Patent Publication Number: US-2023158848-A1

Title: Rear suspension assembly for a vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to U.S. Provisional Patent Application No. 63/282,368, filed Nov. 23, 2021, the entire disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to a rear suspension assembly for a utility vehicle and, more particularly, to a rear suspension assembly including a suspension member configured to control toe of the rear ground-engaging members during suspension travel. 
     BACKGROUND OF THE DISCLOSURE 
     On-road and off-road vehicles include a rear suspension assembly. For example, in the context of off-road vehicles, various embodiments of a rear suspension assembly may include trailing arms which generally extend in a forward-aft direction and control arms or radius rods which generally extend in a lateral direction. 
     However, despite the inclusion of a trailing arm and/or radius rod, the rear wheel may toe in or toe out when the vehicle rebounds or at full compression, and through the full travel of the suspension. In this way, the vehicle may not rebound with the rear wheels facing in the longitudinal direction. As such, there is a need for a rear suspension assembly which decreases the toe change, especially when the vehicle rebounds and when the rear suspension assembly is at a full compression position. 
     SUMMARY OF THE DISCLOSURE 
     According to an illustrative embodiment of the present disclosure, a utility vehicle includes a frame assembly extending longitudinally along a centerline of the vehicle; at least one front ground-engaging member supporting the frame assembly; at least one rear ground-engaging member supporting the frame assembly; and a rear suspension assembly operably coupled to the frame assembly and the at least one rear ground-engaging member, the rear suspension assembly including a trailing arm generally extending longitudinally and operably coupled to the frame assembly and the at least one rear ground-engaging member, the trailing arm including a joint along a longitudinal length of the trailing arm; an upper radius rod extending in a generally lateral direction relative to the centerline of the vehicle and operably coupled to the trailing arm; a lower radius rod extending in the generally lateral direction relative to the centerline of the vehicle and operably coupled to the trailing arm; and a suspension member configured to control toe of the at least one rear ground-engaging member and operably coupled to the trailing arm and to the frame assembly. 
     In a further embodiment, the suspension member is operably coupled to the trailing arm forward of the joint. 
     In a further embodiment, the suspension member is operably coupled to the trailing arm rearward of the joint. 
     In a further embodiment, the suspension member includes a first link positioned at least partially forward of a longitudinal midpoint of the at least one ground engaging member and a second link positioned at least partially rearward of the longitudinal midpoint of the at least one ground engaging member, the suspension member being coupled to the first link forward of the a longitudinal midpoint of the at least one ground engaging member 
     In a further embodiment, the suspension member is operably coupled to the trailing arm at the joint. 
     In a further embodiment, the joint includes one degree of freedom. 
     In a further embodiment, the joint includes a substantially vertical axis of rotation. 
     In a further embodiment, the rear suspension assembly includes a shock absorber having an upper end operably coupled to the frame assembly and a lower end operably coupled to the trailing arm rearward of the joint. 
     According to an illustrative embodiment of the present disclosure, a utility vehicle includes a frame assembly extending longitudinally along a centerline of the vehicle; at least one front ground-engaging member supporting the frame assembly; at least one rear ground-engaging member supporting the frame assembly; and a rear suspension assembly operably coupled to the frame assembly and the at least one rear ground-engaging member, the rear suspension assembly comprising a trailing arm generally extending longitudinally and including a front end operably coupled to the frame assembly and a rear end operably coupled to the at least one rear ground- engaging member; an upper radius rod extending in a generally lateral direction relative to the centerline of the vehicle and including an outside end operably coupled to the trailing arm and an inside end extending toward the centerline of the vehicle; a lower radius rod extending in the generally lateral direction relative to the centerline of the vehicle and operably coupled to the trailing arm; and a suspension member configured to control toe of the at least one rear ground-engaging member and operably coupled to the trailing arm and to the frame assembly at positions within a zone defined by the trailing arm, the upper radius rod, and a plane defined between the front end of the trailing arm and the inner end of the upper radius rod as viewed from above. 
     In a further embodiment, a distance between a position at which the suspension member  70  is coupled to the frame and a nearest point on the plane P is about 1:12 of a distance from the front end of the trailing arm and the inner end of the upper radius rod which define the plane P. 
     In a further embodiment, the trailing arm includes a first longitudinal portion and a second longitudinal portion, the first and second longitudinal portions are pivotable relative to each other at a joint. 
     In a further embodiment, the joint includes one degree of freedom. 
     In a further embodiment, the joint defines a substantially vertical pivot axis. 
     In a further embodiment, the suspension member is coupled to the first longitudinal portion of the trailing arm. 
     In a further embodiment, the suspension member is coupled to the second longitudinal portion of the trailing arm. 
     In a further embodiment, the suspension member includes a first link positioned at least partially forward of a longitudinal midpoint of the at least one ground engaging member and a second link positioned at least partially rearward of the longitudinal midpoint of the at least one ground engaging member, the suspension member being coupled to the first link forward of the a longitudinal midpoint of the at least one ground engaging member 
     In a further embodiment, the suspension member is coupled to the trailing arm at the joint. 
     In a further embodiment, at least one rear ground-engaging member includes a knuckle, the trailing arm and the upper and lower radius rods being coupled to the knuckle. 
     In a further embodiment, the second longitudinal portion of the trailing arm is angled relative to the centerline of the vehicle at a fixed angle and the rear suspension assembly is operable to maintain the second longitudinal portion at the fixed angle relative to the centerline of the vehicle through travel of the rear suspension assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above mentioned and other features of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings. 
