Patent Publication Number: US-2021171132-A1

Title: Stand up vehicle

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is related to and claims priority benefit from U.S. Provisional Application No. 62/945,066 (“the &#39;066 application”), filed on Dec. 6, 2019 and entitled “OFF ROAD VEHICLE.” The &#39;066 application is hereby incorporated in its entirety by this reference. 
    
    
     FIELD OF THE INVENTION 
     The field of the invention relates to vehicles, particularly vehicles designed as a skateboard for a single standing passenger. 
     BACKGROUND 
     Modern transportation systems include compact vehicles designed for a single passenger. For example, some branches of the U.S. military are interested in a compact all-terrain vehicle capable of being deployed with airborne troops. However, conventional scooters or skateboards are too heavy and/or not sufficiently robust for off road use. 
     To increase comfort, maneuverability, and off road capability while minimizing weight, it may be desirable to design new electrically-powered vehicles that allow the passenger to operate the vehicle hands free to handle a weapon or other equipment. 
     SUMMARY 
     The terms “invention,” “the invention,” “this invention” and “the present invention” used in this patent are intended to refer broadly to all of the subject matter of this patent and the patent claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below. Embodiments of the invention covered by this patent are defined by the claims below, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this patent, any or all drawings and each claim. 
     According to certain embodiments of the present invention, a vehicle for transporting a passenger in a standing position comprises: a frame; a rear axle assembly disposed at a rear end of the frame; a front suspension assembly disposed at a front end of the frame; a rear deck attached to the frame to accommodate a trailing foot of the passenger; a front deck attached to the frame to accommodate a leading foot of the passenger; and a driveshaft extending forward from the rear axle assembly such that the driveshaft transmits power to the rear axle assembly. 
     According to certain embodiments of the present invention, a powered vehicle for transporting a passenger in a standing position comprises: a frame; a rear axle assembly disposed at a rear end of the frame with at least one rear wheel; a front suspension assembly disposed at a front end of the frame with at least one front wheel; a rear deck attached to the frame to accommodate a trailing foot of the passenger; a front deck attached to the frame to accommodate a leading foot of the passenger; and a steering mechanism controlled by input from a foot of the passenger. 
     According to certain embodiments of the present invention, an axle assembly for a powered vehicle comprises: a solid axle extending approximately the full width of the axle assembly; a plurality of longitudinal plate members extending along a length of the axle assembly; and a plurality of hoop plate members located perpendicular to the solid axle, wherein each of the plurality of hoop plate members comprises a plurality of notches for engaging at least one of the longitudinal plate members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a rear right perspective view of a vehicle according to certain embodiments of the present invention. 
         FIG. 1B  is a front left perspective view of the vehicle of  FIG. 1A . 
         FIG. 2A  is a partial front perspective view of a front suspension assembly of the vehicle of  FIG. 1A . 
         FIG. 2B  is a perspective view of an adjustable steering linkage member of the front suspension assembly of  FIG. 2A . 
         FIG. 2C  is a perspective view of a steering arm of the front suspension assembly of  FIG. 2A . 
         FIG. 3A  is a front perspective view of a rear axle assembly of the vehicle of  FIG. 1A . 
         FIG. 3B  is a rear perspective view of the rear axle assembly of  FIG. 3A . 
         FIG. 3C  is a perspective view of an inner hoop plate member of the rear axle assembly of  FIG. 3A . 
         FIG. 3D  is a perspective view of a longitudinal plate member of the rear axle assembly of  FIG. 3A . 
         FIG. 3E  is a perspective view of a longitudinal front plate member of the rear axle assembly of  FIG. 3A . 
         FIG. 4A  is a perspective view of the rear axle assembly of  FIG. 3A  including a shroud member. 
         FIG. 4B  is a perspective view of the shroud member of  FIG. 4A . 
         FIG. 5  is a perspective view of a rear drivetrain assembly of the vehicle of  FIG. 1A . 
         FIGS. 6A and 6B  are schematic views of a rear suspension assembly of the vehicle of  FIG. 1A . 
     
    
    
     DETAILED DESCRIPTION 
     The subject matter of embodiments of the present invention is described here with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described. 
     Although the illustrated embodiments shown in  FIGS. 1A-5  illustrate components of various skateboard vehicles for a single passenger, the features, concepts, and functions described herein are also applicable (with potential necessary alterations for particular applications) to scooters, seated vehicles, vehicles for multiple passengers, or any other type of vehicle. 
