019, which is hereby incorporated by reference in its entirety.

FIELD

[0002] Embodiments of the invention relate to brake systems for vehicles. Other embodiments relate to friction devices (e.g., brake shoes) for vehicle brake systems.

BACKGROUND

[0003] For different braking applications, various types of friction devices (e.g., brake shoes) having different compositions may be used to achieve specific braking requirements. For example, these compositions may include cast iron and various other types of friction materials that are formulated for predetermined applications. Different friction materials will exhibit uniquely different friction characteristics upon a wheel of a rail vehicle, specifically the wheel tread, for braking. Friction characteristics may also include reconditioning a wheel tread for removal of surface defects such as shells or spalls.

[0004] However, the shape of current brake shoes may allow for gradual lateral migration of the brake shoe across the tread of a wheel during operation. The lateral migration may result in asymmetric brake shoe wear, which has been associated with asymmetric wheel tread wear. It may also result in an overhanging brake shoe, which occurs when at least a portion of the brake shoe hangs off the wheel. This may reduce brake effectiveness during a braking operation. Lateral migration may lead to other undesirable conditions such as high contact conicities along the wheel tread and the formation of heat checks on the rim side of a wheel. These conditions may result in a shortened lifespan of the brake shoe and/or of the wheel itself. [0005] Efforts to prevent the negative consequences of lateral migration are often expensive and time consuming in terms of validation and testing. For example, improving the brake rigging associated with the brake shoes adds cost and complexity, as do features like outfitting brake shoe backing plates with metal alignment flanges or the like. Therefore, it may be desirable to provide a friction device (e.g., brake shoe) that mitigates lateral migration, which is different from existing friction devices.

BRIEF DESCRIPTION

[0006] A friction device for a rail vehicle or other vehicle having a flanged wheel (e.g., the wheel has a wheel flange and wheel tread) includes a backing plate and a friction structure. The backing plate is configured to interface with a brake actuator of the vehicle. The friction structure is attached to the backing plate and comprises a friction material; the friction structure has a longitudinal flange side, a longitudinal rim side, and two opposing ends, and defines a brake surface for engaging a wheel for braking. The friction structure includes an extended volume portion of the friction material on the longitudinal flange side. The extended volume portion defines a flange contact region of the brake surface that is configured to at least partially engage the flange (during initial and subsequent use), e.g., to align the friction device with the wheel tread. For example, the flange contact region may be complementary in shape to at least part of the flange.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Reference is made to the accompanying drawings in which:

[0008] FIG. l is a bottom view of an embodiment of a friction device;

[0009] FIG. 2 is a cross-sectional end view of the friction device of FIG. 1 taken along line 2-2, as applied to a flanged wheel;

[0010] FIG. 3 is an end view of a friction device, according to another aspect of the invention, as applied to a flanged wheel; [0011] FIG. 4 is a bottom view of the friction device of FIG. 3;

[0012] FIG. 5 is a perspective view of the friction device of FIG. 3;

[0013] FIG. 6 is a top view of the friction device of FIG. 3;

[0014] FIG. 7 is a bottom view of another embodiment of a friction device;

[0015] FIG. 8 is a bottom view of another embodiment of a friction device;

[0016] FIG. 9 is a bottom view of another embodiment of a friction device;

[0017] FIG. 10 is a top view of the friction device of FIG. 9 applied to a flanged wheel;

[0018] FIG. 11 is a cross-sectional end view of the friction device applied to the flanged wheel of FIG. 10 along line 11-11;

[0019] FIG. 12 is a top view of two friction devices applied to flanged wheels;

[0020] FIG. 13 is a detailed sectional view of an interface between a wheel flange and an embodiment of a friction device;

[0021] FIG. 14 is a detailed sectional view of an interface between a wheel flange and another embodiment of a friction device; and

[0022] FIG. 15 is a detailed sectional view of an interface between a wheel flange and another embodiment of a friction device.

DETAILED DESCRIPTION

[0023] Embodiments of the inventive subject matter described herein relate to friction devices (e.g., brake shoes) for vehicles with flanged wheels, e.g., for rail vehicles having flanged metal wheels for traveling along a set of railroad tracks. The flanged wheels typically each include a flange (for maintaining the wheel aligned with and against the track) and a tread that contacts the top of the rail for tractive effort/propulsion. In an embodiment, a friction device includes a backing plate and a friction structure (e.g., brake pad). The backing plate is configured to interface with a vehicle brake actuator, e.g., a brake head. The friction structure is attached to the backing plate and comprises (i.e., is comprised of, or is made of) a friction material. The friction structure has a longitudinal flange side, a longitudinal rim side, and two opposing ends, and defines a brake surface for at least partially engaging a flanged wheel for braking. The friction structure includes a tread portion on the longitudinal rim side (which is configured to engage the wheel tread when the friction device is actuated for use), and an extended volume portion on the longitudinal flange side. The extended volume portion defines a flange contact region of the brake surface (e.g., that is complementary shaped to a shape of at least part of the flange) for the extended volume portion to at least partially engage the flange and to align the friction device with the wheel tread when the friction device is actuated.

[0024] In this manner, according to aspects of the invention, a shaped friction device (which may also be“extra wide” relative to friction devices without an extended volume portion) may mitigate or prevent lateral migration of the friction device, thereby reducing uneven or undesired wear of the friction device and/or undesirable interaction between the friction device and wheel.

[0025] According to one aspect, the region of the brake surface defined by the tread portion (tread contact region) is configured to engage the wheel tread during use of the friction device for braking. The tread contact region may be curved, e.g., arcuate, in correspondence to the shape of the wheel tread. The flange contact region, which is complementary in shape to at least part of the wheel flange, is angled (e.g., at a non-zero degree angle) relative to the tread contact region.

[0026] According to one aspect, the extended volume portion is initially manufactured (e.g., cast, machined, molded, printed, assembled, or otherwise formed) for the flange contact region, located on an underside of the extended volume portion as part of the brake surface, to be curved and otherwise dimensioned to correspond to the shape of the flange in a designated area of where the flange contact region will contact the flange when the friction device is installed (in a designated manner for operation) and then actuated for use against the wheel for a braking operation. Thereby, even when the friction device is used initially, the friction device contacts the flange in this manner for braking and alignment (e.g., alignment of the friction device relative to both the flange and wheel tread), as opposed to, for example, the friction device eventually wearing into a particular shape over time due to friction.

[0027] In another aspect, the friction structure may define both the brake surface generally and the flange contact region more specifically, e.g., the curvature or other shape of the flange contact region is formed in the friction structure, and the flange contact region is supported by the friction structure and may be continuous with the tread contact region of the brake surface. As opposed to, for example, a flange engagement surface being defined and supported by a metal U-shaped alignment flange, or the like, attached to the backing plate, or by some other element other than the friction structure.

[0028] According to another aspect, the extended volume portion of the friction structure is extended relative to the tread portion and wheel flange, that is, the extended volume portion is attached to and extends laterally outwards from the tread portion so as to at least partially overlap the flange when the friction device is installed for use. If the tread portion of the friction structure has the same width as a friction device without the extended volume portion, then the friction device may be characterized as being wider or “extra wide.” The same is true where the tread portion of the friction structure is the same width as the wheel tread, as may be defined (for example) by the distance between the start of the flange root and the start of the wheel rim curvature on the rim side of the wheel, i.e., the tread width is the width of the surface between the flange root and the rim curvature (generally the tread surface is frustoconical, but in a plane coincident with an the axis of the wheel the distance may be a straight line). That is, due to the extended volume portion that extends for partially overlapping and engaging with the flange, and where the tread portion of the friction structure is the same width as the wheel tread, the friction device is wider or“extra wide” relative to friction devices that have a tread portion the same width as the tread but are lacking an extended volume portion.

[0029] In one embodiment, the tread portion of the friction structure (again, the portion of the friction structure that aligns for contacting the wheel tread when the friction device is installed for use in a designated manner) is the same width as the wheel tread. In another embodiment, a width of the tread portion is at least 90% the width of the wheel tread. In another embodiment, a width of the tread portion is at least 80% the width of the wheel tread. In another embodiment, a width of the tread portion is at least 75% the width of the wheel tread. In another embodiment, a width of the tread portion is at least 70% the width of the wheel tread. In another embodiment, a width of the tread portion is from 70% to less than 100% of the width of the wheel tread. The particular width may be selected based on the material composition of the friction structure, the material (e.g., metal) composition of the wheel, a desired area of friction device-to-wheel contact (when the friction device is installed and used), and a desired level of friction to be obtained between the friction device and wheel during operation.

[0030] In an embodiment, a maximum thickness of the friction structure at the longitudinal flange side of the friction structure (i.e., a maximum thickness of the extended volume portion at its terminating edge), after manufacturing of the friction device is complete but prior to use, may be from 30% to 75% of a maximum thickness of the tread portion of the friction structure (the portion that is positioned for contact with the wheel tread when the friction device is installed for use). The thickness may be defined by a distance between the backing plate (or an intermediate adhesive layer) and the brake surface along a direction normal to a plane of interface between the backing plate (or intermediate adhesive layer) and friction structure. In another embodiment, a maximum thickness of the friction structure at the longitudinal flange side of the friction structure, after the friction device is manufactured but prior to use, is from 40% to 60% of a maximum thickness of the tread portion of the friction structure. In another embodiment, a maximum thickness of the friction structure at the longitudinal flange side of the friction structure, after the friction device is manufactured but prior to use, is at least 40% of a maximum thickness of the tread portion of the friction structure. In another embodiment, a maximum thickness of the friction structure at the longitudinal flange side of the friction structure, after the friction device is manufactured but prior to use, is at least 50% of a maximum thickness of the tread portion of the friction structure. In any such embodiments, thereby, the thickness of the extended volume portion may be a substantial fraction of the thickness of the tread portion of the friction structure, reflecting it being (at least in effect) an extension of the tread portion and that the flange contact region of the brake surface is directly and primarily supported by the friction structure. This may also be indicative of the extended volume portion (and thereby the flange contact region of the brake surface) contributing to braking over the life of the friction device, or some substantial portion thereof, considering that the flange contact region and extended volume portion may wear at a different rate (e.g., to a lesser extent) than the rest of the friction structure due to differences in forces on different portions of the friction device when the friction device is actuated for use in braking a vehicle.