         FIG.  1    is a front left perspective view of a utility vehicle of the present disclosure; 
         FIG.  2    is a rear right perspective view of the vehicle of  FIG.  1   ; 
         FIG.  3    is a left side view of the vehicle of  FIG.  1   ; 
         FIG.  4    is a right side view of the vehicle of  FIG.  1   ; 
         FIG.  5    is a top view of the vehicle of  FIG.  1   ; 
         FIG.  6    is a front view of the vehicle of  FIG.  1   ; 
         FIG.  7    is a rear view of the vehicle of  FIG.  1   ; 
         FIG.  8    is a front view of a schematic of a rear suspension assembly of the vehicle of  FIG.  1   ; 
         FIG.  9    is a side view of the rear suspension assembly of  FIG.  8   ; 
         FIG.  10    is a rear view of a rear suspension assembly of  FIG.  8   ; 
         FIG.  11    is a top view of the rear suspension assembly of  FIGS.  8   ; 
         FIG.  12    is a front left perspective view of the rear suspension assembly of  FIG.  8   ; 
         FIG.  13    is a rear left perspective view of the rear suspension assembly of  FIG.  8   ; 
         FIG.  14    is a detailed view of the rear suspension assembly of  FIG.  8    engaged with a rear-ground engaging member; 
         FIG.  15    is another detailed view of the rear suspension assembly of  FIG.  14   ; 
         FIGS.  16 - 20    are front views of the rear suspension assembly of  FIG.  8    illustrated throughout varying loading configurations of the rear suspension assembly; 
         FIGS.  21 - 25    are top views of the rear suspension assembly of  FIG.  8    illustrated throughout varying loading configurations of the rear suspension assembly; 
         FIG.  26    is a front view of another embodiment of a rear suspension assembly of the vehicle of  FIG.  1   ; 
         FIG.  27    is a side view of the rear suspension assembly of  FIG.  26   ; 
         FIG.  28    is a rear view of a rear suspension assembly of  FIG.  26   ; 
         FIG.  29    is a top view of the rear suspension assembly of  FIG.  26   ; 
         FIG.  30    is a front left perspective view of the rear suspension assembly of  FIG.  26   ; 
         FIG.  31    is a rear left perspective view of the rear suspension assembly of  FIG.  26   ; 
         FIG.  32    is an expanded view of the rear suspension assembly of  FIG.  26    engaged with a rear-ground engaging member; 
         FIG.  33    is another detailed view of the rear suspension assembly of  FIG.  32   ; 
         FIGS.  34 - 38    are front views of the rear suspension assembly of  FIG.  26    illustrated throughout varying loading configurations of the rear suspension assembly; 
         FIGS.  39 - 42    are top views of the rear suspension assembly of  FIG.  26    illustrated throughout varying loading configurations of the rear suspension assembly; 
         FIG.  43    is a front view of another embodiment of a rear suspension assembly of the vehicle of  FIG.  1   ; 
         FIG.  44    is a side view of the rear suspension assembly of  FIG.  43   ; 
         FIG.  45    is a rear view of a rear suspension assembly of  FIG.  43   ; 
         FIG.  46    is a top view of the rear suspension assembly of  FIG.  43   ; 
         FIG.  47    is a front left perspective view of the rear suspension assembly of  FIG.  43   ; 
         FIG.  48    is a rear left perspective view of the rear suspension assembly of  FIG.  43   ; 
         FIG.  49    is an expanded view of the rear suspension assembly of  FIG.  43    engaged with a rear-ground engaging member; 
         FIG.  50    is another detailed view of the rear suspension assembly of  FIG.  49   ; 
         FIGS.  51 - 55    are front views of the rear suspension assembly of  FIG.  43    illustrated throughout varying loading configurations of the rear suspension assembly; and 
         FIGS.  56 - 60    are top views of the rear suspension assembly of  FIG.  43    illustrated throughout varying loading configurations of the rear suspension assembly. 
         FIG.  61    is a front view of another embodiment of a rear suspension assembly of the vehicle of  FIG.  1   ; 
         FIG.  62    is a side view of the rear suspension assembly of  FIG.  61   ; 
         FIG.  63    is a rear view of a rear suspension assembly of  FIG.  61   ; 
         FIG.  64    is a top view of the rear suspension assembly of  FIG.  61   ; 
         FIG.  65    is a front left perspective view of the rear suspension assembly of  FIG.  61   ; 
         FIG.  66    is a rear left perspective view of the rear suspension assembly of  FIG.  61   ; 
         FIG.  67    is an expanded view of the rear suspension assembly of  FIG.  61    engaged with a rear-ground engaging member; 
         FIG.  68    is another detailed view of the rear suspension assembly of  FIGS.  67   ; 
         FIGS.  69 - 73    are front views of the rear suspension assembly of  FIG.  61    illustrated throughout varying loading configurations of the rear suspension assembly; and 
         FIGS.  74 - 77    are top views of the rear suspension assembly of  FIG.  61    illustrated throughout varying loading configurations of the rear suspension assembly. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the some of the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The embodiments disclosed below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. For example, while the following description refers primarily to utility vehicles, certain features described herein may be applied to other applications such as all-terrain vehicles, snowmobiles, motorcycles, mopeds, etc. 
     Referring to  FIG.  1   , an illustrative embodiment of a utility vehicle  10  is shown which is configured to traverse a variety of terrains, including mud, rocks, dirt, and other trail or off-road conditions. The vehicle  10  may be referred to as a utility vehicle (“UV”), an all-terrain vehicle (“ATV”), or a side-by-side vehicle (“S×S”) and is configured for travel over various terrains or surfaces. More particularly, the vehicle  10  may be configured for military, industrial, agricultural, or recreational applications. 
     The vehicle  10  includes a plurality of ground-engaging members, including front ground-engaging members  12  (e.g., front wheels) and rear-ground engaging members  14  (e.g., rear wheels), a powertrain assembly  16 , a frame assembly  20 , a plurality of body panels  22  coupled to frame assembly  20 , a front suspension assembly  24  supported by a front portion of frame assembly  20 , a rear suspension assembly  26  supported by a rear portion of frame assembly  20 , and a rear cargo area  28  supported by the rear portion of frame assembly  20 . As shown in  FIG.  1   , the vehicle  10  extends between the front and rear ground-engaging members  12 ,  14  in a longitudinal direction along a longitudinal vehicle centerline L ( FIG.  3   ). A prop shaft or other mechanism may extend between various components of the powertrain assembly  16  to provide motive power to the front and/or rear ground-engaging members  12 ,  14 . 
     In one embodiment, one or more ground-engaging members  12 ,  14  may be replaced with tracks, such as the PROSPECTOR II tracks available from Polaris Industries, Inc. located at 2100 Highway 55 in Medina, Minn. 55340, or non-pneumatic tires as disclosed in any of U.S. Pat. No. 8,109,308, filed on Mar. 26, 2008; U.S. Pat. No. 8,176,957, filed on Jul. 20, 2009; and U.S. Pat. No. 9,108,470, filed on Nov. 17, 2010; and U.S. Patent Application Publication No. 2013/0240272, filed on Mar. 13, 2013, the complete disclosures of which are expressly incorporated by reference herein. 
