Abstract:
A vehicle suspension provides increased auxiliary roll stiffness by utilizing spring assemblies having a thick truncated half-leaf, a thin full-leaf, and a thin truncated half-leaf located opposite the thick truncated half-leaf. The thick truncated half-leaf increases the torsional rigidity of the spring assembly in order to increase the leaf twist sub-component of auxiliary roll stiffness and increases the bending rigidity of half of the spring assembly in order to increase the axle torsion sub-component of auxiliary roll stiffness. The thin full-leaf provides structural integrity, and the thin half-leaf allows tuning of the overall vertical spring rate of the suspension and limits the leaf stresses in the thin full-leaf.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to the use of leaf springs as suspension elements for ground-traveling vehicles and the role that they play in resisting vehicle body roll. Specifically, a set of leaf springs is set forth utilizing thick and thin truncated half-leafs, such that auxiliary roll stiffness, or that component of roll stiffness not related to lateral spacing, is increased.  
       SUMMARY OF THE INVENTION  
       [0002]     Ground-traveling vehicles are generally provided with suspension elements to absorb shocks to the vehicle resulting from unevenness of the ground and the forward velocity of the vehicle. As is well-known in the art, these suspension elements include some type of spring, some type of damping element, and either a full or partial axle. The simplest type of vehicle suspension, and still commonly used in heavy-duty vehicles, is the double leaf spring and solid axle arrangement. This type of vehicle suspension has many positive attributes. It is robust and simple to manufacture. It is vertically compliant and laterally rigid, yet capable of carrying heavy vehicle loads. However, unmodified it is also yields unacceptably to vehicle body roll.  
         [0003]     A major limiting factor in a double leaf spring and solid axle suspension&#39;s ability to resist vehicle body roll is the lateral spacing between the spring centers. This, in turn is limited by overall vehicle width and the amount of space required both by wheel and tire articulation, and by the vehicle brakes. The relationship between a double leaf spring and solid axle suspension&#39;s vertical spring rate, its lateral spacing between spring centers, and its roll stiffness has heretofore been somewhat fixed. Specifically, the roll stiffness for a suspension of this configuration equals the leaf spring vertical spring rate multiplied by the square of the spring center distance, plus an auxiliary roll stiffness generated primarily by leaf twist and torsion of the axle. The most generally employed solution to overcoming this fixed relationship has been the use of a stabilizer bar, which is a member that is attached to the vehicle frame in two places and linked to the axle at its ends. Alternately, the stabilizer bar may be attached to the axle in two places and linked to the vehicle frame at its ends. During vertical motion of the axle, the stabilizer bar articulates freely, but during vehicle body roll, the stabilizer bar undergoes torsion along its length, thus resisting the vehicle body roll.  
         [0004]     The invention as set forth herein discloses techniques for increasing the auxiliary roll stiffness component of roll stiffness, thus reducing or eliminating the need for a stabilizer bar. The ability of a traditional multi-leaf or taper-leaf spring to deliver auxiliary roll stiffness previous to this invention has been limited. For a twelve-thousand pound capacity suspension having fifty-eight inch long springs on approximately fifty-two-inch spring centers, for example, fifteen thousand inch pounds per degree of body roll are contributed by primary roll stiffness due to spring rate and spacing. Only ten thousand inch pounds per degree of body roll are contributed by auxiliary roll stiffness.  
         [0005]     Some attempts to increase this auxiliary roll stiffness component have been made previous to the invention set forth herein. Vehicle manufacturers have achieved limited success by increasing the longitudinal asymmetry of the spacing of the axle upon the springs. Specifically, by locating the axle at a point between of the midpoint of the leaf springs and their direct connection to the vehicle frame via the spring hanger, and by increasing the torsional stiffness of the axle, approximately ten percent gains have been made in the auxiliary roll stiffness component. This is due to a correlating increase in both of the two subcomponents of the auxiliary roll stiffness component, leaf twist and axle torsion.  
