Patent Publication Number: US-2021190167-A1

Title: Elastomeric bearing for a suspension assembly

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/950,355 filed on Dec. 19, 2019, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention is directed to an elastomeric bearing with a split outer ring and an inner member with shim layers and layers of elastomeric materials disposed between the outer ring and the inner member, and more specifically to an elastomeric bearing with two shim layers for installation into a support linkage for use in a rail car suspension assembly. 
     BACKGROUND 
     Support linkages, particularly those incorporated into rail car suspension assemblies, are subject to significant reverse loading during operation. In other words, bearings incorporated into support linkages must withstand reversing loads along a longitudinal axis thereof, rotational forces in alternating directions or movement in both the clockwise and counterclockwise directions about either of two central axes of the bearing, which causes significant stress on components of the bearing. The opposite movements of the bearing about the central axes also impedes the ability of the bearing to remain fixed within the bore of the support linkage. The alternating angular movement of the inner member often results in movement of the bearing outer ring relative to the bore of the support linkage. 
     Methods of inserting elastomeric bearings in bores subject to reverse loading, such as is the case with support linkages, typically require heating of the support linkage to insert a bearing with an adequate interference fit between the bearing and the bore. This heating is an additional procedure that complicates assembly and can result in changes to the material properties affecting the strength and reliability of the support linkage and the connection between the bearing and the support linkage. The heating can also make the requisite interference fits between the bearing and bore difficult to achieve. 
     As a result, there exists a need in the art for an elastomeric bearing that accommodates reverse loading without requiring complicated assembly methods that impede the functionality of the bearing and surrounding member. 
     SUMMARY 
     The present invention includes an elastomeric bearing including an inner member that has a spherical exterior surface and is symmetric about a central axis C and a hollow annular outer structure that is axially split thereby forming a first outer segment and a second outer segment. The first outer segment and second outer segment form a substantially cylindrical exterior surface. One or more shim structures are formed around the inner member and are disposed at least partially inside the hollow annular outer structure. The shim structure has a radially outward facing surface and a radially inward facing surface. One or more layers of elastomeric material are disposed on each of the radially outward facing surface and the radially inward facing surface. 
     In some embodiments, the shim structure(s) include a first shim structure and a second shim structure. A portion of the first shim structure has a first spherical contour. The first shim structure is axially split, formed around the inner member and disposed at least partially inside the hollow annular outer structure. A portion of the second shim structure has a second spherical contour. The second shim structure is axially split, formed around the first shim structure and disposed at least partially inside the hollow annular outer structure. One or more layers of an elastomeric material including a first layer of elastomeric material bonded to the inner member and the first shim structure and extending continuously along the first shim structure; a second layer of the elastomeric material bonded to the first shim structure and the second shim structure and extending continuously along the second shim structure; and a third layer of the elastomeric material bonded to the second shim structure and the hollow outer structure and extending continuously along the hollow outer structure. 
     In some embodiments, in a relaxed state the first outer segment and the second outer segment are separated by a first gap and a second gap. Each of the first gap and the second gap is of a magnitude sufficient to allow the first outer segment and the second outer segment to engage each other in a compressed state to compress the first outer segment and the second outer segment over the first layer, the second layer and the third layer of the elastomeric material to a predetermined compression and to configure the cylindrical exterior surface of the outer structure for press fitting into a bore of a housing and maintaining the outer structure in a fixed relation to the housing. 
     In some embodiments, the first outer segment and a second outer segment abut one another along circumferentially facing surfaces thereof. 
     In some embodiments, the abutment of first outer segment and a second outer segment is configured to limit compressive forces on the at least one layer of elastomeric material. 
     In some embodiments, the abutment of first outer segment and a second outer segment is configured to establish an interference fit of the hollow annular outer structure in a bore of a housing. 
     In some embodiments, the shim structure(s) (e.g., the first shim structure and/or the second shim structure) include at least two gaps therein which have opposing circumferentially facing surfaces that extend axially along the shim structures, for example the gaps have a spacing of about 5 mm to about 10 mm. 
     In some embodiments, the predetermined compression of the first segment and the second segment over the first layer, the second layer and the third layer of the elastomeric material causes the outer structure to elastically deform thereby maintaining a radially outward force to maintain the outer structure in a fixed relation to the housing. 
     In some embodiments, the predetermined compression of the first segment and the second segment over the first layer, the second layer and the third layer of the elastomeric material causes the outer structure to elastically deform thereby maintaining a radially outward force to maintain the outer structure in a fixed relation to the housing when the inner member is rotated up to 30 degrees relative to the outer structure about the central axis C. 
     In some embodiments, the hollow outer structure has an interior surface, and the inner member, the first shim structure, the second shim structure, and the interior surface have complementary shapes. 
     In some embodiments, the inner member comprises a spherical ball having a first mounting leg and a second mounting leg extending outwardly from the spherical ball in opposite directions. 
     In some embodiments, the first mounting leg has a first hole extending therethrough and the second mounting leg has a second hole extending therethrough. 
     The present invention includes a suspension linkage for a rail car suspension assembly that includes an elongate shaft which extends between a first end and a second end thereof along a longitudinal axis. A first head is formed proximate to the first end. The first head has a first bearing receiving bore extending through. The first head is perpendicular to the longitudinal axis. The first bearing receiving bore defines a first interior receiving surface. A second head is formed proximate to the second end. The second head has a second bearing receiving bore extending through the second head perpendicular to the longitudinal axis. The second bearing receiving bore defines a second interior receiving surface. A first elastomeric bearing and a second elastomeric bearing each have an inner member that has a spherical exterior surface which is symmetric about a central axis. Each of the elastomeric bearings includes a hollow annular outer structure that is axially split thereby forming a first outer segment and a second outer segment. The first outer segment and second outer segment form a substantially cylindrical exterior surface. The axial split is defined by opposing circumferentially faces on the first outer segment and the second outer segment. Each of the elastomeric bearings includes one or more shim structures that are formed around the inner member and are disposed at least partially inside the hollow annular outer structure. The shim structures have a radially outward facing surface and a radially inward facing surface. One or more layers of elastomeric material are disposed on each of the radially outward facing surface and the radially inward facing surface. The first elastomeric bearing is press fit into the first bearing receiving bore such that the cylindrical exterior surface of the outer structure is in fixed frictional engagement with the first interior receiving surface and the opposing circumferentially faces on the first outer segment and the second outer segment abut one another; and the second elastomeric bearing is press fit into the second bearing receiving bore such that the cylindrical exterior surface of the outer structure is in fixed frictional engagement with the second interior receiving surface and the opposing circumferentially faces on the first outer segment and the second outer segment abut one another. 