     Referring still to  FIG.  1   , the vehicle  10  includes an operator area  30  supported by frame assembly  20  and which includes seating for at least an operator and a passenger. Illustratively, one embodiment of the vehicle  10  includes an operator seat  32  and a front passenger seat  34 . More particularly, the operator seat  32  and front passenger seat  34  are in a side-by-side arrangement. The operator seat  32  includes a seat bottom, illustratively a bucket seat, and a seat back. Similarly, the front passenger seat  34  includes a seat bottom, illustratively a bucket seat, and a seat back. 
     Referring to  FIGS.  2 - 4   , the rear suspension assembly  26  is shown. The rear suspension assembly  26  is a trailing arm-type suspension generally comprised of trailing arms  40 , an upper or first radius rod  42 , a lower or second radius rod  44 , a torsion or sway bar  46 , and shock absorbers  48 . Illustratively, both a right and left side of vehicle  10  includes the trailing arm  40 , radius rods  42 ,  44 , and shock absorbers  48  such that both right and left rear ground-engaging members  14  are each operably coupled to one trailing arm  40 , upper and lower radius rods  42 ,  44 , and one shock absorber  48 . More particularly, each of the rear ground-engaging members  14  includes a wheel hub  50  and a knuckle  52 , and at least the trailing arms  40  and radius rods  42 ,  44  are operably coupled to the knuckle  52 . 
     Additionally, each of the rear ground-engaging members  14  includes a rear axle  56  (e.g., a half shaft) extending between a rear final drive member (not shown) and the knuckle  52 . The rear axles  56  are configured to rotate the rear ground-engaging members  14  during operation of the vehicle  10 . The rear axles  56  extend laterally and may be generally perpendicular to the centerline L of vehicle  10  ( FIG.  3   ). 
     Referring again to  FIGS.  2 - 4   , the trailing arms  40  include a first coupler  58  positioned at a forward portion thereof and a second coupler  60  positioned at a rearward portion thereof. The first coupler  58  is configured to operably couple trailing arms  40  to the frame assembly  20  ( FIG.  3   ) and the second coupler  60  is configured to operably couple the trailing arms  40  to the rear ground-engaging member  14  ( FIG.  2   ). The first coupler  58  is configured to allow the trailing arms  40  to pivot or rotate in a generally vertically direction relative to the frame assembly  20 . The trailing arm  40  is operably coupled to the knuckle  52  of rear ground-engaging member  14  through the second coupler  60 . 
     In one embodiment, the trailing arms  40  are configured to extend in a generally longitudinal or forward-aft direction between the first and second couplers  58 ,  60 . More particularly, the trailing arms  40  may be generally parallel to the centerline L of vehicle  10  and/or may have a longitudinal directional component angled less than  45 ° relative to the centerline L. Through the couplers  58 ,  60 , the trailing arms  40  are configured to pivot about a generally horizontal axis during operation of the vehicle  10 , especially as the vehicle  10  traverses various terrain. 
     Various configurations of the rear suspension assembly  26  may be implemented on the vehicle  10  are shown schematically and discussed herein in more detail. For example,  FIGS.  8 - 25    illustrate a first embodiment of a rear suspension assembly  26  for controlling toe of the rear ground-engaging members  14 . 
     As illustrated in  FIGS.  8 - 15   , each of the trailing arms  40  may be comprised as a single component or may be comprised of a plurality of components coupled together, such as a first longitudinal portion  67 , a second longitudinal portion  69 , and a joint  68  positioned between the first and second longitudinal portions  67 ,  69 . The joint  68  is operable to permit the first and second longitudinal portions  67 ,  69  to pivot relative to each other. Any number of types of joints may be implemented. For example, in one embodiment, the joint  68  includes one degree of freedom. The joint  68  may include a substantially vertical axis of rotation A ( FIG.  9   ). This configuration allows the first and second longitudinal portions  67 ,  69  to pivot relative to one another within a substantially horizontal plane whereas the first and second longitudinal portions  67 ,  69  do not pivot relative to each other within a vertical plane. In this way, the first and second portions  67 ,  69  move laterally relative to each other and do not move vertically relative to each other. Rather, the vertical movement of trailing arm  40  occurs during travel of rear suspension assembly  26  and first and second portions  67 ,  69  move together during such vertical travel. The joint  68  can couple the first and second longitudinal portions  67 ,  69  via a revolute joint such as a pin, hinge, or knuckle joint. 
     The rear suspension assembly  26  further includes a suspension member  70 . The suspension member  70  includes a first portion  72 A and a second portion  72 B. The first portion  72 A is coupled to the trailing arm  40  and the second portion  72 B is coupled to the frame assembly  20 . For example, the trailing arm  40  may include a first coupler  74  that is positioned along the longitudinal length of the trailing arm  40 . The first coupler  74  is operable to allow the suspension member  70  to pivot relative to the trailing arm  40 . For example, the first coupler  74  may include various types of joints including a ball joint or any other joint or combination of joints that facilitate pivoting of the suspension member  70  relative to the trailing arm  40 . In some embodiments, the first coupler  274  includes a bearing carrier or hub. A second coupler  76  may be positioned on the frame assembly  20  to which the second portion  72 B of the suspension member  70  is coupled and which is operable to allow the suspension member  70  to pivot relative to the frame assembly  20 . For example, the second coupler  76  may include a variety of joints including a ball joint or any other joint or combination of joints that facilitate pivoting of the suspension member  70  relative to the frame assembly  20 . In some embodiments, the suspension member  70  may include an actuator that allows for active control of toe of the rear ground-engaging members  14  (e.g., pneumatic, motor, and so forth). Furthermore, it is understood that an actuator may be coupled to the suspension members  70  allowing for active control of toe of the rear ground-engaging members  14  (e.g., coupled between the suspension member  70  and the frame assembly  20  or coupled between the suspension members  70  on each side of the vehicle  10 ). 