         [0006]     The increase in the leaf twist subcomponent can be visualized as follows. As the vehicle negotiates a change in direction, the springs are loaded asymmetrically in the lateral direction. As a result the vehicle body leans. This produces an angularity between the axle and the vehicle frame in the lateral direction, with the outer spring compressed to a greater extent, and the inner spring relieved to some extent. The springs become the compliant member which accepts this angular difference. That is, they are twisted slightly along their length. Because the leaf springs are affixed to the chassis at their extremities, the twist occurs between the front spring eye and the mid-point axle attachment, and between the rear spring eye and the mid-point axle attachment. The ability of each spring half-portion of the overall length to resist this twist is a function of the shear modulus of the material, its polar moment of inertia, and the length of that half-portion. Because the torsional spring rate of the spring half-portion of the overall length is a function of the inverse of the length of that half-portion, the rate at which the torsional spring rate increases for the spring half-portion which is made shorter by longitudinal asymmetry becomes rapidly greater than the rate at which the torsional spring rate decreases for the spring half-portion which is made longer by that same longitudinal asymmetry. Because the direct connection between the spring and the vehicle frame via the spring hanger is generally more rigid than the connection via the spring shackle, or the member which compensates for the variation of the spring length upon deflection, that is generally the end of the spring toward which the axle is located.  
         [0007]     The increase in the axle torsion subcomponent of auxiliary roll stiffness can be visualized as follows. As the vehicle leans, the outer spring is compressed to a greater extent, and the inner spring is relieved to some extent, as mentioned previously. As a leaf spring is compressed, it generally flattens in the case of a parabolic spring, or becomes invertedly parabolic in the case of a flat spring. It also changes in distance between the spring eyes, which explains the need for the spring shackle mentioned previously. At some point at or near its mid-point, a tangent drawn to the spring at that point remains at a fairly constant angle relative to the longitudinal axis of the vehicle throughout deflection of the spring. Forward and rearward of that theoretical midpoint, the angle between a tangent drawn to the spring and the longitudinal axis of the vehicle will change throughout deflection of the spring. By attaching the axle to a point other than that theoretical midpoint, generally in the direction from the theoretical midpoint toward the direct connection between the spring and the vehicle frame via the spring hanger, torsion is introduced to the axle, due to the fact that the inner and outer springs are deflecting in opposite directions resulting in opposite changes in the angularity between the tangents drawn to the springs and the longitudinal axis of the vehicle. By also increasing the torsional rigidity of the axle, the axle torsion subcomponent of auxiliary roll stiffness is increased.  
         [0008]     Remembering that these subcomponents together have previously contributed to an approximate increase in auxiliary roll stiffness of only ten percent when longitudinal asymmetry has been increased previous to the invention disclosed herein, attempts have been made to further increase the contribution of both subcomponents of the auxiliary roll stiffness component, leaf twist and axle torsion, by thickening a half-portion of the leaf spring overall length. Typically, the half-portion of the overall length of the leaf spring toward the direct connection between it and the vehicle frame via the spring hanger has been made thicker, so that the half-portion of the leaf spring toward the spring shackle was required to accommodate a greater degree of deflection. This increased the polar moment of inertia of the thicker half-portion of the leaf spring, thereby increasing the leaf twist subcomponent of the auxiliary roll stiffness component. Thickening the half-portion of the leaf spring also forced the angle between the tangent drawn to the spring at the point where the axle is attached and the longitudinal axis of the vehicle to change to a greater degree during deflection. The resulting increase in torsion of the axle increased the axle torsion subcomponent of the auxiliary roll stiffness component of overall roll stiffness.  
         [0009]     The approach of thickening a half-portion of the leaf spring overall length in order to increase auxiliary roll stiffness is limited, however, by a corresponding increase in leaf spring stress in the thinner half-portion of the spring. This increase in leaf spring stress has forced vehicle suspension manufacturers to include additional spring elements, typically air or rubber springs located between the axle and the vehicle frame, in order to reduce the leaf spring stress to an acceptable level. These additional spring elements are often added at a significant cost penalty, in order to achieve the level of roll stiffness desired.  