     In some embodiments, the shim structure(s) include a first shim structure and a second shim structure. A portion of the first shim structure has a first spherical contour. The first shim structure is axially split, formed around the inner member and disposed at least partially inside the hollow annular outer structure. A portion of the second shim structure has a second spherical contour. The second shim structure is axially split, formed around the first shim structure and disposed at least partially inside the hollow annular outer structure. One or more layers of an elastomeric material including a first layer of elastomeric material bonded to the inner member and the first shim structure and extending continuously along the first shim structure; a second layer of the elastomeric material bonded to the first shim structure and the second shim structure and extending continuously along the second shim structure; and a third layer of the elastomeric material bonded to the second shim structure and the hollow outer structure and extending continuously along the hollow outer structure. 
     In some embodiments, the first hole of the first elastomeric bearing and the first hole of the second elastomeric bearing are coaxial and the second hole of the first elastomeric bearing and the second hole of the second elastomeric bearing are coaxial. 
     In some embodiments, the first mounting leg of the first elastomeric bearing includes a first flat surface and the first mounting leg of the second elastomeric bearing includes a second flat surface. The second mounting leg of the first elastomeric bearing includes a third flat surface and the second mounting leg of the second elastomeric bearing comprises a fourth flat surface. The first flat surface and the second flat surface are parallel to each other; and the third flat surface and the fourth flat surface are parallel to each other. 
     In one embodiment of the suspension linkage, the predetermined compression of the first segment and the second segment of the outer structure over the first layer, the second layer and the third layer of the elastomeric material causes the outer structure to elastically deform. 
     In one embodiment of the suspension linkage, the fixed frictional engagement of the cylindrical exterior surface of the outer structure within the first interior receiving surface is maintained when the inner member is rotated up to 30 degrees relative to the outer structure, about the central axis C. 
     In one embodiment of the suspension linkage, the fixed frictional engagement of the cylindrical exterior surface of the outer structure within the second interior receiving surface is maintained when the inner member is rotated up to 30 degrees relative to the outer structure, about the central axis C. 
     There is also disclosed herein a jig assembly for installing the first elastomeric bearing and the second elastomeric bearing into the suspension linkage. The jig assembly includes a support system, a tapered die system, a press arrangement and an alignment rod. The support system has a first annular support and a second annular support. The first annular support has a first pocket and the second annular support has a second pocket. The first annular support is spaced apart from the second annular support. The first annular support has a first lateral opening and the second annular support has a second lateral opening that faces the first lateral opening. The tapered die system has a first tapered die and a second tapered die. The first tapered die is removably disposed on the first head, coaxial with the first annular support and the second tapered die is removably disposed on the second head, coaxial with the second annular support. The press arrangement has a first annular ram and a second annular ram. A first lateral slot extends radially through the first annular ram and an opening is on a first axial ram-end of the first annular ram. A second lateral slot extends radially through the second annular ram and an opening is on a second axial ram-end of the second annular ram. A first passage extends axially through the first annular ram and a second passage extends axially through the second annular ram. The first annular ram is removably disposed, coaxially on the first tapered die, such that the first lateral slot opens outwardly away from the first tapered die. The second annular ram is removably disposed, coaxially on the second tapered die, such that the second lateral slot opens outwardly away from the second tapered die. An alignment rod extends between a first rod-end and a second rod-end. A first portion of the rod, proximate to the first rod-end, is removably disposed in the first lateral slot and a second portion of the rod, proximate to the second rod-end, is removably disposed in the second lateral slot for alignment of the first elastomeric bearing and the second elastomeric bearing. For example, the first hole of the first elastomeric bearing is aligned with first hole of the second elastomeric bearing and the second hole of the first elastomeric bearing is aligned with the second hole of the second elastomeric bearing. 
     In one embodiment of the jig assembly, the support system removably retains the first head of the suspension linkage in the first pocket and removably retains the second head of the suspension linkage in the second pocket. 
     In one embodiment of the jig assembly, the first annular ram forces the first elastomeric bearing through the first tapered die, compressing the first segment of the outer structure of the first elastomeric bearing against the second segment of the outer structure of the first bearing and press fitting the first elastomeric bearing into the first bearing receiving bore. The second annular ram forces the outer structure of the second elastomeric bearing through the second tapered die, compressing the first segment of the outer structure of the second elastomeric bearing against the second segment of the outer structure of the second elastomeric bearing and press fitting the second bearing into the second elastomeric bearing receiving bore. 
     In one embodiment of the jig assembly, the first passage has a first anti-rotation arrangement therein to prevent rotation of the first mounting leg of the first elastomeric bearing when the mounting leg is disposed in the first anti-rotation arrangement. The second passage has an anti-rotation arrangement to prevent rotation of the first mounting leg of the second elastomeric bearing when the mounting leg is disposed in the second anti-rotation arrangement. 