[0031] In an embodiment, the flange contact region of the brake surface, defined by the extended volume portion of the friction structure, extends from the tread contact region of the brake surface in the direction of the longitudinal flange side of the friction device according to a first sectional curvature that matches the shape of the flange root (of the flange of the wheel configuration with which the friction device is configured for use). Continuing in the direction of the longitudinal flange side of the friction device, the flange contact region may include a straight section, again, in correspondence with the shape of the flange. (“Straight” in terms of a cross-sectional line in the direction of the longitudinal flange side; generally speaking, such a straight section would be a cross-section of an arcuately curved surface of the flange contact region as extending between the two ends of the friction structure.) From the straight section, or if the flange contact region lacks a straight section, the flange contact region transitions to a different, opposite curvature (i.e., curves in an opposite direction), in correspondence with the shape of the transition to the top of the flange. In one aspect, thereby, the flange contact region, in cross-section as between the longitudinal rim and flange sides, may be S-shaped. In an embodiment, the longitudinal flange side of the friction structure may be dimensioned to terminate no further than the top of the flange when the friction device is installed for initial use with a wheel. That is, the terminal edge of the extended volume portion of the friction structure, as between the ends of the friction structure on the longitudinal flange side of the friction structure, may extend no further than the top of the wheel flange. In this manner, sufficient alignment may be achieved while keeping any overall increased manufacturing costs or complexity (of the friction device with the extended volume portion relative to friction devices otherwise similar but without an extended volume portion) to a minimum. In another embodiment, the longitudinal flange side of the friction structure may be dimensioned to terminate further than a top of the wheel flange, in the longitudinal flange direction away from the friction device, when the friction device is installed for initial use with a wheel. That is, the terminal edge of the extended volume portion of the friction structure, on the longitudinal flange side of the friction structure, may extend to and past the top of the wheel flange. Such a configuration may be used, based on the shape/configuration of the wheel flange, if an additional degree of alignment is needed for the application in question. In one embodiment, the longitudinal flange side of the friction structure may be dimensioned to terminate, in relation to the top of the flange, within plus or minus 25% of the total width of the flange, reflecting that relatively minor variances on either side of the top of the flange may not significantly affect alignment and braking functionality versus cost/complexity of manufacture.

[0032] In an embodiment, the entirety of the extended volume portion of the friction structure is backed by the backing plate. Alternatively, in another embodiment, at least an outermost part of the extended volume portion, along the longitudinal flange side of the friction structure, may not be backed by the backing plate. Alternatively, in another embodiment, the entirety of the extended volume portion is not backed by the backing plate. This reflects that, according to one aspect, the material of the extended volume portion may be thick enough to support itself and the flange contact region of the brake surface during use, without a backing (either partially or entirely) provided by a backing plate or other support member (e.g., metal support member). Such a configuration may be desirable for reducing manufacturing costs, for reducing the weight of the friction device, and/or for enabling use of the same or similar configuration of backing plate both for “normal width” applications (e.g., friction structure is no wider than the width of the wheel tread) and“extra wide” applications (e.g., friction structure is as wide as the width of the wheel tread and also has an extended volume portion that extends outwards on the flange side for engagement, during use, with the wheel flange). In one embodiment, a width of the unsupported portion of the extended volume portion of the friction structure, along a normal line extending between the rim and flange sides of the friction structure (lateral axis), is greater than 0% of a total width of the friction structure and no more than 35% of the total width of the friction structure. In another embodiment, the width of the unsupported portion of the extended volume portion of the friction structure is greater than 0% of the total width of the friction structure and no more than 25% of the total width of the friction structure. In another embodiment, at least 75% of the width of the extended volume portion is not supported by a metal backing plate or other metal support member.

[0033] The friction structure may comprise or include a shaped block-like body or bodies of the friction material and other materials/components, which include the tread portion and the extended volume portion and together define the longitudinal flange side, the longitudinal rim side, the two opposing ends, an upper surface, and a lower or underside surface that defines the brake surface. In embodiments, the tread portion and the extended volume portion may be monolithic, meaning (in this context) integrally formed and comprised of the same friction material. This does not preclude one or both portions being provided with metal or other inserts (or other features) after being formed as a monolithic block or otherwise as part of the manufacturing process (e.g., the friction material may be deployed around one or more metal or other inserts disposed in a mold). However, generally speaking, as a monolithic element and even in conjunction with the possible inclusion of inserts, etc., regions of common material type (without grain boundaries at the micro level) extend between the two portions. In other embodiments, the tread portion and the extended volume portion comprise the same friction material (i.e., same type of material), but are separately initially manufactured and then assembled or otherwise attached, e.g., by welding, thermocompression, an adhesive, mechanical fasteners, etc. In other embodiments, the tread portion and the extended volume portion comprise different friction materials, and are also separately initially manufactured and then assembled or otherwise attached. In other embodiments, the tread portion and the extended volume portion are integrally formed, such as in a cast or mold, but comprise different friction materials, or they may comprise one or more common friction materials but also regions of different materials. Also, each of the tread portion and the extended volume portion may comprise a single type of friction material (the same or different as between the two portions), or it may comprise plural types of friction materials in different regions, layers, etc.

[0034] Thereby, in embodiments, regions of the friction material (or other materials) of the tread portion and the extended volume portion may differ in terms of composition, component materials, properties, etc., even if other regions of the two portions have the same composition, component materials, properties, etc. For example, regions of materials of the extended volume portion and the tread portion may have different friction qualities, different wear properties, different hardness levels, different heat transfer qualities, different colors (e.g., for wear indication), etc. For example, the outermost region of the extended volume portion (along the longitudinal flange side) may comprise a material composition that has different properties (e.g., is harder or softer) than those (e.g., hardness) of a material composition of the tread portion of the friction structure, so that the two portions exhibit different wear properties during use. Also, different regions within the same portion (tread portion or extended volume portion) may differ in terms of composition, component materials, properties, etc. For example, the region of the extended volume portion that is positioned/dimensioned to engage the flange root during use of the friction device may comprise a material composition that has different properties than those of a material composition of the region of the extended volume portion that is positioned/dimensioned to engage the top area of the flange during use of the brake, e.g., again, so the two regions exhibit different wear properties during use. It may be desirable, for example, for different parts of the friction device to exhibit different wear properties so that the friction device wears evenly during intended use over the lifetime of the friction device, differences in material thickness and operational forces notwithstanding.

[0035] As noted, in one aspect, the tread portion and extended volume portion of the friction structure (e.g., body of friction material) may be integrally formed even if they are not wholly or partially comprised of the same friction material(s). For example, the two portions may be arranged in a common mold with each portion separately temporarily contained and comprising a different friction material. During subsequent manufacturing steps (e.g., heat and pressure treatment, curing, drying, sintering, etc.) the two portions are allowed to intermingle at their interface, thereby bonding at the micro level, with some intermixing of the different materials at the interface.

[0036] Referring to FIGS. 1-3, an embodiment of a friction device 10 (e.g., brake shoe) includes a backing plate 12 and a friction structure 20 (e.g., brake pad) disposed on the backing plate. The friction structure may comprise (e.g., be made or formed of, at least in part) a friction material. The friction structure includes a flange side 22 that is configured to face in the direction of a flange 102 of a flanged wheel 100, a rim side 24 that is configured to face a rim 106 of the wheel 100, first 26 and second 28 opposing ends, and top and bottom surfaces. The flange and rim sides 22, 24 extend along the length of the friction device 10, and the opposing ends 26, 28 extend between and connect the flange and rim sides 22, 24. The bottom surface (underside) of the friction structure 20 opposite the backing plate defines a brake surface 30. By virtue of the material or materials that form the friction structure, the brake surface is configured to exhibit desired (e.g., known and controlled) frictional characteristics in interaction with a wheel or other moving element when the brake surface is selectively brought to bear against (e.g., pressed against) the wheel or other moving element. For example, for a given material composition of the friction structure, there may be a higher degree of friction between the friction structure and the wheel for a given application force than if the friction structure was comprised of different materials. When the friction device is actuated for use, frictional interaction between the friction device and wheel converts kinetic energy of the wheel and vehicle into thermal energy (heat), thereby braking/sl owing the wheel and vehicle. Thus, the brake surface is dimensioned and/or otherwise configured so that when the friction device is installed and actuated for use in braking, the brake surface contacts the wheel in order to apply a friction force to the wheel. For example, if the wheel tread is frustoconical (as may be the case for rail vehicle wheels), the brake surface may be generally arcuate (along the long axis of the friction device) and slightly tapered (along a short or cross axis of the friction device) in correspondence.

[0037] The friction structure 20 includes a tread portion 31 and an extended volume portion 32 (also referred to as a flange engagement portion or flange alignment portion). The tread portion extends between the two ends 26, 28, and also extends from the rim side 24 of the friction structure (where the tread portion at least partially defines the rim side) in the flange direction to where it meets the extended volume portion, e.g., along an interface region generally indicated by line 23 in the drawings. An underside of the tread portion defines a tread contact region of the brake surface 30. The tread contact region is configured (e.g., dimensioned and positioned) to engage the wheel tread when the friction device is installed for use and actuated for braking. The extended volume portion 32 extends between the two ends 26, 26, and out from the tread portion in the direction of the flange to terminate at and at least partially define the flange side 22 of the friction structure. An underside of the extended volume portion 32 defines a flange contact region 34 of the brake surface, which is complementary shaped to at least part of the flange 102, e.g., to a flange root 108 and/or to the top region of the flange. Thereby, the flange contact region 34 engages or abuts the flange 102 (e.g., flange root and/or top region of the flange) during use of the friction device 10.

