Patent Publication Number: US-2005129490-A1

Title: Apparatus and method for lifting and carrying objects on a vehicle

Description:
1. FIELD OF THE INVENTION  
      The present invention relates generally to a lift apparatus that is attached to a vehicle and, more particularly, to a lift apparatus that may be attached to a female adapter of tow hitch provided at the rear end of a vehicle.  
     2. BACKGROUND OF THE INVENTION  
      It is often desirable to transport a bulky or odd sized object, such as for example, a wheelchair, a motorcycle, or cargo, which cannot because of its size be fitted into a vehicle. In these situations, the vehicle owner is faced with the options of hiring someone to transport the object, renting a vehicle capable of transporting the object or adding some type of cargo carrier onto their existing vehicle to allow them to transport the object with their vehicle. Some objects are too heavy to lift and, as such, devices that lift and carry objects are needed to raise these objects from ground level to a desired position above ground and hold that position.  
      It is well known in the field that lifting and carrying devices may be attached to vehicles to aid a user in lifting objects from ground level to a position above ground. Traditional devices are permanently fixed to the vehicle. However, these devices are also very large and cover a substantial area of the rear of the vehicle. Another limitation of the conventional devices is that the carrying device remains in one fixed position when not in use. As such, these devices permanently block the rear doors of vans, tailgates of trucks, trunks of cars and the like. The whole point of purchasing such vehicles, for many people, is to gain the cargo space provided thereby and to gain access to that space through the rear door of the vehicle. If the rear door is rendered useless by the attachment of a vehicle carrier apparatus of the type currently commercially available, the investment in the vehicle is wasted to some extent.  
      More current devises incorporate under vehicle systems in order to allow access to the rear door of the vehicle while the device remains attached to the vehicle. Many of these devices are located underneath the vehicle below the rear door. It is difficult, however, to position a lift platform under the rear of a vehicle because the rear axle interferes with the stowage of the platform. There is not enough room under most vehicles between the rear axle and the rear door to stow a known lifting platform when not in use.  
      Other devises incorporate low profile hitch type receivers in order to allow access to the rear door of the vehicle. The devices, unlike its lifting device predecessors, are removable and therefore transferable from vehicle to vehicle by simply sliding them into and out from standard tow hitch receivers found on many trucks, vans and recreational vehicles. These hitch type devices also remedy the problem of axle interference in under vehicle lift systems. However, these prior low profile designs contain significant flaws and limitations that interfere with their utility.  
      For example, in U.S. Pat. No. 5,122,024, the platform must traverse along a stationary vertical member. This configuration mirrors an elevator system in that the platform must traverse along the vertical member to reach its various positions. As such, the distance that the platform can travel is directly dependent upon and directly limited to the length of the vertical member. This poses a number of problems because the platform may not reach its desired positions. If the vehicle is too high or if the vertical member is not long enough the platform may not reach the ground. Furthermore, if the vertical member, due to being stationary, is located too far above the bumper it will obstruct rear door accessibility in vehicles. A subsequent patent, U.S. Pat. No. 5,431,522 explains another low profile vehicle carrier, however, this patent fails to overcome the limitations of U.S. Pat. No. 5,122,024 because the platform must still traverse along a stationary vertical member, or in this case, an elongated drive screw.  
      What is desired or needed in the art, therefore, is a lift apparatus that is attachable to the rear end of a passenger vehicle wherein the apparatus does not adversely affect the utility of the vehicle and the apparatus allows flexibility to accommodate vehicles with various heights and configurations.  
     3. SUMMARY  
      The invention includes a lift apparatus for supporting an object in the proximity of a vehicle traversing a terrain. The lift apparatus includes a mounting plate that is mounted to the vehicle, and a platform to support and carry the object. The lift apparatus also includes an arm assembly having a pair of parallel gear arms. The arm assembly is pivotally connected to the mounting plate at an upper end of the arm assembly, and is pivotally connected to the platform at a lower end of the arm assembly. A drive motor assembly is mounted to the mounting plate and is laterally offset from the gear arms. A link extends between the drive motor assembly and one of the gear arms to rotate the gear arms about their upper ends, thereby raising the platform.  
    
    
     4. BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an isometric view of a lift apparatus in accordance with an embodiment of the invention, illustrating the lift apparatus in a lowered position.  
       FIG. 2  is an isometric view of the lift apparatus embodiment of  FIG. 1 , illustrating the lift apparatus in a raised position.  
       FIG. 3  is a front view of the lift apparatus embodiment of  FIG. 1 .  