     There is also disclosed herein, a method of installing the first elastomeric bearing and the second elastomeric bearing in a suspension linkage. The method includes providing the first bearing, a second bearing, a support system, a tapered die system, a press arrangement, an alignment rod and a suspension linkage. The support system has a first annular support with a first pocket and a second annular support with a second pocket. The first annular support is spaced apart from the second annular support. The first annular support has a first lateral opening and the second annular support has a second lateral opening that faces the first lateral opening. The tapered die system has a first tapered die and a second tapered die. The press arrangement has a first annular ram and a second annular ram. A first lateral slot extends radially through the first annular ram and an opening is on a first axial end of the annular ram. A second lateral slot extends radially through the second annular ram and opening is on a second axial end of the second annular ram. A first passage extends axially through the first annular ram and a second passage extends axially through the second annular ram. The alignment rod extends between a first rod end and a second rod end. The suspension linkage has an elongate shaft extending between a first end and a second end along a longitudinal axis L. A first head is formed proximate to the first end and a second head is formed proximate to the second end. The first head has a first bearing receiving bore, defining a first interior receiving surface, extending through the first head perpendicular to the longitudinal axis L. The second head has a second bearing receiving bore, defining a second interior receiving surface, extending through the second head perpendicular to the longitudinal axis L. The method includes positioning the first head in the first pocket of the first annular support and the second head in the second pocket of the second annular support. The method then includes positioning the first tapered die on the first head, coaxial with the first annular support and positioning the second tapered die on the second head, coaxial with the second annular support. The method then includes positioning the first bearings over the first tapered, positioning the second bearing over the second tapered die, aligning the first hole of the first of the bearing with the first hole of the second of the bearing and aligning the second hole of the first bearing with the second hole of the second of the bearing. The method then includes positioning the first annular ram over the first bearing, coaxially with the first tapered die, such that the first lateral slot opens outwardly away from the first tapered die and positioning the second annular ram over the second bearing, coaxially with the second tapered die, such that the second lateral slot opens outwardly away from the second tapered die. The method then includes positioning a first portion of the rod, proximate to the first rod end, in the first lateral slot and positioning a second portion of the rod, proximate to the second rod end, in the second lateral slot. The method includes applying a first force to the first annular ram to compress the first bearings in and through the first tapered die and out of the first tapered die into the first bearing receiving bore, such that the cylindrical exterior surface of the outer structure is in fixed frictional engagement with the first interior receiving surface of the first head and applying a second force to the second annular ram to compress the second bearing in and through the second tapered die and out of the second tapered die into the second bearing receiving bore, such that the cylindrical exterior surface of the outer structure is in fixed frictional engagement with the second interior receiving surface of the second head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a side view of a suspension linkage with two elastomeric bearings according to the present disclosure; 
         FIG. 2  depicts a top view of the suspension linkage with the two elastomeric bearings of  FIG. 1 ; 
         FIG. 3  depicts an isometric view of the suspension linkage with the two elastomeric bearings of  FIG. 1 ; 
         FIG. 4  depicts a side view of an elastomeric bearing according to the present disclosure; 
         FIG. 5  depicts a side cross-sectional view along line  5 - 5  of  FIG. 4  of the elastomeric bearing of  FIG. 4 ; 
         FIG. 6  depicts an isometric view of an elastomeric bearing in a relaxed state according to the present disclosure; 
         FIG. 7A  depicts a top view of the elastomeric bearing of  FIG. 6 ; 
         FIG. 7B  is a cross-sectional view of section  7 - 7  of  FIG. 6  for the portion highlighted by Detail  7 B of  FIG. 7A ; 
         FIG. 7C  is a cross-sectional view of the portion of the elastomeric bearing illustrated in  FIG. 7B  but shown in a compressed state in the second head of the suspension linkage of  FIG. 2 ; 
         FIG. 7D  is a cross-sectional view of another embodiment of the elastomeric bearing of the present invention with the layers of elastomeric material being completely separated from one another; 
         FIG. 8  depicts a partial side cross-sectional view of a jig assembly according to the present disclosure with a side view of an elastomeric bearing according to the present disclosure depicted therein; 
         FIG. 9  depicts a side cross-sectional view along line  9 - 9  of  FIG. 9  of the second annular ram and the second tapered die with a side view of the elastomeric bearing depicted therein; 
         FIG. 10  depicts a side cross-sectional view of a jig assembly, a suspension linkage, and two elastomeric bearings according to the present disclosure; 
         FIG. 11  depicts a side cross-sectional view of the jig assembly, the suspension linkage, and the two elastomeric bearings of  FIG. 10  with one of the elastomeric bearings installed in the suspension linkage; 
         FIG. 12  depicts an isometric view of a rail car suspension assembly and two suspension linkages according to the present disclosure; 
         FIG. 13  depicts an alternate isometric view of the rail car suspension assembly and two suspension linkages of  FIG. 12 ; 
         FIG. 14  is a partial view of the rail car suspension assembly and two suspension linkages of  FIG. 13 ; 
         FIG. 15A  is an isometric view of an annular ram according to the present disclosure; 
         FIG. 15B  is an alternate isometric view of the annular ram of  FIG. 15A ; 
         FIG. 15C  is another alternate isometric view of the annular ram of  FIG. 15A   
         FIG. 16  is a graph showing a plot of compression force on the outer structure versus decreasing gap size. 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIGS. 1-14 , an elastomeric bearing according to the present disclosure is generally designated by numeral  10 . 
