Patent Publication Number: US-10766325-B2

Title: Vehicle suspension

Description:
BACKGROUND 
     The present invention generally relates to vehicle suspensions. More particularly, the present invention relates to vehicle suspensions using bolster springs. Examples of vehicle suspensions having bolster springs are disclosed in U.S. Pat. No. 6,585,286 entitled “Vehicle Suspension” that issued on Jul. 1, 2003, herein incorporated by reference in its entirety. This application also claims priority to U.S. patent application Ser. No. 29/574,562 filed on Aug. 16, 2016, the contents of which are herein incorporated by reference in its entirety. The present application includes improvements and advancements over the vehicle suspensions disclosed in the &#39;286 patent noted above. 
     SUMMARY 
     A vehicle suspension is provided having a frame attachment portion attached to a saddle, first and second bolster springs mounted to spring mounts on an outboard side of the saddle and mounted on walls of a spring mount on an outboard side of an equalizing beam, and third and fourth bolster springs mounted to walls of a spring mount on an inboard side of the saddle and mounted to spring mounts on an inboard side of the equalizing beam. Upwardly extending flanges including a pair of ears is provided on the bottom of the first and second bolster springs that are mounted to each other with common fasteners, and wherein upwardly extending flanges on the bottom of the third and fourth bolster springs are mounted to each other with common fasteners. The mechanical joints provide retention integrity allowing for the use of fewer and smaller fasteners resulting in a lighter, more optimized design. In addition, an apex angle between the bolster springs has been reduced allowing them to operate more in shear thereby providing for a decrease in the primary and secondary suspension spring rates, as well as reduced axle translation during braking and acceleration. In addition, the reduced apex angle and direct mounting of the bolster springs provides for additional clearance for vehicle tires. 
     In one aspect, a bolster spring for a vehicle suspension is provided including a base plate, a top plate, elastomeric material positioned between the base plate and the top plate, a first flange comprising a pair of ears having a bottom mounting surface upwardly extending from a first end of the base plate at an angle ½α, and one or more mounting holes positioned in the pair of ears in the first flange adapted for attachment to a pair of ears on an upwardly extending flange on a second bolster spring. 
     In another aspect, a bolster spring for a vehicle suspension is provided including a base plate, a top plate, elastomeric material positioned between the base plate and the top plate, a first flange having a bottom mounting surface upwardly extending from a first end of the base plate at an angle ½α, and a tie-bar mounting flange rearwardly extending from an end of an intermediate plate positioned between the base plate and the top plate. 
     In a further aspect, a suspension subassembly is provided including a first bolster spring that comprises a base plate, a top plate, elastomeric material positioned between the base plate and the top plate, a first flange comprising a pair of ears having a bottom mounting surface upwardly extending from a first end of the base plate at an angle ½α, one or more mounting holes positioned in the pair of ears in the first flange adapted for attachment to a pair of ears on an upwardly extending flange on a second bolster spring, the second bolster spring including a base plate, a top plate, elastomeric material positioned between the base plate and the top plate, a first flange comprising a pair of ears having a bottom mounting surface upwardly extending from a first end of the base plate at an angle ½α, and one or more mounting holes positioned in the pair of ears in the first flange adapted for attachment to the pair of ears on the upwardly extending flange on the first bolster spring. 
    
    
     
       BRIEF DESCRIPTION OF THE 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 the outboard side of vehicle suspension  50 , according to an example embodiment; 
         FIG. 1B  is a perspective view of vehicle suspension  50  shown in  FIG. 1  and oppositely disposed vehicle suspension  50 ; 
         FIG. 2  is a front view of the outboard side of vehicle suspension  50  shown in  FIGS. 1A and 1B ; 
         FIG. 3  is a perspective view of the inboard side of vehicle suspension  50  shown in  FIGS. 1A, 1B, and 2 ; 
         FIG. 4  is a rear view of the inboard side of vehicle suspension  50  shown in  FIGS. 2 and 3 ; 
         FIG. 5  is a bottom view of vehicle suspension  50  shown in  FIGS. 1A-4 ; 
         FIG. 6  is a top view of vehicle suspension  50  shown in  FIGS. 1A-5 ; 
         FIG. 7  is a right side view of vehicle suspension  50  shown in  FIGS. 1A-6 ; 
         FIG. 8  is a left side view of vehicle suspension  50  shown in  FIGS. 1A-7 ; 
         FIG. 9  is a close up front view of vehicle suspension  50  showing bolster springs  70  and  72 , and load cushion  90 ; 
         FIG. 10  is a close up front perspective view of vehicle suspension  50  shown in  FIG. 9 ; 
         FIG. 11  is a perspective view of bolster spring  200 , according to an example embodiment; 
         FIG. 12  is a perspective bottom view of bolster spring  200  shown in  FIG. 11 ; 
         FIG. 13  is a left side view of bolster spring  200  shown in  FIGS. 11 and 12 ; 
         FIG. 14  is a right side view of bolster spring  200  shown in  FIGS. 11-13 ; 
         FIG. 15  is a top view of bolster spring  200  shown in  FIGS. 11-14 ; 
         FIG. 16A  is a perspective top view of load cushion  300 , according to an example embodiment; 
         FIG. 16B  is a perspective bottom view of load cushion  300  shown in  FIG. 16A ; 
         FIG. 17  is a right side view of load cushion  300  shown in  FIGS. 16A-16B ; 
         FIG. 18  is front view load cushion  300  shown in  FIGS. 16A-17 ; 
         FIG. 19  is a bottom view of load cushion  300  shown in  FIGS. 16A-18 ; 
         FIG. 20  is a top view of load cushion  300  shown in  FIGS. 16A-19 ; 
         FIG. 21A  is a cross-sectional, perspective view of the inboard side of vehicle suspension  50 , taken along line  21 A- 21 A in  FIG. 4 ; 
         FIG. 21B  is a cross-sectional, perspective view of the outboard of vehicle suspension  50 , taken along line  21 B- 21 B in  FIG. 2 ; 
         FIG. 22A  is a cross-sectional, perspective view of the inboard side of vehicle suspension  50 , taken along line  22 A- 22 A in  FIG. 4 ; 
         FIG. 22B  is a cross-sectional, perspective view of the outboard of vehicle suspension  50 , taken along line  22 B- 22 B in  FIG. 2 ; 
         FIG. 23A  is a cross-sectional, perspective view of the inboard side of vehicle suspension  50 , taken along line  23 A- 23 A in  FIG. 4 ; 
         FIG. 23B  is a cross-sectional, perspective view of the outboard of vehicle suspension  50 , taken along line  23 B- 23 B in  FIG. 2 ; 
         FIG. 24  is a perspective view of equalizing beam  100  of vehicle suspension  50  shown in  FIGS. 1A-10 ; according to an example embodiment; 
         FIG. 25  is a top view of equalizing beam  100  shown in  FIG. 24 ; 
         FIG. 26  is a close up view showing how bolster springs  70  and  72  may be mounted to each other with a common fastener; 
         FIG. 27  is a perspective view of bolster spring  400 ; 
         FIG. 28  is a rear view of bolster spring  400 ; 
         FIG. 29  is a front view of bolster spring  400 ; 
         FIG. 30  is a right side view of bolster spring  400 ; 
         FIG. 31  is a left side view of bolster spring  400 ; 
         FIG. 32  is a top view of bolster spring  400 ; 
         FIG. 33  is a bottom view of bolster spring  400 ; 
         FIG. 34  is a bottom view of a suspension subassembly including bolster springs  400   a  and  400   b;    
         FIG. 35  is a perspective view of a suspension subassembly including bolster springs  400   a  and  400   b , shown in  FIG. 34 ; 
         FIG. 36  is another perspective view of a suspension subassembly shown in  FIGS. 34 and 35 , including bolster springs  400   a  and  400   b;    
         FIG. 37  is a perspective view of a suspension subassembly including bolster springs  400   a  and  400   b;    
         FIG. 38  is another perspective view of a suspension subassembly shown in  FIG. 37 ; and 
         FIG. 39  is a perspective view of tie-bar  470  shown in  FIGS. 37 and 38  with fasteners  443   b ′ and  441   b′.    