       FIG. 4  is a bottom view of the lift apparatus embodiment of  FIG. 1 .  
       FIG. 5  is a side view of the lift apparatus embodiment of  FIG. 1 , illustrating the lift apparatus mounted to the rear hitch of a vehicle with a rear door.  
       FIG. 6  is a side view of the lift apparatus embodiment of  FIG. 1 , illustrating the lift apparatus mounted to the rear hitch of a vehicle with a tailgate.  
       FIG. 7  is an isometric view of the lift apparatus embodiment of  FIG. 1 , illustrating the lift apparatus in the folded position.  
       FIG. 8  is an isometric view of a lift apparatus in accordance with another embodiment of the invention, illustrating the lift apparatus in a lowered position.  
       FIG. 9  is an isometric view of the lift apparatus embodiment of  FIG. 8 , illustrating the lift apparatus in a raised position.  
       FIG. 10  is an isometric view of a lift apparatus in accordance with another embodiment of the invention.  
       FIG. 11  is an isometric view of the lift apparatus embodiment of  FIG. 10 .  
       FIG. 12  is a side view of an adjustable clamp in the lift apparatus embodiment of  FIG. 10 .  
       FIG. 13  is a front view of an adjustable clamp in the lift apparatus embodiment of  FIG. 10 .  
       FIG. 14  is an isometric view of a lift apparatus in accordance with another embodiment of the invention.  
       FIG. 15  is a front view of the lift apparatus embodiment of  FIG. 14 .  
       FIG. 16  is a top view of the lift apparatus embodiment of  FIG. 14 .  
       FIG. 17  is a side view of the lift apparatus embodiment of  FIG. 14 .  
       FIG. 18  is a rear view of the lift apparatus embodiment of  FIG. 14 .  
       FIG. 19  is an isometric view of platform of the lift apparatus embodiment of  FIG. 14 .  
       FIG. 20  is an isometric view of a set of guide arms and gear arms of the lift apparatus embodiment of  FIG. 14 .  
       FIG. 21  is an isometric view of the guide arms and gear arms of  FIG. 20 , illustrating an electric actuator.  
       FIG. 22  is an isometric view of the guide arms and gear arms of  FIG. 20 , illustrating a cable and locking mechanism.  
       FIG. 23  is an isometric view of a cylinder support assembly of the lift apparatus embodiment of  FIG. 14 .  
       FIG. 24  is an isometric view of a lift apparatus in accordance with another embodiment of the invention.  
       FIG. 25  shows an isometric view of the lift apparatus mounted onto the rear side of a vehicle.  
    
    
     5. DETAILED DESCRIPTION OF THE INVENTION  
      Although the following detailed description contains many specific details for purposes of illustration, anyone of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the exemplary embodiment of the invention described below is set forth without any loss of generality to, and without imposing limitations thereon, the claimed invention.  
       FIG. 1  illustrates an embodiment of a lift apparatus  46  of the present invention. The lift apparatus  46  may include a back plate  7  affixed with a power screw fixture  1 , which may secure a gear-driving device such as a power screw  2 , commonly known as a worm gear. A motor  4  may be used to turn the power screw  2 , thereby causing a power screw collar  3  to traverse along a power screw  2 . The power screw  2  may also be turned manually or hydraulically. As a power screw collar  3  traverses along a power screw  2 , a torque transfer arm  6  may raise or lower a left gear arm  9  which in turn may cause a right gear arm  8  to raise or lower simultaneously with the left gear arm  9 . One end of the gear arms  8 ,  9  may comprise a meshing mechanism, such as sprockets or teeth, that when turned allow for simultaneous raising or lowering of the platform  47 . The torque transfer arm  6  may be affixed to a power screw collar  3  and a left gear arm  9  with respective bolts  23 ,  24 . The gear arms  8 ,  9  may be affixed to a back plate  7  with bolts  38 ,  39  and rotate radially about said bolts  38 ,  39 .  
      The hitch adapter  11  may comprise a plurality of holes to enable the lift apparatus  46  to be adjusted closer or farther from the vehicle in order to accommodate differences in vehicle configurations. The hitch adapter  11  may be affixed by conventional means, such as welding, to a bracket plate  12 , which in turn may be affixed to a back plate  7  with bolts  26 . The horizontal plane guide  5  may be affixed on top of a lift bracket  10 , which may be affixed to a back plate  7  with bolts  25 . A female guide base component  14  may connect to a horizontal plane guide base  5  and a platform  47 .  