     Referring to  FIGS. 4-7B , the elastomeric bearing  10  has an inner member  12  and a hollow outer structure  14  centered on a central axis C. The hollow outer structure  14  is axially split, forming a first segment  14 A and a second segment  14 B. As shown in  FIG. 5 , the first segment extends axially from a first axial end  14 XA to a second axial end  14 YA thereof. The second segment  14 B extends axially from a first axial end  14 XB to a second axial end  14 YB thereof. As shown in  FIG. 7A , the axial split of the outer structure  14  is defined by (a) a first circumferentially facing surface  14 A 1  on the first segment  14 A that extends from the first axial end  14 XA to the second axial end  14 YA thereof; (b) a second circumferentially facing surface  14 A 2  on the first segment  14 A that extends from the first axial end  14 XA to the second axial end  14 YA thereof (c) a first circumferentially facing surface  14 B 1  on the second segment  14 B that extends from the first axial end  14 XB to the second axial end  14 YB thereof and (d) a second circumferentially facing surface  14 B 2  on the second segment  14 B that extends from the first axial end  14 XB to the second axial end  14 YB thereof. The first segment  14 A and the second segment  14 B form a substantially cylindrical exterior surface  14 E that has an outer structure outside diameter. A first shim structure  16  is formed around the inner member  12  and is disposed at least partially inside the hollow outer structure  14 . Referring to  FIG. 7B , the first shim structure  16  is axially split, forming a first shim segment  16 A and a second shim segment  16 B that are separated from one another by two first spacings S 1 . In one embodiment, the two first spacings S 1  each having a magnitude of about 5 mm to about 10 mm. A second shim structure  18  is formed around the first shim structure  16  and is disposed at least partially inside the hollow outer structure  14 . The second shim structure  18  is axially split, forming a third shim segment  18 A and a fourth shim segment  18 B that are separated from one another by two second spacings S 2 . In one embodiment, the two second spacings S 2  each having a magnitude of about 5 to about 10 mm. 
     As shown in  FIG. 7B , the outer structure  14  has a radial thickness T 14 , the first shim structure  16  has a radial thickness T 16  and the second shim structure  18  has a radial thickness T 18 . In one embodiment, the radial thicknesses T 14 , T 16  and T 18  are of equal magnitudes. In some embodiments, the radial thicknesses T 14 , T 16  and T 18  have different magnitudes, including but not limited to the radial thickness T 14  being greater than the radial thicknesses T 16  and T 18 ; the radial thickness T 16  being greater than the radial thicknesses T 14  and T 18 ; and the radial thickness T 18  being greater than the radial thicknesses T 14  and T 16 . 
     The inner member  12 , the outer structure  14  and the first and second shim structures  16 , 18  are made from metallic materials such as, but not limited to, steel alloys such as 4300 series steel, e.g., 17CrNiMo6 (18CrNiMo7-6) and in particular AISI 4340, carbon steel such as AISI 1035 or AISI 1045 (equivalent to C35, C45 or C45E) and precipitation hardening steels, such as 17-4PH, PH13-8Mo, and 15-5PH. In one embodiment, all of the inner member  12 , the outer structure  14  and the first and second shim structures  16 , 18  are made from the same material. In another embodiment, the inner member  12 , the outer structure  14  and the first and second shim structures  16 , 18  are made from different materials. 
     Referring to  FIG. 7B , a first layer  20  of elastomeric material (e.g., a vulcanizable elastomeric compound) is bonded (e.g., via vulcanization or via an adhesive such as epoxy or phenolic resin) to aspherical exterior surface of the inner member  12  and the first shim structure  16 . A second layer  22  of elastomeric material is bonded (i.e., e.g., via vulcanization or via an adhesive such as epoxy or phenolic resin) to the first shim structure  16  and the second shim structure  18 . A third layer  24  of elastomeric material is bonded (i.e., e.g., via vulcanization or via an adhesive such as epoxy or phenolic resin) to the second shim structure  18  and the hollow outer structure  14 . It is contemplated that the first layer  20  of the elastomeric material, the second layer  22  of the elastomeric material, and the third layer  24  of the elastomeric material are all the same material and are interconnected to one another via a single bonding process. However, different elastomeric materials can be used for the first layer  20 , the second layer  22 , and the third layer  24 , e.g., one elastomeric material can be used for the first layer  20  and a different elastomeric material can be used for the second layer  22  and the third layer  24 . Other combinations of elastomeric materials are within the scope of this invention. While the first layer  20  of the elastomeric material, the second layer  22  of the elastomeric material, and the third layer  24  of the elastomeric material are all the same material and are shown and described as being interconnected to one another via a single bonding process, the present invention is not limited in this regard as other configurations are within the scope of the present invention including but not limited to the first layer  20  of the elastomeric material, the second layer  22  of the elastomeric material, and the third layer  24  of the elastomeric material being separate from one another as illustrated, for example, in  FIG. 7D . 
     As shown in  FIG. 7B  the first layer  20  of the elastomeric material has a radial thickness T 20 , the second layer  22  of the elastomeric material has a radial thickness T 22 , and the third layer  24  of the elastomeric material has a radial thickness T 24 . In one embodiment, the radial thicknesses T 20 , T 22  and T 24  are of equal magnitudes. In some embodiments, the radial thicknesses T 20 , T 22  and T 24  have different magnitudes, including but not limited to the radial thickness T 20  being greater than the radial thicknesses T 22  and T 24 ; the radial thickness T 22  being greater than the radial thicknesses T 20  and T 24 ; and the radial thickness T 24  being greater than the radial thicknesses T 20  and T 24 . 
     In one embodiment, the surface of the first shim structure  16  and the surface of the second shim structure  18  are each treated or roughened (e.g., sand blasted) and one or more layers of primer is applied to the first shim structure  16  and the second shim structure  18  to ensure optimal bonding with the elastomeric material during vulcanization. The elastomeric material is injected under pressure between the first shim structure  16  and the second shim structure  18  and heated to obtain the vulcanization. Referring to  FIGS. 7A and 7B , the hollow outer structure  14  has an interior surface  14 F that is complementary in shape to the inner member  12 , the first shim structure  16 , and the second shim structure  18 . 