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1A-10  provide various views of vehicle suspension  50 . Vehicle suspension  50  is designed to support longitudinally extending vehicle frame rails (not shown) which can be of various types that are positioned above laterally extending vehicle axles. As will be appreciated by those skilled in the art, components of vehicle suspension  50  are duplicated on each side of the vehicle as shown in  FIG. 1B . It will also be appreciated that vehicle wheels may be mounted to the ends of the vehicle axles in a known manner. Further, it will be appreciated that the vehicle frame rails may be connected by one or more vehicle frame cross members. 
     Those skilled in the art will further understand that a suspension, arranged in accordance with the suspension  50  and the components thereof, alternatively may be attached to frame rails of a trailer (for example, a trailer that connects to a semi-tractor). The frame rails of a trailer may comprise frame rails such as those described above or another type of frame rail. 
     For purposes of this description, unless specifically described otherwise, hereinafter, “vehicle” refers to a vehicle or a trailer. In this way, for example, a vehicle frame refers to a vehicle frame or a trailer frame. Furthermore, for purposes of this description, the left side of a vehicle refers to a side of the vehicle on an observer&#39;s left-hand side when the observer faces the back of the vehicle, and the right side of the vehicle refers to a side of the vehicle on an observer&#39;s right-hand side when the observer faces the back of the vehicle. Furthermore still, for purposes of this description, “outboard” refers to a position further away from a center line, running from the front to the back of a vehicle, relative to “inboard” which refers to a position closer to that same center line. 
       FIG. 1A  is a perspective view of an outboard side of vehicle suspension  50  having a frame attachment portion  62  that is adapted for attachment to a vehicle frame or frame rail with a plurality of mounting holes  63 . Frame attachment portion  62  includes outer gussets  66  and  68  and central flange  64  that provide additional strength and rigidity to the vehicle suspension  50 . Frame attachment portion  62  is attached to saddle  60 . Bolster springs  70  and  72  are provided that each have a top attached bolster spring mounts  170  and  172  extending from an outboard side of saddle  60  and a bottom attached to walls of bolster spring mount  107   b  positioned on equalizing beam  100 . Equalizing beam  100  has a beam hub  102  on a first end and a beam hub  104  on a second end. Beam hub  102  includes a bar pin  110  adapted for attachment to a first axle (not shown) and beam hub  104  includes a bar pin  112  adapted for attachment to a second axle (not shown). 
     A pair of shock absorbers  120  and  122  each have one end mounted to the equalizing beam  100  and another end mounted to saddle  60  on the inboard side of vehicle suspension  50 . In some applications, shock absorbers may not be used. A load cushion  90  is mounted to load cushion mount  94  extending from saddle  60  and load cushion  90  is positioned beneath saddle  60  and positioned inwardly from and generally above bolster springs  70  and  72 . A first rebound strap  80  is mounted to load cushion mount  94 , and a second rebound strap is mounted to load cushion mount  92  (shown in  FIG. 3 ). A bracket  191  having U-shaped ends that are used to mount rebound straps  80  may be positioned between the load cushion and the load cushion mounts  92  and  94 . In addition, shims of varying thickness may positioned between the load cushion  90  and bracket  191  to change the ride characteristics of the vehicle suspension  50 . 
       FIG. 1B  includes a second vehicle suspension  50   a  that is a mirror image of vehicle suspension  50 , and may be positioned on an opposite side of a vehicle frame. Accordingly,  FIG. 1B  provides a perspective view of the inboard side of vehicle suspension  50   a . Vehicle suspension  50   a  includes a frame attachment portion  62   a  that is adapted for attachment to a vehicle frame or frame rail with a plurality of mounting holes  63   a . Frame attachment portion  62   a  further includes outer gussets  66   a  and  68   a  that along with a central flange provide additional strength and rigidity to the vehicle suspension  50   a . Frame attachment portion  62   a  is attached to saddle  60   a . Bolster springs  71   a  and  73   a  are provided that each have a top attached to bolster spring mounts extending from the inboard side of saddle  60   a  and a bottom attached to bolster spring mount  107   a  positioned on equalizing beam  100   a . Equalizing beam  100   a  has a beam hub  102   a  on a first end and a beam hub  104   a  on a second end. Beam hub  102   a  includes a bar pin  110   a  adapted for attachment to a second axle (not shown) and beam hub  104   a  includes a bar pin  112   a  adapted for attachment to a first axle (not shown). 
     A pair of shock absorbers  120   a  and  122   a  each have one end mounted to the inboard side of equalizing beam  100   a  and another end mounted to the inboard side of saddle  60   a . A load cushion is mounted to load cushion mount  92   a  extending from saddle  60   a . A rebound strap  80   a  is mounted to load cushion mount  92   a.    