      Still referring to  FIG. 1 , the platform  47  may comprise a collapsible back plate  17 , a right access exit collapsible ramp  15  and right access exit collapsible ramp  16 . The collapsible ramps  15 ,  16  may be spring loaded with a spring-loaded joint  30  such that the collapsible ramps  15 ,  16  may fold outward and spring back upright. The collapsible ramps  15 ,  16  may further include a no slip surface  29 . The collapsible back plate  17  may be spring loaded with a spring loaded joint  30  such that the collapsible back plate  17  may fold inward to allow for the platform  47  to be placed in the stored position, then spring back upright when unfolded. The bottom plates  27 ,  28  of the platform  47  may also include a no slip surface. A roller lift arm guide plate  22  with slots  49 ,  50  may lie below and affixed to the platform  47 . Roller arms  18 ,  20  may house roller arm pins  19 ,  21 . As gear arms  8 ,  9  raise and lower, the roller arms  18 ,  20  may traverse across the bottom of the platform  47  as the roller arm pins  19 ,  21  traverse within the slots  49 ,  50 .  
       FIG. 2  illustrates the platform  47  in a lowered position, and shows the right and left collapsible ramps  15 ,  16  in the fold-down position to allow users to easily place items such as wheel chairs, scooters, ATV vehicles, snowmobiles, motorcycles, other motorized vehicles, or cargo onto the platform  47 .  FIG. 3  illustrates the platform  47  in a raised position.  
      Referring to  FIG. 4 , when lowering the platform  47 , the DC motor  4  turns the power screw  2  thereby causing the power screw collar  3  to traverse toward one end of the power screw  2 . The torque transfer arm  6  extends to one of the gear arms, thereby causing the gear arms  8 ,  9  to move in a downward direction. As the gear arms  8 ,  9  move downward, the roller arms  18 ,  20  traverse along the platform  47  in an inward direction and may reach full low position when the pins  19 ,  21  reach the end of the slots  49 ,  50 . Collapsible lift arm rods  31 ,  33  connect the roller arms  18 ,  20  to the arm fixtures  32 ,  34 , which are affixed to the gear arms  8 ,  9 .  
      Still referring to  FIG. 4 , when raising the platform  47 , as shown in the dashed lined diagram of  FIG. 4 , the DC motor  4  turns the power screw  2  thereby causing the power screw collar  3  to traverse toward an opposite end of the power screw  2 . The torque transfer arm  44  extends to one of the gear arms, thereby causing the gear arms  43 ,  45  to move in an upward direction. As the gear arms  43 ,  45  move upward, the roller arms  40 ,  41  traverse along the platform  47  in an outward direction and may reach full height position when the pins  19 ,  21  reach the other end of the slots  49 ,  50 .  
       FIG. 5  illustrates the lift apparatus mounted to the rear hitch of a vehicle with a rear door, shown with the door ajar to show rear door clearance.  FIG. 6  illustrates the lift apparatus mounted to the rear hitch of a vehicle with a tailgate, shown with the tailgate down to show tailgate clearance.  FIG. 7  illustrates the lift apparatus in a folded or stowed position. The arm pins  35 ,  36  may create a joint between the collapsible lift arm rods  31 ,  33  and the arm fixtures  32 ,  34  to allow the platform  47  to fold substantially perpendicular to the hitch adapter  11 .  
       FIG. 8  illustrates another embodiment of the invention shown in a lowered position, and  FIG. 9  illustrates the embodiment in a raised position. Lift apparatus  48  may include a back plate  7 A affixed with a power screw fixture  1 , which may secure a gear driving device such as a power screw  2 , commonly known as a worm gear. A motor  4  may be used to turn the power screw  2 , thereby causing a power screw collar  3  to traverse along a power screw  2 . The power screw  2  may also be turned manually or hydraulically. As a power screw collar  3  traverses toward one end of a power screw  2 , a torque transfer arm  6  affixed to a left arm swing  9 A, may cause arm a left swing  9 A to raise platform  47 . As a power screw collar  3  traverses toward an opposite end of a power screw  2 , a torque transfer arm  6 , affixed to a left arm swing  9 A, may cause arm a left swing  9 A to lower platform  47 . The arms swings  8 A,  9 A may be solidly affixed to the platform lift arm plate  22 A with platform pins  19 A,  21 A. The right arm swing  8 A may raise or lower freely with respect to and simultaneously to the left arm swing  9 A. The torque transfer arm  6  may be affixed to a power screw collar  3  and a left arm swing  9 A with respective bolts  23 ,  24 . The arms swings  8 A,  9 A may be affixed to a back plate  7 A with bolts  38 ,  39 . The hitch adapter  11  may comprise a plurality of holes to enable the lift apparatus  46  to be adjusted closer or farther from the vehicle in order to accommodate differences in vehicle configurations. The hitch adapter  11  may be affixed by conventional means, such as welding, to a bracket plate  12  and a lift bracket  10 , which in turn may be affixed to a back plate  7 A.  