     In a relaxed state, as depicted in  FIGS. 6, 7A and 7B , before the hollow outer structure  14  is inserted into a bore  34 A,  34 B formed in a head  32 A,  32 B, respectively of the suspension linkage  30  (as depicted in  FIGS. 1-3 ), the first segment  14 A and the second segment  14 B are separated by a first gap G 1  at one end and a second gap G 2  at a second end opposite the first end (as depicted in  FIG. 6 ). The first gap G 1  is measured between the first circumferentially facing surface  14 A 1  of the first segment  14 A and the first circumferentially facing surface  14 B 1  of the second segment  14 B. The second gap G 2  is measured between the second circumferentially facing surface  14 A 2  of the first segment  14 A and the second circumferentially facing surface  14 B 2  of the second segment  14 B. In the relaxed state, the first gap G 1  and the second gap G 2  are each approximately 1 mm. The magnitude of each of the first gap G 1  and the second gap G 2  allows the first segment  14 A and the second segment  14 B to engage each other (i.e., the first circumferentially facing surface  14 A 1  of the first segment  14 A engages the first circumferentially facing surface  14 B 1  of the second segment  14 B; and the second circumferentially facing surface  14 A 2  of the first segment  14 A engages the second circumferentially facing surface  14 B 2  of the second segment  14 B). 
     As shown in  FIG. 7C  in a compressed state, in which the cylindrical exterior surface  14 E of the outer structure  14  is press fit into a bore (e.g., first bearing receiving bore  34 A of the first head  32 A and the second bearing receiving bore  34 B of the second head  32 B of  FIG. 2 ) of a housing (e.g., the first head  32   a  and the second head  32 B of  FIG. 2 ) to maintain the outer structure  14  in a fixed position relative to the housing. The spacing S 1  in the relaxed state (see  FIG. 7B ) between the first shim segment  16 A and the second shim segment  16 B is reduced in magnitude when in a compressed state ( FIG. 7C ) to a spacing S 1 ′ which is less than S 1 . The spacing S 2  in the relaxed state (see  FIG. 7B ) between the third shim segment  18 A and the fourth shim segment  18 B is reduced in magnitude when in a compressed state ( FIG. 7C ) to a spacing S 2 ′ which is less than S 2 . The magnitude of spacings S 1 ′ and S 2 ′ are greater than zero. The radial thickness of each of the first layer  20 , the second layer  22 , and the third layer  24  of the elastomeric material is between 2 mm and 3 mm in the relaxed stated. In the compressed state, the first layer  20 , the second layer  22  and the third layer  24  of the elastomeric material compress a predetermined amount. When assembled, each of the first layer  20 , the second layer  22  and the third layer  24  of the elastomeric material receives the same amount of stress to ensure an equal lifetime of each layer with beneficial fatigue properties to prevent localized failure of the elastomeric bearing  10  due to the failure of any single layer of elastomeric material. In one embodiment, the predetermined amount of compression is a maximum of 15% of the radial thickness of the layer of the elastomeric material in the relaxed state. The predetermined amount of compression of the first layer  20 , the second layer  22  and the third layer  24  of the elastomeric material causes the outer structure  14  to elastically deform, as described further herein. The elastic deformation of the outer structure  14  exerts a radially outwardly directed force to maintain the outer structure  14  in a fixed position relative to the housing. In the embodiment depicted in  FIGS. 1-3 , the outer structure  14  is fixed relative to the housing, but allows the inner member  12  to be rotated up to 30 degrees relative to the outer structure  14  about the central axis C. 
     Referring to  FIG. 5 , the inner member  12  is a spherical ball  12 B with a first mounting leg  13 A and a second mounting leg  13 B extending outwardly from the spherical ball  12 B in opposite directions, along the central axis C. A first hole  15 A extends through the first mounting leg  13 A and a second hole  15 B extends through the second mounting leg  13 B. The first hole  15 A penetrates the first mounting leg  13 A and the second hole  15 B penetrates the second mounting leg  13 B perpendicular to the central axis C. 
       FIGS. 1-3, 10 and 11  depict a suspension linkage  30  for a rail car suspension assembly  100  (depicted in  FIGS. 12-14 ) that incorporates two elastomeric bearings  10 . Referring to  FIGS. 1-3 , the suspension linkage  30  is an elongate shaft  31  extending between a first end  31 A and a second end  31 B along a longitudinal axis L. Referring to  FIG. 2 , the suspension linkage  30  has a first head  32 A formed proximate to the first end  31 A and a second head  32 B formed proximate to the second end  31 B. The first head  32 A has a first bearing receiving bore  34 A defined by a first interior receiving surface  33 A, extending through the first head  32 A, perpendicular to the longitudinal axis L and centered on the central axis C. The second head  32 B has a second bearing receiving bore  34 B defined by a second interior receiving surface  33 B, extending through the second head  32 B, perpendicular to the longitudinal axis L and centered on the central axis C. Both of the first interior receiving surface  33 A and the second interior receiving surface  33 B are cylindrical and have a receiving surface inside diameter. A first bearing  10  is press fit into the first bearing receiving bore  34 A such that the cylindrical exterior surface  14 E of the outer structure  14  is in fixed frictional engagement with the first interior receiving surface  33 A of the first head  32 A. A second bearing  10  is press fit into the second bearing receiving bore  34 B such that the cylindrical exterior surface  14 E of the outer structure  14  is in fixed frictional engagement with the second interior receiving surface  33 B of the second head  32 B. The receiving surface inside diameter of each of the first receiving surface  33 A and the second receiving surface  33 B are slightly less in magnitude than the outer structure outside diameter of the exterior surface  14 E of the outer structure  14  to establish the press fit (i.e., interference fit). Referring to  FIG. 3 , the first hole  15 A and the second hole  15 B of each bearing  10  are parallel to one another. The first hole  15 A of the first of the bearings  10  is coaxial with the first hole  15 A of the second of the bearings  10  and the second hole  15 B of the first of the bearings  10  is coaxial with the second hole  15 B of the second of the bearings. 