     In some cases, a vehicle  1000  includes a rear axle assembly  100 , a front suspension assembly  200 , a front deck  11 , a rear deck  12 , a plurality of wheels/tires  13 - 16 , a plurality of shocks  17 - 20 , a longitudinal frame member  21 , and a lateral frame member  22 . The vehicle  1000  may also include a driveshaft  29 , at least one electric motor  31 , and at least one battery module  33  (see  FIGS. 1A and 1B ). In lieu of or in addition to the at least one electric motor  31 , the vehicle  1000  may include other engines or motors including internal combustion engine(s), electric motor(s) disposed at one or more of the wheels/tires  13 - 16 , and/or any other appropriate manner for moving the vehicle  1000 . 
     The vehicle  1000  may be configured such that the passenger stands with his/her leading foot on the front deck  11  and his/her trailing foot on the rear deck  12 . Accordingly, the passenger can ride the vehicle  1000  facing the right/starboard side (left foot is the leading foot) or can ride the vehicle  1000  facing the left/port side (right foot is the leading foot). 
     Although not illustrated, the vehicle  1000  may be designed to include a first binding for securing the passenger&#39;s leading shoe/boot to the front deck  11  and a second binding for securing the passenger&#39;s trailing shoe/boot to the rear deck  12 . As described in greater detail below, the front deck  11  may pivot based on input from the passenger to control the steering. In other embodiments, the rear deck  12  is designed for the majority of the passenger&#39;s weight such that the passenger would sit on the rear deck and his/her feet would each be located on the front deck  11 . In some embodiments, the overall suspension design for the vehicle  1000  is based on a scaled version of a trophy truck such that the suspension has large amounts of travel or articulation to allow the vehicle  1000  to move at high speeds over rough terrain with limited shock and vibration transferred to the passenger. Although the vehicle  1000  is illustrated as rear wheel drive with a locked rear differential, the vehicle  1000  may be designed with a lockable or selectable rear differential and/or with four wheel drive. The vehicle  1000  is shown with a solid axle rear and independent front suspension, but the vehicle  1000  may be designed with all independent suspension or solid axles front and rear. In some embodiments, a significant portion of the structure of the vehicle  1000  is designed and assembled from standard sheet parts without welding such that the vehicle  1000  can be shipped unassembled in a small package (i.e., a “flat pack”). 
     As shown in  FIGS. 1A-2A , the front suspension assembly  200  may be an independent A-arm suspension that includes a left upper control arm  203 , a right upper control arm  204 , a left lower control arm  205 , and a right lower control arm  206 . Movement of the front suspension assembly  200  may be controlled by the front left shock  19  and the front right shock  20 . The upper ends of the front shocks  19 ,  20  may be sandwiched between a first shock tower member  211  and a second shock tower member  212 . The lower ends of the front shocks  19 ,  20  may be attached to the lower control arms  205 ,  206 . The inboard side of the upper control arms  203 ,  204  may be attached to (i) a forward bracket  25  connected to the longitudinal frame member  21  and (ii) at least one of the first and second shock tower members  211 ,  212 . As shown in  FIG. 2A , the inboard side of the lower control arms  205 ,  206  may include a first pivotable attachment that is sandwiched between the first shock tower member  211  and the second shock tower member  212  and a second pivotable attachment that is sandwiched between a pair of deck plates  24 . At the upper end of the deck plates  24 , a pivotable deck member  23  shares a common fastener with the deck plates  24  (where the fastener extends in a fore/aft direction defining axis A) and the pivotable deck member  23  is attached to the underside of the front deck  11  (shown transparent in  FIG. 2A ) such that the front deck  11  can pivot about axis A. As shown in  FIG. 1B , there may be a second pair of deck plates  24  that are attached to a second pivotable deck member on the underside of the front deck  11 . The vehicle  1000  may include at least one frame plate  27  (see  FIG. 1B ) to protect the underside of longitudinal frame member  21  and to define distances between relevant components (e.g., between the two pairs of deck plates  24 ). 