     Referring still to  FIGS.  8  and  9   , the rear suspension assembly  26  includes the shock absorbers  48 . The shock absorbers  48  are coupled between the trailing arm  40  and the frame assembly  20  ( FIG.  2   ). The positions at which the shock absorber  48  is coupled to the trailing arm  40  and the suspension member  70  is coupled to the trailing arm  40  are different positions. For example, the position at which the shock absorber  48  is coupled to the trailing arm  40  is longitudinally spaced from the position at which the suspension member  70  is coupled to the trailing arm  40 . The shock absorber  48  is coupled to the frame assembly  20  at a position spaced from the coupling position of the suspension member  70  to the frame assembly  20 . For example, the shock absorber  48  may be coupled to the frame assembly  20  at or near a rear cargo area  28  and the suspension member  70  is coupled to the frame assembly at or near lower frame members. Both coupling positions are outside of any envelope defined by the powertrain assembly  16  so as to not interfere with the operation or location of any powertrain component. For example, the coupling position of shock absorber  48  to frame  20  may be positioned at least vertically higher than an upper surface of an engine of the powertrain assembly  16  while the coupling position of suspension member  70  to frame  20  may be positioned at least laterally outward of the engine. 
     Referring more specifically to  FIG.  11   , the first coupler  58  of the trailing arm  40  is shown positioned at a forward end of the first longitudinal portion  67  of the trailing arm  40 . The first radius rod  42  is shown with a coupling position  43  at which the first radius rod  42  couples to the frame assembly  20 . A plane P is illustrated extending between the first coupler  58  of the trailing arm  40  and the coupling position  43  of the first radius rod  42 , the plane extending vertically (i.e., as illustrated in the top view of  FIG.  11   , into and out of the page). The suspension member  70  couples to the frame assembly  20  at the second coupler  76 , wherein the second coupler  76  is positioned within or adjacent the plane P defined between the first coupler  58  of the trailing arm  40  and the coupling position  43  of the first radius rod  42 . For example, the second coupler  76  is coupled to the frame assembly  20  such that the distance between the second coupler  76  of the suspension member  70  and the nearest point on the plane P is about 1:12 of the distance from the first coupler  58  of the trailing arm and the coupling position  43  of the first radius rod  42  which define the plane P. Various rations of the distances described above are contemplated including about 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, or less. In some embodiments, another way of defining the relative position of the second coupler  76  with respect to components of the rear suspension assembly  26  includes defining a zone Z within which the second coupler  76  is positioned. The zone Z is defined as a space as viewed from above and bounded by the trailing arm  40 , the upper radius rod  42 , and an interior edge defined between the front end of the trailing arm and the inner end of the upper radius rod as viewed from above (i.e., the plane P described previously). The second coupler  76  is positioned within the zone Z adjacent the interior edge (i.e., the plane P). 
     As illustrated in  FIG.  11   , the shock absorber  48  is coupled to the trailing arm  40  rearward of the joint  68 . In some embodiments, the shock absorber  48  is coupled between a longitudinal midpoint of the second longitudinal portion  69  of the trailing arm  40  and the joint  68 . The placement of the coupling between the shock absorber  48  and the trailing arm  40  in combination with the first coupler  74  of the suspension member  70  to the trailing arm  40  provides control of toe of the rear ground-engaging members  14 . In some embodiments, the first coupler  74  of the suspension member  70  is spaced from the joint  68  between the first and second longitudinal portions  67 ,  69  approximately the same distance as the coupling of the shock absorber  48  to the trailing arm  40  is spaced from the joint  68 . 
     Referring to  FIGS.  16 - 25   , the embodiment of  FIG.  8    is illustrated with the rear suspension assembly  26  in various positions through the travel of the rear suspension assembly  26  (i.e., through travel of the shock absorber  48  in loaded, unloaded, and partially loaded conditions).  FIGS.  16 - 20    show views of the rear suspension assembly  26  through its travel from a front view, and  FIGS.  21 - 25    show views of the rear suspension assembly  26  through its corresponding travel from a top view. In other words, the position of the rear suspension assembly  26  of  FIG.  16    corresponds with the position of the rear suspension assembly  26  of  FIG.  21   , the position of the rear suspension assembly  26  of  FIG.  17    corresponds with the position of the rear suspension assembly  26  of  FIG.  22   , the position of the rear suspension assembly  26  of  FIG.  18    corresponds with the position of the rear suspension assembly  26  of  FIG.  23   , the position of the rear suspension assembly  26  of  FIG.  19    corresponds with the position of the rear suspension assembly  26  of  FIG.  24   , and the position of the rear suspension assembly  26  of  FIG.  20    corresponds with the position of the rear suspension assembly  26  of  FIG.  25   . Although the frame assembly  20  is not shown in these figures, it is understood that the coupling positions of the rear suspension assembly  26  to the frame assembly  20  (e.g., coupling position  43 , at first coupler  58 , and at second coupler  76 ) represent the correct positions of the couplings (e.g., those positions are substantially static) and other portions and/or components of the rear suspension assembly  26  move with respect to the frame assembly  20 . 
       FIGS.  16  and  21    illustrate the rear suspension assembly  26  in a substantially unloaded state. As discussed, the coupling positions at which the rear suspension assembly  26  is coupled to the frame assembly  20  are substantially static. The toe of the rear ground-engaging members  14  is generally neutral or zero (or at a predetermined toe such as plus or minus three degrees) when the rear suspension assembly  26  is in a substantially unloaded state (and throughout the loading process, as illustrated in  FIGS.  17 - 20  and  22 - 25   ). The joint  68  between the first and second longitudinal portions  67 ,  69  of the trailing arm  40  allows the second longitudinal portion  69  to have a substantially fixed configuration relative to the rear ground-engaging member  14  while the first longitudinal portion  67  pivots generally laterally at the joint  68  and relative to the first coupler  58  to adjust for positional adjustment of other components of the rear suspension assembly  26 . This pivoting and moving of the first longitudinal portion  67  can be appreciated in the remaining  FIGS.  17 - 20  and  22 - 25   .  FIGS.  17 - 19  and  22 - 24    show a progression of the rear suspension assembly  26  through loading of the rear suspension assembly  26  until the rear suspension assembly  26  is illustrated in a fully loaded state in  FIGS.  20  and  25   . 
     As the suspension is loaded, the suspension member  70  pivots relative to the frame assembly  20  and the trailing arm  40  in order to constrain the trailing arm in a configuration that maintains the rear ground-engaging member  14  in a neutral toe configuration (or at a predetermined toe such as plus or minus three degrees) while permitting the remaining components of the rear suspension assembly  26  to pivot and move as appropriate to travel during loading and unloading. The relative positioning of the coupling positions (e.g., the joint  68 , the first coupler  74  of the suspension member  70 , and the coupling of the shock absorber  48  to the trailing arm  40 ) is operable to adjust the sensitivity of the toe control of suspension member  70 . As mentioned, the relative position of the second coupler  76  relative to the coupling position  43  of the first radius rod  42  and the first coupler  58  of the trailing arm  40  is operable to adjust the sensitivity of the toe control of suspension member  70 . It is noted that in some embodiments, the toe of the rear ground-engaging member  14  may not be such that the rear ground-engaging member  14  are exactly parallel to each other, however, the toe of the rear ground-engaging members  14  is constrained to less than five degrees off-axis of the desired longitudinal axis of the rear ground-engaging members  14  as the rear suspension assembly  26  travels through varying levels of loading (e.g., compression and decompression of the shock absorbers  48 ). 