       FIG. 10  illustrates another embodiment of a lift apparatus  51 . The lift apparatus  51  may have a tubular platform  54  to accommodate items such as a bicycle or motorcycle. Adjustable clamps  52  may be affixed to platform  54  to secure the wheels of a bicycle or a motorcycle to platform  54 . A retaining rack  53  may be affixed to platform  54  to secure bicycle or motorcycle about an upright position.  FIG. 11  illustrates the lift apparatus  51  with an adjustable securing device  60  to further secure a traveling apparatus, such as a bicycle  61 , onto the platform  54 .  FIG. 12  illustrates a side view of the adjustable clamp  52  with a locking device  55 , and  FIG. 13  illustrates a front view of the clamp  52 . The locking device  55  may comprise a threaded rod  56 , a nut  57  and a lever  58 . The user locks the wheel into the platform  54 , and may seat the lever  58  into the hook  59  and close the lever  55  to secure the wheel into the locking device  55 . To unlock the locking device  55 , the user may open the lever  58  and remove the lever  55  from hook  59 . The adjustable clamp tension may be adjusted by turning the nut  57 .  
       FIGS. 14-18  show several different views of another embodiment of the lift apparatus, including a tubular platform  101 . A pair of collars  126  are rigidly mounted on the underside of the platform  101 . A right guide arm  118  and a left guide arm  120  extend through the collars  126 , and collars  126  mounted to the platform  101  are capable of traversing along the guide arms  118 ,  120 . A rim  160 , as shown in  FIG. 24 , may be included on the guide arms  118 ,  120 , for providing a boundary to prevent further displacement of the platform  101  along the guide arms  118 ,  120 . The ability of the platform  101  to move along the guide arms  118 ,  120  allows for proper position of the platform  101  along the guide arms, and also allows for multiple platforms  101  to potentially fit on the length of the guide arms  118 ,  120 , provided that the guide arms  118 ,  120  are lengthy enough to support more than one platform  101 .  
      The tubular platform  101  may have a retaining rack  128  mounted on one lateral side of the platform  101 , and a collapsible ramp  116  mounted on the other lateral side of the platform  101 , as shown in  FIG. 19 . The ramp  116  has a dual purpose. First, the ramp  116  provides a means to smoothly guide the load onto the platform  101 . Second, after the load is positioned properly on the platform  101 , the ramp  116  folds up to support the load at its rear end, while the retaining rack  128  supports the load at its front end, thereby ensuring the load is supported on both of its lateral sides. Additionally, a pair of small wheels  122 ,  124  is positioned on the underside of the platform  101  at each lateral end of the platform  101  for additional support when the platform  101  is lowered toward the ground.  
      Referring to  FIGS. 14-18 , the right guide arm  118  is joined by a pin to an end portion of gear arm  108 , and the left guide arm  120  is joined by a pin to an end portion of gear arm  109 , as shown also in  FIG. 20 . The end portions of gear arms  108 ,  109  opposite from the guide arms  118 ,  120  are joined by pins to the back plate  107 . A torque transfer arm  106  is mounted to the back plate  107 , and operates to raise and lower the platform  101 . The torque transfer arm  106  may be a hydraulic, electrical, mechanical, or manual mechanism, or another suitable mechanism. The torque transfer arm  106  is attached to an intermediate gear arm  110  that is joined to the middle portion of the left gear arm  109  by a pin, and extends to the middle portion of the right gear arm  108  where it is joined by a pin.  
       FIG. 21  shows an embodiment of the invention utilizing an electrical acutator as the torque transfer arm  106 , utilizing electric actuator to effectuate the raising and lowering of the platform  101 . The actuator may provide as much as 6000 lbs. of torsion to raise and lower the platform  101 . As the torque transfer arm  106  applies a force to the intermediate gear arm  110 , the intermediate gear arm  110  causes the right gear arm  108  and the left gear arm  109  to swing in an angular motion. When the torque transfer arm  106  applies a pulling force on the intermediate gear arm  110 , the gear arms  108 ,  109  swing upward, causing the platform  101  to be raised. When the torque transfer arm  106  applies a pushing force on the intermediate gear arm  110 , the gear arms  108 ,  109  swing downward, causing the platform  101  to be lowered.  