[0038] As shown in FIGS. 2-3, the flange contact region 34 may be shaped to engage with and be complementary to the flange 102, including the flange root 108. The extended volume portion 32 also includes an exposed surface 36, the bottom edge of which may rest on the top of the flange 102 when the flange contact region 34 is engaged and in contact with the flange 102. The bottom edge of the exposed surface 36 may still rest on the top of the flange 102 when the flange contact region 34 is engaged and in contact with the flange root 108. In other words, in one embodiment, the flange contact region is configured (e.g., positioned and dimensioned) to contact the flange root when the friction device is actuated, but not the top or top region of the flange, e.g., the extended volume portion either terminates before reaching the top or top region of the flange, or even if the extended volume portion overlaps with the top region of the flange there is a space between the overlap of the extended volume portion and the top region of the flange when the friction device is actuated. See FIG. 13 for example. In other embodiments, such as shown in FIG. 2, the flange contact region is configured to contact both the flange root and the top region (e.g., top) of the flange when the friction device is actuated.

[0039] In one aspect, as extending along the length of the friction structure between its two ends, the flange contact region 34 of the brake surface may be arcuate, to match the rounded (e.g., conical) shape of the wheel. Crosswise, e.g., from the perspective of FIG. 2, the flange contact region may be S-shaped, multi-segmented (e.g., a series of connected straight line sections, or a series of different connected curved sections, or a series of alternating straight and curved sections), or otherwise shaped to at least partially engage the flange 102 during use. In embodiments, the brake surface may be configured for the entirety of the flange contact region to contact and engage the flange when the friction device is actuated. In other embodiments, the brake surface may be configured for only portions of the flange contact region to contact and engage the flange when the friction device is actuated. (Thereby, the flange contact region is the region of the brake surface defined by the extended volume portion, at least part of which, and not necessarily all of which, is configured to contact at least part of the flange during use of the friction device. Also, as described herein, the degree or extent to which the flange contact region contacts the flange during use of the friction device may change over time.) For example, as noted above, and as shown in FIG. 13, the brake surface may be configured for the terminal edge portion of the flange contact region (e.g., as generally indicated by edge 36) to not engage the top region of the flange when the friction device is actuated. As another example, with reference to FIG. 14, the brake surface may be configured for an intermediate portion of the flange contact region to lie away from (not contact) the flange when the friction device is actuated. In this embodiment, from a cross-sectional perspective, the flange contact region of the brake surface includes two straight sections 43 that in effect form a trough like notch or indentation in and along the extended volume portion of the friction structure. Thereby, when the friction device is actuated for use and the flange contact region contacts the flange generally, a gap 45 is established between the extended volume portion and the flange, in an intermediate area in between two contact areas. Alternatively, the gap 45 could be a curved indentation or another shape of indentation, or there could be multiple different indentations of the same or different configuration. For example, as shown in FIG. 15, a gap could be established by a void 47 in the material with a circular or oval or other opening, e.g., the extended volume portion could include one or more voids each defined by a circular, oval, polygonal, or irregular opening 41 in the flange contact region of the brake surface, and an associated sidewall 49 extending from the opening into the material of the extended volume portion. It may be desirable to provide such features, in whole or in part as a function of friction device and wheel frictional interaction properties, to control or tailor the friction engagement and wear characteristics of the friction device and/or wheel over time. For example, with an indentation or void in the material (such as would establish an area of gap between the friction material and flange during use of the friction device), there would be less frictional interaction between the extended volume portion and the flange initially, but as the friction structure wore down over time, the gap might diminish and/or eventually entirely disappear, potentially increasing the degree of frictional interaction between the extended volume portion and flange. A tapered feature (indentation, void, etc.) would result in a gradually changing friction profile over time, whereas a feature (indentation, void, etc.) with a perpendicular side wall(s) (relative to the wear surface) would result in a substantially constant friction profile until the material around the feature wore down to the point where the feature was gone, at which point, if applicable (i.e., if there was still an underlying layer of friction material) there would be an increase in friction as a step-function. [0040] The seating of the flange contact region 34 on or against the flange 102 (including, in embodiments, the seating of the exposed side 36 generally atop the flange 102) serves to keep the friction device 10 in place against the wheel and aligned with the wheel tread. The seating of the flange contact region 34 on the flange 102 may, therefore, help prevent the lateral migration of the friction device 10 towards the rim 106. Because the extended volume portion 32 engages with the flange 102 (e.g., with the flange root 108) during repeated use of the friction device 10, the extended volume portion 32 serves to help prevent or slow the lateral migration of the friction device 10 against the wheel flange 102. Additionally, the extended volume portion 32 may help keep the flange side 22, rim side 24, and/or brake surface 30 in their proper locations against the wheel 100 during use.

[0041 ] In the embodiment of FIG. 2, the tread portion and the extended volume portion of the friction structure are integrally formed and comprised of the same friction material, i.e., the friction structure (including the two portions) is monolithic. (As noted above, this does not preclude the friction structure including tread conditioning inserts, or the like, disposed in the material.) Additionally, from a cross-sectional perspective along at least part of the length of the friction device, the brake surface is continuous, with the region defined by the tread portion extending seamlessly into the region defined by the extended volume portion. (That is, there may be other regions of the brake surface, away from the portion shown in FIG. 2, that include seams, grooves, voids, etc., for example.) Further, as noted, prior to initial use a thickness of the extended volume portion at its terminal edge 36 may be from 30% to 75% (e.g., 40% to 60%) of the maximum thickness of the tread portion.

[0042] In one aspect, the extended volume portion of the friction structure may comprise a volume of one or more friction materials, the same or different type(s) as that of the tread portion of the friction structure, that extends laterally outwards from the tread portion in the direction of the wheel flange (when the friction device is installed and with the tread portion aligned with the wheel tread), an underside of which defines the flange contact region of the brake surface, whether the extended volume portion is integral with the tread portion or is attached thereto in another manner, and where the tread portion and extended volume portion share a common lateral axis (see dotted line“A” in FIG. 2, for example) defined as a straight line extending from the terminal edge of the extended volume portion on the flange side of the friction structure to the terminal edge of the tread portion on the rim side of the friction structure, where both terminal edges define the furthest extent of any friction material of the friction device (at least at that section of the friction device), and where there is continuous friction material(s) along the common lateral axis.

[0043] Referring now to FIGS. 3-6, the extended volume portion 32 may also include one or more protrusions 38 extending from the exposed side 36 in the direction of the wheel flange 102. The protrusions 38 may be configured to engage with the wheel flange 102 (see, e.g., FIG. 10), to assist with aligning the friction device 10 relative to the wheel 100, so that the flange side 22, rim side 24, and/or brake surface 30 are in their designated locations against the wheel 100 during use. The protrusions 38 may also help with braking (by providing additional material to seat against the flange during use of the friction device 10), and with preventing lateral migration of the friction device 10.

[0044] According to one aspect, the extended volume portion, along its length between the two ends 26, 28 and including its side 36, is generally arcuate in correspondence to the shape of the wheel. See, e.g., FIG. 5. The protrusions extend or stick out from (i.e., protrude from) the arcuate surface in the flange direction, and are spaced apart from one another, thereby forming or establishing alternating sections of protruding material and recesses along the length of the extended volume portion and longitudinal flange side. The protrusions may be evenly spaced apart from one another, or they may be unevenly spaced apart from one another, or there may be even intra-group spacing but uneven (different) inter-group spacing (of distinct groups of the protrusions). For example, as shown in the embodiment in FIG. 7, the protrusions in a first pair are spaced apart by a given distance, which is the same distance between the protrusions in a second pair, but the two pairs are spaced apart by a different, longer distance. In the embodiment of FIG. 7, there are four protrusions, but in other embodiments there may be more protrusions (e.g., five or more, such as six or eight) and in other embodiments there may be fewer (e.g., from one to three). All the protrusions may have the same configuration (e.g., material composition, shape, and/or dimensions), or some of the protrusions may have the same configuration while other protrusions have a different configuration, or all the protrusions may have different configurations.

[0045] In embodiments, the protrusions are polyhedral solids. For example, as shown in FIG. 5, the protrusions 38 may have two parts or portions 33, 35. The first part or portion 33 may have a rectangular parallelepiped shape while the second part or portion 35 may have a triangular polyhedron shape (e.g., tetrahedron, pentahedron, triangular prism-shape or wedge shape, quadrilateral pyramid, etc.) Alternatively, the first 33 and second 35 parts of the protrusions 38 may be provided in other shapes to achieve a desired character or aspect of interaction with the wheel flange 102, as is described herein. The first part 33 may directly engage with the wheel flange 102 while the second part 35 may be tapered as it extends towards the flange contact region 34 of the brake surface 30 in order to engage with the flange root (and/or with the flange elsewhere). In one aspect, the first part and the second part may both be tapered (either the same or differently), to facilitate designated alignment of the friction device with the wheel. Alternatively, in other embodiments, neither the first part nor the second part is tapered. In this instance, the first part and the second part may wear away by repeated uses of the friction device against the wheel.