     The predetermined compression of the first segment  14 A and the second segment  14 B over the first layer  20 , the second layer  22  and the third layer  24  of the elastomeric material in each bearing  10  within the suspension linkage  30  causes the outer structure  14  to elastically deform, as described further herein. The fixed frictional engagement of the cylindrical exterior surface  14 E of the outer structure  14  within the first interior receiving surface  33 A of the first head  32 A of the suspension linkage  30  is maintained when the inner member  12  is rotated up to 30 degrees relative to the outer structure  14 , about the central axis C. The fixed frictional engagement of the cylindrical exterior surface  14 E of the outer structure  14  within the second interior receiving surface  33 B of the second head  32 B of the suspension linkage  30  is maintained when the inner member  12  is rotated up to 30 degrees relative to the outer structure  14 , about the central axis C. 
     As shown in  FIGS. 12-14 , in one embodiment, the first head  32 A is positioned in a clevis  102 A, which extends out from a support plate  102  in the rail car suspension assembly  100 . The support plate  102  is pivotally coupled to the rail car suspension assembly  100 . As shown in  FIG. 13 , the suspension linkage  30  extends from the first end  31 A positioned in the clevis  102 A to the second end  31 B positioned in a second clevis  104 A located on the underside of the rail car suspension assembly  100 . 
     Referring to  FIGS. 8-11 , a jig assembly  50  is used to install a bearing  10  into the first bearing receiving bore  34 A and the second bearing receiving bore  34 B of the suspension linkage  30 . Referring to  FIG. 10 , the jig assembly  50  has a support system  51 , a tapered die system  60 , a press arrangement  70  and an alignment rod  80 . The support system  51  has a first annular support  52 A and a second annular support  52 B spaced apart from one another (as depicted in  FIGS. 10 and 11 ). The first annular support  52 A has a first pocket  53 A and a first lateral opening  54 A. The second annular support  52 B has a second pocket  53 B and a second lateral opening  54 B. The second lateral opening  54 B faces the first lateral opening  54 A. The support system  50  removably retains the first head  32 A of the suspension linkage  30  in the first pocket  53 A and removably retains the second head  32 B of the suspension linkage  30  in the second pocket  53 B. The first lateral opening  54 A and the second lateral opening  54 B provide longitudinally opposed stops for opposite ends of the suspension linkage  30 . 
     Referring to  FIG. 10 , the tapered die system  60  has a first tapered die  62 A and a second tapered die  62 B. The first tapered die  62 A is removably disposed on the first head  32 A of the suspension linkage  30 , above the first annular support  52 A. A first interior surface  63 A extends through the first tapered die  62 A, coaxial with the first pocket  53 A of the first annular support  52 A. The second tapered die  62 B is removably disposed on the second head  32 B of the suspension linkage  30 , above the second annular support  52 B. A second interior surface  63 B extends through the second tapered die  62 B, coaxial with the second pocket  53 B of the second annular support  52 B. 
     The press arrangement  70  has a first annular ram  70 A and a second annular ram  70 B. A first lateral slot  71 A extends radially through the first annular ram  70 A and opens towards a first axial end  72 A of the first annular ram  70 A. A second lateral slot  71 B extends radially through the second annular ram  70 B and opens towards a second axial end  72 B of the second annular ram  70 B. In the embodiment depicted in  FIGS. 8-11 , the first lateral slot  71 A and the second lateral slot  71 B are arranged parallel to the longitudinal axis L. A first passage  74 A extends axially through the first annular ram  70 A from the first lateral slot  71 A to a third axial end  72 C of the first annular ram  70 A. A second passage  74 B extends axially through the second annular ram  70 B from the second lateral slot  71 B to a fourth axial end  72 D of the second annular ram  70 B. The first annular ram  70 A is removably disposed on a bearing  10  retained within the first tapered die  62 A with the first passage  74 A of the first annular ram  70 A coaxial with the first tapered die  62 A such that the first lateral slot  71 A opens outwardly away from the first tapered die  62 A. The second annular ram  70 B is removably disposed on the second tapered die  62 B with the second passage  74 B of the second annular ram  70 B coaxial with the second tapered die  62 B such that the second lateral slot  71 B opens outwardly away from the second tapered die  62 B. 
     The alignment rod  80  extends between a first rod end  80 A and a second rod end  80 B. A first portion of the rod  80 , proximate to the first rod end  80 A, is removably disposed in the first lateral slot  71 A of the first annular ram  70 A. A second portion of the rod  80 , proximate to the second rod end  80 B, is removably disposed in the second lateral slot  71 B of the second annular ram  70 B. The first lateral slot  71 A and the second lateral slot  71 B receive the alignment rod  80  to align the bearings  10  (specifically to align the first holes  15 A of each bearing  10  with each other and to align the second holes  15 B of each bearing  10  with each other). 
     Prior to installation in the suspension linkage  30 , a bearing  10  is retained within the first tapered die  62 A and a bearing  10  is retained within the second tapered die  62 B. The bearing  10  retained within the second tapered die  62 B is depicted, for exemplary purposes, in  FIG. 9 . The second interior surface  63 B of the second tapered die  62 B is angled, such that the diameter of the second interior surface  63 B proximate to a fifth axial end  64 A is large enough to accommodate the first segment  14 A and the second segment  14 B of the hollow outer structure  14  in the relaxed state. The diameter of the second interior surface  63 B proximate to a sixth axial end  64 B is small enough to accommodate the first segment  14 A and the second segment  14 B of the hollow outer structure  14  in the compressed state. The angle of the second interior surface  63 B, relative to the central axis C, ensures that the bearing  10  is retained within the second tapered die  62 B prior to insertion in the second interior receiving surface  33 B of the second head  32 B. In order to insert a bearing  10  in each of the first head  32 A and the second head  32 B of the suspension linkage  30 , the first annular ram  70 A forces a first of the bearings  10  through the first tapered die  62 A, compressing the first segment  14 A of the outer structure  14  of the first of the bearings  10  against the second segment  14 B of the outer structure of the first of the bearings  10  and press fitting the first of the bearings  10  into the first bearing receiving bore  34 A. The second annular ram  70 B forces the outer structure  14  of a second of the bearings  10  through the second tapered die  62 B (as depicted in  FIG. 8 ), compressing the first segment  14 A of the outer structure of the second of the bearings  10  against the second segment  14 B of the outer structure of the second of the bearings  10  and press fitting the second of the bearings  10  into the second bearing receiving bore  34 B. The structure and functionality of the first tapered die  62 A is the same as that of the second tapered die  62 B as described above with reference to  FIGS. 8 and 9 . In the embodiment depicted in  FIGS. 8-11 , the first interior surface  63 A and the second interior surface  63 B are each angled relative to the central axes C between 1° and 5° to create a frustoconical surface. 
     As shown in  FIG. 7C , the first segment  14 A and the second segment  14 B of the outer structure  14  are elastically deformed (i.e., press fit or interference fit) into the second bearing receiving bore  34 B such that the cylindrical exterior surface  14 E of the outer structure  14  is in fixed frictional engagement with the second interior receiving surface  33 B of second head  32 B of the suspension linkage  30  (see  FIG. 3 ). The first head  32 A of the suspension linkage  30  is configured similar to the second head  32 B. The elastic deformation of the first segment  14 A and the second segment  14 B of the outer structure  14  is slight compared to elastic deformation (i.e., compression) of the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material. Thus the majority of the elastic deformation is in the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material. 
     The compression of the first segment  14 A and the second segment  14 B of the outer structure  14  causes the elastic deformation (i.e., compression) of the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material and has utility in keeping the outer structure  14  in fixed relation to the second interior receiving surface  33 B of second head  32 B of the suspension linkage  30  (see  FIG. 3 ) during reversing loads and motions. 
     In addition, the compression of the first segment  14 A and the second segment  14 B of the outer structure  14  causes the elastic deformation (i.e., compression) of the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material and has utility in imparting an initial compressive stress in the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material which results in better stiffness behavior and also helps in fatigue resistance of the elastomeric bearing  10  which is configured to withstand more than ten million cycles of reverse loading, oscillation and motion in two rotational axes. 
     The gap G 1  has utility in limiting the compressive force on the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material to a predetermined maximum to prevent damage thereto. As shown in  FIG. 16 , a graph  800  has an X-axis  800 X which represents decreasing magnitude of the first gap G 1  and the second gap G 2 ; and a Y-axis which represents compressive force. The compressive force shown is either of the force applied to the outer structure  14  and the force applied to the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material through the outer structure  14 . A section  888  of the graph  800  shows that as compressive force increases from zero to a threshold force FT the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material are all being compressed. As the as compressive force increases from zero to a threshold force FT the first segment  14 A and the second segment  14 B of the outer section  14  are moved towards each other but are not elastically deformed. The graph  800  illustrates an inflection point GO which illustrates that when the first gap G 1  and the second gap G 2  reach a magnitude of zero and as the compressive force is increased above the threshold force FT compression of the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material ceases as shown by the flat section  880  of the graph. As shown in section  999  of the graph, the compressive force is increased above the threshold force FT towards an interference fit force FI, the outer section  14  begins to elastically deform in compression as indicated by the dashed line section  900  of the graph showing a steep slope, while the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material are no longer compressed and are therefore protected from excessive compression. 
     The inventors have surprisingly discovered that establishing the magnitude of the first gap G 1  and the second gap G 2  at a predetermined magnitude to accomplish the optimum compression of the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material and limiting that compression by having the first gap G 1  and the second gap G 2  close to zero by having the first segment  14 A and the second segment  14 B engage each other (i.e., the first circumferentially facing surface  14 A 1  of the first segment  14 A engages the first circumferentially facing surface  14 B 1  of the second segment  14 B; and the second circumferentially facing surface  14 A 2  of the first segment  14 A engages the second circumferentially facing surface  14 B 2  of the second segment  14 B) also impart an optimum configuration for press fitting the elastomeric bearing  10  in the first bearing receiving bore  34 A and the second bearing receiving bore  34 B to prevent the elastomeric bearing  10  from moving under reversing loading and motion. Thus, the configuration of the first gap G 1  and the second gap G 2  and the compression of the outer structure  14  to close the gap to zero solves the problem of excessive compression of the first layer  20  of elastomeric material, the second layer  22  of elastomeric material and third layer  24  of elastomeric material, problems associated with slippage and movement of bearing in a housing and the problems associated with having housings with various bore diameters that make it difficult to achieve a proper press fit. For example, the inventors have surprisingly discovered that if the first gap G 1  and the second gap G 2  were not closed to zero, that the resultant bearings were sensitive to housing diameter, susceptible to excessive compression of the elastomeric material and negatively impacted fatigue properties of the bearing due to inadequate or excessive compression of the elastomeric material and undesirable slippage of the bearing in the housing. 
     Referring to  FIGS. 15A-15C , the first annular ram  70 A forms a cylindrical member surrounding the first passage  74 A extending between a first end  79 A and a second end  79 C. The second end  79 C of the first annular ram  70 A is defined at an outer surface  73 A by a first ram abutment surface  81 A. A first recess  83 A extends from the first ram abutment surface  81 A towards the first end  79 A of the first annular ram  70 A and in the radially inward direction (towards the central axis C) to the first passage  74 A. In the embodiment depicted in  FIGS. 15A-15C , two first ram bores  85 A penetrate the outer surface  73 A the first annular ram  70 A between the first end  79 A and the second end  79 C. Each of the first ram bores  85 A extends from the outer surface  73 A, at least partially through the first passage  74 A, to the outer surface  73 A. The first ram bores  85 A are spaced apart and parallel to one another and are each aligned generally parallel to the longitudinal axis L. In the embodiment depicted in  FIGS. 15A-15C , the first lateral slot  71 A is centered between and arranged generally parallel to the two first ram bores  85 A. The locations of the first ram bores  85 A are configured such that one first ram bore  85 A can be arranged to one side of the first mounting leg  13 A and the other first ram bore  85 A can be arranged to the other side of the first mounting leg  13 A of an inner member  12 . Each of the first ram bores  85 A receives a first anti-rotation member  75 A (e.g., a pin) that projects into the first passage  74 A of the first annular ram  70 A. The first anti-rotation members  75 A accommodate the first mounting leg  13 A and engage opposing sides of the first mounting leg  13 A to prevent rotation of the first mounting leg  13 A of a first of the bearings  10  about the central axis C. 