         [0010]     The invention disclosed herein allows for an increased level of roll stiffness by increasing the auxiliary roll stiffness component via the use of a thick truncated half-leaf, while alleviating a corresponding increase in leaf stress via the use of an opposing thinner truncated half-leaf. This is accomplished by constructing a leaf spring assembly comprised of a first upper thick truncated half-leaf nearest the direct connection between the spring assembly and the vehicle frame via the spring hanger, a second full length thinner leaf, and a third lower truncated half-leaf of sufficient thickness to generate the desired vertical stiffness, located opposite the first upper thick truncated half-leaf. The upper thick truncated half-leaf gives the increased polar moment of inertia required for increasing the leaf twist subcomponent of the auxiliary roll stiffness component, and forces the angle between the tangent drawn to the spring at the point where the axle is attached and the longitudinal axis of the vehicle to change to a greater degree during deflection, thereby increasing the axle torsion subcomponent of the auxiliary roll stiffness component when used with a torsionally rigid axle. The second full length leaf provides vertical stiffness and structural redundancy via the front eye wrap at the direct connection to the vehicle frame via the spring hanger and the rear eye wrap at the spring shackle connection. The third lower truncated half-leaf allows for tuning of the vertical stiffness while minimizing leaf stresses in itself and the second full length leaf.  
         [0011]     An alternate embodiment is comprised of a leaf spring assembly having a lower thick truncated half-leaf nearest the direct connection between the spring assembly and the vehicle frame via the spring hanger, a second full length thinner leaf, and a third upper truncated half-leaf of sufficient thickness to generate the desired vertical stiffness, located opposite the first lower thick truncated half-leaf. The lower thick truncated half leaf in this embodiment functions in exactly the same way as the upper thick truncated half leaf in the previous embodiment.  
         [0012]     There are many advantages to utilizing a suspension having spring assemblies of this type. The suspension may be tuned more aggressively, having a relatively low vertical spring rate overall, while maintaining high roll stiffness. It exhibits typical jounce and rebound travel, due to control of spring stress to within normal limits. Furthermore, it is economical to implement, as the spring assembly is compatible with conventional spring mounting and axle attachments. There is a reduced need for a stabilizer bar, allowing for the possible elimination of the stabilizer bar and attachments altogether.  
         [0013]     The leafs and half-leafs of the present invention may be of either parabolic taper shape or flat shape. The thick and thin half-leafs may be approximately the same length, or they may be asymmetric in either direction. The suspension utilizing the spring assemblies of the present invention may be located at the front or rear positions upon the vehicle, and may be used with driving or non-driving axles. The spring assemblies may be oriented thick half-leaf forward in a suspension having the spring hanger forward and spring shackle rearward, or may be oriented thick half-leaf rearward in a suspension having the spring hanger rearward and spring shackle forward, depending on the suspension characteristics required. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1 —A ground vehicle traveling over uneven terrain.  
         [0015]      FIG. 2 —A prior-art conventional leaf spring suspension.  
         [0016]      FIG. 3 —A ground vehicle undergoing body roll.  
         [0017]      FIG. 4 —A prior-art conventional leaf spring suspension having a stabilizer bar.  
         [0018]      FIG. 5 —A prior-art asymmetric leaf spring suspension.  
         [0019]      FIG. 6 —A view showing leaf twist operating to resist body roll.  
         [0020]      FIG. 7 —A view showing axle torsion operating to resist body roll.  
         [0021]      FIG. 8 —A prior-art leaf spring suspension having thicker half-portions of the overall spring length, with an additional spring element.  
         [0022]      FIG. 9 —A view of a first embodiment of the invention.  
         [0023]      FIG. 10 —A view of a second embodiment of the invention.  
         [0024]      FIG. 11 —A view of a third embodiment of the invention.  
         [0025]      FIG. 12 —A view of a fourth embodiment of the invention.  
         [0026]      FIG. 13 —A view of a fifth embodiment of the invention.  
         [0027]      FIG. 14 —A view of a sixth embodiment of the invention. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0028]     The vehicle  101  shown in  FIG. 1  has a body  102  attached to a frame  103 . The vehicle  101  is shown traversing uneven terrain  105 , which causes the conventional leaf spring suspension  104  attached to the frame  103  to deflect.  
         [0029]      FIG. 2  shows a prior-art conventional leaf spring suspension  104  attached to the frame  103  of the vehicle  101 . The body  102  of vehicle  101  is not shown. The frame  103  is provided with spring hangers  108  and spring shackle attachments  111 , to which are attached leaf springs  107  and spring shackles  110 . The leaf springs  107  are attached to the spring hangers  108  at the spring hanger connections  109 , and to the spring shackles  110  at the spring shackle connections  112 . Note that one of the spring hangers  108  is shown partially cut-away, in order to better illustrate the attachment of the leaf spring  107  to the spring hanger connection  109 . A solid front steerable axle  106  is attached to the leaf springs  107  by the axle attachments  113 . The conventional leaf spring suspension  104  is further provided with damper elements  114  and a stabilizer bar  115 , which stabilizer bar  115  is attached to the solid front steerable axle  106  at two stabilizer bar axle connections  117 , and linked to the frame  103  by the stabilizer bar frame links  116 . The damper elements  114  are connected to the frame  103  and to the leaf springs  107  at or near the axle attachments  113 .  
         [0030]      FIG. 3  shows a vehicle  101  undergoing body roll. Centripetal force acting upon the tire to ground contact patches  118  results in a moment about the vehicle center of gravity  119 , which moment is counteracted by the conventional leaf spring suspension  104 . As a result, the frame  103  and body  102  lean outward, partially compressing outer leaf spring  107   b , and partially relieving inner leaf spring  107   a . The solid front steerable axle  106  remains relatively level with the ground.  
         [0031]      FIG. 4  shows a vehicle  101  having a prior-art conventional leaf spring suspension  104  having a stabilizer bar  115  and undergoing deflection as a result of vehicle body roll. The conventional leaf spring suspension  104  is comprised of the solid front steerable axle  106 , the leaf springs  107 , the damper elements  114 , and the stabilizer bar  115 . The body  102  of vehicle  101  is not shown. The frame  103  is at an angle relative to the solid front steerable axle  106 , causing the outer leaf spring  107   b  to be partially compressed and the inner leaf spring  107   a  to be partially relieved. The stabilizer bar  115  is connected to the solid front steerable axle  106  at two stabilizer bar axle connections  117 , and is linked to the frame  103  by two stabilizer frame links  116 . The damper elements  114  are connected to the frame  103  and to the leaf springs  107  at or near the axle attachments  113 . The angle between the frame  103  and the solid front steerable axle  106  causes the stabilizer bar  115  to twist along its length. This twist is emphasized in  FIG. 4  by a reference line  120 , which reference line  120  is straight and parallel to the axis of the stabilizer bar  115  when the stabilizer bar  115  is not undergoing twist. The stabilizer bar  115  has a given torsional spring rate, such that it exerts torque in the restorative direction when it is twisted, and thereby resists vehicle body roll.  
         [0032]      FIG. 5  shows a prior-art asymmetric leaf spring front suspension  121 . The asymmetric leaf spring front suspension  121  is comprised of the solid front steerable axle  106 , the leaf springs  107 , the damper elements  114 , and the stabilizer bar  115 . Neither the body  102  nor the frame  103  of the vehicle  101 , to which the asymmetric leaf spring front suspension  121  would be attached, are shown. The solid front steerable axle  106  is attached to the leaf springs  107  at the axle attachments  113 , which are more proximate to the spring hangers  108  and spring hanger connections  109  than to the spring shackles  110 , spring shackle attachments  111 , and spring shackle connections  112 . As in the conventional leaf spring suspension  104  of  FIG. 2 , the stabilizer bar  115  is attached to the solid front steerable axle  106  at two stabilizer bar axle connections  117 , and linked to the frame  103 , which is not shown in  FIG. 5 , by the stabilizer bar frame links  116 , which are also not shown in  FIG. 5 . Similar to the conventional leaf spring suspension  104  of  FIG. 2 , the damper elements  114  are connected to the frame  103 , which is not shown in  FIG. 5 , and in this particular embodiment to the solid front steerable axle  106  at or near the axle attachments  113 .  
         [0033]      FIG. 6  shows a vehicle  101  having a conventional leaf spring suspension  104  and undergoing deflection as a result of vehicle body roll. The conventional leaf spring suspension  104  is comprised of the solid front steerable axle  106  and the leaf springs  107 . The solid front steerable axle  106  is attached to the leaf springs  107  at the axle attachments  113 . The leaf springs  107 , in turn, are connected to the spring hangers  108  at the spring hanger connections  109 , of which only the right side spring hanger  108   a  and the right side spring hanger connection  109   a  are shown attached to the right leaf spring  107   a . The left side spring hanger  108   b  and the left side spring hanger connection  109   b  are removed to better show the left leaf spring  107   b . The spring hangers  108  are in turn attached to the frame  103 . For simplicity, the body  102  of vehicle  101  is not shown, nor are the stabilizer bar  115 , the two stabilizer frame links  116 , nor the damper elements  114  of the conventional leaf spring suspension  104 . The frame  103  is at an angle “A” relative to the solid front steerable axle  106 , causing the outer leaf spring  107   b  to be partially compressed and the inner leaf spring  107   a  to be partially relieved. The angle “A” between the frame  103  and the solid front steerable axle  106  causes the leaf springs  107  to twist along their length between the spring hanger connections  109  and the axle attachment  113 . The resistance of the leaf springs  107  to being twisted in this way contributes the leaf twist subcomponent of the auxiliary roll stiffness component mentioned previously. Similarly, the angle “A” between the frame  103  and the solid front steerable axle  106  causes the leaf springs  107  to twist along their length between the axle attachment  113  and the spring shackles  110  (not shown). This also contributes to the leaf twist subcomponent of the auxiliary roll stiffness.  
         [0034]      FIG. 7  shows a vehicle  101  having an asymmetric leaf spring front suspension  121  and undergoing deflection as a result of vehicle body roll. The asymmetric leaf spring front suspension  121  is comprised of the solid front steerable axle  106  and the leaf springs  107 . The solid front steerable axle  106  is attached to the leaf springs  107  at the axle attachments  113 . The leaf springs  107 , in turn, are connected to the spring hangers  108  at the spring hanger connections  109 , which spring hangers  108  are attached to the frame  103 . The leaf springs  107  are also connected to the spring shackles  110  at the spring shackle connections  112 , which spring shackles  110  are in turn connected to the spring shackle attachments  111 . The spring shackle attachments  111  are attached to the frame  103 . Note that the axle attachments  113  are located upon the leaf springs  107  nearer the spring hangers  108  than to the spring shackles  110 . For simplicity, the vehicle body  102 , the damper elements  114 , and the stabilizer bar  115  are not shown. In  FIG. 7 , the frame  103  is shown level, such that the viewpoint of  FIG. 7  uses the leaning vehicle  101  as its frame of reference. Therefore, the outer leaf spring  107   b  is shown partially compressed, and the inner leaf spring  107   a  is shown partially relieved relative to the level frame  103 . The point at which the solid front steerable axle  106  is attached to the outer leaf spring  107   b  is rotated in a positive direction relative to the frame of reference of  FIG. 7  as a result of the compression of the outer leaf spring  107   b  and the proximity of the axle attachment  113  of the solid front steerable axle  106  along the length of the outer leaf spring  107   b  to the spring hanger  108 . The point at which the solid front steerable axle  106  is attached to the inner leaf spring  107   a  is rotated in a negative direction relative to the frame of reference of  FIG. 7  as a result of the relief of the inner leaf spring  107   a  and the proximity of the axle attachment  113  of the solid front steerable axle  106  along the length of the inner leaf spring  107   a  to the spring hanger  108 . The opposite rotations of the axle attachments  113  of the solid front steerable axle  106  to the inner leaf spring  107   a  and to the outer leaf spring  107   b  causes the solid front steerable axle  106  to twist along its length. The resistance of the solid front steerable axle  106  to being twisted in this way contributes the axle torsion subcomponent of the auxiliary roll stiffness component mentioned previously.  
         [0035]      FIG. 8  shows a prior-art leaf spring suspension  122  having thicker half-portions  123  of the overall length of the leaf springs  107  and thinner half-portions  124  of the overall length of the leaf springs  107 . Note for clarity, neither the body  102  nor the frame  103  are shown. The leaf spring suspension  122  is generally comprised of the leaf springs  107  and the solid front steerable axle  106 . The solid front steerable axle  106  is attached to the leaf springs  107  at the axle attachments  113 . The leaf springs  107 , in turn, are connected to the spring hangers  108  at the spring hanger connections  109 . The damper elements  114  are connected to the frame  103 , which is not shown in  FIG. 8 , and to the solid front steerable axle  106  at or near the axle attachments  113 . The leaf springs  107  are also connected to the spring shackles  110  at the spring shackle connections  112 , which spring shackles  110  are in turn connected to the spring shackle attachments  111 . Note that in this particular design, the spring shackles  110  are inverted and the spring shackle connections  112  are of a sliding nature. This is inconsequential to the performance of the leaf spring suspension  122  having leaf springs  107  with thicker half-portions  123  and thinner half-portions  124 . However, the additional elements that are consequential to the performance of the leaf spring suspension  122  having leaf springs  107  with thicker half-portions  123  and thinner half-portions  124 , and which must be present in order for the leaf springs  107  of the leaf spring suspension  122  in this configuration to withstand normal stresses, are the additional spring elements  125 . The additional spring elements  125  are attached to the leaf springs  107  at or near the axle attachments  113 , and are further attached to the frame  103 , which is not shown in  FIG. 8 .  
         [0036]      FIG. 9  shows an embodiment of the present invention, a parabolic leaf spring front suspension  126  having upper thick truncated half-leafs  127 , thin full leafs  129  with front eye wraps  130  and rear eye wraps  131 , and lower thin truncated half-leafs  128 . Note for clarity, the body  102  is not shown. The solid front steerable axle  106  is shown partially cut-away, such that the axle attachments  113  to the upper thick truncated half-leafs  127 , the thin full leafs  129 , and the lower thin truncated half-leafs  128  may be more clearly illustrated. In the same way, one spring hanger  108  is shown partially cut-away, so that the front eye wraps  130  may be more clearly illustrated as attached to the spring hanger connections  109 . One spring shackle  110  is shown partially cut-away as well, so that the rear eye wraps  131  may be more clearly illustrated as attached to the spring shackle connections  112 . As in the prior art suspensions, the spring hangers  108  are attached to the frame  103 , and the spring shackle connections  112  are attached to the spring shackles  110 , which spring shackles  110  are connected to the spring shackle attachments  111 , which spring shackle attachments  111  are attached to the frame  103 . The parabolic leaf spring front suspension  126  with the upper thick truncated half-leafs  127 , the thin full leafs  129 , and the lower thin truncated half-leafs  128 , is provided with damper elements  114 , which are also shown partially cut-away, and a stabilizer bar  115 . However, the parabolic leaf spring front suspension  126  of the present invention may be provided with or without the stabilizer bar  115 . As in the prior art suspensions, the stabilizer bar  115  is attached to the solid front steerable axle  106  by means of the stabilizer bar axle connections  117 , and is attached to the frame  103  by means of the stabilizer bar frame links  116 . The damper elements  114  are connected to the frame  103  and to the solid front steerable axle  106  at or near the axle attachments  113 .  
         [0037]      FIG. 10  shows an embodiment of the present invention, a flat leaf spring front suspension  132  having upper thick truncated half-leafs  127 , thin full leafs  129  with front eye wraps  130  and rear eye wraps  131 , and lower thin truncated half-leafs  128 . Note for clarity, the body  102  is not shown. The solid front steerable axle  106  is shown partially cut-away, such that the axle attachments  113  to the upper thick truncated half-leafs  127 , the thin full leafs  129 , and the lower thin truncated half-leafs  128  may be more clearly illustrated. In the same way, one spring hanger  108  is shown partially cut-away, so that the front eye wraps  130  may be more clearly illustrated as attached to the spring hanger connections  109 . One spring shackle  110  is shown partially cut-away as well, so that the rear eye wraps  131  may be more clearly illustrated as attached to the spring shackle connections  112 . As in the prior art suspensions, the spring hangers  108  are attached to the frame  103 , and the spring shackle connections  112  are attached to the spring shackles  110 , which spring shackles  110  are connected to the spring shackle attachments  111 , which spring shackle attachments  111  are attached to the frame  103 . The flat leaf spring front suspension  132  with the upper thick truncated half-leafs  127 , the thin full leafs  129 , and the lower thin truncated half-leafs  128 , is provided with damper elements  114 , which are also shown partially cut-away, and a stabilizer bar  115 . However, like the parabolic leaf spring front suspension  126  in  FIG. 9 , the flat leaf spring front suspension  132  of the present invention shown in  FIG. 10  may be provided with or without the stabilizer bar  115 . As in the prior art suspensions, the stabilizer bar  115  is attached to the solid front steerable axle  106  by means of the stabilizer bar axle connections  117 , and is attached to the frame  103  by means of the stabilizer bar frame links  116 . The damper elements  114  are connected to the frame  103  and to the solid front steerable axle  106  at or near the axle attachments  113 .  
         [0038]      FIG. 11  shows an embodiment of the present invention, a flat leaf spring front suspension  132 , similar to the flat leaf spring front suspension  132  in  FIG. 10 . The flat leaf spring front suspension  132  shown in  FIG. 11  is provided with lower thick truncated half-leafs  133 , thin full leafs  129  with front eye wraps  130  and rear eye wraps  131 , and upper thin truncated half-leafs  134 . Note for clarity, the body  102  is again not shown. The solid front steerable axle  106  is shown partially cut-away, such that the axle attachments  113  to the lower thick truncated half-leafs  133 , the thin full leafs  129 , and the upper thin truncated half-leafs  134  may be more clearly illustrated. In the same way, one spring hanger  108  is shown partially cut-away, so that the front eye wraps  130  may be more clearly illustrated as attached to the spring hanger connections  109 . One spring shackle  110  is shown partially cut-away as well, so that the rear eye wraps  131  may be more clearly illustrated as attached to the spring shackle connections  112 . As in the prior art suspensions, the spring hanger  108  is attached to the frame  103 , and the spring shackle connection  112  is attached to the spring shackle  110 , which spring shackle  110  is connected to the spring shackle attachment  111 , which spring shackle attachment  111  is attached to the frame  103 . The flat leaf spring front suspension  132  with the lower thick truncated half-leafs  133 , the thin full leafs  129 , and the upper thin truncated half-leafs  134 , is provided with damper elements  114 , which are also shown partially cut-away, and a stabilizer bar  115 . As in the previous embodiments of the present invention, the flat leaf spring front suspension  132  of the present invention shown in  FIG. 11  may be provided with or without the stabilizer bar  115 . As in the prior art suspensions, the stabilizer bar  115  is attached to the solid front steerable axle  106  by means of the stabilizer bar axle connections  117 , and is attached to the frame  103  by means of the stabilizer bar frame links  116 . The damper elements  114  are connected to the frame  103  and to the solid front steerable axle  106  at or near the axle attachments  113 .  
         [0039]      FIG. 12  shows an embodiment of the present invention, an asymmetric leaf spring front suspension  135  having upper thick truncated half-leafs  127 , thin full leafs  129  with front eye wraps  130  and rear eye wraps  131 , and lower thin truncated half-leafs  128 . Note for clarity, the body  102  is not shown. The solid front steerable axle  106  is shown partially cut-away, such that the axle attachments  113  to the upper thick truncated half-leafs  127 , the thin full leafs  129 , and the lower thin truncated half-leafs  128  may be more clearly illustrated. In the same way, one spring hanger  108  is shown partially cut-away, so that the front eye wraps  130  may be more clearly illustrated as attached to the spring hanger connections  109 . One spring shackle  110  is shown partially cut-away as well, so that the rear eye wraps  131  may be more clearly illustrated as attached to the spring shackle connections  112 . Note that the solid front steerable axle  106  and axle attachments  113  are located proximate to the spring hangers  108  along the length of the thin full leafs  129 , and distant from the spring shackles  110 . The upper thick truncated half-leafs  127  are therefore shorter in length than in previous embodiments of the present invention, and the lower thin truncated half-leafs  128  are longer than in previous embodiments. As in the prior art suspensions, the spring hangers  108  are attached to the frame  103 , and the spring shackle connections  112  are attached to the spring shackles  110 , which spring shackles  110  are connected to the spring shackle attachments  111 , which spring shackle attachments  111  are attached to the frame  103 . The asymmetric leaf spring front suspension  135  is further provided with damper elements  114 , which are also shown partially cut-away. The damper elements  114  are connected to the frame  103  and to the solid front steerable axle  106  at or near the axle attachments  113 .  
         [0040]      FIG. 13  shows an isometric view of an embodiment of the present invention, a flat leaf spring front suspension  132 , similar to the flat leaf spring front suspension  132  shown in  FIG. 10 . The flat leaf spring front suspension  132  shown in  FIG. 13  again is provided with upper thick truncated half-leafs  127 , thin full leafs  129  with front eye wraps  130  and rear eye wraps  131 , and lower thin truncated half-leafs  128 . The front eye wraps  130  engage the spring hanger connections  109 , which are attached to the spring hangers  108 , which are in turn attached to the frame  103 . The rear eye wraps  131  engage the spring shackle connections  112 , which are attached to the spring shackles  110 , which are in turn connected to the spring shackle attachments  111 . The spring shackle attachments  111  are again attached to the frame  103 . The solid front steerable axle  106  is attached to the upper thick truncated half-leafs  127 , the thin full leafs  129 , and the lower thin truncated half-leafs  128  by the axle attachments  113 . The flat leaf spring front suspension  132  shown in  FIG. 13  is again provided with damper elements  114 , which damper elements  114  are connected to the frame  103  and to the solid front steerable axle  106  at or near the axle attachments  113 .  
         [0041]      FIG. 14  shows an isometric view of an embodiment of the present invention, a leaf spring rear suspension  136  having upper thick truncated half-leafs  127 , thin full leafs  129  with front eye wraps  130  and rear eye wraps  131 , and lower thin truncated half-leafs  128 . Of the front eye wraps  130  and rear eye wraps  131 , note that only the left side eye wraps are visible in  FIG. 14 . Note also for clarity, neither the body  102 , the frame  103 , nor the damper elements  114  are shown. The solid rear driving axle  137  is attached to the upper thick truncated half-leafs  127 , the thin full leafs  129 , and the lower thin truncated half-leafs  128  by the axle attachments  113 . The front eye wraps  130  engage the spring hanger connections  109 , which spring hanger connections  109  are attached to the spring hangers  108 , which spring hangers  108  are in turn attached to the frame  103 , which frame  103  is not shown in  FIG. 14 . The rear eye wraps  131  engage the spring shackle connections  112 , which spring shackle connections  112  are attached to the spring shackles  110 , which spring shackles  110  are in turn connected to the spring shackle attachments  111 . The spring shackle attachments  111  are again attached to the frame  103 , which frame  103  is not shown in  FIG. 14 .  
         [0042]     Other permutations of the invention are possible without departing from the teachings disclosed herein, provided that the function of the invention is to provide an increased auxiliary roll stiffness in a vehicle suspension via the use of thick truncated half-leafs, while alleviating a corresponding increase in leaf stress via the use of opposing thinner truncated half leafs. Other advantages to a vehicle suspension equipped with opposed thick and thin truncated half leafs may also be inherent in the invention, without having been described above.