       FIG. 22  shows another embodiment of the invention utilizing a wire or cable as the torque transfer arm  106 , utilizing a pulling force from the wire or cable to raise the platform  101  and a gravitational force to lower the platform  101  (while relaxing the pulling force of the wire or cable). As the torque transfer arm  106  applies a force to the intermediate gear arm  110 , the intermediate gear arm  110  causes the right gear arm  108  and the left gear arm  109  to swing in an angular motion. When the torque transfer arm  106  applies a pulling force on the intermediate gear arm  110 , the gear arms  108 ,  109  swing upward, causing the platform  101  to be raised. When the platform  101  is raised to the desired vertical level, a locking mechanism may lock the wire or cable in place in order to stabilize the platform  01  in place. When the torque transfer arm  106  releases the pulling force of the wire or cable on the intermediate gear arm  110 , a gravitational force causes the gear arms  108 ,  109  swing downward, allowing the platform  101  to be lowered.  
      Referring to  FIGS. 14-18 , a pair of cylindrical supports  140 ,  142  is mounted to the back plate  107 , on the opposite side of the back plate  107  from where the gear arms  108 ,  109  and the torque transfer arm  106  are mounted. A pair of extension arms  144 ,  146  extend from the cylinder supports  140 ,  142  and are mounted to a bracket arm  150 . The bracket arm  150  is positioned perpendicular to the extension arms  144 ,  146 . A brace plate  132  mounted to each of the extension arms  144 ,  146  braces the bracket arm  150  to each of the extension arms  144 ,  146 .  
      Referring to  FIG. 24 , an adjustment mechanism  170  is used for adjusting the position or the relative height of the lift apparatus. The adjustment mechanism  170  is mounted to the back plate  107 , on the same side of the back plate  107  on which the cylinder supports  140 ,  142  are mounted. The adjustment mechanism  170  extends vertically downward and mounts to an upward facing surface of a wheel housing  172 , inside of which a large support wheel  174  resides. The adjustment mechanism  170  is adjusted to the proper height upon which the large support wheel  174  contacts the relative height of the ground surface, so that the platform  101  maintains an adequate ground clearance in both standard road conditions and off-road conditions. The adjustment mechanism may be a lead screw hand crank, or other suitable mechanism for adjusting the wheel.  
      The cylinder supports  140 ,  142  are designed to cause the support wheel  174  to support the weight of the load on the platform  101 , so that the rear of the vehicle does not have the burden or strain of supporting the load. As shown in  FIG. 23 , the cylinder supports  140 ,  142  include a female cylinder  148  with a larger diameter and a male cylinder  149  with a smaller diameter. The male cylinder  149  is mounted to an extension arm  146  extending perpendicular from the middle of the male cylinder  149 . The female cylinder  148  is mounted onto the back plate  107 , and the male cylinder  149  fits inside and traverses vertically within the female cylinder  148 . The female cylinder  148  features a cut-away section  147  through which the extension arm  146  extends. The extension arm  146  traverses vertically along the cut-away section  147  as the female cylinder  148  traverses vertically within the male cylinder  149 .  
      A lubricant may be used between the female cylinder  148  and the male cylinder  149  to reduce the friction created between the female cylinder  148  and the male cylinder  149 . Alternatively, bushings, ball bearings, precision balls, or other friction reducing elements may be used betwen the female cylinder  148  and the male cylinder  149 . Additionally, an impact absorber may be coupled with the cylinder supports  140 ,  142  to absorb the impact of the vertical movements of the vehicle and the lift apparatus upon the terrain. For example, the impact absorber may include shock absorbers, struts, springs, or another force-absorbing element may be used in association with the cylinder supports  140 ,  142  in order to reduce the impact of uneven terrain on the lift apparatus.  
      The cylinder supports  140 ,  142  enable the support wheel  174  to operate independently of the vehicle. The support wheel  174  supports the entire load, which enables the rear of the vehicle to be free from the load on the platform  101 . The support wheel  174  operates with full flexibility to move independently of the vehicle, which may be important when operating the vehicle on inclined roadways or uneven terrain.  