     Referring to  FIGS. 15A-15C , the second annular ram  70 B forms a cylindrical member surrounding the second passage  74 B extending between a first end  79 B and a second end  79 D. The second end  79 D of the second annular ram  70 B is defined at an outer surface  73 B by a second ram abutment surface  81 B. A second recess  83 B extends from the second ram abutment surface  81 B towards the first end  79 B of the second annular ram  70 B and in the radially inward direction (towards the central axis C) to the second passage  74 B. In the embodiment depicted in  FIGS. 15A-15C , two second ram bores  85 B penetrate the outer surface  73 B the second annular ram  70 B between the first end  79 B and the second end  79 D. Each of the second ram bores  85 B extends from the outer surface  73 B, at least partially through the second passage  74 B, to the outer surface  73 B. The second ram bores  85 B are spaced apart and parallel to one another and are each aligned generally parallel to the longitudinal axis L. In the embodiment depicted in  FIGS. 15A-15C , the second lateral slot  71 B is centered between and arranged generally parallel to the two second ram bores  85 B. The locations of the second ram bores  85 B are configured such that one second ram bore  85 B can be arranged to one side of the first mounting leg  13 A and the other second ram bore  85 B can be arranged to the other side of the first mounting leg  13 A of an inner member  12 . Each of the second ram bores  85 B receives a second anti-rotation member  75 B (e.g., a pin) that projects into the second passage  74 B of the second annular ram  70 A. The second anti-rotation members  75 B accommodate the first mounting leg  13 A and engage opposing sides of the first mounting leg  13 A to prevent rotation of the first mounting leg  13 A of a second of the bearings  10  about the central axis C. 
     The first recess  83 A and the second recess  83 B provide axial space for accommodating an edge of the first shim structure  16  and the second shim structure  18  that project beyond the outer structure  14 . The first ram abutment surface  81 A and the second ram abutment surface  81 B axially engage the outer structure  14  to translate a force exerted by the user from the first annular ram  70 A or the second annular ram  70 B to each of the bearings  10 , as discussed in detail below. In the embodiment depicted in  FIGS. 15A-15C , each of the first anti-rotation members  75 A and the second anti-rotation members  75 B are cylindrical pins, but other types of retainers do not depart from the present disclosure. 
     A method of installing the bearings  10  in the suspension linkage  30  using the jig assembly  50  is also disclosed herein. The method of installing the bearings  10  begins by providing a first of the bearings  10 , a second of the bearings  10 , a support system  51 , a tapered die system  60 , a press arrangement  70 , an alignment rod  80  and a suspension linkage  30  of a rail car suspension system  100  as disclosed herein. A user positions the first head  32 A of the suspension linkage  30  in the first pocket  53 A of the first annular support  52 A and positions the second head  32 B of the suspension linkage  30  in the second pocket  53 B of the second annular support  52 B. The user positions the first tapered die  62 A on the first head  32 A, coaxial with the first annular support  52 A and the second tapered die  62 B on the second head  32 B, coaxial with the second annular support  52 B. The user positions the first of the bearings  10  over the first tapered die  62 A and the second of the bearings  10  over the second tapered die  62 B, aligning the first of the bearings  10  with the second of the bearings  10 . The user positions the first annular ram  70 A over the first of the bearings  10  coaxially with the first tapered die  62 A such that the first lateral slot  71 A opens outwardly away from the first tapered die  62 A and positions the second annular ram  70 B over the second of the bearings  10  coaxially with the second tapered die  62 B such that the second lateral slot  71 B opens outwardly away from the second tapered die  62 B. The method then includes inserting a first anti-rotation member  75 A in each of the two first ram bores  85 A such that each first anti-rotation member  75 A engages the first mounting leg  13 A of one of the bearings  10  and inserting a second anti-rotation member  75 B in each of the two second ram bores  85 B such that each second anti-rotation member  75 B engages the first mounting leg  13 A of the second of the bearings  10 . The method of installation involves placing a first portion of the rod  80  proximate the first rod end  80 A in the first lateral slot  71 A and placing a second portion of the rod  80  proximate the second rod end  80 B in the second lateral slot  71 B. The user applies a first force F 1  to the first annular ram  70 A, along the central axis C towards the first head  32 A, compressing the first of the bearings  10  in and through the first tapered die  62 A and out of the first tapered die  62 A into the first bearing receiving bore  34 A, such that the cylindrical exterior surface  14 E of the outer structure  14  is in fixed frictional engagement with the first interior receiving surface  33 A of the first head  32 A (as depicted in  FIG. 11 ). The user applies a second force F 2  to the second annular ram  70 A, along the central axis C towards the second head  32 B, compressing the second of the bearings  10  in and through the second tapered die  62 B and out of the second tapered die  62 B into the second bearing receiving bore  34 B such that the cylindrical exterior surface  14 E of the outer structure  14  is in fixed frictional engagement with the second interior receiving surface  33 B of the second head  32 B. In the embodiment depicted in  FIGS. 8-11  the alignment rod  80  is free to move out of the first lateral slot  71 A and the second lateral slot  71 B in a direction away from the press arrangement  70  and the first rod end  80 A and the second rod end  80 B are free to translate in a generally longitudinal direction (parallel to longitudinal axis L). 
     While the present disclosure has been described with reference to various exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.