[0046] One or more of the protrusions may comprise the same material or material(s) as the extended volume portion and/or the tread portion. Alternatively or additionally, one or more of the protrusions may comprise a different material or materials than the extended volume portion and/or the tread portion. One or more of the protrusions may be integrally formed with the extended volume portion (e.g., as a monolithic structure). Alternatively or additionally, one or more of the protrusions may be separately manufactured from the extended volume and then attached to the extended volume portion by an adhesive, mechanical fasteners, welding, etc. In one embodiment, the tread portion, extended volume portion, and plural protrusions are integrally formed and comprised of the same material(s). For example, all the protrusions of the friction device may be integrally formed with the extended volume portion and tread portion and made of the same material(s). In another example, plural but fewer than all of the protrusions are integrally formed with the extended volume portion and tread portion and made of the same material(s), whereas the remaining, non-integral protrusion(s) are made of a different material or materials and attached to the extended volume portion. For example, the integral protrusions could be comprised of a friction material, and the other, non-integral protrusions could comprise a metal or metal alloy, for flange conditioning of the wheel.

[0047] An example of a suitable friction structure is a brake pad. The brake pad may be useful to slow or stop a vehicle. Suitable vehicles may include automobiles, trucks, busses, mining equipment, aircraft, and railway vehicles. Railway vehicles may include locomotives and railcars, and may be for transport of freight and/or passengers. The friction structure may be formed of a friction material. The friction material optionally may include filler material.

[0048] In one embodiment, a suitable friction material is rated for a Rubbing Pressure (RP) in a range of less than about 800 N/cm ² , in a range of from about 801 N/cm ² to about 1000 N/cm ² , in a range of from about 1001 N/cm ² to about 1500 N/cm ² , or greater than about 1501 N/cm ² . In one embodiment, a suitable friction material is rated for a Rubbing Speed (RV) in a range of less than about 20 m/s, in a range of from about 21 m/s to about 30 m/s, in a range of from about 31 m/s to about 50 m/s, or greater than about 51 m/s. In one embodiment, a suitable friction material is rated for Continuous Temperature operation (CT) in a range of from about 300 °C to about 350 °C, from about 351 °C to about 400 °C, from about 401 °C to about 450 °C, or greater than about 451 °C. In one embodiment, a suitable friction material is rated for Short Term Temperature (ST) in a range of from about 500 °C to about 600 °C, from about 601 °C to about 700 °C, from about 701 °C to about 800 °C, from about 801 °C to about 900 °C, or greater than about 901 °C. The preceding ranges are based at least in part on, and determined by, the friction material selection, the physical configuration, and the end use application of the friction device.

[0049] In other embodiments, a suitable friction structure may include be semi- metallic. Semi-metallic may include a non-metallic matrix, such as a ceramic or a polymer, with a metallic filler. For example, a semi-metallic puck of iron or copper powder may be bound together by a ceramic or polymer. The fill content may be selected based at least in part on the desired performance of the friction material and friction structure made therefrom. Suitable filler content may be expressed as a ratio of metallic material to matrix material by volume or by weight. In various embodiments, a suitable ratio may be in a range of less than 50% by weight, in a range of from about 51% to about 75% by weight, from about 76 to about 90% by weight, or greater than 91% by weight. For example, a suitable formulation may be 90 grams of metal per 10 grams of matrix. In various embodiments, the fill content for the friction structure may be metal, as disclosed, a non- metal, or a combination of metal and non-metal materials.

[0050] The ceramic/iron materials may be mixed, compressed, and/or sintered at a high temperature to form a solid friction structure. Suitable binding or matrix materials may include one or more of resin (such as phenol formaldehyde), graphite (which can also serve as a friction material, zirconium silicate and the like. An example formulation, including binder, is shown in Table 1.

[0051] The powder size, fiber size, concentration distribution, grain size distribution, and morphology may be selected or controlled to affect performance of the friction structure. If the fill content is a powder, suitable powder size averages may be in a range of less than 100 micrometers, in a range of from about 101 micrometers to about 250 micrometers, in a range of from about 251 micrometers to about 500 micrometers, or greater than about 501 micrometers. The grain size distribution may be in a range of from about 0.5 to about 1, from about 1 to about 2, or greater than about 2 as a distribution relative to mean particle size. The morphology of the particles may be selected from suitable shapes. Suitable shapes may include spherical, ovoid, irregular, flake, and polygonal. In some examples the more surface area of the particle, the lower the friability of the friction structure; and in other examples, the more edged particles provide relatively more aggressive friction and conditioning than the smoother or rounder particles. The hardness of the material selected as the filler powder, in combination with the filler content, and particle morphology can contribute to the performance of the friction structure. If the fill content is a fiber, the fiber thickness and fiber length may be selected or controlled to affect performance. The fiber may be the same material as the powder fill content, and the fill content may be a mixture of powder and fiber in one embodiment. Other suitable fibers may be formed from an aromatic polyamide or aramid, such as Kevlar™, Twaron™, Nomex™, and Technora™. Other suitable fibers may be formed from an aliphatic or semi aromatic polyamides, such as Nylon™. Polymeric fibers may include one or more copolymers to control and affect crystallinity, melting or softening points, and the like. The length of the fibers may be controlled to affect performance. Suitable fiber lengths may be in a range of less than about 1 millimeter (mm), in a range of from about 1.1 mm to about 2 mm, in a range of from about 2.1 mm to about 5 mm, or in a range of greater than about 5.1 mm. Fiber thickness may be selected to control and affect performance. Suitable fiber thickness may be in a range of from about In one embodiment, the fibers have a Denier in a range of less than about 20d, in a range of from about 21 d to about lOOd, in a range of from about 101 d to about 500d, in a range of from about 50 Id to about 1500d, in a range of from about 1501d to about 3000d, or greater than about 3000d selected based at least in part on application specific parameters.

[0052] Suitable polymer or polymeric matrices may include phenolics, urea- formaldehyde, epoxy, cyanate ester, aromatic heterocyclics (such as Polyimides, polybenzoxazoles (PBOs), polybenzimidazoles, and polybenzthiazoles (PBTs)), inorganic and semiorganic polymers (such as may be derived from silicon-nitrogen, boron-nitrogen, and phosphorus-nitrogen monomers), and silicon-based polymers, as well as mixtures and copolymers of the foregoing. The polymeric matrix, along with other additives, may include a flame retardant. Suitable flame retardants may include a composition that includes one or more of aluminum, phosphorus, nitrogen, antimony, chlorine, bromine, and in some applications magnesium, zinc, and carbon.

[0053] Referring now to FIG. 6 as one example, embodiments of the friction device 10 include the backing plate 12 that supports and carries the friction structure. Suitable backing plates may be made of metallic material or non-metallic material, or a combination or composite material. Suitable metallic materials may include iron, iron alloys, aluminum, titanium, etc. Suitable iron alloys may include steel. In one embodiment, the backing plate may be made of a reinforced composite material, e.g., carbon fiber-reinforced polymer. The backing plate may be coated. Suitable coatings may include galvanic coatings (particularly if the backing plate is formed of a corrodible metal), paint, and anodized layers. Suitable paints include enamel, epoxy, and powder coatings.

[0054] The backing plate 12 has a top surface and a bottom surface, and may be generally arcuate in shape, or otherwise shaped in correspondence with the shape of the wheel (or portion thereof) with which the friction device is configured for use. The backing plate may be curved axially so as to follow the curvature of a wheel. The axis for the curve may be a wheel axis. In one embodiment, the friction structure is curved and is coaxial to the wheel, while the backing plate follows the curve of the friction structure to be coaxial to the wheel. In another embodiment, the backing plate is curved but is not coaxial with the wheel or with the working surface of the friction structure. The degree of separation of the curvature of the backing plate relative to the friction structure may be selected based on application specific parameters.

[0055] The backing plate may have surfaces that are relatively smooth, and may have one or more defined apertures therethrough and/or protrusions extending therefrom. In one embodiment, the backing plate is undulate so as to increase its surface area. An increased surface area may provide more bonding surface to which the friction structure may bond. The undulations may be dispersed evenly across the backing plate, or may be patterned so that some undulations are at a proximate edge or some undulations are concentrated nearer the center line. The undulations may run the length of the backing plate, or may be oriented width-wise. Undulations may impart stiffness in the direction of their run, and flexion perpendicular to their run. In one embodiment, the undulations direction is skew relative to the length and the width of the backing plate. In one embodiment, a checkered pattern or equivalent is present to allow for control over the stiffness and the flexion of the backing plate while still increasing the surface area. Various patterns and similar effects can be created by selecting either a uniform thickness of the backing plate (and thus by bends in the plate) or by using non-uniform thicknesses across the backing plate.

[0056] In one embodiment, the width of the backing plate is the same as the width of the friction structure. In another embodiment, the width of the backing plate differs from the width of the friction structure. A backing plate that is smaller than the width of the friction structure may be sufficient to perform the support function of the backing plate, while reducing overall weight and/or cost. A backing plate that is larger than the width of the friction structure may be sufficient to perform the support function of the backing plate, while providing enhanced support to edges of the friction material. In one embodiment, the width ratio of the backing plate to the friction structure, the length ratio of the backing plate to the friction structure, and the ratio of the backing plate’s thickness to a starting thickness of the friction structure is, independently of each other, in a range of less than about 0.5, in a range of from about 0.6 to about 0.9, about 1, in a range of from about 1.1 to about 1.2, in a range of from about 1.2 to about 1.5, or in a range of greater than about 1.6. Suitable backing plate configurations may include a full unbroken plate, a mesh, a wire form, a reinforced wire form, a mesh, or a molded composite.

[0057] In one embodiment, the width of the friction device’s working (or brake) surface relative to the wheel tread (which includes at least a portion of the wheel flange that touches the friction device during use) is in a range of less than about 35%, in a range of from about 36% to about 50%, in a range of from about 51% to about 75%, in a range of from about 76% to about 100%, or greater than about 101%. A suitable friction device width may vary from side to side or from end to end. A suitable shape of the friction structure may follow a contour of wheel, having a matching complementary profile. This shaped edge may be formed with one or more of a chamfer, ridge, edge, or radius. In one embodiment, only one edge of the friction structure is contoured. In another embodiment, both edges are contoured to allow for installation in either orientation. In one embodiment, the friction device is configured to fit to a new vehicle wheel having a diameter in a range of less than about 600 mm, in a range of from about 601 mm to about 1300 mm, or in a range of greater than about 1301 mm.