      The support wheel  174  is responsible for supporting only the weight of the carried load on the platform  101 , and thus the support wheel  174  is never responsible for supporting the additional load of the entire vehicle. Furthermore, the vehicle suspension system is unaffected by the load, and the rear portion of the vehicle is not responsible for supporting the load vertically. The cylinder supports  140 ,  142  and support wheel  174  cause the vehicle receiver hitch to be unaffected by the load on the platform  101 , but the vehicle continues to provide lateral support for the lift apparatus while in transit.  
      The independent movement of the lift apparatus relative to the vehicle is important in cases where the load on the platform  101  is of a substantial weight. A standard hitch (Class C) has a tongue load carrying capacity of approximately 500 lbs. The cylinder supports  140 ,  142  and the support wheel  174  enable the lift apparatus to carry in excess of 900 lbs., because the vehicle receiver hitch is not burdened by the 900 lb. load.  
      Another embodiment of the lift apparatus may include an actuator (not shown), or alternatively a winch mechanism (not shown) that allows the user to detach the lift cable from the lift apparatus and use it for a standard 2000 lb. winch. The winch allows dual use of the electrical power system to operate the lift apparatus to lift the platform  101 , and additionally may be used to attach the vehicle to a strong point and pull the vehicle from mud, snow, or other difficult terrain.  
      In operation, and in accordance with an embodiment of a motorcycle load supported on the platform  101  of  FIG. 14 , the user first pushes a switch button on the lift apparatus to cause the torque transfer arm  106  to lower the platform  101 . After the platform  101  reaches the ground, the user swings the ramp  116  about its hinge and rests the end portion of the ramp  116  on the ground. The user rolls the tires of the motorcycle up the ramp  116  and onto the platform  101 , into engagement with the retaining rack  128 . Then the user straps a series of cables or tie-downs to various points on the motorcycle to secure the motorcycle in place. For example, the user may strap the tie-downs around the handlebars and the neck of the motorcycle until the tightening of the straps causes the suspension to begin to drop. The user may also use a cross-tie to provide balance. After the straps or tie-downs are sufficiently tight around the motorcycle, the user swings the ramp  116  about its hinge until it contacts the rear tire of the motorcycle. A strap is wrapped around the rear tire and tied to the ramp  116  for lateral support. The retaining rack  128  provides lateral support for the front tire of the motorcycle. Finally, the user presses the switch button on the lift apparatus to cause the torque transfer arm  106  to raise the platform  101 , and operates the vehicle to transport the motorcycle to the desired destination.  
       FIG. 25  shows the lift apparatus used in connection with a truck. The lift apparatus may also be used in connection with sport utility vehicles, vans, automobiles, and other recreational vehicles that have a tow hitch, trailer hitch, bumper hitch, or other mounting structure at the rear of the vehicle. The lift apparatus may be operated electrically, hydraulically, mechanically, or manually to raise the platform  101  from a first level to a second level in order to provide substantial ground clearance to the rear of a vehicle. The lift apparatus attaches to the rear of the vehicle and lowers to ground level for positioning an object on the platform  101 . This ground level position is highly desirable because disabled people may drive their powered vehicles onto the platform in preparation for storage and transportation. Furthermore, this ground level position allows users to easily slide or roll objects onto the lift apparatus thereby reducing physical stress or strain to their bodies. The platform may be varied about any position between the first substantially horizontal position and a second substantially vertical position. The platform may also be raised or lowered in these varied positions by using the adjustment mechanism  170 .  
      The invention also provides other important advantages. In some embodiments, when in the stowed position, the platform may fold securely to a position substantially parallel to the rear door of the vehicle and substantially perpendicular to the ground, thereby creating a compact assembly that minimally extends the overall length of the vehicle. While in this folded position, the platform may be raised or lowered.  
      Another advantage is that the lift is relatively simple to install and to remove. It provides a safe and secure means of transporting a variety of cargo and accessories. It is universally adaptable to any type of vehicle, regardless of make, model or size. It does not require attachment to the bumper or bumper mounting brackets, frame of the vehicle, or the body of the vehicle.  
      Another advantage is that the lift apparatus of the invention may be adjusted closer or farther from the rear of the vehicle in order to accommodate differences in vehicle configurations. For example, custom bumpers may extender father from the vehicle than would a vehicle manufacturer&#39;s standard bumper. Some vehicles have optional spare tire mounts that attach to the rear of the vehicle. In both of these examples, the lift apparatus can be adjusted to accommodate these variations. It is adaptable to any size receiver hitch configuration. Also the lift apparatus may not be subject to state motor vehicle licensing fees, as in the case with wheeled devices.  
      Although some embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents.