CN111836733A

CN111836733A - Lever pin bushing for vehicle suspension

Info

Publication number: CN111836733A
Application number: CN201980018716.5A
Authority: CN
Inventors: R·J·齐默曼; H·克伦迪安; J·梅里曼
Original assignee: Hendrickson USA LLC
Current assignee: Hendrickson USA LLC
Priority date: 2018-01-12
Filing date: 2019-01-09
Publication date: 2020-10-27
Also published as: MX2020007465A; AU2019206508A1; WO2019140004A1; EP3737570A1; AU2019206508B2; CA3088137A1

Abstract

A bar pin bushing assembly (400), the bar pin bushing assembly (400) comprising: a bar pin (220) having at least one end with at least one aperture (221) to receive a fastener, the at least one aperture (221) extending through the at least one end, the bar pin (220) having a central portion (26), the central portion (26) having a diameter greater than a width or diameter of the at least one end of the bar pin (220); a compressible rubber section (242) positioned around a central portion of the bar pin (220), the compressible rubber section (242) further extending around a downwardly tapered surface adjacent the central portion of the bar pin (220); an outer metal shell (232) mold bonded to the compressible rubber section (242); a first disc insert (260a) positioned on a first end of the outer metal shell (232); a second disc insert (260b) positioned on a second end of the outer metal shell (232); and a tubular outer metal wall (250) positioned over the outer metal shell (232), the first disk insert (260a), and the second disk insert (260 b).

Description

Lever pin bushing for vehicle suspension

Priority requirement

This application claims priority from us patent application No. 15/869,834 entitled Bar Pin Bushing for vehicle suspension filed on 12.1.2018, which is incorporated herein by reference in its entirety.

Technical Field

The present application relates generally to bushings used to connect components in vehicle systems, such as suspension and axle systems/subsystems. More particularly, the present application relates to an improved spherical beam end bushing that may be used in heavy haul truck applications.

Background

Bar pin bushing assemblies for use in vehicle systems, such as suspensions, are known. Such assemblies may be used to connect different components of a vehicle system, such as beams, brackets, arms, clamps, frames, rails, rods, and other similar components. A rotatable bar pin bushing is disclosed in U.S. patent No. 8,579,510 issued on 11/12/2013. The spherical rubber bushing design is also designed to use a snap ring to hold the parts together. A moderate level of pre-compression of the rubber can be achieved by loading in the axial direction.

In heavy truck applications, at high articulation angles, the bushing must be very robust to withstand high radial and axial loads, as well as high articulation angles that may be encountered in operation. The sleeve design with snap ring connection is not robust for heavy truck applications. In heavy truck applications, high radial and axial load capacity is desirable.

In view of the conditions identified above with respect to existing bar pin bushing assemblies for vehicle systems, such as suspension and axle systems/subsystems, it would be desirable to provide a new and improved bar pin bushing assembly that may be used in heavy duty truck applications, where high radial and axial loading may be encountered, and high articulation angles may be required. It is desirable to provide a bar pin bushing assembly that allows for a more uniform stress distribution for improved bushing fatigue and improved radial and axial load capacity.

Disclosure of Invention

A bar pin bushing assembly for connecting components in a vehicle system, such as a suspension or axle system/subsystem, is disclosed herein. The bushing assembly includes a bar pin compressible rubber section positioned about a central portion of the bar pin and advantageously includes a plurality of outer metal shell segments mold bonded to the compressible rubber section. When the bushing is inserted into the tubular outer metal wall, the plurality of outer metal shell segments move radially inward to compress the compressible rubber section to provide a rubber bushing assembly for substantial pre-compression. Such precompression provides for more uniform stress distribution and improved bushing fatigue, and also allows for higher radial and axial load capacity. The bar pin, the compressible rubber section and the plurality of outer metal shell segments may also advantageously be inserted into the tubular outer metal wall. Disk inserts may be positioned on the ends of the plurality of outer metal shell segments and within the ends of the tubular outer metal wall to provide increased hoop strength at the ends of the bar pin bushing assembly.

Additionally, axial or longitudinal voids may be formed in the compressible rubber section during the molding process. When the plurality of outer metal shell segments are moved radially inward to compress the compressible rubber section during insertion into the tubular outer metal wall, the rubber may move into the void and the longitudinal edges of the plurality of outer metal shell segments may come together.

In one aspect, a bar pin bushing assembly for connecting components in a vehicle system is provided, comprising: a bar pin having at least one end with at least one aperture extending therethrough to receive a fastener, the bar pin having a central portion with a diameter greater than a width or diameter of the at least one end of the bar pin; a compressible rubber section positioned around the central portion of the bar pin, the compressible rubber section further extending around a downwardly tapered surface adjacent the central portion of the bar pin; an outer metal shell mold bonded to the compressible rubber section; a first disc insert positioned on the first end of the outer metal shell; a second disc insert positioned on the second end of the outer metal shell; and a tubular outer metal wall positioned over the outer metal shell, the first disk insert, and the second disk insert.

Also disclosed herein is a method for assembling a bar pin bushing assembly, the method comprising the steps of: (i) providing a bar pin having at least one end with at least one aperture extending through the at least one end for receiving a fastener, the bar pin having a central portion having a diameter greater than a width or diameter of the at least one end of the bar pin; (ii) positioning an outer metal shell around the bar pin; (iii) injecting molten rubber into the space between the central portion of the bar pin and the inner surface of the outer metal shell to form a compressible rubber section; (iv) inserting a bar pin and a compressible rubber section into the tubular outer metal wall; (v) positioning an inner surface of the first disc insert into engagement with an outer surface of the first end of the outer metal shell and positioning an outer surface of the first disc insert into engagement with an inner surface of the first end of the tubular outer metal wall; (vi) positioning an inner surface of the second disk insert into engagement with an outer surface of the second end of the outer metal shell and positioning an outer surface of the second disk insert into engagement with an inner surface of the second end of the tubular outer metal wall; (v) forcing the inner surface of the first end of the tubular outer metal wall into further engagement with the outer surface of the first disc insert; and (vi) forcing the inner surface of the second end of the tubular outer metal wall into further engagement with the outer surface of the second disc insert.

Drawings

Exemplary embodiments of the invention are described herein with reference to the drawings, wherein like parts are designated by like reference numerals, and wherein:

FIG. 1A is a perspective view of an exemplary embodiment of a bar pin bushing assembly 10.

FIG. 1B is a longitudinal right side view of the bar pin bushing assembly 10 shown in FIG. 1A.