[0058] For rail vehicle applications, the backing plate 12 may include a pair of rejection lugs 14a, 14b. The rejection lugs 14a, 14b may be integrally formed with the backing plate 12 and may extend from a top surface of the backing plate 12. The rejection lugs 14a, 14b are sized and positioned to mate with corresponding rejection lug receptacles (not shown) on a corresponding vehicle brake head (not shown). The rejection lugs 14a, 14b may be configured to be compatible with a variety of brake heads, or they may be configured to only correspond with certain types of brake heads in order to prevent the installation of the friction device 10 in incompatible systems. The friction device 10 may also include a keybridge 16. The keybridge 16 may be integrally formed with the backing plate 12 or it may be attached to the backing plate 12 prior to installation. Like the backing plate 12, the keybridge 16 may be made of a metallic material or a reinforced composite material. The keybridge 16 is configured to be coupled to a brake head (not shown) of a railway vehicle. As shown in FIGS. 2 and 3, an opening 18 in the keybridge 16 is configured to accept a locking key (not shown) which fastens the friction device 10 to the railway vehicle brake head. The keybridge may take any shape necessary to facilitate fastening of the keybridge 16 to a designated configuration of brake head.

[0059] The friction structure 20 is affixed to and extends from the bottom surface of the backing plate. The friction structure may be affixed to the backing plate with an adhesion/adhesive layer (not shown). Alternatively, the friction structure may be affixed to the backing plate by mechanical fasteners, welding, or similar operations, thermocompression, etc. Alternatively, or in conjunction with any of the attachment means described herein, the friction structure may be deposited onto the backing plate, or the friction structure may be formed and attached to the backing plate in a combined operation, e.g., a backing plate may be disposed in a mold that also receives the friction material(s) for forming the friction structure on the backing plate in the mold. (In such an embodiment or otherwise, the backing plate may include features that protrude up into the friction material, for helping to affix the friction structure to the backing plate and/or for carrying out functions like wheel conditioning during use of the friction device.) The friction structure may be affixed to the backing plate by means that may be selected based at least in part on application specific parameters.

[0001] A suitable friction structure may include an outer layer that is the first to contact a wheel surface when newly installed. This outer lay may perform one or more of the following functions: prevent exposure of the friction material during storage, transport or installation to corrosion, chipping, moisture or fouling; provide an initial coating to the wheel surface on the first few rotations after installation and braking to condition or treat the wheel surface; to condition the wheel surface and remove any debris or corrosion; to fill in cracks, pits and defects in the wheel surface; and the like. In one embodiment, the outer layer is removed from the working surface of the friction structure through friction in the first few rotations during braking after installation. In one embodiment, the outer layer is peeled off after installation or a part of the installation process. [0002] The friction structure may include one or more wear indicators. In one embodiment, the wear indicators are molded into the friction material of the friction structure. A suitable location for the wear indicator is at the back of the shoe. The backing plate may be configured to form the wear indicator, or may have material removed to allow a wear indicator to be visible. Other suitable locations for wear indicators may include proximate to an end, around a periphery, at the centerline of the friction structure, at a distal end (or both ends) of the friction structure, as a part of a conditioning insert, or the like. During use, the wear indicators allows an observer to determine useful life of the friction structure. In one example, a groove is formed in the friction structure from the working surface down to a determined depth. During use, the depth of the groove diminishes as the working surface is worn away. An observer would then look for the groove and determine life by its remaining depth (or absence if it was at end of life and completely worn away). Other examples of wear indicators may include a differently colored portion of the friction structure. Or, the conditioning insert can be configured to perform the wear indication function. In one embodiment, an RFID chip (or equivalent) is disposed in the friction structure at the depth for which the end of life is set for the friction structure. When the friction structure is worn to expose the RFID chip, the chip will no longer function and provide a signal in response to a query (for passive chips, active chips may broadcast signals and the absence of a broadcast signal would indicate end-of-life). Naturally, an RFID sensor would communicate with the wear indicator chip and thereby one could determine when a brake change was needed.

[0060] In embodiments, one or more wheel conditioning inserts may be disposed within the material of the friction structure. The wheel conditioning insets are configured to interact with a wheel for a function other than primarily for braking, e.g., to clean, scrape, treat, or otherwise condition the wheel tread, rim, and/or flange. FIG. 7 shows one embodiment of rectangular wheel conditioning inserts 40 disposed within the friction structure 20, e.g., in this example there are three inserts. The wheel conditioning inserts 40 each include a respective elongated portion 42. The elongated portion 42 has a wheel conditioning surface 44 that extends along the brake surface 30 adjacent to and generally parallel with the rim side 24 of the friction structure 20, i.e., a long axis of the surface 44 is generally parallel to the rim side 24. In this configuration, the wheel conditioning surfaces 44 of the wheel conditioning inserts 40 are positioned to condition the rim 106 of a wheel 100, e.g., to mitigate hollow wheel wear or otherwise. Prior to initial use of the friction device, the friction device may be configured for the wheel conditioning surface 44 to be exposed to and flush with the brake surface 30. It is also contemplated that the wheel conditioning inserts 40 may be initially fully encapsulated within the friction structure 20 of the friction device. In this instance, repeated braking of the vehicle will wear away the outer layer of the composite friction material, eventually exposing the wheel conditioning surfaces 44 of the wheel conditioning inserts 40 to the wheel 100. In other words, during initial use of the friction device the wheel conditioning inserts are covered with friction material, but after use of the friction device the wheel conditioning inserts eventually become exposed for wheel conditioning.

[0061] In another embodiment, as shown in FIG. 8, a T-shaped wheel conditioning insert 46 may be disposed within the friction structure 20. The T-shaped wheel conditioning insert 46 has a first elongated portion 48 and a second elongated portion 50 both of which form the wheel conditioning surface 52. The first elongated portion 48 has an end 54 that extends along the brake surface 30 adjacent to and generally parallel with the rim side 24 of the friction structure 20. The second elongated portion 50 extends along the brake surface 30 generally perpendicular to the first elongated portion 48. The second elongated portion 50 has an end 56 that is adjacent to the flange side 22 of the friction structure 20. A central axis I-I of the friction device 10, equidistant between the flange side 22 and the rim side 24, crosses the T-shaped wheel conditioning insert 46 substantially halfway between the ends 54, 56 of the insert 46. With the first elongated portion 48 adjacent to and extending along the rim side 24 and the second elongated portion 50 disposed in a central location along the brake surface 30, the T-shaped wheel conditioning insert 46, when applied to a wheel 100, is configured to condition both the wheel tread 104 and the wheel rim 106. This configuration conditions the wheel tread 104, removing tread defects while simultaneously conditioning the wheel rim 106, e.g., for removing rim defects and reducing the rate of hollow wheel wear.

[0062] The wheel conditioning inserts 40, 46 may comprise a hardened material such as cast iron or another metal or metal alloy, or any material with abrasive properties suitable for a desired degree or character of conditioning interaction between the inserts and a wheel material. The wheel conditioning inserts 40, 46 may also be formed of a material harder and/or more abrasive than the friction material of the friction structure. As the friction device 10 is applied to the surface of the wheel 100, the wheel conditioning inserts 40, 46 contact the wheel’s surface. The abrasive properties of the wheel conditioning inserts 40, 46 may condition the wheel surface to prevent, reduce, or remove defects. Along with the conditioning properties, the wheel conditioning inserts 40, 46 also serve to provide an additional braking force that may be helpful in adverse weather conditions.

[0063] A conditioning insert material and other parameters may be selected with reference to the conditioning function and the friction material may be selected with reference to the braking or friction function. Thus, they may contain similar materials in some embodiments, but the compositions differ such to perform their intended function. This difference may be substantial (e.g., a metal conditioning insert within a composite friction structure) or may be relatively subtle (e.g., both are ceramic iron metal-filled structures, with one having a different concentration of metal content). In one embodiment, the conditioning insert may be formed of a material relatively harder and/or more abrasive than the friction structure. For example, the wheel conditioning insert may be formed of a material with suitably abrasive properties for the wheel conditioning insert. As the friction device may be applied to the surface of a wheel, the wheel conditioning insert rubs against the wheel surface. The abrasive properties of the insert conditions the wheel surface to prevent, reduce, or remove defects.

[0064] A suitable wheel conditioning insert may be formed from a relatively hard material. Suitable materials may be metal. Suitable metal may include one or more of Al, Si, P, S, Cl, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn, Sb, Tl, and oxides, carbides, and alloys of the foregoing. In one embodiment, the metal is iron or an iron alloy. Suitable iron, and iron alloys, may include those as used in, and process to form, cast iron, forged iron, wrought iron and the like. Suitable cast iron may include malleable cast iron or ductile cast iron. Other suitable iron inserts include treated iron, regardless of its manufacturing process. Suitable treated irons may include phosphated iron, nitrided iron, heat treated iron, and the like. Some steels may be used in various embodiments. The steel may have controlled amounts of carbon and/or chromium, as well as a controlled ratio of martensite relative to cementite structure. Selecting the alloy content may control the hardness, and therefore the performance of the conditioning insert. In other embodiments, the conditioning insert may include a non-ferrous metal.