       FIG. 2  provides a front view of the outboard side of vehicle suspension  50  and  FIGS. 3 and 4  provide views of the inboard side of vehicle suspension  50 . In  FIG. 2 , load cushion  90  is shown mounted to load cushion mount  94  extending from saddle  60 . Bolster springs  70  and  72  are mounted to bolster springs mounts  170  and  172  outwardly extending from outboard wall  65  of saddle  60 , and also to bolster spring mount  107   b  on the outboard side of the equalizing beam  100 . As shown in  FIG. 3 , bolster springs  71  and  73  are mounted to bolster spring mounts  171  and  173  extending from inboard wall  67  of saddle  60  and to walls of bolster spring mount  107   a  positioned on the inboard side of the equalizing beam  100 . The configuration of bolster springs  70 - 73  results in a balanced, split bolster spring arrangement where one pair of bolster springs  70  and  72  is positioned on the outboard side of equalizing beam  100  and one pair of bolster springs  71  and  73  is positioned on the inboard side of equalizing beam  100 . 
     As shown in  FIG. 3 , shock absorber  120  has a first end secured to mount  108  positioned on equaling beam  100  and a second end secured to mount  69  positioned on saddle  60 , and shock absorber  122  has a first end secured to mount  106  positioned on equalizing beam  100  and a second end secured to mount  13  positioned on saddle  60 . In other embodiments, the second ends of shock absorbers  120  and  122  could also be mounted to a vehicle frame or frame rail, or not used at all. 
     Prior vehicle suspensions employing bolster springs typically provided an acute angle, or apex angle, between the bottoms of the bolster springs of 53 degrees, which has become a de facto industry standard. However, as best shown in  FIGS. 2 and 9 , vehicle suspension  50  significantly departs from the de facto apex angle standard of 53 degrees. In particular, an apex angle α is provided that is significantly less than 53 degrees. In the embodiments shown in  FIGS. 1-10 , the apex angle α between the bottom of bolster springs  72  and  70  (and the apex angle between bolster springs  71  and  73 ) is 37 degrees. While an apex angle of 37 degrees is preferred, the apex angle α may range between 34-40 degrees, or from 30-45 degrees, all lower than a standard apex angle of 53 degrees. 
     By reducing the apex angle α to 37 degrees, a number of important advantages are achieved. For example, the reduced apex angle α allows the springs to be positioned closer together, and thereby taking up less space longitudinally. In turn, a greater clearance between the vehicle tires and the bolster spring arrangement is provided, which may provide greater tire chain clearance or allow for the use of larger tires. In addition, by reducing the apex angle α, the bolster springs are put more into a shear, rather than compression. As a result, a lower primary vehicle spring rate may be achieved, while at the same time providing for increased longitudinal stiffness. The present configuration of the bolster springs with an apex angle α of 37 degrees has increased the longitudinal stiffness of the suspension resulting in a corresponding decrease in the longitudinal deflection to less than an inch. As a result, the reduced apex angle α has resulted in reduced axle translation along the SAE X-Axis during braking and acceleration. 
     Reducing the apex angle α between the bolster springs has advantageously resulted in a reduction in the primary suspension spring rate to 1.5-2.0 kN/mm depending upon the elastomer used to create the bolster springs. Furthermore, a secondary spring rate of the vehicle suspension when the load cushion is engaged measured at 1.0 g ranges from 2.0-3.5 kN/mm depending upon the elastomers chosen for both the bolster springs and initial gap between the load cushion and its reaction plate. These primary and second vehicle suspension spring rates are orders of magnitude lower than traditional elastomeric suspensions and are on the same order of magnitude as parabolic 6-rod suspensions. 
     Additionally, as discussed in more detail below with respect to  FIG. 26 , in addition to reducing the apex angle α between the bolster springs  70  and  72 , and  71  and  73 , vehicle suspension  50  also incorporates a unique bolster spring mounting arrangement wherein an angled flange  230  on the bottom plate  220  of bolster spring  70  is directly mounted to a corresponding angled flange  230  on bottom plate  220  of bolster spring  72  using a pair of common fasteners for retention. Bolster springs  71  and  73  are also directly mounted to each other using a pair of common fasteners in the same manner. As used herein, the term “directly mounted” means that the flanges are mounted together using a common fastener without a portion of the equalizing beam or bolster spring mount positioned therebetween, although a gasket or spacer, or portion of a spring saddle, could be positioned therebetween and the flanges would still be “directly mounted” to each other. 
     Directly mounting bolster springs  70  and  72  to each other, and directly mounting bolster springs  71  and  73  to each other using common fasteners provides a number of advantages. In particular, the bolster springs may be able to be positioned even closer together because there is no portion of the equalizing beam or a bolster spring mount extending between the flanges of the bolster springs. Furthermore, using common fasteners allows the positioning of the bolster springs to be closer together than if independent fasteners were used for each bolster spring. The closer positioning of the bolster springs allows even further clearance from the tires, again providing even greater clearance for tire chains or larger tires. The end result of directly mounting the flanges of the bolster springs with common fasteners provides for the use of fewer fasteners, faster assembly, improved clearances to surrounding components (because bolster springs are closer together), as well as the creation of a mechanical joint between the mounted flanges of the bolster springs. 
     As known to those skilled in the art, a mechanical joint formed between two components improves retention integrity and can permit the use of smaller fasteners compared to typical bolster spring designs. A benefit of smaller fasteners is improved clearances to surrounding packages, a more weight optimized design, and improved serviceability because smaller fasteners require less torque to achieve design load as a percent of proof load. Therefore, smaller fasteners are more easily and likely to be tightened appropriately. 
       FIG. 5  is a bottom view of vehicle suspension  50 . From this view, the equalizing beam  100  is shown with beam hub  104  having inboard side  104   a  on one end with bar pin  112  and with beam hub  102  having inboard side  102   a  with bar pin  110 . A center-plane  100   c  of equalizing beam  100  is shown offset towards inboard side  104   a  and inboard side  102   a  a distance d from a center-plane of beam hubs  104  and  102 . In this embodiment, the center-plane is offset a distance d of 11 millimeters. Providing such an offset on the equalizing beam has the effect of moving the vehicle suspension towards the inboard side of the vehicle frame, thereby advantageously providing additional clearance on the outboard side of the vehicle suspension. 
     In  FIG. 5 , there is a clear view of bolster spring  70  and bolster spring  72  mounted to opposing walls of bolster spring mount  107   b  extending from an outboard side the vehicle suspension  50 , as well as of bolster spring  71  and bolster spring  73  mounted to opposing walls of bolster spring mount  107   a  extending from the inboard side of vehicle suspension  50 . 
       FIG. 6  shows a top view of vehicle suspension  50 . In  FIGS. 5 and 6 , shock absorbers  120  and  122  can be seen secured to the inboard side of saddle using shock absorber mounts  106 ,  108 ,  13 , and  69 . In addition, a gap  105  is shown on the surface of beam hubs  104  and  102  as a result of the offset d of center-plane  100   c . In  FIG. 6 , load cushion mount  94  is shown extending from an outboard side of saddle  60  and load cushion mount  92  is shown extending from an inboard side of saddle  60 . In addition, central flange  64  is shown positioned on top surface  91  of saddle  60  attached to frame attachment portion  62 . 
       FIG. 7  is a right side view of vehicle suspension  50  and  FIG. 8  is a left side view of vehicle suspension  50 . Beam hub  102  is shown with bar pin  110  adapted for attachment to a first axle (not shown) and beam hub  104  is shown with bar pin  112  adapted for attachment for a second axle (not shown). Frame attachment portion  62  with gussets  68  and  66  are shown extending above outboard wall  65  and inboard wall  67  of the saddle and load cushion mount  94  is shown extending from the outboard side of vehicle suspension  50 . Shock absorber  122  is shown mounted to shock absorber mount  13  and shock absorber  120  is shown mounted to shock absorber mount  69 . In addition, a pair of rebound straps  80  are shown extending from inboard and outboards sides of the vehicle suspension  50 . Rebound straps  80  serve to prevent bolster springs  70 - 73  from being overstretched and overstressed when vehicle suspension  50  is placed in hang or rebound, such as when a vehicle is lifted with an outrigger, hits a large pothole, or during a sudden drop when going over a steep drop in the road. 
       FIG. 9  is a close up front view of, and  FIG. 10  is a close up perspective view of, the bolster springs  70  and  72  and load cushion  90  on the outboard side of vehicle suspension  50 . Bolster spring  70  is attached to bolster spring mount  170  on saddle  60  using fasteners  270   b  and  270   c , and also attached to bolster spring mount  107   a  on the equalizing beam  100  using fastener  270   a . Similarly, bolster spring  72  is attached to bolster spring mount  172  on saddle  60  using fasteners  272   b  and  272   c , and also attached to bolster spring mount  107   a  on the equalizing beam  100  using fastener  272   a . As illustrated in  FIG. 26 , upwardly extending flange  230  of bolster spring  70  is directly mounted to a corresponding upwardly extending flange  230  of bolster spring  72  using common fasteners, with a portion of spring saddle  193  positioned therebetween. In other embodiments, the bolster springs flanges  230  may be directly mounted to each other using common fasteners without a portion of a spring saddle positioned between them. As discussed above, apex angle α is formed between the bottom plates of bolster springs  70  and  72 . 
     To further strengthen the bolster spring assembly, a tie-bar  130  is used to tie outboard bolster spring  70  to inboard bolster spring  71  (shown in  FIG. 3  and  FIG. 5 ) and tie-bar  132  is used to tie inboard bolster spring  72  to inboard bolster spring  73  (shown in  FIG. 3  and  FIG. 5 ). In this embodiment, the tie-bar is mounted in an intermediate plate located at a midpoint between the top plate and bottom plate of the bolster spring. The midpoint is the point most susceptible to buckling, bulging, or splaying. Therefore, the tie-bar serves to react the inboard and outboard bolster springs to prevent buckling or bulging at the most vulnerable point on the bolster spring. The tie-bar therefore provides greater rigidity and strength to the bolster spring assembly. 
     Furthermore, by directly mounting bolster spring  70  to bolster spring  72  with common fasteners and directly mounting bolster spring  71  to bolster spring  73  with common fasteners, and by connecting bolster spring  70  to bolster spring  71  using tie-bar  130  and by connecting bolster spring  72  to bolster spring  73  using tie-bar  132 , all four bolster springs  70 ,  71 ,  72 , and  73  are interconnected. As a result, the present embodiments provide a unified, interconnected assembly of bolster springs that is more rigid and stable than if the bolster springs were not connected. 
     In addition, as shown in  FIGS. 9 and 10 , load cushion  90  is secured to outboard load cushion mount  94  (and to inboard load cushion mount  92  shown in  FIG. 4 ), and is positioned above reaction plate  190 . Rebound strap  80  is attached to rebound strap flange  80   a  and to rebound strap flange  80   b . The reaction plate  190  is secured via attachment to rebound strap flange  80   b . In this embodiment, a bottom surface of the load cushion  90  is positioned a distance D above the reaction plate  190 . Distance D may preferably be 19 mm. Therefore, a primary spring rate is based on the bolster springs, and when the load cushion  90  engages the reaction plate  190 , a secondary spring rate that includes the load cushion  90  is provided. In this embodiment, a hard stop has been included at 68 mm of travel to protect the bolster springs and load cushion from becoming overcompressed. 
     The hard stop feature is best shown in  FIGS. 22A and 22B , where fasteners  290   a  used to mount the load cushion  90  downwardly extend towards the reaction plate  190 . Sleeves  291  are positioned around the fasteners  290   a  and in this embodiment fasteners  290   a  have a head  293  extending from the end of sleeves  291 . When load cushion  90  is significantly compressed, e.g. at 50% compression, the heads  293  of fasteners  290   a  that contact the reaction plate  190  to provide a hard stop and prevent further compression of the load cushion  90 . In other embodiments, the bottom of sleeves  291  may be counterbored to enclose head  293  so that the head  293  does not extend from the bottom of the sleeve  291  and instead the bottom of the sleeve  291  contacts the reaction plate  190  to provide the hard stop. The bottom of the sleeve  291  has a greater surface area than head  293  of fasteners  290   a  to spread the forces upon impact with the reaction plate  190 . As a result of the hard stop, there is a ceiling on the amount of strain that will experienced by the bolster springs and load cushion. In this embodiment, the rebound strap  80  is comprised of woven material that is advantageously removable to allow for easy repair or replacement of the rebound strap  80 . It should be noted that depending upon the application, the disclosed vehicle suspensions may be used without a load cushion. 
     The components of the vehicle suspension  50  shown in  FIGS. 1-10  may comprise cast or fabricated metal or composite material, including iron, steel, or aluminum. Frame attachment portion  62  and saddle  60 , and equalizing beam  100  could also be cast with any suitable castable material. Similarly, the saddle  60  may comprise cast or fabricated metal or composite material. Depending on the application, the metal may, for example, be nodular ductile iron (or more simply, ductile iron), steel, such as a high strength low alloy steel, or aluminum. Typically, high strength low alloy steels are a preferred material to use for the frame hanger and the saddle, although aluminum is often desired when weight considerations are of greater importance. 
       FIGS. 11-15  are views of a bolster spring  200 . Bolster springs  70 ,  71 ,  72 , and  73  may be configured as bolster spring  200 . As shown in  FIGS. 11-14 , bolster spring  200  includes a base plate  220  and a top plate  210 . Bolster spring  200  includes an elastomeric section  260  between base plate  220  and intermediate plate  250 , an elastomeric section  262  between intermediate plate  250  and intermediate plate  252 , an elastomeric section  264  between intermediate plate  252  and intermediate plate  254 , and an elastomeric section  266  between intermediate plate  254  and top plate  210 . It should be noted that in other embodiments a greater or lesser number of intermediate plates can be used, including no intermediate plates. 
     Top plate  210  includes mounting holes  212  and  214  that are positioned on flanges of the top plate that extend beyond the elastomer zone with mounting hole  212  located on a flange on a first end of top plate  210  and mounting hole  214  located on a flange on a second end of top plate  210 . Such a mounting hole arrangement allows for mounting to a bolster spring mount without using studs extending from the elastomer zone. Bottom plate  220  includes mounting hole  222  that is positioned on a flange on a first end of bottom plate  220  that is also beyond the elastomer zone. An angled flange  230  extends from a second end of bottom plate  220 . Angled flange  230  includes a pair of spaced mounting holes  232  and  234  positioned beyond the elastomer zone that are adapted to be directly mounted to a corresponding angled flange of an adjacent bolster spring, as illustrated in  FIG. 26 . Top plate  210  and bottom plate  220  advantageously extend beyond the elastomer zone, and may be formed complementary in shape with the mounting surface of a bolster spring mount to provide a larger mounting surface area, which forms a stronger mechanical joint. 
     As shown in  FIGS. 13 and 14 , angled flange  230  may extend at an angle that is one half of apex angle α, so that when directly mounted to the angled flange of an adjacent bolster spring having the same configuration, an apex angle α is formed between the bottom surfaces of the directly connected bolster springs. In addition, a tie-bar mounting extension  240  having a through hole  241  through which a tie-bar may extend is shown extending from center intermediate plate  252 . 
       FIG. 15  is a top view of bolster spring  200 . As can be seen, mounting hole  222  of the bottom plate  220  extends beyond the elastomer zone. In addition, mounting holes  232  and  234  on angled flange  230  extend outwardly from the bottom plate  220  and have a spacing that is wider than the width of the bottom plate  220  and the top plate  210 . This wide spacing of the mounting holes  232  and  234  on angled flange  230  advantageously provides for greater contact between the angled flange surfaces when mounted as shown in  FIG. 26 , resulting in a stronger mechanical joint being formed between the angled flanges of the bolster springs. 
     The particular configuration of the base plate  220 , top plate  210 , and intermediate plates  250 ,  252 , and  254  of bolster spring  200  is illustrative only, and these components may have a variety of geometries and configurations. Thus, the bolster spring  200  is not required to have, but may have, the geometry shown in  FIGS. 9-15 . Furthermore, the use of a tie-bar may be, but is not required to be, included. 
     A bolster spring is typically constructed from relatively flat first and second end plates with an elastomer connected between them. This spring will then have compressive and shear rates corresponding to the chosen material, cross-section, and thickness of elastomer. In accordance with the disclosed embodiments, bolster spring  200  may be constructed of elastomeric sections  260 ,  262 ,  264 , and  266  bonded to one or more of plates  210 ,  250 ,  252 ,  254 , and  220 . Elastomeric sections  260 ,  262 ,  264 , and  266  may comprise an elastomeric material (i.e., an elastomer) such as natural rubber, synthetic rubber, styrene butadiene, synthetic polyisoprene, butyl rubber, nitrile rubber, ethylene propylene rubber, polyacrylic rubber, high-density polyethylene, thermoplastic elastomer, a thermoplastic olefin (TPO), urethane, polyurethane, a thermoplastic polyurethane (TPU), or some other type of elastomer. In this regard and in particular, elastomeric sections  260 ,  262 ,  264 , and  266  may comprise an elastomer defined as American Society of Testing and Materials (ASTM) D2000 M4AA 717 A13 B13 C12 F17 K11 Z1 Z2. In this case, Z1 represents natural rubber and Z2 represents a durometer selected to achieve a desired shear rate. The selected durometer may be based on a given predefined scale, such as the Shore A scale, the ASTM D2240 type A scale, or the ASTM D2240 type D scale. In a preferred embodiment, in accordance with the Shore A scale, Z2, for example, is preferably 70±5. In another embodiment, in accordance with the Shore A scale, Z2 is, for example, within the range of 50 to 80. Other examples of Z2 and ranges for Z2 are also possible. 
     In another respect, elastomeric sections  260 ,  262 ,  264 , and  266  may comprise a viscoelastomeric material that (i) has elastic characteristics when the bolster spring  200  is under a load within a given range and when that load is removed, and (ii) has non-elastic characteristics (for example, does not return to an original non-loaded shape) if the applied load exceeds the greatest load of the given range. The given range may extend from no load to a maximum expected load plus a given threshold. The given threshold accounts for possible overloading of bolster spring  200 . As an example, the viscoelastomeric material may comprise amorphous polymers, semi-crystalline polymers, and biopolymers. Other examples of the viscoelastomeric material are also possible. 
     In accordance with the example embodiments, elastomeric sections  260 ,  262 ,  264 , and  266  may also comprise one or more fillers. The filler(s) may optimize performance of elastomeric sections  260 ,  262 ,  264 , and  266 . The fillers may include, but are not limited to, wax, oil, curing agents, and/or carbon black. Such fillers may optimize performance by improving durability and/or tuning the elastomeric sections for a given shear load and/or a given compressive load applied to the elastomeric sections. Improving durability through the use of fillers may include, for example, minimizing a temperature rise versus loading characteristic of the elastomeric sections and/or maximizing shape retention of the elastomeric sections. 
     Bolster spring  200  may be formed, for example, by inserting the plates  210 ,  250 ,  252 ,  254 , and  220  into a mold (not shown). The plates may each be coated with a coating material. As an example, the coating material may comprise a material comprising zinc and phosphate, modified with calcium. The coating material may have a coating weight of 200-400 milligrams per square foot. Other examples of the coating material are also possible. A bonding agent may be applied to the coated plates for bonding the plates to the elastomeric sections. As an example, the bonding agent may comprise Chemlok® manufactured by the Lord Corporation, Cary, N.C., USA. Other examples of the bonding agent are also possible. Applying the coating material and/or applying the bonding agent may occur prior to, during, and/or after insertion of the plates into the mold. After applying the coating material and the bonding agent, the elastomeric material (while in a pourable form) may be inserted into the mold to form the elastomeric sections. 
     In a preferred embodiment, any exposed portion of the plates (for example, a portion of the plates not covered by the elastomeric material) is protected against corrosion by a means other than the elastomeric material. In other embodiments, some exposed portions of the plates (e.g., the edges of the plates) may not be protected against corrosion, whereas any other exposed portions of the plates are protected against corrosion. 
     The plates  210 ,  250 ,  252 ,  254 , and  220  can be made of any of a variety of suitable materials, including, but not limited to, iron, steel, aluminum, plastic, a composite material, or some other material. The plates may be fully, or at least substantially, encapsulated in elastomer to further enhance their corrosion resistance and friction at the mating suspension members. As an example, plates  210 ,  250 ,  252 ,  254 , and  220  can comprise plates having a thickness between a range of 0.188 inches (3.00 mm) to 0.25 inches (6.35 mm), or more. 
       FIGS. 16A and 16B  are perspective views of an example load cushion  300  for use in vehicle suspension  50 .  FIG. 17  is a side view,  FIG. 18  is a front view,  FIG. 19  is a bottom view, and  FIG. 20  is a top view of load cushion  300 . Load cushion  90  shown in vehicle suspension  50  in  FIGS. 1-10  may be arranged as load cushion  300 . 
     As shown in one or more of  FIGS. 16A-20 , load cushion  300  includes a top plate  310 , a bottom plate  320 , and a load cushion portion  330 . Top plate  310  includes mounting flange  312  with mounting hole  312   a  and mounting flange  314  with mounting hole  314   a  adapted for mounting to load cushion mounts  92  and  94  (shown in  FIGS. 2 and 4 ) of vehicle suspension  50 . In this embodiment, a horizontal cross section of the cushion portion  330  is generally square with rounded corners, although it could also be generally circular, rectangular, or conic. As shown in  FIGS. 16B and 19 , the bottom plate  320  includes holes  322  that are used during the molding process to provide a passage for the elastomeric material that forms the cushion portion  330 . 
     As shown in  FIG. 17 , the load cushion portion  330  has a unique symmetrical shape that includes curvilinear front and rear outer surfaces  332  and  334  that taper towards the center at the midpoint between the top plate  310  and bottom plate  320  such that the narrowest thickness of the load cushion  330  occurs at the midpoint. Similarly, as shown in  FIG. 18 , the load cushion portion  330  has a unique symmetrical shape that includes curvilinear left and right outer surfaces  336  and  338  that taper towards the center at the midpoint between the top plate  310  and bottom plate  320  such that the narrowest thickness of the load cushion  330  occurs at the midpoint. 
     Load cushion  330  may have a cross section where front and rear outer surfaces  332  and  334  have a negative Gaussian curvature, and similarly load cushion  330  may have a cross section where left and right outer surfaces  336  and  338  have a negative Gaussian curvature. In addition, load cushion portion  330  may be shaped as a hyperboloid. The curved outer surfaces of the load cushion portion result in a much lower elastomeric strain on the load cushion for the same deflection as compared to a linearly reduced cross-section. 
     The load cushion  90  may undergo 50% compression at full jounce, or when the hard stop discussed above is reached. At this point, the cross-section of the load cushion portion  330  changes from a negative Gaussian curvature to a 0 or slightly positive Gaussian curvature. As used herein the term, 0 Gaussian curvature means that the outer surfaces of the cross-section are parallel, and a “slightly positive Gaussian curvature” means that the midpoint of the load cushion portion  330  becomes wider than the end sections, by up to 1 cm on each side of the load cushion portion. 
     It will be appreciated that bottom plate  320  is not required, and the load cushion  330  may have an exposed surface instead of having bottom plate  320 . The use of a bottom plate  320  does not affect in any significant way the load cushion load versus deflection curve. However, the bottom plate  320  may be incorporated to protect the active elastomer of the load cushion portion  330  from debris such as rocks that could inadvertently end up on the reaction plate that is positioned beneath the load cushion. Debris could become embedded temporarily or permanently into the elastomer and create an undesirable crack initiation site. 
     The bottom plate  320  may be encapsulated to provide for improved corrosion resistance, elimination of metal to metal contact resulting in noise reduction upon contact with the reaction plate, improved friction between the load cushion  300  and the reaction plate  190  (shown in  FIGS. 9 and 10 ) to reduce or minimize wear between the bottom plate  320  and the reaction plate  190  during vehicle motion because relative motion is decreased or eliminated. In addition, encapsulation may be used as a service wear and replacement indicator similar to wear bars found between tire treads. 
     Load cushion  300  may have a continuously increasing spring rate as an applied load increases and a continuously decreasing spring rate as an applied load decreases, due to it generally conic shape. 
     The top plate  310  and base plate  320  may be constructed of any of a variety of suitable materials, including, but not limited to, iron, steel, aluminum, plastic, and a composite material. As an example, the base plate can comprise a plate having a thickness between a range of 0.188 inches (3.00 mm) to 0.25 inches (6.35 mm), or more. The plates can be encapsulated in elastomer and/or bonded to the load cushion portion using a bonding agent. The plate dimensions and shape can be varied to any dimension or shape desired for packaging, weight, and aesthetics. Preferably, the load cushion top plate  310  is dimensioned to (i) match the surface of the load cushion mount described herein, such as load cushion mounts  92  and  94 , (ii) locate mounting holes for securing the load cushion  300  to the load cushion mounts  92  and  94 , and (iii) minimize overall mass. 
     The size and dimensions of the elastomer used for the cushion portion  330  of load cushion  300  may be optimized for the vertical spring rate requirements. As noted above, the vertical spring rate for the load cushions  300  may continuously increase with increasing load and continuously decreases with decreasing load, defining a curvilinear shape with no discontinuities on a graph illustrating spring rate as a function of sprung load. 
     Preferably, load cushion portion  330  has a generally conic shape as it extends towards a midpoint between top plate  310  and bottom plate  320 . With this preferred shape, the vertical spring rate for the load cushion  300  linearly increases with increasing load and linearly decreases with decreasing load. In this regard, load cushion  300  is operable as a progressive spring rate load cushion. In one embodiment, the cross section of load cushion portion  330  adjacent top plate  310  and adjacent bottom plate  320  is 110 mm by 110 mm. At the midpoint between the top plate  310  and the bottom plate  320  the load cushion portion  330  the cross section is 88 mm by 88 mm, and the height of load cushion portion  330  is 105 mm not including plates or wear layer encapsulation. Other example dimensions of portions of load cushion  300  are also possible. For a given geometry, the spring rate of load cushion  300  may be optimized by varying the durometer of the elastomer. By varying the durometer, a family of interchangeable progressive spring rate load cushions can be created. 
     It will further be appreciated that the load cushion  300  may be mounted with the cushion portion  330  extending either above or below the bottom plate  310 . Likewise, the load cushion  300  may be mounted such that the top plate  310  extends beneath the bottom plate  320 . Therefore, the use of the terms “top” and “bottom” are used simply to describe the plates  310  and  320  that are attached to the load cushion portion  330 , and do not in any way require that the load cushion  300  is mounted in any particular configuration. 
       FIG. 21A  is a cross sectional inboard perspective view of vehicle suspension  50  taken along line  21 A- 21 A shown in  FIG. 4 , and  FIG. 21B  is a cross sectional inboard perspective view of vehicle suspension  50  taken along line  21 B- 21 B shown in  FIG. 2 . Frame attachment portion  62  with mounting holes  63  is shown extending upwardly from upper surface  91  of the saddle with central flange  64  and gusset  68 . Shock absorber  122  is shown mounted to inboard surface  67  of the saddle and rebound strap  80  is shown extending beneath load cushion mount  92 . Bolster springs  70  and  71  are shown mounted to bolster spring mounts  170  and  171  on opposite sides of equalizing beam  100 . Similarly, bolster springs  72  and  73  are shown mounted to bolster springs mounts  172  and  173  on opposite sides of equalizing beam  100 . In addition, common fastener  71   b  is shown directly mounting bolster spring  71  to bolster spring  73  and common fastener  70   b  is shown directly mounting bolster spring  70  to bolster spring  72 . 
       FIG. 22A  is a cross sectional inboard perspective view of vehicle suspension  50  taken along line  22 A- 22 A shown in  FIG. 4 , and  FIG. 22B  is a cross sectional outboard perspective view of vehicle suspension  50  taken along line  22 B- 22 B shown in  FIG. 2 . Frame attachment portion  62  with mounting holes  63  is shown extending upwardly from upper surface  91  of the saddle with central flange  64  and gusset  68 . Shock absorber  122  is shown mounted to inboard surface  67  of the saddle and rebound straps  80  are shown extending on opposite sides of load cushion  90 . Load cushion  90  can be seen positioned directly above reaction plate  190 . Load cushion  90  is also shown mounted to the load cushion mounts extending from walls  65  and  67  of the saddle using fasteners  290   a.    
     Spring saddle  193  is shown supporting reaction plate  190 . Throughhole  70   d  is positioned in reaction plate  190  to allow a fastener to extend therethrough for mounting together the angled flanges of bolster springs  70  and  72 . Similarly, throughhole  71   d  is positioned in reaction plate  190  to allow a fastener to extend therethrough for mounting together the angled flanges of bolster springs  71  and  73 . 
     In addition, equalizing beam  100  is shown having a U-shaped cross section with opposed walls  100   a  and  100   b . A tie-bolt  101  having a sleeve  103  is used to tie the two walls  100   a  and  100   b  together. Tie-bolt  101  is used to relieve stress in the equalizing beam  100  where the bolster springs  70 - 73  are attached by “pinching” walls  100   a  and  100   b  together such that their inner surfaces contact respective end surfaces of sleeve  103 . 
       FIG. 23A  is a cross sectional inboard perspective view of vehicle suspension  50  taken along line  23 A- 23 A shown in  FIG. 4 , and  FIG. 23B  is an outboard perspective cross sectional view of vehicle suspension  50  taken along line  23 B- 23 B shown in  FIG. 2 . Frame attachment portion  62  with mounting holes  63  is shown extending upwardly from upper surface  91  of the saddle with central flange  64  and gusset  68 . Shock absorber  122  is shown mounted to inboard surface  67  of the saddle and rebound straps  80  are shown extending on opposite sides of load cushion  90 . Load cushion  90  can be seen positioned directly above reaction plate  190 . Load cushion  90  is also shown mounted to the load cushion mounts extending from walls  65  and  67  of the saddle. 
       FIG. 24  is a perspective view of the inboard side of equalizing beam  100  and  FIG. 25  is a top view of equalizing beam  100 . Beam hubs  102  and  104  are located on opposite ends of the equalizing beam  100 . Shock absorber mount  106  having mounting hole  106   a  and shock absorber mount  108  having mounting hole  108   a  are shown positioned on the inboard side of the equalizing beam  100 . Bolster spring mounts  107   a  and  107   b  extend from opposite sides of the center of equalizing beam  100 . On the inboard side, the walls of bolster spring mount  107   a  include mounting holes  109   a  and  109   b  that are used to mount bolster springs  71  and  73  (shown in  FIG. 3 ), and on the outboard side, the walls of bolster spring mount  107   b  include mounting holes  108   b  and  108   a  that are used to mount bolster springs  70  and  72  (shown in  FIG. 2 ). 
     The equalizing beam  100  is shown in an illustrative configuration. However, equalizing beam  100  may be constructed in any of a variety of arrangements and with a variety of configurations and/or materials. 
       FIG. 26  provides an illustration showing how bolster springs  70  and  72  may be directly mounted to each other using common fasteners. In particular, flanges  230  of bolster springs  70  and  72  are positioned together as shown, with spring saddle  193  extending therebetween, wherein a pair of common fasteners may be used to directly mount the bolster springs  70  and  72  together. Spring saddle  193  may be formed from a pair of bent plates having a thickness of 6 mm, such that the flanges  230  are positioned 12 mm apart. In addition, apex angle α is shown between the bottom surfaces of bottom plates  220  of bolster springs  70  and  72 . 
       FIGS. 27-33  show various view of bolster spring  400 , that may be used in suspension assembly  50  described above. Bolster spring  400  includes a top plate  410  having mounting apertures  412  and  414 . Bolster spring  400  also includes a bottom plate  420  having mounting aperture  422 . Intermediate plates  450 ,  452 , and  454  are positioned between top plate  410 . Elastomeric section  460  is positioned between bottom plate  420  and intermediate plate  450 . Elastomeric section  462  is positioned between intermediate plate  450  and intermediate plate  452 . Elastomeric section  464  is positioned between intermediate plate  452  and intermediate plate  454 . Elastomeric section  466  is positioned between intermediate plate  454  and top plate  410 . Elastomeric sections  460 ,  462 ,  464 , and  466  may be constructed in the same manner and with the same materials as described above with respect to bolster spring  200 . In addition, top plate  410 , bottom plate  420 , and intermediate plates  450 ,  452 , and  454  may be constructed in the same manner and the same materials as described above with respect to bolster spring  200 . 
     Bottom plate  420  includes an extending section  430  from which upwardly extending ears  436  and  438  extend at an angle. A gap  439  extends between ears  436  and  438  to provide additional mounting clearance. Ear  436  includes a mounting aperture  432  and ear  438  includes a mounting aperture  434 . Ears  436  and  438  together constitute an upwardly extending flange. Intermediate plate  452  advantageously includes a rearwardly extending flange  440  that includes mounting apertures  444 ,  445 , and  446  that are adapted for attachment to a tie-bar. 
       FIG. 34  is a bottom view of a suspension subassembly including bolster springs  400   a  and  400   b .  FIG. 35  is a perspective view of a suspension subassembly including bolster springs  400   a  and  400   b , shown in  FIG. 34 .  FIG. 36  is another perspective view of a suspension subassembly shown in  FIGS. 34 and 35 , including bolster springs  400   a  and  400   b.    
     Bolster springs  400   a  and  400   b  are secured to each other with tie-bar  470 . In particular bolts  441   a  and  443   a  are used to secure tie-bar  470  to rearwardly extending flange  440   a  with nuts  445   a  and  447   a  respectively. Similarly, bolts  441   b  and  443   b  are used to secure tie-bar  470  to rearwardly extending flange  440   b  with nuts  445   b  and  447   b . Gap  439  between ears  436  and  438  (shown in  FIG. 27 ) provides clearance for the bolts to connect with the rearwardly extending flange  440   a  and  440   b , respectively. 
     It will be appreciated that ears  436  and  438  of the suspension subassembly shown in  FIGS. 34-36  may be secured to a corresponding suspension subassembly with a common fastener in the same manner as shown in suspension  50  and bolster springs  200 . 
       FIGS. 37-39  show alternate fasteners  443   b ′ and  441   b ′ that may be used to secure tie-bar  470  to rearwardly extending mounting flange  440   b  with nuts  447   b  and  445   b , and also alternate fasteners  441   a ′ and  443   a ′ that may be used to secure tie-bar  470  to rearwardly extending mounting flange  440   a  with nuts  445   a  and  445   b . Fasteners  443   b ′,  441   b ′,  441   a ′, and  443   a ′ differ from fasteners  443   b ,  441   b ,  441   a , and  443   a  in that rather than have a nut-shaped head, fasteners  443   b ′,  441   b ′,  441   a ′, and  443   a ′ have a round, low-profile head that is much thinner than the nut-shaped head of fasteners  443   b ,  441   b ,  441   a , and  443   a . As a result, the low-profile head provides for additional clearance to provide for wider articulation angles that may be experienced during operation of a vehicle. The term “low-profile” means that the head has a thickness that is 50% or less than the thickness of a nut shaped head. For example the nut-shaped head on an M12 bolt has a thickness of 12 mm, whereas the low-profile head on an equivalent bolt may have a thickness of 3-6 mm. The head of fasteners  443   b ′,  441   b ′,  441   a ′, and  443   a ′ is shown as round, although it could other shapes, such as square or hexagonal. 
     Although not required, fasteners  443   b ′ and  441   b ′ may have a stud that is knurled and which may be advantageously press fit into corresponding holes in rearwardly extending mounting flange  440   b  and a bottom of the low profile head may be drawn into engagement with surfaces  474  and  472  respectively of tie-bar  470  by tightening a nut onto a threaded end of the stud. Fasteners  441   a ′ and  443   b ′ may be configured in the same manner and press fit into corresponding rearwardly extending mounting flange  440   a  and drawn into engagement with surfaces of tie-bar  470  in the same manner. In other applications, the fasteners  443   b ′,  441   b ′,  441   a ′, and  443   a ′ may not have a knurled surface and may not be press fit into the corresponding mounting holes of rearwardly extending mounting flanges  440   b , and  440   a.    
     The current tie-bar setup shown in  FIGS. 27-38 , with its fastener (rearwardly extending flange  440 ) that bolts two rate plates together is great for articulation levels up to a certain degree. In high severity applications, the bolster twists to the point where the curl plate itself (shown in bolster spring  200 ) starts to overcome the preload on the bolt, put the bolt in bending, and stress up the curl plates to where expensive material options would be the only fix (without affected packaging). 
     With the tie-bar forging with the rearwardly extending flange  440  shown in  FIGS. 27-38 , the bending stiffness can be tuned in multiple directions so that in severe applications the bar itself stresses up, keeps load out of the bolts, and allows the plates to rotate relative to one another (with the forging bending and/or twisting in between). This increases integrity of the entire joint, as the 1 main bolt moves to 4 separate bolts, distributing load, and the forging stresses up instead of the rate plates. 
     This has the added benefit of keeping high strength steel rate plates out of the mold, which are harder to use in processing. The forging doesn&#39;t need to go in the mold and can be tuned (material and process/design wise) for different applications of the same bolster. 
     Example embodiments of the present invention have been described above. Those skilled in the art will understand that changes and modifications may be made to the described embodiments without departing from the true scope and spirit of the present invention, which is defined by the claims.