Fig. 2 is a cross-sectional front view of the bar pin bushing assembly 10 shown in fig. 1A and 1B.

FIG. 3 is a cross-sectional front view of a bar pin bushing assembly 10' further including a plastic bushing 60 and an intermediate sleeve 50.

FIG. 4 is a cross-sectional front view of the bar pin bushing assembly 10 "further including a rubber layer 80 and an intermediate sleeve 70.

Fig. 5A is a front view of bar pin bushing assembly 10 after insertion into spar hub 90 (with internal structures shown in phantom) and including

collars

100 and 100 a.

FIG. 5B is a cross-sectional front view of the bar pin bushing assembly 10 of FIG. 5A shown within the spar hub 90 and including the

collars

100 and 100 a.

FIG. 6A is a perspective view of the bar pin bushing assembly 10 positioned within the beam hub with the beam hub removed to show how the plurality of outer metal shells move and engage radially inward to compress the compressible rubber section when inserted within the beam hub.

FIG. 6B is a cross-sectional view of the bar pin bushing assembly 10 shown in FIG. 6A, showing the

collars

110 and 110a positioned on flanges extending from the ends of the multiple outer metal shells.

FIG. 7A is a perspective view of bar pin bushing assembly 10 positioned within spar hub 90 and including

collars

115 and 115a retained between the end of spar hub 90 and the extended flanges of the outer metal sections.

Fig. 7B is a cross-sectional view of the bar pin bushing assembly 10 shown in fig. 7A.

FIG. 8A is a perspective view of bar pin bushing assembly 10 positioned within spar hub 90 and including

collars

120 and 120a retained within the extended flanges of the outer metal sections.

Fig. 8B is a cross-sectional view of the bar pin bushing assembly 10 shown in fig. 8A.

FIG. 9A is a cross-sectional view of the bar pin bushing assembly 200 including a tubular outer metal wall 250.

FIG. 9B is an end view of the bar pin bushing assembly 200 shown in FIG. 9A prior to insertion into the tubular outer metal wall 250.

Fig. 9C is a perspective view of the bar pin bushing assembly 200 shown in fig. 9B.

Fig. 9D is a cross-sectional view of the bar pin bushing 200 shown in fig. 9B and 9C.

Fig. 9E is a cross-sectional view of the bar pin bushing 200 after insertion into the tubular outer metal wall 250.

Fig. 9F is an end view of the bar pin bushing assembly 200 shown in fig. 9E.

Fig. 9G is a perspective view of the bar pin bushing assembly 200 shown in fig. 9E and 9F.

Fig. 10A is a cross-sectional view of the bar pin bushing 200'.

Fig. 10B is a perspective view of the bar pin bushing 200' shown in fig. 10A.

Fig. 11 is a perspective view of the bar pin bushing 200 ".

Fig. 12A is a cross-sectional view depicting a first stage in an assembly method of the bar pin bushing 200 shown in fig. 9A-9G.

Fig. 12B is a cross-sectional view depicting a second stage in the method of assembling the bar pin bushing 200 shown in fig. 9A-9G prior to the crimping process.

Fig. 12C is a cross-sectional view depicting a third stage in the method of assembling the bar pin bushing 200 shown in fig. 9A-9G after the crimping process.

Fig. 13A is a cross-sectional view of a bar pin bushing 400 before the outer metal wall 250 and the disk inserts 260a and 260b are crimped, according to an example embodiment.

Fig. 13B is a cross-sectional view of the bar pin bushing 400 shown in fig. 13A after the ends of the outer metal wall 250 have been forced into engagement with the outer surfaces of the disk inserts 260a and 260B.

Fig. 14A is a side view of the disc insert 260B shown in fig. 13A and 13B according to an exemplary embodiment.

FIG. 14B is a cross-sectional view of the tray insert 260B taken along line 14B-14B in FIG. 14A.

Detailed Description

Fig. 1A-14B illustrate exemplary embodiments of a bar pin bushing assembly and components thereof, and methods of assembly. The bar pin bushing assembly shown in the figures provides a unique spherical bushing design that provides for high radial load capacity, high axial load capacity, and high articulation angle. As shown in fig. 1A, 1B and 2, a bar pin bushing assembly 10 is shown that includes a bar pin 20 having ends 20a, 20B and an end face 21A. End 20a includes a through bore 22a, and through bore 22a may be used to secure bar pin bushing assembly 10 to an axle set or other component of a vehicle or suspension. Similarly, end 20b includes a through hole 22b that may be used to secure the bar pin bushing assembly 10 to an axle set or other component of a vehicle or suspension. In particular, the bar pin bushing assembly 10 may be used to connect components in a variety of vehicle systems (such as vehicle suspension and/or axle systems/subsystems), as well as other applications that require the use of a bar pin bushing assembly for connecting components. For example, the lever pin bushing assembly 10 may be used to connect a walking beam to an axle bracket in a vehicle suspension/axle system, and may be used in heavy-duty vehicle applications, and may also be used in other applications. It should be understood that the term "vehicle" is used broadly herein to encompass all types of vehicles including, but not limited to, all forms of cars, trucks, buses, Recreational Vehicles (RVs), motorcycles, and the like. Further, for purposes of this description, the term "vehicle" refers herein to a vehicle or trailer unless specifically described otherwise. In this way, for example, the vehicle suspension system refers to a vehicle suspension or a trailer suspension.

The bar pin bushing assembly 10 includes an outer sleeve 30 made of a plurality of outer

metal shell segments

32, 34, 36 and 38 that are mold bonded to a rubber portion 40 positioned on the bar pin 20. Fig. 1A, 1B and 2 show a bar pin bushing assembly 10 prior to insertion into a beam hub (such as the hub of a walking beam).

As shown in fig. 1B, a plurality of axial or

longitudinal voids

43, 44, 45 and 46 are shown positioned in the rubber portion 40. In particular, the longitudinal void 43 is positioned below the gap between the longitudinal edge 32a of the outer metal shell 32 and the longitudinal edge 34b of the outer metal shell 34; the longitudinal void 44 is positioned below the gap between the longitudinal edge 32b of the outer metal shell 32 and the longitudinal edge 38a of the outer metal shell 38; the longitudinal void 45 is positioned below the gap between the longitudinal edge 38b of the outer metal shell 38 and the longitudinal edge 36a of the outer metal shell 36; and the longitudinal void 46 is positioned below the gap between the longitudinal edge 36b of the outer metal shell 36 and the longitudinal edge 34a of the outer metal shell 34.

The

longitudinal voids

43, 44, 45 and 46 may be defined in part by the configuration of the outer

metal shell segments

32, 34, 36 and 38. Referring to fig. 1B, the innermost portions (i.e., the portions closest to the bar pin 20) of the outer

metal shell segments

32, 34, 36 and 38 shown in fig. 1B have a smaller radial length (in radians) than the radial length (in radians) of the outermost portions of the outer

metal shell segments

32, 34, 36 and 38 shown in fig. 1B. As shown in fig. 1B, the

longitudinal edges

32a, 32B, 34a, 34B, 36a, 36B, 38a, and 38B may include two straight portions and a tapered middle portion connecting the two straight portions.

When the bushing assembly 10 is inserted into the spar hub, the plurality of outer

metal shell segments

32, 34, 36 and 38 are forced to move radially inward to compress the rubber portion 40 relative to the bar pin 20. As the plurality of outer

metal shell segments

32, 34, 36 and 38 are forced radially inward during insertion into the spar hub, gaps between adjacent longitudinal edges of the plurality of outer

metal shell segments

32, 34, 36 and 38 are eliminated and engaged. At the same time, during compression of the rubber section 40, rubber from the rubber section 40 is forced into the

longitudinal voids

43, 44, 45 and 46 to allow the rubber section to become compressed. The use of longitudinal voids in the rubber advantageously allows the amount and direction of rubber expansion to be controlled during assembly for uniform stress distribution and optimized performance. The use of longitudinal voids in the bushing facilitates expansion of the rubber in both the axial and tangential directions while bushing assembly 10 is compressed during insertion into the beam hub.

In the embodiment of the bushing assembly 10 shown in fig. 1A and 1B, there are four outer

metal shell segments

32, 34, 36 and 38 used. However, a lesser or greater number of outer metal shell segments may also be used, but four outer metal shell segments have been found to provide an acceptable design for the bushing assembly 10, as the stresses on the rubber section 40 are too high in heavy truck applications if only three outer metal shell segments are used, and effective bonding may be lost in heavy truck applications if more than four outer metal segments are used. Each outer metal shell segment may be formed by a stamping process. In other words, each outer metal shell segment may comprise a stamped outer metal shell segment.

Fig. 2 shows a cross-sectional view of the bushing assembly 10 shown in fig. 1A and 1B. A bar pin 20 having

ends

20a and 20b extends within an outer sleeve 30 and outer metal sleeve segments 32 and 36 (shown in fig. 2). In this embodiment, two through

holes

22a and 22b are shown for attachment to a vehicle or suspension member, such as a wheel axle support component. It is also possible that only a single through hole is provided on the bar pin 20, or that no through hole is used.

The bar pin 20 includes a central portion 26 having a diameter greater than the

ends

20a and 20b, with upwardly and inwardly sloping walls that increase in diameter, eventually becoming a flat outer cross-section with a constant outer diameter. A bushing assembly having a bar pin with inwardly and upwardly sloped walls to provide a larger diameter central portion having a uniform thickness rubber section around the central portion (with the rubber section extending in an arc around a downwardly tapered edge adjacent the central portion) may be referred to as a spherical bushing assembly having a spherical bar pin. The central portion 26 of the bar pin 20, which has a constant diameter, is positioned below the outer sleeve 30 of the bushing assembly 10 and (as shown in fig. 2) below the outer

metal shell segments

32 and 36. The central portion 26 having a constant diameter extends between the arrows showing the uniform thickness d of the rubber section 42 shown in fig. 2. The rubber sections 40 are mold bonded to the inner surfaces of the plurality of outer metal shell segments, including the

inner surfaces

32c and 36c of the outer

metal shell segments

32 and 36 shown in FIG. 2. In this embodiment of the bushing assembly 10, the rubber section is also mold bonded to the bar pin 20 including the central portion 26. In addition, the downwardly inclined section adjacent to the central portion 26 of the bar pin 20 may also be surrounded by a rubber section having a thickness d which is the same as the thickness d of the rubber area 42 surrounding the central portion 26 of the bar pin 20.

With such a configuration, the rubber section 40 includes a rubber section 42 having a uniform thickness. The rubber section 42 may be referred to as the "working" portion of the rubber section 40. A rubber section 42 having a uniform thickness d provides for significant advantages. In particular, the uniform thickness provides for a uniform stress distribution in the working rubber and maximizes rubber fatigue as compared to working rubbers with lower fatigue performance having non-uniform thickness.

In fig. 2, the bar pin 20 further comprises a circular portion 24 extending into the outer sleeve. The bushing assembly 10 also provides a high degree of articulation for the bar pin within the bushing assembly 10. In particular, the outer metal shell segments (including outer

metal shell segments

32 and 36 shown in fig. 2) are "adjusted" to allow the bar pin to articulate at a large angle. To provide for a large articulation angle, the ends of the outer metal shell segments, including outer

metal shell segments

32 and 36, have

outer ends

32d, 32e, 36d, and 36e, respectively, configured to allow articulation of bar pin 20 up to 11.2 degrees from the axial or longitudinal centerline of bar pin 20 before circular section 24 contacts end 32d or 36d of outer

metal shell segments

32 and 36 and prevents further articulation. The same is true for the

end portions

32e and 36 e. Smaller or larger articulation angles may also be provided depending on the application.

During insertion of the bushing assembly 10 into the beam hub, the working rubber section 42 is pre-compressed. For example, depending on the application, the rubber section 42 may be compressed 15% to 25%, or less. In one embodiment, the rubber section 42 is compressed from a thickness of 16.25mm to a thickness of 13mm when the bushing assembly is inserted into the beam hub.

Rubber sections

40 and 42 may comprise natural rubber, but synthetic rubber or other elastomeric materials may also be used for the rubber sections.

As mentioned above, the spherical bushing design of bushing assembly 10 begins with a bar pin 20, which bar pin 20 may be a high strength metal, such as 1045 or 1144 heat treatable high yield strength steel, which may be attached to the axle via fasteners. The bar pin 20 may comprise a forged pin having a rough texture to improve the bonding of the rubber to the bar pin 20. A unique rubber shape with a uniform wall thickness (rubber section 42) is mold bonded to the bar pin and to the outer metal shell. The

outer metal shells

32, 34, 36 and 38 are in multiple sections to accommodate rubber shrinkage after molding and to provide high radial precompression during assembly into the walking beam hub of the suspension. During assembly, the bushing assembly 10 is squeezed together in a radial direction, providing high radial and medium axial precompression. The

unique voids

43, 44, 45 and 46 in the bushing facilitate the expansion of the rubber in the axial and tangential directions as it is compressed during assembly. The large thin rubber section 42 with high precompression provides high radial and axial load bearing capability. The unique rubber shape of the rubber under shear provides conical compliance during articulation (conical rotation) of the bar pin 20 and allows for a high taper angle. The taper angle is controlled via features in the end of the outer metal shell that limit the maximum shear strain in the rubber by limiting the allowable articulation angle.

In some embodiments, the installed diameter of the bushing assembly 10 may be 117mm, and the uninstalled diameter may be 124 mm. The flats on

ends

20a and 20b of bar pin 20 may be 52mm by 48 mm. The overall length of the bar pin may be 272mm and the length of the outer metal shell may be 118mm, and the outer metal shell may be made of a rigid material, such as aluminum, stainless steel, brass, or other suitable material. The outer metal shell may be constructed as a stamped, cast or forged shell made of steel, iron, aluminum or other suitable material. Also, the outer metal shell may have a thickness of 4.76 mm.

Fig. 3 is a cross-section of the bushing assembly 10'. The bushing assembly 10' is constructed in the same manner as the bushing assembly 10 shown in fig. 1A, 1B and 2, including a plurality of outer metal shells (which include the outer metal shells 32 and 36), and

rubber sections

40 and 42, and the bar pin 20 having ends 20a and 20B shown in the cross-sectional view of fig. 2, with minor modifications (which will be described herein). In the bushing assembly 10', a slip feature is provided that allows the bar pin 20 to rotate or slip relative to the rubber section 42 and the plurality of outer metal shells. To provide for this slip feature, the rubber section 40 is not mold bonded to the central portion of the bar pin 20 as in the bushing assembly 10. Alternatively, the rubber section 42 having a uniform thickness as in the bushing assembly 10 is mold bonded to the intermediate sleeve 50, the intermediate sleeve 50 being positioned between the outer metal shell of the bar pin 20 and the central portion 26'. The intermediate sleeve 50 is in turn bonded to a plastic bushing 60 having an inner surface 60a in contact with the outer surface 26 'of the central portion 26' of the bar pin 20. The interface between the inner surface of plastic bushing 60a and outer surface 26a 'of bar pin 20 allows outer surface 26' of bar pin 20 to slip or rotate relative to inner surface 60a of plastic bushing 60.

With this configuration, the working portion or rubber section 42 is positioned between the inner surface of the outer metal shell segment (which includes the inner surface 32c of the outer metal shell 32 and the inner surface 36c of the outer metal shell 36) and the outer surface 50a of the intermediate sleeve 50. In addition, the intermediate sleeve 50 is positioned between the rubber section 42 and the upper surface 60b of the plastic bushing.

The ability to have slippage or rotation between the central portions 26a ' of bar pin 20 provides for an increase in the taper angle in bushing assembly 10' while also allowing for a high radial load capacity of bushing assembly 10 '. The bushing assembly 10' has a rubber section 42 that is mold bonded to an intermediate sleeve 50, which intermediate sleeve 50 may be a metal stamping to provide the desired uniform rubber shape. The ends of the intermediate sleeve may be forced downward during insertion into the spar hub as shown. The inner metal stamping may be bonded to plastic bushing 60, and plastic bushing 60 may be a polymer-based bushing, such as polyurethane, that provides free rotation (torsion and taper) and high wear resistance. In the bushing assembly 10', the metal stamping and the plastic or polymeric bushing may be combined by mold bonding the rubber directly to the combined metal stamping and polymeric bushing. The combination of the highly pre-compressed rubber bushing and the wear-resistant polymeric bushing ensures a relatively tight slip joint over the life of bushing assembly 10', which resists degradation due to harsh environmental conditions (e.g., corrosion).

The intermediate sleeve 50 and plastic bushing 60 may also be formed in multiple segments in the manner of the outer

metal shell segments

32, 34, 36 and 38 as shown in fig. 1A and 1B.

FIG. 4 is a cross-section of the bushing assembly 10 ". The bushing assembly 10 "is constructed in the same manner as the bushing assembly 10 shown in fig. 1A, 1B and 2, including a plurality of outer metal shells (which include the outer metal shells 32 and 36), and

rubber sections

40 and 42, and the bar pin 20 having ends 20a and 20B shown in the cross-sectional view of fig. 2, with minor modifications (which will be described herein). In bushing assembly 10 ", similar to bushing assembly 10' shown in fig. 3, a slip feature is provided that allows rotation or slippage of bar pin 20 relative to

rubber sections

40 and 42 and the plurality of outer metal shells. To provide this slip feature for use in bushing assembly 10 ", rubber section 40 is not mold bonded to the central portion of bar pin 20 as in bushing assembly 10. Alternatively, the rubber section 42 having a uniform thickness as in the bushing assembly 10 is mold bonded to the intermediate sleeve 70, the intermediate sleeve 70 being positioned between the central portion 26' of the bar pin 20 and the outer metal shell. The thin rubber layer 80 is also molded under the intermediate sleeve 70 such that the upper surface 70a of the intermediate sleeve 70 is positioned under the working rubber section 42 and the lower surface 70b of the intermediate sleeve 70 is positioned over the thin rubber layer 80. The interface between the inner surface of the thin rubber layer 80 and the outer surface 26'a of the bar pin 20 allows slippage or rotation of the outer surface 26a' of the bar pin relative to the inner surface of the thin rubber bushing 80.

With this configuration, the working portion or rubber section 42 is positioned between the inner surface of the outer metal shell segment (which includes the inner surface 32c of the outer metal shell 32 and the inner surface 36c of the outer metal shell 36) and the outer surface 70a of the intermediate sleeve 70.

As mentioned with respect to the bushing assembly 10 'shown in fig. 3, the ability to have slippage or rotation between the central portion 26a' of the bar pin 20 and the thin rubber layer 80 provides for an increase in the taper angle in the bushing 10 ", while also allowing for a high radial load carrying capacity of the bushing assembly 10", while also allowing for a high taper angle. The bushing assembly 10 "has a rubber section 42 mold bonded to an intermediate sleeve 70, which intermediate sleeve 70 may be a metal stamping, cast metal (iron or aluminum), forged steel, or plastic insert to provide the desired uniform rubber shape. The combination with the highly pre-compressed rubber bushing of the thin metal layer ensures a relatively tight slip joint over the life of the bushing assembly 10', which resists degradation due to harsh environmental conditions (e.g., corrosion).

In the bushing assembly 10 ", the main" working "rubber section 42 is mold bonded to the outside of the intermediate sleeve 70, which may be a plastic or metal feature. In addition, there is a secondary membrane of rubber 80 near the central portion 26' of the bar pin 20 that allows the sleeve to slip at high twist or taper angles. The rubber membrane 80 is mold bonded to the inner surface of the plastic or metal feature and also holds the joint tight for improved corrosion resistance. For the two alternative bushing assemblies 10 'and 10 ″ shown in fig. 3 and 4, the intermediate sleeve or plastic bushing (in bushing assembly 10') may be segmented (e.g., via a "slit" or slits in metal or plastic) to facilitate assembly and high radial precompression. Assembly may occur before or after molding depending on design details.

The

bushing assemblies

10, 10', and 10 ″ shown in fig. 1A, 1B, 2, 3, and 4 advantageously include

outer metal shells

32, 34, 36, and 38 in multiple segments to allow for a high level of radial precompression when installed into the walking beam hub of the suspension. High radial precompression results in high radial stiffness and load bearing capacity while the spherical shape provides a high taper angle for suspension articulation. The curved end features of the

outer metal shells

32, 34, 36 and 38 provide axial precompression in the rubber and therefore high axial load capacity. The taper angle of the hinge is controlled by design features in the end of the outer metal shell that limit the maximum rubber strain level. Uniquely shaped axial or

longitudinal voids

43, 44, 45 and 46 in the rubber (between the outer metal shells) control the amount and direction of rubber expansion during assembly for uniform stress distribution and optimized performance. The inner metal, rubber and outer metal design of the bushing combined with the precompression method is designed for maximum bushing fatigue properties for uniform stress in the rubber. Thus, the

bushing assemblies

10, 10', and 10 ″ provide for an improved bushing fatigue characteristic for uniform stress distribution.

The bushing precompression is applied during assembly to the beam hub. The stress distribution in the rubber is more uniform due to the unique rubber shape. Furthermore, press fitting the pre-compressed bushing into the spar hub is a very robust method for assembly.

FIGS. 5A-8B relate to various collar embodiments that may be used to increase the hoop strength of the end of the outer metal shell and the strength of the bushing assembly, and to retain the bushing assembly within the spar hub. In fig. 5A-8B, a collar embodiment is shown having a bushing assembly 10 shown in fig. 1A, 1B, and 2. However, the collar embodiment of fig. 5A-8B may also be used with the bushing assembly 10' shown in fig. 3 and the bushing assembly 10 ″ shown in fig. 4, as well as variations thereof.

FIG. 5A is a front view of the bar pin bushing assembly 10 after insertion into the spar hub 90, with internal structures shown in phantom, and FIG. 5B is a cross-sectional front view of the bar pin bushing assembly 10 of FIG. 5A shown within the spar hub 90. To provide additional hoop strength on the ends of the multiple outer metal shells and to retain the boss assembly 10 within the spar hub 90, the collar 100 may be welded around one end of the boss assembly and the collar 100a may be welded around the other end of the boss assembly 10. In particular, as shown in fig. 5B, the collar 100 may be welded to the outer metal shell (or spar hub) including the

outer metal shells

32 and 36 along weld lines 92 on the end face of the boss hub 90 and the edges of the collar 100. The collar 100a may also be welded to the other end of the outer metal shell or spar hub 90. The collar 100a may be configured the same as (or different from) the collar 100. The collar 100a may be welded to the outer metal shell (which includes the outer metal shells 32 and 36) along weld lines 92a on the end face of the boss 90 and the edge of the collar 100 a.

Collars

100 and 100a provide increased strength and rigidity to bushing assembly 10 and increase hoop stress at the ends of bushing assembly 10. In addition, the collar configuration shown in fig. 5A and 5B is a very small overall axially extending compact collar arrangement with the length of the outer metal shell, which may be valuable in applications involving small clearances.

FIG. 6A is a perspective view of the bar pin bushing assembly 10 positioned within the beam hub with the beam hub removed to show how the plurality of outer metal shells move and engage radially inward to compress the compressible rubber section when inserted within the beam hub. In particular, the longitudinal edges 32b of the

outer metal shell

32 and 38a of the outer metal shell 38 are radially compressed during insertion into the beam hub to pull the

edges

32b and 38a into engagement. FIG. 6B is a cross-sectional view of the bar pin bushing assembly 10 shown in FIG. 6A, showing the

collars

110 and 110a positioned on the bushing assembly 10. In this collar arrangement, a flange 35a extends from a first end of the outer metal shell (which includes outer metal shells 32 and 36), and the collar 110 may be press fit over the extended flange 35a of the outer metal shell. Similarly, a flange 35b extends from the second end of the outer metal shell (which includes outer metal shells 32 and 36), and collar 110a may be press fit over extended flange 35b of the outer metal shell. A crimping or swaging operation may then be used which further assists in holding the collars 100 to 100a in place. Such crimping or swaging operations further constrain the

collars

100 and 100 a.

As with

collars

100 and 100a shown in fig. 5,

collars

110 and 110a provide increased strength and rigidity to bushing assembly 10 and increase the hoop strength of the ends of bushing assembly 10.

Fig. 7A is a perspective view of the bar pin bushing assembly 10 positioned within the spar hub 90, and fig. 7B is a cross-sectional view of the bar pin bushing assembly 10 shown in fig. 7A.

Collars

115 and 115a are positioned on the ends of the outer metal shells of bushing assembly 10, including

outer metal shells

32 and 36. In this collar configuration, a flange 39a extends from the outer metal shell on the first end of the bushing assembly 10. Collar 115 is positioned on flange 39a and once in place, flange 39a is crimped or bent upward to hold collar 115 relative to the end of spar hub 90 to hold collar 115 in place relative to the end of spar hub 90. Similarly, a flange 39b extends from the outer metal shell on the second end of the bushing assembly 10. Collar 115a is positioned on flange 39b and once in place, flange 39b is crimped or bent upward to hold collar 115a relative to the end of spar hub 90 to hold collar 115a in place relative to the end of spar hub 90.

Collars

115 and 115a provide increased strength and rigidity to bushing assembly 10 and increase the hoop strength of the ends of bushing assembly 10. In addition, the collar configuration shown in fig. 7A and 7B is a very small overall axially extending compact collar arrangement with the length of the outer metal sleeve, which may be valuable in applications involving small clearances.

Fig. 8A is a perspective view of the bar pin bushing assembly 10 positioned within the spar hub 90, and fig. 8B is a cross-sectional view of the bar pin bushing assembly 10 shown in fig. 8A. In this collar configuration,

collars

120 and 120a are positioned on the ends of the outer metal shells of the bushing assembly 10, including the

outer metal shells

32 and 36. In this collar configuration, a flange 41a extends from the

outer metal shells

32 and 36 on a first end of the bushing assembly 10 including the outer metal shells. Collar 120 is positioned over flange 41a and once in place, flange 41a is crimped or bent upwardly to retain collar 120 relative to the first ends of the plurality of outer metal shells to retain collar 120 in place relative to the ends of the plurality of outer metal shells including

outer metal shells

32 and 36. Similarly, a flange 41b extends from the outer metal shell on the second end of the bushing assembly 10. Collar 120a is positioned over flange 41b and, once in place, flange 41b is crimped or bent upwardly to retain collar 120a relative to the ends of the plurality of outer metal shells, including

outer metal shells

32 and 36.

Collars

120 and 120a provide increased strength and rigidity to bushing assembly 10 and increase the hoop strength of the ends of bushing assembly 10. Variations of the collar configuration shown in fig. 5A-8B may also be provided.

The collars depicted in fig. 5A-8B may be made from cut metal tubing, cast, forged, or made from thick washers, as the case may be.

Fig. 9A-G disclose an alternative bar pin bushing assembly 200 that includes a bar pin 220 having oppositely disposed ends. Each end includes a through hole 21 that may be used to secure the bar pin bushing assembly 200 to an axle set or other component of a vehicle or suspension. The bar pin bushing assembly 200 includes an outer metal sleeve 232, the outer metal sleeve 232 being made of a plurality of outer metal shell segments 232a-d (referred to as outer metal shells) as shown in fig. 9C, which are mold bonded to a rubber portion 242 positioned on the bar pin 220. Fig. 9B-9D illustrate the bar pin bushing assembly 200 prior to insertion into the tubular outer metal wall 250 shown in fig. 9E-9G.

As shown in fig. 9B, a plurality of axial or longitudinal voids 252 are shown positioned in rubber portion 242. The longitudinal void 252 may be defined in part by the configuration of the outer metal shells 232a-d shown in FIG. 9C. The bar pin 220, the rubber section 242, and the outer metal shells 232a-d may be constructed in the same manner as similar elements shown in the bar pin bushing assembly shown in fig. 1A, 1B, and 2. When the bushing assembly 200 is inserted into the tubular outer metal wall 250 as shown in fig. 9E-9G, the plurality of outer metal shells 232a-d are forced to move radially inward to compress the rubber portion 242 relative to the bar pin 220. As the plurality of outer metal shells 232a-d are forced radially inward during insertion into the tubular outer metal wall 250, the gaps between the adjacent longitudinal edges of the plurality of outer metal shells 232a-d are eliminated and they are brought into engagement. At the same time, during compression of the rubber section 242, rubber from the rubber section 242 is forced into the longitudinal void 252 to allow the rubber section to become compressed. The use of longitudinal voids in the rubber advantageously allows the amount and direction of rubber expansion to be controlled during assembly for uniform stress distribution and optimized performance. The use of longitudinal voids in the bushing facilitates expansion of the rubber in both the axial and tangential directions while bushing assembly 200 is compressed during insertion into tubular outer metal wall 250.

Upon insertion of the bushing assembly 200 into the tubular outer metal wall 250, the rubber section 242 is pre-compressed. For example, depending on the application, the rubber section 242 may be compressed 15% to 25%, or less. In one embodiment, the rubber section 242 compresses from a thickness of 16.25mm to a thickness of 13mm when the bushing assembly is inserted into the tubular outer metal wall 250.

Rubber sections

40 and 42 may comprise natural rubber, although synthetic rubber or other elastomeric materials may also be used for the rubber sections, and the term "rubber" is defined to encompass all compressible materials.

Fig. 9E-9G show the bar pin bushing assembly 200 after the bar pin 220, the rubber section 242, and the plurality of outer metal shells 232a-d are inserted into the tubular outer metal wall 250. FIG. 9A shows the bar pin bushing assembly 200 after pushing down on the end of the tubular outer metal wall 250 to conform to the outer surface of the end of the plurality of outer metal shells 232 a-d. In the bar pin bushing assembly 200, the wall thickness of the plurality of outer metal shells 232a-d is substantially equal to the wall thickness of the tubular outer metal wall 250. In some embodiments, the wall thickness may be 1/8 inches or 3 mm. The tubular outer metal wall may be made of 1020 draw mandrel tube steel, although other metal materials may be used.

Fig. 10A and 10B illustrate a bar pin bushing assembly 200' that is similar to the bar pin bushing assembly 200 shown in fig. 9A-9G, including having the same bar pin 220 and rubber section 242, but with a slight difference. In particular, in the bar pin bushing assembly 200', the plurality of outer metal shells 232a-d ' have a thinner wall thickness than the outer metal shells 232a-d in the bar pin bushing assembly 200, and the tubular outer metal wall 250' has a greater wall thickness than the tubular outer metal wall 250. In some embodiments, the tubular outer metal wall may have a wall thickness that is twice the wall thickness of the plurality of outer metal shells 232 a-d'. In one embodiment, the tubular outer metal wall 250 'may have a wall thickness of 4mm, while the wall thickness of the plurality of outer metal shells 232a-d' may be 2 mm. Other ratios are also possible.

Additionally, in the bar pin bushing assembly 200 'shown in fig. 10A and 10B, the tubular outer metal wall 250' has an end portion 250A 'that is pushed downward at an angle that is perpendicular to the major surface of the tubular outer metal wall 250' such that there is a gap between the inner surface of the end portion of the tubular outer metal wall 250 'and the outer surface of the end portions of the plurality of outer metal shells 232 a-d'. This same method may also be used with the bar pin bushing assembly 200.

FIG. 11 illustrates a bar pin bushing assembly 200 ", an alternative embodiment of bar pin bushing assembly 200. In this embodiment, the bar pin 220 is the same as in the bar pin bushing assemblies 200 and 200'. However, in the bar pin bushing assembly 200 ", a plurality of outer metal shells are not used. Alternatively, the tubular outer metal wall 251 is positioned over a plurality of lobes (such as four lobes) for the rubber section 243 and may be mold bonded thereto. Additionally, the plurality of lobes may include one or more voids 245 that provide for flow of the rubber section into the void 245 when the rubber section 243 and the bar pin 220 are inserted into the tubular outer metal shell 251. In this embodiment, the end of the tubular outer metal wall 251 is undercut to provide for a thinner end to facilitate crimping.