[0065] In other embodiments, a suitable conditioning insert may include a non-metallic matrix, such as a ceramic or a polymer, preferably with a metallic filler. For example, a puck of iron powder or iron filling filled ceramic may be used. The iron may be the same, or different, from the identified suitable iron types. The fill content may be selected based at least in part on the desired performance of the conditioning insert. Suitable filler content may be expressed as a ratio of metallic material to matrix material by volume or by weight. In various embodiments, a suitable ratio may be in a range of less than 50% by weight, in a range of from about 51% to about 75% by weight, from about 76 to about 90% by weight, or greater than 91% by weight. For example, a suitable formulation may be 90 grams of iron powder per 10 grams of ceramic matrix. The ceramic/iron materials may be mixed, compressed, and sintered at a high temperature to form a solid conditioning insert. The powder size and grain size distribution may be controlled to affect performance, as well. Suitable powder size averages may be in a range of less than 100 micrometers, in a range of from about 101 micrometers to about 250 micrometers, in a range of from about 251 micrometers to about 500 micrometers, or greater than about 501 micrometers. The grain size distribution may be in a range of from about 0.5 to about 1, from about 1 to about 2, or greater than about 2 as a distribution relative to mean particle size. The morphology of the particles may be selected from suitable shapes. Suitable shapes may include spherical, ovoid, irregular, flake, and polygonal. In some examples the more surface area of the particle, the lower the friability of the conditioning insert; and in other examples, the more edged particles provide relatively more aggressive friction and conditioning than the smoother or rounder particles. The hardness of the material selected as the filler powder, in combination with the filler content, and particle morphology can contribute to the performance of the conditioning insert. In one embodiment, the wheel conditioning insert may be formed of a material relatively harder and/or more abrasive than the friction material. For example, the wheel conditioning insert may be formed of a material with suitably abrasive properties for the wheel conditioning insert. As the friction device may be applied to the surface of a wheel, the wheel conditioning insert rubs against the wheel surface. The abrasive properties of the insert conditions the wheel surface to prevent, reduce, or remove defects.

[0066] Although various wheel conditioning inserts are shown, other embodiments may have a different number (e.g., more or fewer) of wheel conditioning inserts utilized along the rim side that is determine with reference to application specific parameters. Further, in other embodiments, these inserts may have a shape other rectangular and selected to condition the wheel rim. Other suitable shapes may be selected with reference to the desired performance, but polygonal and ovoid shapes may be broadly useful across use types. The wheel conditioning surface may remove imperfections from the wheel when in use and/or may impart a coating layer on the subsequently conditions surface. The shape of the inserts, the number of inserts, the insert material, and other factors (such as volume, weight, density, and end use application) may be selected to achieve a desired and proportional effect from the insert.

[0067] Referring now to FIG. 9 as one exemplary embodiment, one or more voids 60 may be formed within the friction structure. While the term“void” as used may sometimes indicate an entirely empty and hollow volume, in various embodiments it may include materials other than the friction composite material, or may be filled with gas, or a vacuum so as to be a true void. In embodiments where the void in the friction material is filled with a filler material, suitable void filler materials may include metallic, inorganic, and organic material. Suitable metallics include relatively softer metals. Example metals may include tin, zinc, lead, aluminum, copper, and the like, as well as mixtures, oxides, and alloys thereof. Suitable inorganic materials may include silicon and silicon-based oxides thereof; with yet other materials containing molybdenum or lithium in amounts and locations that lubricate and/or reduce wear. A suitable void filler may be a solid extreme-pressure and/or extreme-temperature lubricant. Suitable lubricants may include graphite and/or molybdenum disulfide to provide protection under heavy loadings. The solid lubricants may bond to the surface of the metal, and thereby reduce or prevent metal-to-metal contact and the resulting friction and wear when the lubricant film gets too thin. Solid additives such as copper or ceramic powder may be added to the lubricant for static high pressure and/or high temperature applications, or where corrosion might be a concern. These compounds may work as a release agent. Suitable organic materials may include carbon and polymeric materials.

[0068] The void filler polymeric materials can be homogeneous or can be composite or filled polymers. These filled polymers may include metals, such as that used for the conditioning insert, but in concentrations and/or morphologies that differ from the conditioning insert. In other embodiments, the filled polymers that constitute the void filler may include non-metallic aggregates such that the overall weight of the friction structure is less than one with no voids. If a relatively harder void filler is desired, particles such as silicon carbide, aluminum oxide or silicon oxide particles may be used. If a relatively softer void filler is used, then iron oxide or zinc oxide particles may be used. The selection of filler aggregate may include mixtures of different particles types, particle sizes, and particle size distributions. The binding agent may be selected, as well as the concentration of filler particles, to control and affect the action of the void filler and/or friction structure on the respective wheel surface, the overall weight of the friction structure, and the like.

[0069] The voids may constitute a varying amount of the working surface of the friction structure during the life of the brake device. In one embodiment, the ratio of working surface (capable of contacting the wheel surface) and the cross sectional area of the void at the working surface is less than 5% (and in some cases zero at various life stages of the friction structure), in a range of from about 6% to about 10%, in a range of from about 11% to about 25%, in a range of from about 26% to about 50%, in a range of from about 51% to about 70%, in a range of from about 71% to about 80%, or in a range of greater than about 81%.

[0070] In one embodiment, there may be more than one void. In one embodiment, there may be less than about 50 voids. Note that the voids may be spaced at different thickness levels in the friction structure such that an unused friction structure has zero voids exposed, but a partially or fully used friction structure has some percentage of its working surface exposed as voids (absence of friction material). In one embodiment, the voids are placed such that as the friction structure wears different locations of the wheel surface contact the friction structure owing to the void placement and thus exposure at that point in the life cycle. In one embodiment, the voids define a channel that can run the length (or width) of the brake device. In some embodiments, the channel may operate to allow cooling air flow through the friction structure during use, and may provide an egress for particulate and/or water if such are present during use.

[0071] Suitable void shapes may be circular, ovoid or ovular, or elliptical in cross sectional profile or shape. Other suitable void shapes may include T-shaped and X-shaped. In one embodiment, the void is shaped as a cone, a hemi-sphere, a full sphere, a cylinder, a cube or cuboid, a triangular prism, a triangular pyramid, a pentagonal prism, a pentagonal pyramid, a tetrahedron, a hexagonal pyramid, parallelepiped, hexagon, other prism, a toms, an ellipsoid, an icosahedron, and the like. The voids may be shaped based at least in part on the specific end use parameters. Suitable shapes may be polygonal. In one embodiment, the shape may be capable of reducing some of the volume of composite friction material in order to reduce the wear applied to the wheel tread. The void, as shown, may be conical or tapered, having a larger cross-sectional area at the brake surface which tapers or reduces to a smaller cross-sectional area nearest the backing plate. The void may be elongated in a direction perpendicular to the axis I-I. Orienting an elongated void may have a technical effect of reducing wear of along a width of a wheel tread.

[0072] The presence of voids in the friction structure may lessen the amount of wear the brake shoe contributes to the wheel tread in some embodiments. The use of some void materials may contribute to conditioning, may lubricate, and/or may reduce weight. By varying the relative amount of available working surface area (brake surface) as the friction structure wears, the braking capacity of the brake shoe may be controlled. For example, if the void(s) is/are shaped so that the void cross sectional profile decreases in response to wear of the friction structure the result may be a relative increase in working surface area, and more available braking capability. Conversely, a configuration may be selected such that the exposed void cross sectional area increases in response to wear, and that may have the effect of reducing a braking capability of the brake shoe as it wears. In one embodiment, the relative amount of working surface available remains constant during its use and irrespective of the amount of wear. Even as the working surface area remains constant the location(s) of the void(s) and the relative wear pattern caused by the complementary working surface on the wheel surface may change.

[0073] In embodiments, for each void the material of the friction structure may define an opening in the brake surface, and one or more sidewalls extending from the opening into the material. The voids 60 are generally aligned with the wheel tread 104 when applied to the wheel 100 as shown in FIGS. 10 and 11. The voids 60 may serve to lessen the amount of wear the friction device 10 contributes to the wheel tread 104. The voids 60 lack friction material in their respective locations, and this lack of friction material prevents the wheel tread 104 from continually wearing away when the friction device 10 is applied to the wheel 100. The void openings as shown are substantially circular, oval, or elliptical in shape, but in other embodiments the voids (openings and/or sidewalls/interior) may take any shape, such as polygonal, capable of reducing some of the volume of friction material in order to reduce the wear applied to the wheel tread. The voids 60, as shown, may also be conical or tapered, having a larger cross-sectional area at the brake surface 30 which tapers or reduces to a smaller cross-sectional area nearest the backing plate 12. In FIG. 9, the voids 60 are shown with a rectangular wheel conditioning insert 40, however the voids 60 can also be used in conjunction with T-shaped conditioning inserts or other inserts. In another embodiment, a friction device includes one or more voids but lacks any conditioning inserts. It is contemplated that the additional features of a friction device 10 described herein can be utilized in any functional combination on a friction device.

[0074] In embodiments, an area of the opening of each of at least one of the voids (or the respective areas of all the voids), coincident with the brake surface, is from 2% to 6% of the entire area of the brake surface. In another embodiment, the area of the opening of each of at least one of the voids (or the respective areas of all the voids), coincident with the brake surface, is from 3% to 4% of the entire area of the brake surface. This approximately reflects the geometry illustrated in the embodiment of FIG. 9, as representative of an example of one possible application (where some material at the brake surface/wheel interface is lacking, to achieve the functions as stated herein, while the overall friction device still provides a typical desired level of friction interaction with a wheel for braking).