     Rotation of the front deck  11  about axis A causes a steering arm  202  (shown transparent in  FIG. 2A ) to move with the front deck  11 . In other words, the passenger can steer the vehicle  1000  using his/her leading foot to pivot the front deck  11 . The steering arm  202  is attached to the front deck  11  via fasteners in holes  202 . 2  of the steering arm  202  (see  FIG. 2C ). The steering arm  202  is also attached to an upper end of an adjustable steering linkage member  201  by a fastener that is common to (i) slot  202 . 1  of the steering arm  202  and (ii) slot  201 . 2  of the adjustable steering linkage member  201 . Rotation of the steering arm  202  (with the front deck  11 ) causes the adjustable steering linkage member  201  to pivot about hole  201 . 1 . Accordingly, the lower end of the adjustable steering linkage member  201  (including holes  201 . 7  and  201 . 8 ) moves in the opposite direction of the upper end of the adjustable steering linkage member  201 . As shown in  FIG. 2A , the lower end of the adjustable steering linkage member  201  is attached to a left tie rod  207  and a right tie rod  208 . In other words, the lower left hole  201 . 7  is attached to the left tie rod  207  and the lower right hole  201 . 8  is attached to the right tie rod  208 . Movement of the fastener along the length of slot  201 . 2  of the adjustable steering linkage member  201  allows the passenger to adjust the amount and the sensitivity of the steering for the vehicle  1000  (i.e., based on user preference and/or conditions of the operating environment). In some embodiments, moving the fastener to the upper end of the slot  201 . 2  creates an approximately 1:1 ratio for movement of the front deck  11  to movement of the front wheels/tires  15 ,  16 . Moving the fastener toward the lower end of the slot  201 . 2  causes more travel and greater sensitivity for the front wheels/tires  15 ,  16  (i.e., relatively minor movement of the front deck  11  will cause significant movement of the front wheels/tires  15 ,  16 ). Although the vehicle  1000  is shown with two front wheels/tires  15 ,  16 , the vehicle  1000  may be designed with a single front wheel/tire for steering (in combination with either: (i) two rear wheels/tires for a 3-wheel vehicle; (ii) one rear wheel/tire for a 2-wheel vehicle; or (iii) any other appropriate configuration). 
     As shown in  FIGS. 1A, 1B, 3A, and 3B , the rear axle assembly  100  may be attached to the vehicle  1000  in a triangulated four link arrangement that includes a left trailing arm  103 , a right trailing arm  104 , a left upper arm  105 , and a right upper arm  106 . Movement of the rear suspension may be controlled by the rear left shock  17  and the rear right shock  18 . The upper end of the left rear shock  17  may be sandwiched between an outer shock tower plate  107  and an inner shock tower plate  109  and the lower end of the left rear shock  17  may be attached to an upper portion of the left trailing arm  103 . The left rear shock  17  may include a conventional spring, or in some embodiments, may include a progressive spring (i.e., softer in the first part of travel to soak up small bumps, and stiffer over larger bumps). As shown in  FIGS. 1A and 1B , the vehicle  1000  may be configured such that the left rear shock  17  can be mounted in a plurality of configurations. For example, the upper end of the left rear shock  17  can be attached in three different locations including: (1) at holes  107 . 1  and  109 . 1 ; (2) at holes  107 . 2  and  109 . 2 ; and (3) at holes  107 . 3  and  109 . 3 . The lower end of the left rear shock  17  can also be attached in three different configurations including: (1) at hole  103 . 1 ; (2) at hole  103 . 2 ; and (3) at hole  103 . 3 . 
     The upper end of the right rear shock  18  may be sandwiched between an outer shock tower plate  108  and an inner shock tower plate  110  and the lower end of the right rear shock  18  may be attached to an upper portion of the right trailing arm  104 . The right rear shock  18  may include a conventional spring, or in some embodiments, may include a progressive spring (i.e., softer in the first part of travel to soak up small bumps, and stiffer over larger bumps). As shown in  FIGS. 1A and 1B , the vehicle  1000  may be configured such that the right rear shock  18  can be mounted in a plurality of configurations. For example, the upper end of the right rear shock  18  can be attached in three different configurations including: (1) at holes  108 . 1  and  110 . 1 ; (2) at holes  108 . 2  and  110 . 2 ; and (3) at holes  108 . 3  and  110 . 3 . The lower end of the right rear shock  18  can also be attached in three different configurations including: (1) at hole  104 . 1 ; (2) at hole  104 . 2 ; and (3) at hole  104 . 3 . 
     The left trailing arm  103  includes a forward connection that is sandwiched between the outer shock tower plate  107  and the inner shock tower plate  109  and a rear connection that is attached to rear axle assembly  100  at hole  103 . 11  (sandwiched between outer hoop plate members  123  and  125 ). In some cases, the left trailing arm  103  can be attached to the static structure of the vehicle  1000  (shock tower plates  107  and  109 ) in three different configurations indicated by holes  107 . 4 ,  107 . 5 , and  107 . 6  (the corresponding holes in inner shock tower plate  109  are not annotated for simplicity). Similarly, the right trailing arm  104  includes a forward connection that is sandwiched between the outer shock tower plate  108  and the inner shock tower plate  110  and a rear connection that is attached to rear axle assembly  100  at hole  104 . 11  (sandwiched between outer hoop plate members  124  and  126 ). In some cases, the right trailing arm  104  can be attached to the static structure of the vehicle  1000  (shock tower plates  108  and  110 ) in three different configurations indicated by holes  108 . 4 ,  108 . 5 , and  108 . 6  (the corresponding holes in inner shock tower plate  110  are not annotated for simplicity). 
     In some embodiments, the left upper arm  105  includes a forward connection that is sandwiched between the inner shock tower plate  109  and a portion of the lateral frame member  22  and a rear connection that is attached to rear axle assembly  100  at hole  105 . 1  (sandwiched between middle hoop plate member  127  and inner hoop plate member  129 ). Similarly, the right upper arm  106  includes a forward connection that is sandwiched between the inner shock tower plate  110  and a portion of the lateral frame member  22  and a rear connection that is attached to rear axle assembly  100  at hole  106 . 1  (sandwiched between middle hoop plate member  128  and inner hoop plate member  130 ). In some embodiments, the holes  105 . 1  and  106 . 1  are coaxial and are arranged such that a single fastener extends through these holes. In some cases, this fastener holds a spacer between inner hoop plate member  129  and inner hoop plate member  130 . 
       FIGS. 1A and 1B  show a direct or non-linkage attachment of the rear shocks  17 ,  18  extending between (i) the structure of the vehicle  1000  (shock tower plates  107 - 110 ) and (ii) the moveable portion of the rear suspension (trailing arms  103 ,  104 ). However, in some embodiments, the vehicle  1000  may include a link suspension. For example, as shown in  FIGS. 6A and 6B , one or both of the rear shocks  17 ,  18  may attach at the lower end to a shock arm  1001 . The shock arm  1001  may also include a pivoting attachment to the corresponding trailing arm  103 ,  104  (at the relevant portion  103   a ,  104   a ) and a pivoting attachment to a first end of a shock link  1002 . The second end of the shock link  1002  may include a pivoting attachment to the corresponding structure of the vehicle  1000  (shock tower plates  107 - 110 ). The shock arm  1001  and the shock link  1002  may allow the suspension to be tuned or adjusted with as much rising rate as desired by adjusting the geometry (length, shape, etc.) of the components. Varying the geometry affects leverage such that the link suspension may provide a smooth ride over small bumps and a more controlled ride over larger bumps. The rear shock  17 ,  18  may be smaller because the linkage can translate a small shock stroke into significant suspension travel. In some embodiments, as shown in  FIG. 6A , the upper end of the rear shock  17 ,  18  may be attached to the static structure of the vehicle  1000  (shock tower plates  107 - 110 ). In other embodiments, as shown in  FIG. 6B , the upper end of the rear shock  17 ,  18  may be attached to the corresponding trailing arm  103 ,  104  (at the relevant portion  103   b ,  104   b ). The arrangement illustrated in  FIG. 6B  isolates the static frame, the front suspension assembly  200 , and the steering mechanisms (described above) from the shocks and stresses exerted on the rear suspension, which results in sharper, more responsive handling while also allowing improved weight distribution of the vehicle  1000 . 
     As shown in  FIG. 5 , the rear drivetrain for the vehicle  1000  may include a solid axle shaft  101  and an input shaft  102 . The forward end of the input shaft  102  interfaces with a driveshaft  29  (see  FIGS. 1A  and &#39;B). The driveshaft  29  transmits energy from the at least one electric motor  31  to the input shaft  102 . The vehicle  1000  may include a transmission for transmitting energy from the at least one electric motor  31  to the driveshaft  29 . For example, for embodiments with multiple electric motors  31 , each electric motor  31  may include a spur gear that interfaces with a main gear where the main gear is constrained or attached to the driveshaft  29 . As shown in  FIG. 5 , the input shaft  102  interfaces with at least one bearing (e.g., bearings  185  and  186 ) and the rear end of the input shaft  102  interfaces with a bevel gear  192 . The bevel gear  192  may be secured to the input shaft  102  by engaging a set screw within a keyway in the input shaft  102  (keyway is visible in  FIG. 5 ), by welding the bevel gear  192  to the input shaft  102 , by pinning the bevel gear  192  to the input shaft  102 , or by any other appropriate manner. 
     The solid axle shaft  101  may have a bevel gear  191  that interfaces with the bevel gear  192  of the input shaft  102  (see  FIG. 5 ). The bevel gear  191  may be secured to the solid axle shaft  101  by engaging a set screw within a keyway in the solid axle shaft  101 , by welding the bevel gear  191  to the solid axle shaft  101 , by pinning the bevel gear  191  to the solid axle shaft  101 , or by any other appropriate manner. The solid axle shaft  101  may interface with left center bearing  183  and right center bearing  184 . In addition, the solid axle shaft  101  may interface with left outer bearing  181  and right outer bearing  182 . In some embodiments, the rear drivetrain may include a spacer  183 . 1  between the left center bearing  183  and the bevel gear  191 . In addition, the rear drivetrain may include a spacer  184 . 1  between the right center bearing  184  and the bevel gear  191 . The rear drivetrain may include a spacer  187  between the left outer bearing  181  and the wheel lock pin  139   a . The wheel lock pin  139   a  engages the wheel lock  139   b  to transfer energy from the solid axle shaft  101  to the wheel/tire  13  (see  FIGS. 3A, 3B, and 4A ). Similarly, the rear drivetrain may include a spacer  188  between the right outer bearing  182  and the wheel lock pin  140   a . The wheel lock pin  140   a  engages a right hand side wheel lock to transfer energy from the solid axle shaft  101  to the wheels/tire  14  (the right hand side wheel lock is not illustrated but is similar to wheel lock  139   b ). 
     As shown in  FIGS. 3A-4B , the rear axle assembly  100  may be designed to include a plurality of sheet components such that the components can be assembled around the drivetrain using basic hand tools. In some embodiments, the sheet components are two-dimensional sheet metal parts cut from standard size sheet metal (e.g., aluminum or steel). The basic structure of the rear axle assembly  100  includes a plurality of longitudinal plate members extending along a length of the rear axle assembly  100  and a plurality of hoop plate members. Based on this design, the rear axle assembly  100  can be assembled and disassembled without any tube members and without any welding (i.e., mechanical connections only). It should be noted that the rear axle assembly  100 , the construction thereof, the method of assembly, and other relevant features may be adapted for various other vehicles, including smaller and much larger vehicles (passenger vehicles, military transport vehicles, large-scale construction equipment, etc.). 
     The rear axle assembly  100  is illustrated with longitudinal plate members arranged every 45° (arranged radially around the solid axle shaft  101 ) where 7 longitudinal plate members extend the full length of the rear axle assembly  100  and 1 longitudinal plate member is split into 2 parts on the forward side of the rear axle assembly  100  (due to the input shaft  102 ). Accordingly, there are 9 longitudinal plate member components. The following parts extend the full length of the rear axle assembly  100 : longitudinal plate member  121   a , longitudinal plate member  121   b , longitudinal plate member  121   d , longitudinal plate member  121   e , longitudinal plate member  121   f , longitudinal plate member  121   g , and longitudinal plate member  121   h . The front longitudinal plate member  121   c  is split into two parts where the front longitudinal plate member  121   c - 1  is located on the left side of the rear axle assembly  100  closer to wheel/tire  13  and the front longitudinal plate member  121   c - 2  is located on the right side of the rear axle assembly  100  closer to wheel/tire  14  (see  FIGS. 3A and 3E ). 
     Although the illustrated embodiments show longitudinal plate members every 45°, the rear axle assembly  100  may be constructed with a different number of longitudinal plate members, including either more or fewer longitudinal plate members. As one example, the rear axle assembly  100  may be constructed with longitudinal plate members every 90°. In some embodiments, the rear axle assembly  100  may be constructed without the longitudinal plate member  121   b , the longitudinal plate member  121   d , the longitudinal plate member  121   f , and the longitudinal plate member  121   h  (i.e., the remaining longitudinal plate members would be arranged every 90°). Other variables, such as the thickness of the longitudinal plate members can vary (i.e., reduced thickness for each longitudinal plate member with more longitudinal plate members). 
     The rear axle assembly  100  is illustrated with 8 hoop plate members that includes 4 members on the left hand side of the rear axle assembly  100  and 4 members on the right hand side of the rear axle assembly  100 . On the left side, the rear axle assembly  100  includes outer hoop plate member  123 , outer hoop plate member  125 , middle hoop plate member  127 , and inner hoop plate member  129 . The right side of the rear axle assembly  100  includes outer hoop plate member  124 , outer hoop plate member  126 , middle hoop plate member  128 , and inner hoop plate member  130 . As described above in the context of the rear suspension, the pair of outer hoop plate members attach to the respective rear ends of the trailing arms  103 ,  104  and the rear ends of the upper arms  105 ,  106  attach between the inner plate members. The rear end of the left trailing arm  103  is attached between outer hoop plate members  123  and  125 . Similarly, the rear end of the right trailing arm  104  is attached between outer hoop plate members  124  and  126 . The rear end of the upper arm  105  is attached between the middle hoop plate member  127  and inner hoop plate member  129 . The rear end of the upper arm  106  is attached between the middle hoop plate member  128  and inner hoop plate member  130 . 
       FIGS. 3D and 3E  show two examples of longitudinal plate members. The longitudinal plate member  121   a  is shown in  FIG. 3D . In some cases, the longitudinal plate member  121   a  is substantially or exactly the same as longitudinal plate member  121   b , longitudinal plate member  121   d , longitudinal plate member  121   e , longitudinal plate member  121   f , longitudinal plate member  121   g , and longitudinal plate member  121   h . For example, the holes  121   a . 17 ,  121   a . 18  may not be necessary for longitudinal plate members other than longitudinal plate member  121   a . Hole  121   a . 17  may be used to secure outer retaining plates  133 ,  135  and hole  121   a . 18  may be used to secure outer retaining plates  134 ,  136  (see  FIG. 3A ). The illustrated embodiments show holes  121   a . 17 ,  121   a . 18  for all of the longitudinal plate members (see  FIGS. 3A and 3B ). The advantage of including holes  121   a . 17 ,  121   a . 18  in all members is to reduce unique part numbers and to simplify assembly. However, the other similar members (longitudinal plate members  121   b  and  d - h ) do not attach to any retaining plates in these areas. Accordingly, in some embodiments, holes  121   a . 17 ,  121   a . 18  are only present in longitudinal plate member  121   a  and would be absent in all other members, which would reduce time for making the longitudinal plate members. 
     The longitudinal plate member  121   a  includes a series of notches on the outer surface and a series of recesses on the inner surface. On the left side, the outer surface of the longitudinal plate member  121   a  includes a notch  121   a . 3  that engages the outer hoop plate member  123 , a notch  121   a . 5  that engages the outer hoop plate member  125 , a notch  121   a . 7  that engages the middle hoop plate member  127 , and a notch  121   a . 9  that engages the outer hoop plate member  129 . On the right side, the outer surface of the longitudinal plate member  121   a  includes a notch  121   a . 4  that engages the outer hoop plate member  124 , a notch  121   a . 6  that engages the outer hoop plate member  126 , a notch  121   a . 8  that engages the middle hoop plate member  128 , and a notch  121   a . 10  that engages the outer hoop plate member  130 . The inner surface on the left side of the longitudinal plate member  121   a  includes a recess  121   a . 11  that engages left outer bearing  181  and a recess  121   a . 13  that engages left center bearing  183 . The inner surface on the right side of the longitudinal plate member  121   a  includes a recess  121   a . 12  that engages right outer bearing  182  and a recess  121   a . 14  that engages right center bearing  184 . 
     As shown in  FIG. 3E , the longitudinal plate member  121   c - 2  includes a series of notches on the outer surface and a series of recesses on the inner surface. The notches on the outer surface of longitudinal plate member  121   c - 2  are similar to those on the right side of the other longitudinal plate members where the outer surface of the longitudinal plate member  121   a  includes a notch  121   c . 4  that engages the outer hoop plate member  124 , a notch  121   c . 6  that engages the outer hoop plate member  126 , and a notch  121   c . 8  that engages the middle hoop plate member  128 . As discussed above, the longitudinal plate member  121   c  is split into two parts (longitudinal plate member  121   c - 1  and longitudinal plate member  121   c - 2 ) due to the location of the input shaft  102 . Accordingly, the inner surface of longitudinal plate member  121   c - 2 , in addition to a recess  121   c . 12  that engages right outer bearing  182  and a recess  121   c . 14  that engages right center bearing  184  (which are similar to recesses described above for longitudinal plate member  121   a ), includes a recess  121   c . 15  that engages bearing  185  and a recess  121   c . 16  that engages bearing  186 . In some embodiments, the longitudinal plate member  121   c - 1  is identical to longitudinal plate member  121   c - 2 . 
       FIGS. 3C  shows inner hoop plate member  129  as an example of a hoop plate member. Each hoop plate member includes an external hole for attachment to a rear suspension component and a series of notches on the inner surface for interfacing with the longitudinal plate members. As shown in  FIG. 3C  and as described above, the inner hoop plate member  129  includes hole  105 . 1  for attachment of the rear end of the upper arm  105 . The inner surface of the inner hoop plate member  129  includes a notch  129   a  that engages the longitudinal plate member  121   a , a notch  129   b  that engages the longitudinal plate member  121   b , a notch  129   c  that engages the longitudinal plate member  121   c , a notch  129   d  that engages the longitudinal plate member  121   d , a notch  129   e  that engages the longitudinal plate member  121   e , a notch  129   f  that engages the longitudinal plate member  121   f , a notch  129   g  that engages the longitudinal plate member  121   g , and a notch  129   h  that engages the longitudinal plate member  121   h . Because the inner hoop plate member  129  is located near the interface between the solid axle shaft  101  and the input shaft  102 , the inner hoop plate member  129  may include a protruding portion  129 . 1  that extends forward. The protruding portion  129 . 1  includes features such that the inner surface of the inner hoop plate member  129  also includes (i) a pair of notches  129   k . 1 ,  129   k . 2  for engaging input shaft hoop plate  141  and (ii) a pair of notches  129   m . 1 ,  129   m . 2  for engaging input shaft hoop plate  142 . The four hoop members located closest to the center of the rear axle assembly  100  (hoop plate members  127 - 130 ) also interface with a pair of center retaining plates  137 ,  138 . The outer surface of the inner hoop plate member  129  includes a notch  129   i  that engages the center retaining plate  137  and a notch  129   j  that engages the center retaining plate  138 . The 4 outer hoop plate members  123 - 126  may include similar features for interfacing with outer retaining plates  133 - 136 . In some embodiments, the inner hoop plate member  130  is identical to inner hoop plate member  129 . 
       FIGS. 3A and 3B  show the rear axle assembly  100  as a skeleton structure where the internal components (drivetrain, etc.) are visible from the exterior. However, in some embodiments, the rear axle assembly  100  may include a plurality of shroud members for covering and protecting internal components from foreign objects. One exemplary shroud member  145  is shown in  FIGS. 4A and 4B . The shroud member  145  may include a lip at each end (e.g., see lip  145 . 1 ) to interface with the adjacent hoop plate member. For example, lip  145 . 1  engages the relevant innermost surface of outer hoop plate member  125  (shown transparent in  FIG. 4A ) and prevents the shroud member  145  from moving outward away from the center of the rear axle assembly  100 . The lower surface  145 . 3  and the upper surface  145 . 4  may be tapered to approximately match the adjacent surface of the relevant longitudinal plate member. For example, the lower surface  145 . 3  may be tapered to match the adjacent surface of the longitudinal plate member  121   f  and the upper surface  145 . 4  may be tapered to match the adjacent surface of the longitudinal plate member  121   g . These interfaces between the shroud member  145  and the adjacent longitudinal plate members prevent the shroud member  145  from moving inward toward the center of the rear axle assembly  100 . Shroud members may be arranged to fill all of the openings of the cylindrical grid created by the plate members of the rear axle assembly  100  (i.e., all of the longitudinal plate members and the hoop plate members). The shroud members may be lightweight materials such as polymer, plastic, or any other appropriate material. 
     In some embodiments, the rear axle assembly  100  is designed to be assembled from a plurality of flat sheet components without any complex or expensive tools. An exemplary method for assembling the rear axle assembly  100  may include some or all of the following steps. All of the longitudinal plate members can be inserted into one of the outer hoop plate members. For example, the longitudinal plate members can be inserted into the notches of outer hoop plate member  124  to hold an approximate location and orientation (note that outer hoop plate member  124  would hold longitudinal plate member  121   c - 2  but not longitudinal plate member  121   c - 1 ). The drivetrain components (see  FIG. 5 ) should be located in the appropriate locations within the longitudinal plate members. In some embodiments, the only longitudinal plate member that is different and must be inserted into a specific notch is longitudinal plate member  121   c  (i.e., all other longitudinal plate members are interchangeable). In some cases, the next step would be to add the left side hoop plate members onto the opposite end of the longitudinal plate members, starting with the inner hoop plate member  129 . After the inner hoop plate member  129  is engaged with the appropriate mating portions of the longitudinal plate members and the input shaft hoop plates  141 ,  142  are in position, the middle hoop plate member  127  can be moved from the left end toward the center to the appropriate position. The longitudinal plate member  121   c - 1  will need to be placed in position before moving the middle hoop plate member  127  into position. After the middle hoop plate member  127  is engaged with the appropriate mating portions of the longitudinal plate members, the outer hoop plate member  125  can be moved from the left end toward the center to the appropriate position. After the outer hoop plate member  125  is engaged with the appropriate mating portions of the longitudinal plate members, the outer hoop plate member  123  can be moved from the left end toward the center to the appropriate position. After both outer hoop plate member  123  and outer hoop plate member  125  are in position, the outer retaining plates  133 ,  135  can be located to engage with longitudinal plate member  121   a , outer hoop plate member  123 , and outer hoop plate member  125 . 