It should be noted that the use of a tubular outer metal wall in the bar

pin bushing assemblies

200, 200', and 200 ″ provides increased hoop strength at the ends for multiple outer metal shells in the case of the bar pin bushing assemblies 200 and 200', such that a collar of the type set forth in fig. 5A-8B is not required. Thus, the need for such collars at both ends of the dowel sleeve assembly is not required, providing for reduced complexity in manufacturing and reduction in required parts. The tubular outer metal wall in the bar

pin bushing assemblies

200, 200', and 200 ″ demonstrates that it provides sufficient strength and durability for use on 48 ton tandem axle applications.

It should also be noted that bar

pin bushing assemblies

200, 200', and 200 ″ also provide a high degree of articulation for the bar pins within the bushing assemblies in the same manner as described above with respect to bar pin bushing assembly 10. In particular, the outer metal shell and/or the tubular outer metal wall are "adjusted" to allow the bar pin to articulate at a wide angle in the same manner as described above with respect to the bar pin bushing assembly 10.

Fig. 12A-12C illustrate a method of assembling a bar pin bushing assembly 200, the bar pin bushing assembly 200 including a central portion 226 of a bar pin, a rubber section 226, and a plurality of outer metal shells (collectively referenced as 232). In this method of assembly, as shown in fig. 12A, the tubular metal outer wall 250 is positioned within the outer wall restraint 310, which abuts the entire outer surface of the tubular metal outer wall 250. The outer wall restraint 310 includes a tapered inner surface that "funnels" the four sleeve lobes into the tubular metal outer wall 250. During insertion into the tubular metal outer wall 250, the outer wall restraint 310 helps support the tubular metal outer wall 250 so that it does not deform or separate during assembly. The lower stop 320 abuts the lower end of the tubular metal outer wall 250 and the lower end of the outer metal wall restraint 310. The bar pin bushing assembly is shown positioned over the tubular outer metal wall 250 and ready for insertion therein by the pushing element 300.

In fig. 12B, the bar pin bushing assembly 200 is inserted into the tubular outer metal wall 250. Crimping element 330 is shown positioned above and below tubular outer metal wall 250 with pusher block 340 in place to push crimping element 330 into engagement with the outer surface of the end of the tubular outer metal wall.

In fig. 12C, push blocks 340 and 320 force crimping elements 330 into engagement with the ends of tubular outer metal wall 250 and the ends of tubular outer metal wall 250 into engagement with the ends of the outer surfaces of the plurality of outer metal shells 232. In this manner, the bar pin bushing can be inserted into the tubular outer metal wall and assembled. The assembly method may also be used to assemble and/or crimp the bar pin bushing assemblies 200' and 200 ″. As shown in fig. 10A and 10B, the structure of the assembled bar pin bushing assembly may also be designed to include a gap between the inner surface of the end of the tubular metal outer wall and the outer surface of the end of the plurality of outer metal shells. The crimping and machining process shown in fig. 12A-C is designed to provide an equivalent degree of crimping on both ends of the bar pin bushing assembly.

Additionally, the intermediate sleeve and bushing or rubber layers shown in fig. 3 and 4 may be used in the bar pin bushing assembly 200, 200', and/or 200 ″ to provide a rotatable bar pin bushing.

Fig. 13A and 13B disclose an alternative bar pin bushing assembly 400 that includes a bar pin 220 having oppositely disposed ends. The bar pin bushing assembly 400 has the same construction as the bar pin bushing 200 shown in fig. 9E, but also includes disk inserts 260a and 260 b. Each end of the bar pin 220 includes a through hole 221 that may be used to secure the bar pin bushing assembly 400 to an axle set or other component of a vehicle or suspension. The bar pin bushing assembly 400 includes an outer metal sleeve 232 made of a plurality of outer metal shell segments 232a-d (referred to as outer metal shells and shown in fig. 9C), which outer metal shell segments 232a-d are mold bonded to a rubber portion 242 positioned on the bar pin 220. In other embodiments, the outer metal sleeve 232 may be a single continuous sleeve. Fig. 13A shows the bar pin 220, the outer metal sleeve 232, and the disk inserts 260a and 260b after insertion into the tubular outer metal wall 250.

The rubber portion 242 is pre-compressed when inserted into the tubular outer metal wall 250. For example, depending on the application, the rubber section 242 may be compressed 15% to 25%, or less. The rubber section 242 may be composed of natural rubber, but synthetic rubber or other elastomeric materials may also be used for the rubber section.

The bar pin bushing assembly 400 advantageously uses disk inserts 260a and 260b having inner surfaces that conform to the outer surface of the end of the outer metal sleeve 232. The disk inserts 260a and 260b may be constructed of a metallic material, such as 1045 steel, and other suitable materials may also be used. The disk inserts 260a and 260b advantageously provide the necessary hoop strength to the bar pin bushing assembly 400. After the outer metal sleeve 232 is inserted into the tubular outer metal wall 250, the disc inserts 260a and 260b may be positioned on the ends of the outer metal sleeve 232. In this manner, the disk inserts 260a and 260b may be press fit within the tubular outer metal wall 250 such that the outer diameters of the disk inserts 260a and 260b engage the inner surface of the tubular outer metal wall 250. The ends of the tubular outer metal wall 250 may be crimped or crimped over the tray inserts 260a and 260b using the method shown in fig. 12A-C and described above. To ensure that the disk inserts 260a and 260b remain in place relative to the ends of the outer metal sleeve 232 prior to crimping the ends of the tubular outer metal wall 250 onto the disk inserts 260a and 260b, adhesive (such as Loctite @) may be applied to the inner surfaces of the disk inserts 260a and 260b so that they remain in place prior to and during the end crimping process of the tubular outer metal wall 250. Alternatively, the disk inserts 260a and 260b may be positioned on the ends of the tubular outer metal sleeve 232 prior to inserting the tubular outer metal sleeve 232 into the tubular outer metal wall 250.

FIG. 13B shows a cross-sectional view of the bar pin bushing assembly 400 after pushing the end of the tubular outer metal wall 250 downward such that the inner surface of the end of the tubular outer metal wall 250 conforms to the outer surface of the disc inserts 260a and 260B. In this manner, no gap is provided between the outer surfaces of the disk inserts 260a and 260b and the inner surface of the end of the tubular outer metal wall 250, and no gap is provided between the inner surfaces of the disk inserts 260a and 260b and the outer surface of the end of the outer metal sleeve 232. As a result, rod pin bushing assembly 400 has suitable strength and rigidity, and this arrangement provides increased hoop strength to the rod pin bushing assembly. However, in other embodiments, there may be a gap between the inner surface of the disc insert and the end of the outer metal sleeve, and there may also be a gap between the outer surface of the disc insert and the end of the tubular outer metal wall.