[0075] FIGS. 10-12 show an embodiment of a friction device 10 that includes the extended volume portion 32, protrusions 38, a wheel conditioning insert 40, and at least one void 60, as described above. As shown in FIGS. 10 and 12, the protrusions 38 contact the wheel flange 102, and, as shown in FIG. 11, the extended volume portion 32 and the flange contact region 34 contact the wheel flange, e.g., the flange root and top regions of the flange. The contact between the respective elements aligns the friction device with the wheel in a designated and controlled manner. For example, as shown in FIG. 11, the wheel conditioning insert may be aligned with the wheel rim so that the wheel conditioning insert conditions the wheel rim during use. The void(s) and a majority of the brake surface are aligned with the wheel tread 104 in order to prevent over conditioning of the wheel tread while still applying a designated/desired braking force to the wheel when the friction device is actuated. As shown in FIG. 12, the alignment facilitated by the extended volume portion and the protrusions leads to the friction device remaining against the wheel surface with no overhang. (A small portion 110 of the wheel rim 106 is exposed next to the rim side 24 of the friction structure 20, further demonstrating the lack of overhang.)

[0076] As discussed, it may be desirable to mitigate or prevent the lateral migration of a friction device relative to a wheel over time, to avoid or reduce degradation of the friction device and/or wheel and to maintain a desired, consistent quality of braking performance. This may be accomplished by providing a shaped or“extra-wide” friction device according to one or more embodiments of the invention, as set forth herein. For example, embodiments of the subject matter described herein relate to friction devices having an extended volume portion of the friction material that is contoured to complement a contour of a flange of the wheel. The extended volume portion is configured to mechanically contact the flange when the friction device is applied against the wheel. Unlike other friction devices, the complementary engagement between the extended volume portion and the flange may prevent or mitigate the lateral migration of the friction device across a flanged wheel. This may maintain the proper alignment of braking and conditioning surfaces against the wheel tread, wheel flange, and/or wheel rim, reducing wear of the friction device and/or the wheel over repeated use relative to other friction devices that experience lateral migration.

[0077] In an embodiment, a friction device (e.g., brake shoe) includes a backing plate and a friction structure (e.g., brake pad). The backing plate is configured to interface with a brake actuator of a vehicle having a wheel with a wheel flange and a wheel tread. The friction structure is attached or coupled to the backing plate and comprises a friction material. The friction structure has a longitudinal flange side, a longitudinal rim side, and two opposing ends and defines a brake surface for engaging the wheel. The friction structure includes a tread portion on the longitudinal rim side and a flange engagement portion on the longitudinal flange side. The flange engagement portion is attached to the tread portion and defines a flange contact region of the brake surface that is configured to at least partially engage the flange at least during initial use of the friction device with the wheel. (That is, the flange engagement portion engages the flange both when the friction device is used initially with a designated type of wheel and when the friction device is used subsequently.) For example, the flange contact region may be complementary shaped to a shape of at least part of the flange, for the flange engagement portion to engage the flange during use. A maximum thickness of the flange engagement portion at the longitudinal flange side of the friction structure, prior to use, is from 30% to 75% of a maximum thickness of the tread portion.

[0078] In an embodiment, a friction device (e.g., brake shoe) includes a backing plate and a friction structure (e.g., brake pad). The backing plate is configured to interface with a brake actuator of a vehicle having a wheel with a wheel flange and a wheel tread. The friction structure is attached or coupled to the backing plate and comprises a friction material. The friction structure has a longitudinal flange side, a longitudinal rim side, and two opposing ends and defines a brake surface for engaging the wheel. The friction structure includes a tread portion on the longitudinal rim side and a flange engagement portion on the longitudinal flange side. The flange engagement portion is attached to the tread portion and defines a flange contact region of the brake surface that is configured to at least partially engage the flange at least during initial use of the friction device with the wheel. (For example, the flange contact region may be complementary shaped to a shape of at least part the flange, for the flange engagement portion to engage the flange during use.) A maximum thickness of the flange engagement portion at the longitudinal flange side of the friction structure, prior to use, is from 30% to 75% of a maximum thickness of the tread portion. Also, a maximum width of the tread portion between the longitudinal rim side and the flange engagement portion is equal to a width of the wheel tread.

[0079] In an embodiment, a friction device (e.g., brake shoe) includes a backing plate and a friction structure (e.g., brake pad). The backing plate is configured to interface with a brake actuator of a vehicle having a wheel with a wheel flange and a wheel tread. The friction structure is attached or coupled to the backing plate and comprises a friction material. The friction structure has a longitudinal flange side, a longitudinal rim side, and two opposing ends and defines a brake surface for engaging the wheel. The friction structure includes a tread portion on the longitudinal rim side and a flange engagement portion on the longitudinal flange side. The flange engagement portion is attached to the tread portion and defines a flange contact region of the brake surface that is configured to at least partially engage the flange at least during initial use of the friction device with the wheel. (For example, the flange contact region may be complementary shaped to a shape of at least part the flange, for the flange engagement portion to engage the flange during use.) A maximum thickness of the flange engagement portion at the longitudinal flange side of the friction structure, prior to use, is from 40% to 60% of the maximum thickness of the tread portion.

[0080] In an embodiment, a friction device (e.g., brake shoe) includes a backing plate and a friction structure (e.g., brake pad). The backing plate is configured to interface with a brake actuator of a vehicle having a wheel with a wheel flange and a wheel tread. The friction structure is attached or coupled to the backing plate and comprises a friction material. The friction structure has a longitudinal flange side, a longitudinal rim side, and two opposing ends and defines a brake surface for engaging the wheel. The friction structure includes a tread portion on the longitudinal rim side and a flange engagement portion on the longitudinal flange side. The flange engagement portion is attached to the tread portion and defines a flange contact region of the brake surface that is configured to at least partially engage the flange at least during initial use of the friction device with the wheel. (For example, the flange contact region may be complementary shaped to a shape of at least part the flange, for the flange engagement portion to engage the flange during use.) A maximum thickness of the flange engagement portion at the longitudinal flange side of the friction structure, prior to use, is from 40% to 60% of the maximum thickness of the tread portion. Also, a maximum width of the tread portion between the longitudinal rim side and the flange engagement portion is equal to a width of the wheel tread.

[0081 ] In any of the aforementioned embodiments of a friction device having a friction structure with a tread portion on the longitudinal rim side and a flange engagement portion on the longitudinal flange side, it may be the case that all or at least an outermost part of the flange engagement portion (as defined along the longitudinal flange side) is not backed by the backing plate.

[0082] In another embodiment, a friction device (e.g., brake shoe) includes a backing plate and a friction structure (e.g., brake pad) attached or coupled to the backing plate. The backing plate is configured to interface with a brake actuator of a vehicle having a wheel with a wheel flange and a wheel tread. The friction structure has a longitudinal flange side, a longitudinal rim side, and two opposing ends, and defines a brake surface for engaging the wheel. The friction structure includes a tread portion comprising a friction material on the longitudinal rim side and an extended volume portion of the friction material on the longitudinal flange side. The extended volume portion defines a flange contact region of the brake surface that is configured to at least partially engage the flange at least during initial use of the friction device with the wheel. (For example, the flange contact region may be complementary shaped to a shape of at least part the flange, for the extended volume portion to engage the flange during use.)

[0083] In an embodiment, a friction device (e.g., brake shoe) includes a backing plate and a friction structure (e.g., brake pad) attached or coupled to the backing plate. The friction structure is configured to interface with a brake actuator of a vehicle having a wheel with a wheel flange and a wheel tread. The friction structure comprises a friction material, and has a longitudinal flange side, a longitudinal rim side, and two opposing ends. The friction structure defines a brake surface for engaging the wheel. The friction structure includes an extended volume portion of the friction material on the longitudinal flange side, which defines a flange contact region of the brake surface that is configured to at least partially engage the flange at least during initial use of the friction device with the wheel. (For example, the flange contact region may be complementary shaped to a shape of at least part the flange, for the extended volume portion to engage the flange during use.)

[0084] Optionally, in embodiments of the friction device: the backing plate is flange less; and/or the longitudinal flange side of the friction structure is dimensioned to terminate no further than a top of the wheel flange when the friction device is installed for initial use with the wheel; and/or a maximum thickness of the friction structure at the longitudinal flange side of the friction structure, prior to use, is from 30% to 75% of a maximum thickness of a tread potion of the friction structure that is configured to contact the wheel tread when the brakes shoe is actuated; and/or the friction structure includes the tread portion and the extended volume portion with the two comprising a monolithic block of the friction material; and/or all or at least an outermost part of the extended volume portion (in the flange direction) is not backed by the backing plate.

[0085] Optionally, in embodiments, the maximum thickness of the friction structure at the longitudinal flange side of the friction structure, prior to use, may be from 40% to 60% of the maximum thickness of the tread portion of the friction structure.

[0086] Optionally, in embodiments, the flange contact region of the brake surface may be initially complementary shaped to a shape of a flange root at an area of contact engagement between the extended volume portion and the flange root.

[0087] Optionally, in embodiments, the friction device may further include at least one protrusion extending from the extended volume portion of the friction material. The at least one protrusion is also complementary shaped to the shape of the flange and the flange root at a location of contact engagement between the at least one protrusion and the flange and flange root. The at least one protrusion may include a plurality of protrusions on the extended volume portion of the friction material. Also, one or more of the protrusions may have a first shaped portion nearest the backing plate and a second, differently shaped portion nearest the brake surface, e.g., the first shaped portion may be differently tapered than a taper of the second shaped portion.

[0088] Optionally, in embodiments, the friction device may also include at least one wheel conditioning insert disposed within the friction material and comprising a material different than the friction material. In one embodiment, the at least one wheel conditioning insert has an elongated portion that is offset from a central longitudinal axis of the brake surface and lying adjacent and generally parallel to the longitudinal rim side of the friction structure. In another embodiment, an entirety of the at least one wheel conditioning insert is offset from a central longitudinal axis of the friction device and lies adjacent and generally parallel to the longitudinal rim side of the friction material. In another embodiment, the at least one wheel conditioning insert is generally T-shaped relative to a surface of the insert that is parallel to the brake surface and includes a first elongated portion that is offset from a central longitudinal axis of the brake surface and lies adjacent and generally parallel to the longitudinal rim side of the friction structure, and a second elongated portion substantially perpendicular to the first portion and extending toward the longitudinal flange side of the friction structure. In another embodiment, the at least one wheel conditioning insert includes a plurality of wheel conditioning inserts disposed within the friction material. An entirety of each of the wheel conditioning inserts is offset from a central longitudinal axis of the friction device and lies adjacent and generally parallel to the longitudinal rim side of the friction structure.