     After all of the left side hoop plate members are in position, the outer hoop plate member  124  can be removed. The process for adding the hoop plate members would then be repeated, but for the right hand side (starting with inner hoop plate member  130 ). After both middle hoop plate member  128  and inner hoop plate member  130  are in position, the center retaining plates  137 ,  138  can be located to engage with longitudinal plate member  121   e  and hoop plate members  127 - 130 . Similar to the left hand side, after both outer hoop plate member  124  and outer hoop plate member  126  are in position, the outer retaining plates  134 ,  136  can be located to engage with longitudinal plate member  121   a , outer hoop plate member  124 , and outer hoop plate member  126 . 
     In some embodiments, the assembly process begins with the longitudinal plate members arranged with the bearings  181 - 184  and the bevel gear  191  (along with any relevant spacers) in approximate position (without the solid axle shaft  101 ). At least one of the outer hoop plate member  123  and the outer hoop plate member  124  and then used to hold the longitudinal plate members temporarily in position. Subsequently, the input shaft  102  along with the bevel gear  192  and bearings  185 ,  186  are passed through the opening between longitudinal plate member  121   c - 1  and longitudinal plate member  121   c - 2 . Due to the size of bevel gear  192 , the longitudinal plate member  121   c - 1  and/or the longitudinal plate member  121   c - 2  may need to be moved to allow for clearance (such movements can be accomplished by moving the relevant outer hoop plate member  123 ,  124  outward). At this time, the input shaft hoop plates  141 ,  142  can also be moved into position. The input shaft hoop plates  141 ,  142  will help hold longitudinal plate member  121   c - 1  and longitudinal plate member  121   c - 2  in position. The solid axle shaft  101  can then be inserted into the bearings  181 - 184  (held in place by the longitudinal plate members) with careful attention to fitment between the solid axle shaft  101  and the bevel gear  191 . After removal of the outer hoop plate member  123 , the method for attaching the hoop plate members would be similar to the description above—starting with the inner hoop plate member  129 . After the inner hoop plate member  129  is engaged with the appropriate mating portions of the longitudinal plate members and the input shaft hoop plates  141 ,  142  are in position, the middle hoop plate member  127  can be moved from the left end toward the center to the appropriate position. After the middle hoop plate member  127  is engaged with the appropriate mating portions of the longitudinal plate members, the outer hoop plate member  125  can be moved from the left end toward the center to the appropriate position. After the outer hoop plate member  125  is engaged with the appropriate mating portions of the longitudinal plate members, the outer hoop plate member  123  can be moved from the left end toward the center to the appropriate position. After both outer hoop plate member  123  and outer hoop plate member  125  are in position, the outer retaining plates  133 ,  135  can be located to engage with longitudinal plate member  121   a , outer hoop plate member  123 , and outer hoop plate member  125 . The process would then be repeated for the right hand side, as described above. 
     Although the rear axle assembly  100  is shown within the context of a triangulated four link suspension arrangement, the rear axle assembly  100  is compatible with various other suspension arrangements. For example, the rear axle assembly  100  may attach to a first leaf or coil spring at outer retaining plates  133 ,  135  and a second leaf or coil spring at outer retaining plates  134 ,  136 . 
     In some embodiments, throttle and braking are controlled by the at least one electric motor  31 , which transmits power to the rear axle assembly  100  via driveshaft  29 . The at least one electric motor  31  may be controlled via a handheld device that it connected to the at least one electric motor  31  by a wired or wireless connection. In other embodiments, the at least one electric motor  31  may be controlled via input(s) at the rear deck  12  using the passenger&#39;s trailing shoe/boot (i.e., a pedal, switch, or other relevant input). 
     The components of any of the vehicles  1000  described herein may be formed of materials including, but not limited to, thermoplastic, carbon composite, plastic, nylon, steel, aluminum, stainless steel, high strength aluminum alloy, other plastic or polymer materials, other metallic materials, other composite materials, or other similar materials. Moreover, the components of the vehicles  1000  may be attached to one another via suitable fasteners, which include, but are not limited to, screws, bolts, rivets, welds, co-molding, injection molding, or other mechanical or chemical fasteners. 
     Different arrangements of the components depicted in the drawings or described above, as well as components and steps not shown or described are possible. Similarly, some features and sub-combinations are useful and may be employed without reference to other features and sub-combinations. Embodiments of the invention have been described for illustrative and not restrictive purposes, and alternative embodiments will become apparent to readers of this patent. Accordingly, the present invention is not limited to the embodiments described above or depicted in the drawings, and various embodiments and modifications may be made without departing from the scope of the claims below.