The design of bar pin bushing assembly 400 advantageously allows for a bar pin bushing assembly that is easy to manufacture and results in a reliable construction.

Fig. 14A is a side view of the disc insert 260B, and fig. 14B is a cross-sectional view of the disc insert 260B taken along line 14B-14B of fig. 14A. As shown in fig. 13A and 13B, the disk insert 260B includes an inner surface 262 that is shaped to conform to the outer end of the metal sleeve 232. In addition, as shown in fig. 13A and 13B, the disk insert 260B includes an outer surface 264 that is shaped to conform to the inner surface of the tubular outer metal wall 250.

While the invention has been described with reference to certain illustrative aspects, it will be understood that this description is not intended to be construed in a limiting sense. Rather, various changes and modifications may be made to the illustrative embodiments without departing from the true scope of the invention as defined by the following claims. Moreover, it will be appreciated that any such changes and modifications will be recognized by those skilled in the art as being equivalent to one or more elements of the following claims, and shall be covered by such claims to the fullest extent permitted by law.

Claims

1. A bar pin bushing assembly for connecting components in a vehicle system, the assembly comprising:

a bar pin having at least one end with at least one aperture extending therethrough to receive a fastener, the bar pin having a central portion with a diameter greater than a width or diameter of the at least one end of the bar pin;

a compressible rubber section positioned around a central portion of the bar pin, the compressible rubber section further extending around a downwardly tapered surface adjacent the central portion of the bar pin;

an outer metal shell mold bonded to the compressible rubber section;

a first disc insert positioned on a first end of the outer metal shell;

a second disk insert positioned on a second end of the outer metal shell; and

a tubular outer metal wall positioned over the outer metal shell, the first disk insert, and the second disk insert.

2. The bar pin bushing assembly of claim 1 wherein an inner surface of said first disc insert engages an outer surface of said first end of said outer metal shell; and

wherein an inner surface of the second disk insert engages an outer surface of the second end of the outer metal shell.

3. The bar pin bushing assembly of claim 1 wherein an outer surface of the first disc insert engages an inner surface of the first end of the tubular outer metal wall; and

wherein an outer surface of the second disk insert engages an inner surface of the second end of the tubular outer metal wall.

4. The bar pin assembly of claim 1, wherein an inner surface of the first disc insert engages an outer surface of the first end of the outer metal shell;

wherein an inner surface of the second disk insert engages an outer surface of the second end of the outer metal shell;

wherein an outer surface of the first disc insert engages an inner surface of the first end of the tubular outer metal wall; and

5. The bar pin bushing assembly of claim 2 wherein an inner surface of said first disc insert has a shape conforming to an outer surface of said first end of said outer metal shell; and

wherein an inner surface of the second disk insert has a shape that conforms to an outer surface of the second end of the outer metal shell.

6. The bar pin bushing assembly of claim 3 wherein an outer surface of the first disc insert has a shape that conforms to an inner surface of the first end of the tubular outer metal wall; and

wherein an outer surface of the second disc insert has a shape that conforms to an inner surface of the second end of the tubular outer metal wall.

7. The bar pin bushing assembly of claim 4 wherein an inner surface of said first disc insert has a shape that conforms to an outer surface of said first end of said outer metal shell;

wherein an inner surface of the second disk insert has a shape that conforms to an outer surface of the second end of the outer metal shell;

wherein the outer surface of the first disc insert has a shape that conforms to the inner surface of the first end of the tubular outer metal wall; and

8. The bar pin bushing assembly of claim 1 wherein said outer metal shell comprises a plurality of outer metal shell segments.

9. The bar pin bushing assembly of claim 8 wherein when a plurality of outer metal segments and compressible rubber sections are inserted into the tubular outer metal wall, the plurality of outer metal shell segments radially compress the compressible rubber sections to provide a pre-compressed bushing assembly.

10. The bar pin bushing assembly of claim 1 wherein said compressible rubber section is mold bonded to said bar pin.

11. The bar pin bushing assembly of claim 9 wherein each of said plurality of outer metal shell segments has a first longitudinal edge and a second longitudinal edge, said first and second longitudinal edges being forced into engagement with edges of adjacent outer metal shell segments when said bushing assembly is inserted into said tubular outer metal wall.

12. The bar pin bushing assembly of claim 11 wherein a longitudinal void is positioned in said compressible rubber section between adjacent edges of said outer metal shell segments; and wherein rubber on an outer surface of the compressible rubber section is forced into the longitudinal void when the bushing assembly is inserted into the tubular outer metal wall.

13. The bar pin bushing assembly of claim 1 wherein said plurality of outer metal shell segments comprises four outer metal shell segments.

14. The bar pin bushing assembly of claim 13 wherein said four outer metal shell segments are of the same size and shape.

15. A method of manufacturing a bar pin bushing assembly, comprising the steps of:

providing a bar pin having at least one end with at least one aperture extending therethrough to receive a fastener, the bar pin having a central portion with a diameter greater than a width or diameter of the at least one end of the bar pin;

positioning an outer metal shell around the bar pin;

injecting molten rubber into the space between the central portion of the bar pin and the inner surface of the outer metal shell to form a compressible rubber section;

inserting the bar pin and the compressible rubber section into a tubular outer metal wall;

positioning an inner surface of a first disc insert into engagement with an outer surface of the first end of the outer metal shell and positioning an outer surface of the first disc insert into engagement with an inner surface of the first end of the tubular outer metal wall;

positioning an inner surface of a second disk insert into engagement with an outer surface of the second end of the outer metal shell and positioning an outer surface of the second disk insert into engagement with an inner surface of the second end of the tubular outer metal wall;

forcing the inner surface of the first end of the tubular outer metal wall into further engagement with the outer surface of the first disc insert; and

forcing the inner surface of the second end of the tubular outer metal wall into further engagement with the outer surface of the second disc insert.

16. The method of claim 15, wherein the inner surface of the first disc insert has a shape that conforms to the outer surface of the first end of the outer metal shell; and

17. The method of claim 15, wherein the outer surface of the first disc insert has a shape that conforms to the inner surface of the first end of the tubular outer metal wall; and

18. The method of claim 15, wherein the inner surface of the first disc insert has a shape that conforms to the outer surface of the first end of the outer metal shell;

19. The method of claim 15, wherein the outer metal shell comprises a plurality of outer metal shell segments.

20. The method of claim 19, wherein the plurality of outer metal shell segments radially compress the compressible rubber section when the plurality of outer metal shell segments and the compressible rubber section are inserted into the tubular outer metal wall.