[0089] Optionally, in embodiments, the friction structure may define at least one void in the friction material. The void is defined by an opening in the friction structure coincident with the brake surface and one or more sidewalls extending into the friction structure down from the opening. For example, the opening may be oval, circular, or polygonal in shape.

[0090] In an embodiment, a friction device (e.g., brake shoe) includes a friction structure (e.g., brake pad) having a brake surface, part of which (i.e., a tread region) is configured to engage a tread of a wheel to slow or stop movement of the wheel. The friction structure includes an extended volume portion disposed along a longitudinal flange side of the friction structure. A contact surface of the extended volume portion is complementary to a contour of a flange of the wheel adjacent to the tread, and the contact surface is configured to engage the flange when the friction structure is applied against the wheel. [0091] Optionally, in embodiments, the friction device also includes a backing plate adapted to interface with a brake actuator (e.g., brake head) of a vehicle that includes the wheel. The friction structure is secured to the backing plate.

[0092] Optionally, in embodiments, the contact surface of the extended volume portion is angled relative to tread region.

[0093] Optionally, in embodiments, the contact surface is arcuate, polygonal, S- shaped, or multi-segmented.

[0094] Optionally, in embodiments, the extended volume portion includes an exposed surface that extends above the flange of the wheel when the friction structure is applied against the wheel.

[0095] Optionally, in embodiments, the friction structure includes at least one protrusion extending from the extended volume portion. The contact surface of the extended volume portion is disposed between the at least one protrusion and the brake surface.

[0096] Optionally, in embodiments, the at least one protrusion has a shape that is complementary to the flange and is configured to contact the flange when the friction structure is applied against the wheel.

[0097] Optionally, in embodiments, each protrusion of the at least protrusion has a rectangular parallelepiped-shaped portion connected to a wedge-shaped portion. The wedge-shaped portion is disposed between the contact surface and the rectangular parallelepiped-shaped portion.

[0098] Optionally, in embodiments, the wedge-shaped portion tapers from the rectangular parallelepiped-shaped portion to the contact surface.

[0099] Optionally, in embodiments, the friction device further includes at least one wheel conditioning insert disposed within the friction structure along the brake surface. The at least one wheel conditioning insert is formed of a different material than the friction structure.

[00100] Optionally, in embodiments, the friction device further includes at least one void disposed within the friction structure along the brake surface.

[00101] In another embodiment, a friction device (e.g., brake shoe) for use on a vehicle includes a backing plate and a friction structure (e.g., brake pad) disposed on the backing plate. The backing plate adapted to interface with a brake actuator/system (e.g., brake head) of the vehicle. The friction structure is composed of a friction material that defines a brake surface, a tread region of which is configured to engage a tread of a wheel of the vehicle to slow or stop movement of the wheel. The friction structure includes an extended volume portion disposed along a longitudinal flange side of the friction structure. A contact surface of the extended volume portion is complementary to a contour of a flange of the wheel adjacent to the tread. The contact surface is configured to engage the flange when the friction structure is applied against the wheel.

[00102] Optionally, in embodiments, the contact surface of the extended volume portion is angled relative to the tread region of the brake surface.

[00103] Optionally, in embodiments, the contact surface is arcuate, polygonal, S- shaped, or multi-segmented.

[00104] Optionally, in embodiments, the extended volume portion includes an exposed surface that extends above the flange of the wheel when the friction structure is applied against the wheel.

[00105] Optionally, in embodiments, the friction structure includes at least one protrusion extending from the extended volume portion. The contact surface of the extended volume portion is disposed between the at least one protrusion and the brake surface. [00106] Optionally, in embodiments, the at least one protrusion includes multiple protrusions aligned in a row between the backing plate and the contact surface of the extended volume portion of the friction structure.

[00107] Optionally, in embodiments, the at least one protrusion has a shape that is complementary to the flange and is configured to contact the flange when the friction structure is applied against the wheel.

[00108] Optionally, in embodiments, the friction device further includes one or more of (i) at least one wheel conditioning insert disposed within the friction material along the brake surface or (ii) at least one void disposed within the friction material along the brake surface.

[00109] In another embodiment, a friction device (e.g., brake shoe) includes a friction structure (e.g., brake pad). The friction structure includes a brake surface that has a tread region configured to engage a tread of a wheel to slow or stop movement of the wheel. The friction structure includes an extended volume portion disposed along a longitudinal flange side of the friction structure. The extended volume portion includes a contact surface that is angled relative to the tread region and is complementary to a contour of a flange of the wheel adjacent to the tread. The contact surface is configured to engage the flange when the friction structure is applied against the wheel. The friction structure also includes at least one protrusion extending from the extended volume portion and configured to engage the flange when the friction structure is applied against the wheel. The contact surface of the extended volume portion is disposed between the at least one protrusion and the tread region.

[00110] In another embodiment, a method of forming a friction device for use on a vehicle may include providing a backing plate adapted to interface with a brake actuator (e.g., brake head) of the vehicle, and disposing a friction material onto the backing plate to form a friction structure that defines brake surface for engaging a wheel of the vehicle. The friction structure may include a longitudinal flange side, a longitudinal rim side, and two opposing ends. An extended volume portion of the friction material may be provided on the longitudinal flange side to at least partially engage a flange on the wheel of the vehicle when the friction device is applied against the wheel. The extended volume portion engaging the flange may align the brake surface of the friction structure with a wheel tread of the wheel. The brake surface of the friction device may be initially complementary shaped to a shape of the flange at a location of contact engagement between the extended volume portion and the flange. The method may also include providing a plurality of protrusions on the extended volume portion of the friction material. At least one of the protrusions may have a first shaped portion nearest the backing plate and a second shaped portion nearest the brake surface. The first shaped portion may be differently shaped from the second shaped portion. The first shaped portion may be differently tapered than a taper of the second shaped portion.

[00111] In another embodiment, a method of forming a friction device for use on a vehicle may include providing a backing plate as described herein, and, separately from the backing plate, forming a friction structure, comprising a friction material, that defines a brake surface for engaging a wheel of the vehicle. Then, the friction structure is secured to the backing plate, e.g., using an adhesive, thermocompression, welding, etc.

[00112] In any of the embodiments herein, the backing plate (and friction device more generally) may be flange-less, meaning lacking a U- or otherwise-shaped metal flange, attached to or otherwise part of the backing plate, for wrapping around and up and over a wheel flange for alignment purposes. By omitting a metal alignment flange, the friction device may be less expensive to manufacture while having improved braking properties. In other embodiments, and depending on the particular shape/configuration of the wheel with which the friction device is intended for use, the friction device, in addition to the friction structure having an extended volume portion, may be outfitted with a metal flange or other supplemental alignment features, for alignment of the friction device with the wheel during use. [00113] The singular forms“a,”“an,” and“the” include plural references unless the context clearly dictates otherwise.“Optional” or“optionally” means that the subsequently described event or circumstance may or may not occur, and that the description may include instances where the event occurs and instances where it does not. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it may be related. Accordingly, a value modified by a term or terms, such as“about,”“substantially,” and“approximately,” may be not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges may be identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

[00114] Spatial or directional terms, such as“left,”“right,”“inner,”“outer,”“above,� � “below,” and the like, relate to the disclosure as shown in the drawing figures and are not to be considered as limiting as the disclosure can assume various alternative orientations.

[00115] All numbers and ranges used in the specification and claims are to be understood as being modified in all instances by the term“about.” By“about” is meant plus or minus twenty- five percent of the stated value, such as plus or minus ten percent of the stated value. However, this should not be considered as limiting to any analysis of the values under the doctrine of equivalents.

[00116] Unless otherwise indicated, all ranges or ratios disclosed herein are to be understood to encompass the beginning and ending values and any and all subranges or sub-ratios subsumed therein. For example, a stated range or ratio of“1 to 10” should be considered to include any and all subranges or sub-ratios between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges or sub-ratios beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less. The ranges and/or ratios disclosed herein represent the average values over the specified range and/or ratio.

[00117] The terms“first”,“second”, and the like are not intended to refer to any particular order or chronology, but refer to different conditions, properties, or elements. The term“at least” is synonymous with“greater than or equal to”. The term“not greater than” is synonymous with“less than or equal to.” As used herein,“at least one of’ is synonymous with“one or more of.” For example, the phrase“at least one of A, B, and C” means any one of A, B, or C, or any combination of any two or more of A, B, or C. For example,“at least one of A, B, and C” includes one or more of A alone; or one or more B alone; or one or more of C alone; or one or more of A and one or more of B; or one or more of A and one or more of C; or one or more of B and one or more of C; or one or more of all of A, B, and C. The terms “includes,” “including,” “have,” and “having” are synonymous with“comprises.”

[00118] As used herein, the terms“parallel” or“substantially parallel” mean a relative angle as between two objects (if extended to theoretical intersection), such as elongated objects and including reference lines, that is from 0° to 5°, or from 0° to 3°, or from 0° to 2°, or from 0° to 1°, or from 0° to 0.5°, or from 0° to 0.25°, or from 0° to 0.1°, inclusive of the recited values. As used herein, the terms “perpendicular” or “substantially perpendicular” mean a relative angle as between two objects at their real or theoretical intersection is from 85° to 95°, or from 87° to 93°, or from 88° to 92°, or from 89° to 91°, or from 89.5° to 90.5°, or from 89.75° to 90.25°, or from 89.9° to 90.1°, inclusive of the recited values.