     Referring now to  FIGS.  26 - 42   , another embodiment of a rear suspension assembly  126  is provided. Referring more specifically to  FIG.  26   , a schematic of the rear suspension assembly  126  is illustrated in which the rear suspension assembly  126  is coupled to rear ground-engaging members  14 . The rear suspension assembly  126  of this embodiment includes a trailing arm  140  with a first longitudinal portion  167  and a second longitudinal portion  169  coupled at a joint  168 . The rear suspension assembly  126  includes an upper or first radius rod  142  coupled to the second longitudinal portion  169  of the trailing arm and a lower or second radius rod  144  coupled to the second longitudinal portion  169  of the trailing arm  140  at a position vertically lower than the coupling position of the first radius rod  142 . 
       FIG.  27    illustrates a side schematic view of the embodiment of  FIG.  26    which includes a shock absorber  148  coupled to the second longitudinal portion  169  of the trailing arm  140  at a position longitudinally rearward of the joint  168 . The rear suspension assembly  126  includes a suspension member  170  that is coupled to the second longitudinal portion  169  of the trailing arm  140  forward of and longitudinally spaced from the coupling position of the shock absorber  148  to the second longitudinal portion  169 . The suspension member  170  is coupled to the second longitudinal portion  69  at a first coupler  174  that is longitudinally rearward of the joint  168  and forward of the position at which the shock absorber  148  is coupled to the trailing arm  140 . The suspension member  170  extends from the trailing arm  140  at an angle greater than zero degrees relative to the trailing arm  140 , for example laterally inward and longitudinally forward (see  FIGS.  28 - 33   ). 
     Referring to  FIG.  29   , the rear suspension assembly  126  is illustrated from a top view. The first portion  172 A of the suspension member  170  is coupled to the second longitudinal portion  167  of the trailing arm  140  (e.g., at the first coupler  174 ). A second coupler  176  may be positioned on the frame assembly  20  to which the second portion  1726  of the suspension member  170  is coupled and which is operable to allow the suspension member  170  to pivot relative to the frame assembly  20 . In some embodiments, the suspension member  170  may include an actuator that allows for active control of toe of the rear ground-engaging members  14  (e.g., pneumatic, motor, and so forth). 
     Referring still to  FIG.  29   , the first coupler  158  of the trailing arm  140  is shown positioned at a forward end of the first longitudinal portion  167  of the trailing arm  140 . The first radius rod  142  is shown with a coupling position  143  at which the first radius rod  142  couples to the frame assembly  20 . A plane P is illustrated extending between the first coupler  158  of the trailing arm  140  and the coupling position  143  of the first radius rod  142 , the plane extending vertically into and out of the page. The suspension member  170  couples to the frame assembly  120  at the second coupler  176 , wherein the second coupler  176  is positioned within or adjacent the plane P defined between the first coupler  158  of the trailing arm  140  and the coupling position  143  of the first radius rod  142 . For example, the second coupler  176  is coupled to the frame assembly  20  such that the distance between the second coupler  176  of the suspension member  170  and the nearest point on the plane P is about  1 : 12  of the distance from the first coupler  158  of the trailing arm and the coupling position  143  of the first radius rod  142  which define the plane P. Various rations of the distances described above are contemplated including about  1 : 15 ,  1 : 20 ,  1 : 25 ,  1 : 30 ,  1 : 35 ,  1 : 40 ,  1 : 45 ,  1 : 50 ,  1 : 55 ,  1 : 60 , or less. In some embodiments, another way of defining the relative position of the second coupler  176  with respect to components of the rear suspension assembly  126  includes defining a zone Z within which the second coupler  176  is positioned. The zone Z is defined as a space as viewed from above and bounded by the trailing arm  140 , the first radius rod  142 , and an interior edge defined between the front end of the trailing arm  140  and the inner end of the first radius rod  142  as viewed from above (i.e., the plane P described previously). The second coupler  176  is positioned within the zone Z adjacent the interior edge (i.e., the plane P). 
     As illustrated in  FIG.  29   , the shock absorber  148  is coupled to the trailing arm  140  rearward of the joint  168 . In some embodiments, the shock absorber  148  is coupled between a longitudinal midpoint of the second longitudinal portion  169  of the trailing arm  140  and the second coupler  160  to the rear ground-engaging member  14  (in some embodiments closer to the longitudinal midpoint than to the second coupler  160 ). The placement of the coupling between the shock absorber  148  and the trailing arm  140  in combination with the first coupler  174  of the suspension member  170  to the trailing arm  140  provides control of toe of the rear ground-engaging members  14 . In some embodiments, the first coupler  174  includes a bearing carrier or hub. 
     Referring to  FIGS.  34 - 42   , the embodiment of  FIG.  26    is illustrated with the rear suspension assembly  126  in various positions through the travel of the rear suspension assembly  126  (i.e., through travel of the shock absorber  148  in loaded, unloaded, and partially loaded conditions).  FIGS.  34 - 38    show views of the rear suspension assembly  126  through its travel from a frontal view, and  FIGS.  39 - 42    show views of the rear suspension assembly  126  through its travel from a top view. The position of the rear suspension assembly  126  of  FIG.  34    corresponds with the position of the rear suspension assembly  126  of  FIG.  39   , the position of the rear suspension assembly  126  of  FIG.  35    corresponds with the position of the rear suspension assembly  126  of  FIG.  40   , the position of the rear suspension assembly  126  of  FIG.  36    corresponds with the position of the rear suspension assembly  126  of  FIG.  41   , and the position of the rear suspension assembly  126  of  FIG.  37    corresponds with the position of the rear suspension assembly  126  of  FIG.  42   . Although the frame assembly  20  is not shown in these figures, it is understood that the coupling positions of the rear suspension assembly  126  to the frame assembly  20  (e.g., coupling position  143 , first coupler  158 , and second coupler  176 ) represent the correct positions of the couplings (e.g., those positions are substantially static) and the rear suspension assembly  126  moves with respect to the frame assembly  20 . 
       FIGS.  34  and  39    illustrate the rear suspension assembly  126  in a substantially unloaded state. As discussed, the coupling positions at which the rear suspension assembly  126  is coupled to the frame assembly  20  are substantially static. The toe of the rear ground-engaging members  14  is generally neutral or zero (or at a predetermined toe such as plus or minus three degrees) when the rear suspension assembly  126  is in a substantially unloaded state. The joint  168  between the first and second longitudinal portions  167 ,  169  of the trailing arm  140  allows the second longitudinal portion  169  to have a substantially fixed configuration relative to the rear ground-engaging member  14  while the first longitudinal portion  167  pivots generally laterally at the joint  168  and relative to the first coupler  158  to adjust for positional adjustment of other components of the rear suspension assembly  126 . This pivoting and moving of the first longitudinal portion  167  can be appreciated in the remaining  FIGS.  35 - 38  and  40 - 42   .  FIGS.  35 - 37  and  40 - 42    show a progression of the rear suspension assembly  126  through loading of the rear suspension assembly  126  until the rear suspension assembly  26  is illustrated in a fully loaded state in  FIG.  38   . 
     As the suspension is loaded, the suspension member  170  pivots relative to the frame assembly  20  and the trailing arm  140  in order to constrain the trailing arm in a configuration that maintains the rear ground-engaging member  14  in a neutral toe configuration (or at a predetermined toe such as plus or minus three degrees) while permitting the remaining components of the rear suspension assembly  126  to pivot and move as appropriate to travel during loading and unloading. The relative positioning of the coupling positions (e.g., the joint  168 , the first coupler  174  of the suspension member  170 , and the coupling of the shock absorber  148  to the trailing arm  140 ) is operable to adjust the sensitivity of the toe control of suspension member  170 . As mentioned, the relative position of the second coupler  176  relative to the coupling position  143  of the first radius rod  142  and the first coupler  158  of the trailing arm  40  is operable to adjust the sensitivity of the toe control of suspension member  170 . It is noted that in some embodiments, the toe of the rear ground-engaging member  14  may not be such that the rear ground-engaging member  14  are exactly parallel to each other, however, the toe of the rear ground-engaging members  14  is constrained to less than five degrees off-axis of the desired longitudinal axis of the rear ground-engaging members  14  as the rear suspension assembly  126  travels through varying levels of loading (e.g., compression and decompression of the shock absorbers  148 ). 
     Referring now to  FIGS.  43 - 60   , another embodiment of a rear suspension assembly  226  is provided. Referring more specifically to  FIG.  43   , a schematic of the rear suspension assembly  226  is illustrated in which the rear suspension assembly  226  is coupled to rear ground-engaging members  14 . The rear suspension assembly  226  of this embodiment includes a trailing arm  240  with a first longitudinal portion  267  and a second longitudinal portion  269 . The trailing arm  240  is coupled to a hub  261  at a joint  268 . In some embodiments, the joint  268  is positioned at a longitudinal position aligned with the center of the rear ground engaging member  14 . The rear suspension assembly  226  includes an upper or first radius rod  242  coupled to the hub  161  at a position longitudinally rearward of the coupling of the trailing arm  240  to the hub  241  (e.g., rearward of the center of the rear ground engaging member  14 ) and a lower or second radius rod  244  coupled to the second the hub  161  at a position vertically lower than the coupling position of the first radius rod  242  and longitudinally rearward of the coupling of the trailing arm  240  to the hub  241  (e.g., rearward of the center of the rear ground engaging member  14 ). 
       FIG.  44    illustrates a side schematic view of the embodiment of  FIG.  43    which includes a shock absorber  248  coupled to the second longitudinal portion  269  of the trailing arm  240  at a position longitudinally rearward of a coupling of a suspension member  270  to the trailing arm  240 . Thus, the suspension member  270  is coupled to the trailing arm  240  forward of and longitudinally spaced from the coupling position of the shock absorber  248  to the second longitudinal portion  269 . The suspension member  270  is coupled to the trailing arm  240  at a first coupler  274  that is longitudinally forward of the position at which the shock absorber  248  is coupled to the trailing arm  240 . The coupling of the suspension member  270  and the shock absorber  248  are both longitudinally forward of the joint  268  at which the trailing arm  240  is coupled to the hub  241 . The suspension member  270  extends from the trailing arm  240  at an angle greater than zero degrees, for example laterally inward and longitudinally forward (see  FIGS.  45 -  49   ) relative to the trailing arm  240 . In some embodiments, the joint  268  includes a bearing carrier or hub. 
     Referring for  FIG.  46   , the rear suspension assembly  226  is illustrated from a top view. The first portion  272 A of the suspension member  270  is coupled to the trailing arm  270  at a position between the first and second longitudinal portions  267 ,  269  (e.g., the first longitudinal portion  267  being positioned forward of the coupling of the suspension member  270  to the trailing arm  240  and the second longitudinal portion  269  being positioned rearward of the coupling of the suspension member  270  to the trailing arm  240 ). A second coupler  276  may be positioned on the frame assembly  20  to which the second portion  272 B of the suspension member  270  is coupled and which is operable to allow the suspension member  270  to pivot relative to the frame assembly  20 . In some embodiments, the suspension member  70  may include an actuator that allows for active control of toe of the rear ground-engaging members  14  (e.g., pneumatic, motor, and so forth). 
     Referring still to  FIG.  46   , the first radius rod  242  is shown with a coupling position  243  at which the first radius rod  242  couples to the frame assembly  20 . A plane P is illustrated extending between the first coupler  258  of the trailing arm  240  and the coupling position  243  of the first radius rod  242 , the plane P extending vertically into and out of the page. The suspension member  270  couples to the frame assembly  20  at the second coupler  276 , wherein the second coupler  276  is positioned within or adjacent the plane P defined between the first coupler  258  of the trailing arm  240  and the coupling position  243  of the first radius rod  242 . For example, the second coupler  276  is coupled to the frame assembly  20  such that the distance between the second coupler  276  of the suspension member  270  and the nearest point on the plane P is about  1 : 12  of the distance from the first coupler  258  of the trailing arm and the coupling position  243  of the first radius rod  242  which define the plane P. Various rations of the distances described above are contemplated including about 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, or less. In some embodiments, another way of defining the relative position of the second coupler  276  with respect to components of the rear suspension assembly  226  includes defining a zone Z within which the second coupler  276  is positioned. The zone Z is defined as a space as viewed from above and bounded by the trailing arm  240 , the first radius rod  242 , and an interior edge defined between the front end of the trailing arm and the inner end of the upper radius rod as viewed from above (i.e., the plane P described previously). The second coupler  276  is positioned within the zone Z adjacent the interior edge (i.e., the plane P). 
     As illustrated in  FIG.  46   , the shock absorber  248  is coupled to the trailing arm  240  rearward of the position at which the suspension member  270  couples to the trailing arm  240 . In some embodiments, the shock absorber  248  is coupled between a longitudinal midpoint of the second longitudinal portion  269  of the trailing arm  240  and the position at which the suspension member  270  couples to the trailing arm  240  (in some embodiments closer to the position at which the suspension member  270  couples to the trailing arm  240  than to the longitudinal midpoint). The placement of the coupling between the shock absorber  248  and the trailing arm  240  in combination with the first coupler  274  of the suspension member  270  to the trailing arm  240  provides control of toe of the rear ground-engaging members  14 . The lengths of the first and second longitudinal portions  267 ,  269  are substantially equal to each other (within about  75 % or more of each other). 
     Referring to  FIGS.  51 - 60   , the embodiment of  FIG.  43    is illustrated with the rear suspension assembly  226  in various positions through the travel of the rear suspension assembly  226  (i.e., through travel of the shock absorber  248  in loaded, unloaded, and partially loaded conditions).  FIGS.  51 - 55    show views of the rear suspension assembly  126  through its travel from a frontal view, and  FIGS.  56 - 60    show views of the rear suspension assembly  226  through its travel from a top view. The position of the rear suspension assembly  226  of  FIG.  51    corresponds with the position of the rear suspension assembly  226  of  FIG.  56   , the position of the rear suspension assembly  226  of  FIG.  52    corresponds with the position of the rear suspension assembly  226  of  FIG.  57   , the position of the rear suspension assembly  226  of  FIG.  53    corresponds with the position of the rear suspension assembly  226  of  FIG.  58   , the position of the rear suspension assembly  226  of  FIG.  54    corresponds with the position of the rear suspension assembly  26  of  FIG.  59   , and the position of the rear suspension assembly  226  of  FIG.  55    corresponds with the position of the rear suspension assembly  26  of  FIG.  60   . Although the frame assembly  20  is not shown in these figures, it is understood that the coupling positions of the rear suspension assembly  226  to the frame assembly  20  (e.g., coupling position  243 , first coupler  258 , and second coupler  276 ) represent the correct positions of the couplings (e.g., those positions are substantially static) and the rear suspension assembly  226  moves with respect to the frame assembly  20 . 
       FIGS.  51  and  56    illustrate the rear suspension assembly  226  in a substantially unloaded state. As discussed, the coupling positions at which the rear suspension assembly  226  is coupled to the frame assembly  20  are substantially static. The toe of the rear ground-engaging members  14  is generally neutral or zero (or at a predetermined toe such as plus or minus three degrees) when the rear suspension assembly  226  is in a substantially unloaded state. The trailing arm  240  pivots with respect to hub  241  at the joint  268 . This pivoting and moving of the trailing arm  240  can be appreciated in the remaining  FIGS.  52 - 55  and  57 - 60   .  FIGS.  52 - 54  and  57 - 59    show a progression of the rear suspension assembly  126  through loading of the rear suspension assembly  126  until the rear suspension assembly  226  is illustrated in a fully loaded state in  FIGS.  55  and  60   . 
     As the suspension is loaded, the suspension member  270  pivots relative to the frame assembly  20  and the trailing arm  240  in order to constrain the trailing arm  240  in a configuration that maintains the rear ground-engaging member  14  in a neutral toe configuration (or at a predetermined toe such as plus or minus three degrees) while permitting the remaining components of the rear suspension assembly  226  to pivot and move as appropriate to travel during loading and unloading. The relative positioning of the coupling positions (e.g., the first coupler  274  of the suspension member  270 , and the coupling of the shock absorber  248  to the trailing arm  240 ) is operable to adjust the sensitivity of the toe control of suspension member  270 . As mentioned, the relative position of the second coupler  276  relative to the coupling position  243  of the first radius rod  242  and the first coupler  258  of the trailing arm  240  is operable to adjust the sensitivity of the toe control of suspension member  270 . It is noted that in some embodiments, the toe of the rear ground-engaging member  14  may not be such that the rear ground-engaging member  14  are exactly parallel to each other, however, the toe of the rear ground-engaging members  14  is constrained to less than degrees off-axis of the desired longitudinal axis of the rear ground-engaging members  14  as the rear suspension assembly  226  travels through varying levels of loading (e.g., compression and decompression of the shock absorbers  48 ). 
     Referring now to  FIGS.  61 - 77   , another embodiment of a rear suspension assembly  326  is provided. Referring more specifically to  FIG.  62   , a schematic of the rear suspension assembly  326  is illustrated in which the rear suspension assembly  326  is coupled to rear ground-engaging members  14 . The rear suspension assembly  326  of this embodiment includes a trailing arm  340  with a first longitudinal portion  367  and a second longitudinal portion  369  coupled at a joint  368 . The rear suspension assembly  326  includes an upper or first radius rod  342  coupled to the second longitudinal portion  369  of the trailing arm and a lower or second radius rod  344  coupled to the second longitudinal portion  369  of the trailing arm  340  at a position vertically lower than the coupling position of the first radius rod  342 . 
       FIG.  63    illustrates a side schematic view of the embodiment of  FIG.  62    which includes a shock absorber  348  coupled to the second longitudinal portion  369  of the trailing arm  340  at a position longitudinally rearward of the joint  368 . The rear suspension assembly  326  includes a suspension member  370  that is coupled to the second longitudinal portion  369  of the trailing arm  340  forward of and longitudinally spaced from the coupling position of the shock absorber  348  to the second longitudinal portion  369 . The suspension member  370  is coupled to the second longitudinal portion  369  at a first coupler  374  that is longitudinally proximate or at the joint  368  and forward of the position at which the shock absorber  348  is coupled to the trailing arm  340 . The suspension member  370  extends from the trailing arm  340  at an angle greater than zero degrees, for example laterally inward and longitudinally forward (see  FIGS.  45 - 49   ) relative to the trailing arm  340 . In some embodiments, the first coupler  374  includes a bearing carrier or hub. 
     Referring to  FIG.  64   , the rear suspension assembly  326  is illustrated from a top view. The first portion  372 A of the suspension member  370  is coupled to the trailing arm  370  at the joint  368  between the first and second longitudinal portions  367 ,  369  (e.g., at the first coupler  374  which is positioned on the joint  368 ). A second coupler  376  may be positioned on the frame assembly  20  to which the second portion  372 B of the suspension member  370  is coupled and which is operable to allow the suspension member  370  to pivot relative to the frame assembly  20 . In some embodiments, the suspension member  70  may include an actuator that allows for active control of toe of the rear ground-engaging members  14  (e.g., pneumatic, motor, and so forth). 
     Referring still to  FIG.  64   , the first radius rod  342  is shown with a coupling position  343  at which the first radius rod  342  couples to the frame assembly  20 . A plane P is illustrated extending between the first coupler  358  of the trailing arm  340  and the coupling position  343  of the first radius rod  342 , the plane extending vertically into and out of the page. The suspension member  370  couples to the frame assembly  20  at the second coupler  376 , wherein the second coupler  376  is positioned within or adjacent the plane P defined between the first coupler  358  of the trailing arm  340  and the coupling position  343  of the first radius rod  342 . For example, the second coupler  376  is coupled to the frame assembly  320  such that the distance between the second coupler  376  of the suspension member  370  and the nearest point on the plane P is about  1 : 12  of the distance from the first coupler  358  of the trailing arm and the coupling position  343  of the first radius rod  342  which define the plane P. Various rations of the distances described above are contemplated including about 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, or less. In some embodiments, another way of defining the relative position of the second coupler  376  with respect to components of the rear suspension assembly  326  includes defining a zone Z within which the second coupler  376  is positioned. The zone Z is defined as a space as viewed from above and bounded by the trailing arm  340 , the first radius rod  342 , and an interior edge defined between the front end of the trailing arm and the inner end of the upper radius rod as viewed from above (i.e., the plane P described previously). The second coupler  376  is positioned within the zone Z adjacent the interior edge (i.e., the plane P). 
     As illustrated in  FIG.  64   , the shock absorber  348  is coupled to the trailing arm  340  rearward of the joint  368 . In some embodiments, the shock absorber  348  is coupled between a longitudinal midpoint of the second longitudinal portion  369  of the trailing arm  340  and the joint  368  (in some embodiments closer to the joint  368  than to the longitudinal midpoint). The placement of the coupling between the shock absorber  348  and the trailing arm  340  in combination with the first coupler  374  of the suspension member  370  to the trailing arm  340  provides control of toe of the rear ground-engaging members  14 . 
     Referring to  FIGS.  69 - 77   , the embodiment of  FIG.  61    is illustrated with the rear suspension assembly  326  in various positions through the travel of the rear suspension assembly  326  (i.e., through travel of the shock absorber  348  in loaded, unloaded, and partially loaded conditions).  FIGS.  69 - 73    show views of the rear suspension assembly  326  through its travel from a frontal view, and  FIGS.  74 - 77    show views of the rear suspension assembly  326  through its travel from a top view. The position of the rear suspension assembly  326  of  FIG.  69    corresponds with the position of the rear suspension assembly  326  of  FIG.  74   , the position of the rear suspension assembly  326  of  FIG.  70    corresponds with the position of the rear suspension assembly  326  of  FIG.  75   , the position of the rear suspension assembly  326  of  FIG.  71    corresponds with the position of the rear suspension assembly  326  of  FIG.  76   , the position of the rear suspension assembly  326  of  FIG.  72    corresponds with the position of the rear suspension assembly  326  of  FIG.  77   . Although the frame assembly  20  is not shown in these figures, it is understood that the coupling positions of the rear suspension assembly  326  to the frame assembly  20  (e.g., coupling position  343 , first coupler  358 , and second coupler  376 ) represent the correct positions of the couplings (e.g., those positions are substantially static) and the rear suspension assembly  326  moves with respect to the frame assembly  20 . 
       FIGS.  69  and  74    illustrate the rear suspension assembly  326  in a substantially unloaded state. As discussed, the coupling positions at which the rear suspension assembly  326  is coupled to the frame assembly  20  are substantially static. The toe of the rear ground-engaging members  14  is generally neutral or zero (or at a predetermined toe such as plus or minus three degrees) when the rear suspension assembly  326  is in a substantially unloaded state. The joint  368  between the first and second longitudinal portions  367 ,  369  of the trailing arm  340  allows the second longitudinal portion  369  to have a substantially fixed configuration relative to the rear ground-engaging member  14  while the first longitudinal portion  367  pivots generally laterally at the joint  368  and relative to the first coupler  358  to adjust for positional adjustment of other components of the rear suspension assembly  326 . This pivoting and moving of the first longitudinal portion  367  can be appreciated in the remaining Figs., as well as a progression of the rear suspension assembly  326  through loading of the rear suspension assembly  326  until the rear suspension assembly  326 . 
     As the suspension is loaded, the suspension member  370  pivots relative to the frame assembly  20  and the trailing arm  340  in order to constrain the trailing arm  340  in a configuration that maintains the rear ground-engaging member  14  in a neutral toe configuration (or at a predetermined toe such as plus or minus three degrees) while permitting the remaining components of the rear suspension assembly  326  to pivot and move as appropriate to travel during loading and unloading. The relative positioning of the coupling positions (e.g., the joint  368 , the first coupler  374  of the suspension member  370 , and the coupling of the shock absorber  348  to the trailing arm  340 ) is operable to adjust the sensitivity of the toe control of suspension member  370 . As mentioned, the relative position of the second coupler  376  relative to the coupling position  343  of the first radius rod  342  and the first coupler  358  of the trailing arm  340  is operable to adjust the sensitivity of the toe control of suspension member  370 . It is noted that in some embodiments, the toe of the rear ground-engaging member  14  may not be such that the rear ground-engaging member  14  are exactly parallel to each other, however, the toe of the rear ground-engaging members  14  is constrained to less than five degrees off-axis of the desired longitudinal axis of the rear ground-engaging members  14  as the rear suspension assembly  326  travels through varying levels of loading (e.g., compression and decompression of the shock absorbers  348 ). 
     While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.