Abstract:
A wheelchair lift ( 10 ) for a vehicle is disclosed. The wheelchair lift includes a lift platform assembly ( 13 ) coupled to a frame ( 18 ). The wheelchair lift also includes a reciprocating assembly ( 12 ) in communication with the lift platform to reciprocate the lift platform between a raised position and a lowered position. A locking mechanism ( 47 ) is coupled to the frame and lockingly engages a portion of the reciprocating assembly ( 34 ) to maintain communication between the reciprocating assembly and the lift platform if a portion of the reciprocating assembly fails.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Serial No. 60/421,018, filed on Oct. 23, 2002, the disclosure of which is hereby expressly incorporated by reference, and priority from the filing date of which is hereby claimed under 35 U.S.C. § 119(e). 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to lifts for mobility impaired persons, and more particularly, to a securing assembly for redundantly securing a reciprocating assembly to a lift platform, the reciprocating assembly adapted to reciprocate the lift platform between a raised and a lowered position.  
         BACKGROUND OF THE INVENTION  
         [0003]    The Americans with Disabilities Act (ADA) requires the removal of physical obstacles to those who are physically challenged. Included within the scope of the ADA are motor vehicles, such as trains and buses. Specifically, new, used, or remanufactured buses sold are required to comply with the applicable provisions of the statute. One such provision requires that deployed lift platforms, when occupied, shall have devices for preventing the lift platform from dropping an occupant in the event of a single failure of any load-carrying component. Therefore, to comply with the ADA, redundant support systems need to be included on passenger lifts.  
           [0004]    Currently, there are a wide variety of passenger lifts available for motor vehicles. One such lift is adapted to be mounted within an entryway of a motor vehicle. Such a lift includes a vertical reciprocating lift platform assembly mounted within the vehicle, the lift platform selectively actuatable between at least a raised and a lowered position. The lift platform assembly consists of an inboard platform and an outboard platform. The outboard platform is hingedly attached to the outboard edge of the inboard platform by two sets of horizontally oriented pin assemblies. The pin assemblies are located on opposite sides of the lift platform assembly. The inboard edge of the inboard platform is hingedly attached to two vertical support members located in the entrance of the passenger vehicle by a second set of two horizontally oriented pin assemblies. The vertical members can be selectively raised and lowered to convey the attached lift platform assembly between the raised and lowered positions.  
           [0005]    The pin assemblies allow the lift platform assembly to be rotatably transfigured from a stowed position to an extended position. In the extended position, the upper planar surface of the inboard platform is oriented parallel with and above the ground. The outboard platform is rotated on the pin assemblies outward from the inboard platform until the upper planar surface of the outboard platform is coplanar with the inboard platform. Once in the extended position as described, the lift platform assembly is lowered to the ground or sidewalk so that a mobility impaired individual may board the lift platform assembly. Two drive chains, one attached to the left vertical member, the other attached to the right vertical member, of a reciprocating assembly are actuated to raise the vertical support members and the attached lift platform assembly. Once in the raised position, the lift platform assembly is level with the floor of the motor vehicle. The mobility impaired person is then free to deboard the lift platform assembly into the passenger compartment of the vehicle.  
           [0006]    The lift platform assembly is then rotatably transfigured into the stowed position. This is done by rotating the folding platform until the upper surface of the folding platform is parallel with and opposing the upper surface of the inboard platform. The inboard platform and outboard platform are further rotated as a unit into a vertical stowed position, nested between and parallel with the vertical support members. Although such a lift is effective at providing mobility impaired persons, such as those in a wheelchair, access into and out of a motor vehicle, it is not without its problems.  
           [0007]    For instance, the drive chains of the reciprocating assembly are coupled to the frame of the lift platform by a single securing device. More specifically, in the above-described lift, each of the drive chains is attached to one of the vertical support members by a clevis. The devises are then adjustably attached to mounting brackets on the vertical support members. The devises have a threaded portion that mates with the mounting bracket through a set of adjusting nuts. By selectively engaging the adjusting nuts associated with either the left or right drive chain, a user can level the lift platform assembly. Although the described apparatus of attaching the drive chains to the vertical support members is advantageous since it allows the leveling of the lift platform assembly, it is not without problems. Specifically, if a catastrophic failure occurs in the clevis, or the lower portion of the mounting bracket, or if the threads of a clevis disengage from the mounting bracket adjusting nuts, or other such failure, the lift platform assembly could canter to one side, or drop, injuring the lift user or others in proximity to the lift.  
           [0008]    Such a passenger lift is not only dangerous, it also fails to comply with the ADA regarding single point failure of any load carrying component. Further, such passenger lifts are also not in compliance with proposed rules recently submitted to the Department of Transportation (DOT) by the National Highway Traffic Safety Administration (NHTSA) for possible inclusion in the Federal Motor Vehicle Safety Standards (FMVSS) that if enacted, will establish even more stringent requirements with at least regard to the single point of failure provision.  
           [0009]    For at least the foregoing reasons, there exists a need for a passenger lift that includes a redundant support in the event of a failure of a portion of the lift, wherein the redundant support complies with the ADA requirements and the proposed FMVSS changes, is economical to install and maintain, and may be easily retrofitted into existing passenger lifts.  
         SUMMARY OF THE INVENTION  
         [0010]    A passenger lift formed in accordance with one embodiment of the present invention is provided. The passenger lift is adapted to convey a passenger between a first elevation and a second elevation and includes a lift platform coupled to a frame. The passenger lift also includes a reciprocating assembly in communication with the lift platform to reciprocate the lift platform between a raised position and a lowered position. A locking mechanism is coupled to the frame and lockingly engages a portion of the reciprocating assembly to maintain communication between the reciprocating assembly and the lift platform if a portion of the reciprocating assembly fails.  
           [0011]    A passenger lift formed in accordance with another embodiment of the present invention is provided. The passenger lift is adapted to convey a passenger between a first elevation and a second elevation and includes a lift platform coupled to a frame. The passenger lift also includes a reciprocating assembly in communication with the lift platform to reciprocate the lift platform between a raised and a lowered position. A locking mechanism couples the reciprocating assembly to the frame. An attachment assembly also couples the reciprocating assembly to the frame. If either the locking mechanism or the attachment assembly fails, the other of the locking mechanism or the attachment assembly provides a continued connection of the reciprocating assembly to the frame.  
           [0012]    A passenger lift formed in accordance with still another embodiment of the present invention is provided. The passenger lift is adapted to convey a passenger between a first elevation and a second elevation and includes a lift platform coupled to a frame. The passenger lift also includes a reciprocating assembly in communication with the lift platform to reciprocate the lift platform between a raised position and a lowered position. The passenger lift further includes a means for lockingly coupling a portion of the reciprocating assembly to the frame. The means for lockingly coupling includes a first coupling means for coupling the reciprocating assembly in communication with the lift platform. The means for lockingly coupling also includes a second coupling means for coupling the reciprocating assembly in communication with the lift platform. The first and second coupling means provide redundant coupling of the reciprocating assembly to the frame. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The foregoing aspects and many of the attendant advantages of this invention will become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0014]    [0014]FIG. 1 is a perspective view of a passenger lift formed in accordance with one embodiment of the present invention having a reciprocating assembly and a securing assembly with redundant securing mechanisms for securing the reciprocating assembly to a frame of the passenger lift;  
         [0015]    [0015]FIG. 2 is a perspective detail view of a pin assembly shown in FIG. 1 coupling an inboard platform to an outboard platform of the passenger lift;  
         [0016]    [0016]FIG. 3 is a perspective detail view of a pin assembly shown in FIG. 1 coupling the inboard platform to a vertical support member;  
         [0017]    [0017]FIG. 4 is a partially exploded perspective detail view of the securing assembly shown in FIG. 1, illustrating the redundant securing mechanisms including a chain clevis and a chain lock block for securing the reciprocating assembly to the frame of the passenger lift;  
         [0018]    [0018]FIG. 5 is a rear perspective view of the chain lock block of FIG. 4;  
         [0019]    [0019]FIG. 6 is a fragmentary elevation planar view of a section of one of the vertical support members of FIG. 1, showing a portion of the reciprocating assembly and securing assembly in greater detail;  
         [0020]    [0020]FIG. 7 is a partially exploded fragmentary cross sectional view of a section of one of the vertical support members, a portion of the reciprocating assembly, and securing assembly taken substantially through Section A-A of FIG. 6, showing the chain lock block prior to attachment to the vertical support member; and  
         [0021]    [0021]FIG. 8 is an assembled fragmentary cross sectional view of a section of one of the vertical support members formed in accordance with one embodiment of the present invention taken substantially through Section A-A of FIG. 6, showing the chain lock block attached to the vertical support member. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    [0022]FIG. 1 illustrates one embodiment of a passenger lift  10  having a reciprocating assembly  12  formed in accordance with the present invention. The reciprocating assembly  12  is designed to be used with a passenger lift  10 , such as the passenger lift disclosed above in the Background of the Invention section of this application. The reciprocating assembly  12  is secured to a lift platform assembly  13  by a securing assembly  15 . The securing assembly  15  includes a pair of locking mechanisms  47   a  and  47   b  and a pair of attachment mechanisms  49   a  and  49   b  for redundantly coupling the reciprocating assembly  12  to a frame  18  of the passenger lift  10 . If one of the locking mechanisms  47  or the attachment assemblies  49  fails, the other of the locking mechanisms  47  or the attachment assemblies  49  provide a continued connection of the reciprocating assembly  12  to the frame  18 . The redundant coupling of the reciprocating assembly  12  to the frame  18  impedes any sudden change in the inclination or elevation of the lift platform assembly  13  in the event of a failure of a component of the locking mechanisms  47  or the attachment assemblies  49 , thus aiding in preventing injury to a passenger of the passenger lift  10  and those in the vicinity of the lift  10 .  
         [0023]    The reciprocating assembly  12  is adapted to couple to the lift platform assembly  13  of the passenger lift  10 , and is actuatable to reciprocate the lift platform assembly  13  between a raised position and a lowered position. The reciprocating assembly  12  includes a driven member  17 , such as a sprocket, attached to a drive source  19 , such as motor. A force transmission member, defined as a member adapted to transmit an actuating force generated by the drive source  19  to a frame  18  of the passenger lift for reciprocating the passenger lift between the raised and lowered positions, extends between the driven member  17  and the frame  18 . The force transmission member is preferably an elongate flexible member, shown in the illustrated embodiment as a drive chain  34 . Although the force transmission member is illustrated as a drive chain  34 , other types of load bearing members, such as cables, belts, straps, rods, etc. are also within the scope of the present invention. When the driven member  17  is actuated by the drive source  19 , the force transmission member transfers the force generated by the drive source  19  to the lift platform assembly  13  to reciprocate the lift platform assembly  13  between the raised and lowered positions.  
         [0024]    For clarity, the vehicle to which the passenger lift  10  may be installed within has not been illustrated. Still further, although the reciprocating assembly  12  and securing assembly  15  are discussed in relation to its use with a passenger lift  10  mounted in a motor vehicle, it is apparent to one skilled in the art that this is done for illustrative purposes and is not limiting. For example, it is apparent to one skilled in the art that the reciprocating assembly  12  and securing assembly  15  are equally applicable to any type of lift, including cargo lifts, and passenger lifts mounted in locations other than in a vehicle, such as a stairway. Still further yet, although illustrative terms, such as vertical, horizontal, left, and right are used, they are descriptive in nature and not limiting.  
         [0025]    Inasmuch as the operation of the passenger lift  10  aids in the understanding of the securing assembly  15 , the operation of the passenger lift  10  will now be described. The passenger lift  10  includes a vertical reciprocating lift platform assembly  13  that is selectively actuatable between at least a raised and a lowered position. In the lowered position, the lift platform assembly  13  is located adjacent a curbside or loading platform. In this position, a mobility impaired person may exit or enter onto the lift platform assembly  13 . In the raised position, the lift platform assembly  13  is substantially level with a floor of a vehicle (not shown), to permit the passage of the mobility impaired individual through an entryway of the motor vehicle and into its interior.  
         [0026]    Still referring to FIG. 1, the passenger lift  10  includes the reciprocating assembly  12 , the securing assembly  15 , the lift platform assembly  13 , which further consists of an inboard platform  14  and an outboard platform  16 , two vertical support members  18 , and two pairs of pin assemblies  20  and  22 . The vertical support members  18  are in turn slidably fastened to a support structure, such as the chassis or door frame, at the entryway of the motor vehicle, as is well know in the art.  
         [0027]    Referring now to FIGS. 1 and 2, the outboard platform  16  is hingedly attached to the inboard platform  14  by a pair of pin assemblies  22 . Each of the pin assemblies  22  has a pivot pin  92  that horizontally extends through the side walls  23  of the inboard and outboard platforms  14  and  16 , pivotally joining the two platforms  14  and  16 . The pin assemblies  22  are located on opposite sides of the inboard platform  14  at the distal ends of the seam defined by the abutting edges of the inboard platform  14  and the outboard platform  16 .  
         [0028]    The inboard edge  26  of the inboard platform  14  is hingedly attached to the two vertical support members  18  by a second pair of pin assemblies  20  (one shown). Each of the pin assemblies  20  has a pivot pin  38  that horizontally extends through the sidewall  23  of the inboard platform  14  and the vertical support member  18 , pivotally joining the inboard platform  14  to the vertical support member  18 . The vertical support members  18  may be selectively raised and lowered to convey the attached lift platform assembly  13  between the raised and lowered positions.  
         [0029]    Referring now to FIGS. 1 and 3, the pin assemblies  20  and  22  allow the lift platform assembly  13  to be rotatably deployed from a stowed position to an extended position. To deploy the lift platform assembly  13  to the extended position, the inboard platform  14  is rotated from its vertical stowed position to a horizontal position on the pair of pin assemblies  20 . Each of the pin assemblies  20  include the pivot pin  38 , a rotation limiting pin  40 , and an inboard platform arm  46  having an inboard limiting pin recess  42  and an outboard limiting pin recess  44 .  
         [0030]    When the inboard platform  14  is rotated to the extended position, the inboard platform  14  rotates about pivot pin  38 . Rotation continues until the rotation limiting pin  40  contacts the inboard limit pin recess  42  on the inboard platform arm  46 . In this position, the upper planar surface  28  of the inboard platform  14  is oriented in a substantially horizontal position and is maintained in a substantially horizontal position through contact of the rotation limiting pin  40  with the inboard limit pin recess  42 . It should be apparent that the phrase “substantially horizontal position” includes the normal operating range of a passenger lift within the scope of this disclosure. At this stage, the outboard platform  16  has yet to be extended and remains folded, resting upon the inboard platform  14 .  
         [0031]    Referring now to FIGS. 1 and 2, in continuing the deployment of the lift platform assembly  13 , the outboard platform  16  is rotated on the pin assemblies  22 , outward from the inboard platform  14  until the outboard edge  24  of the inboard platform  14  contacts the inboard edge  36  of the outboard platform  16 , limiting the further rotation of the outboard platform  16 . Once in the extended position as described, the lift platform assembly  13  may be lowered to the ground or sidewalk to allow a mobility impaired passenger to board the lift platform assembly  13 . Two drive chains  34  of the reciprocating assembly  12  are actuated to raise the vertical support members  18 , and thereby raise the attached lift platform assembly  13 . Once in the raised position, the lift platform assembly  13  is level with the floor of the passenger vehicle (not shown). The mobility impaired passenger is then free to enter into the passenger compartment of the vehicle.  
         [0032]    Referring to FIGS. 1 and 3, once the passenger has entered the vehicle, the lift platform assembly  13  is then rotatably deployed into the stowed position. This is accomplished by rotating the outboard platform until the upper surface  30  of the outboard platform  16  is parallel with and opposing the upper surface  28  of the inboard platform  14 . The inboard platform  14  and outboard platform  16  are rotated about the pin assemblies  20  until rotation results in the limiting pins  40  contacting the outboard limit pin recesses  44  on the inboard platform arms  46 . In this position, the inboard platform  14  and outboard platform  16  are secured by means well know in the art, such as by latches, in their stowed position, nested between and substantially parallel with the vertical support members  18 .  
         [0033]    Referring now to FIG. 1, in light of the above discussion of the components and operation of the passenger lift  10 , the components and operation of the securing assembly  15  will now be described. Generally, the securing assembly  15  secures the drive chains  34  of the reciprocating assembly  12  to the vertical support members  18 . The reciprocating assembly  12  selectively lowers and raises the drive chains  34 , thereby lowering and raising the attached vertical support members  18  and the attached lift platform assembly  13 .  
         [0034]    Referring now to FIGS. 1 and 4, the securing assembly  15  includes a left and a right locking mechanism  47   a  and  47   b  respectively, and a left and right attachment mechanism  49   a  and  49   b  respectively. Each locking mechanism  47  includes a chain lock block  50  and a plurality of block securing bolts  52  Each attachment mechanism  49  includes a mounting bracket  48 , a chain clevis  54 , and two chain clevis adjustment nuts  57 . In the illustrated embodiment, the elements of each of the locking mechanisms  47   a  and  47   b  and each of the attachment mechanisms  49   a  and  49   b  are identical to one another. Where the context permits, reference in the following description to an element of one of the locking mechanism  47  or one of the attachment mechanisms  49  shall be understood as also referring to the corresponding element in the other mechanism.  
         [0035]    Referring to FIG. 4, the mounting brackets  48  of the attachment mechanisms  49  are suitably a planar L-shaped member formed from a high strength material, such as steel. The mounting brackets  48  are mounted to the vertical support members  18  and provide means for coupling the distal ends of the drive chains  34  to the vertical support members  18 . More specifically, the mounting brackets  48  are suitably formed from a rectangular shaped vertically oriented backing plate  56  joined to a horizontally oriented attachment plate  58 , forming the L-shape of the mounting bracket  48 . The backing plate  56  has four apertures  60  bored perpendicularly through the backing plate  56  to allow fasteners to be inserted therethrough and into a set of four corresponding apertures in the vertical support member  18 , removably coupling the mounting bracket  48  and the chain lock block  50  to the vertical support member  18 . The attachment plate  58  has an aperture  68  (see FIG. 7) bored perpendicularly through to allow the insertion of the chain clevis  54  as will be discussed in greater detail below.  
         [0036]    Referring to FIGS. 6 and 7, the chain clevis  54  is formed from a round bar or shaft, having a threaded lower portion  62  and an upper chain mounting portion  64 . The chain mounting portion  64  includes a horizontally oriented bore  66 . The distal end of the drive chain  34  is mounted to the bore  66  by insertion of a pin  72  through the chain  34  and the bore  66  in the chain mounting portion  64  of the clevis  54 , as is well known in the art. The lower threaded portion  62  of the clevis  54  is inserted through the aperture  68  in the attachment plate  58  and secured through the use of washers  70  and an upper and a lower chain clevis adjusting nut  57 .  
         [0037]    As is apparent to one skilled in the art, the height of the lift platform assembly  13  may be adjusted by loosening and rotating the adjusting nuts  57  to either raise or lower the mounting bracket  48  in relation to the threaded portion of the clevis  54 . Fine adjustment of the height of the lift platform assembly  13  allows the lift platform surface to be manipulated so as to be coplanar with the surface of the vehicle floor when in the raised position. Thereby, when the passenger or mobility device exits the lift platform and into the vehicle, the passenger or mobility device is not presented with any obstacle caused by a difference in the height of the two surfaces. Further, the lift platform assembly  13  can be leveled by individually adjusting either the left or the right clevis  54  independently of the other, to raise or lower one side of the lift platform assembly  13  relative to the other.  
         [0038]    The clevis  54  to mounting bracket  48  connections are designed to fully support the passenger lift assembly in operation. However, as a safety precaution, the chain lock blocks  50  provide a secondary means of securing the drive chains  34  to the vertical members  18 , thus preserving the integrity of the passenger lift assembly even in event of a clevis  54  or attachment plate  58  failure, as will be discussed in more detail below.  
         [0039]    Referring to FIGS. 4, 5 and  7 , the chain lock block  50  is a generally rectangular shaped block. Along the center line of the block  50  is a vertically oriented channel  74  dimensioned to accept the length, height and width of the drive chain  34  within its walls. Within the channel  74  are three (3) locking tines  78  that extend horizontally outward from the centerline of the channel  74 . The tines  78  are dimensioned and spaced to be removably insertable within the openings  84  in the drive chain  34 , where the periphery of the openings  84  are defined vertically by the rollers  80  and horizontally by the side links  82  of the drive chain  34 .  
         [0040]    The chain lock block  50  has four (4) oblong apertures  86  bored horizontally through the block  50 . The apertures  86  are located at each of the four (4) corners of the block  50 , with the length of the oblong apertures  86  oriented vertically. The apertures  86  are sized and dimensioned to accept the block securing bolts  52 . The vertical length of the oblong apertures  86  allows the chain lock block  50  to slide along its vertical axis. This is preferably accomplished by loosening, but not removing the block securing bolts  52 . The chain lock block  50  can then be slid vertically, with the path of the chain lock block  50  restricted along the vertical axis by the securing bolts  52  sliding within the vertical length of the oblong apertures  86 . The block securing bolts  52  are then re-tightened, resecuring the chain lock block  50  in position.  
         [0041]    In light of the above description of the components of the securing assembly  15 , the operation of the securing assembly  15  will now be described. Referring to FIG. 7, the vertical support members  18  are lifted by an external means, such as a jack as a non-limiting example, until the upper surface of the lift platform assembly is coplanar with vehicle floor and roughly level. The four apertures  88  in the vertical support member are aligned with the four apertures  60  in the mounting bracket  48  as shown in FIG. 7. Referring now to FIG. 8, the chain locking block  50  is positioned so that the drive chain  34  runs vertically through the channel  74  in the block  50 , and the locking tines  78  are inserted within the openings of the drive chain  34 . The block securing bolts  52  are inserted through the apertures  86 ,  60  and  88  in the chain lock block  50 , mounting bracket  48 , and vertical support member  18 , respectively, and threaded tightly into a set of standard nuts  90  positioned within the vertical member  18 .  
         [0042]    Still referring to FIG. 8, at this point, the external lifting means is removed and the lift platform assembly is leveled by adjusting the chain clevis  54 . This is accomplished by first loosening, but not removing, the block securing bolts  52 . The bolts  52  are loosened until the chain lock block  50  can slide vertically, its movement guided by the securing bolts  52  sliding within the vertical length of the oblong mounting bolt apertures  86  in the block  50 . The chain clevis adjustment nuts  57  are selectively engaged on the threaded portion  62  of the clevis to either raise or lower one side of the lift platform assembly, leveling the lift platform assembly or adjusting its height. As the adjusting nuts  57  are selectively rotated to lower threaded portion  62  relative to the mounting bracket  48 , for example, thereby lifting one side of the lift platform assembly, the chain lock block  50  slides downward, guided by the securing bolts  52  riding within the vertical length of the oblong mounting bolt apertures  86  in the block  50 . Once the lift platform assembly is level and the proper height selected by following the above procedure, the block securing bolts  52  and adjusting nuts  57  are fully tightened, providing a redundant means of securing the drive chain  34  to the vertical member  18 .  
         [0043]    This secondary means of securing the drive chain  34  adds another level of safety to the passenger lift  10 . For example, in the event of a failure (i.e. loss of load bearing capacity) of one of the components of attachment mechanisms  49 , for instance failure of one of the chain devises  54 , mounting bracket  48 , attachment plates  58 , or chain clevis adjustment nuts  57 , the lift platform assembly is maintained in a level position by the chain lock block  50  of the locking mechanism  47 . More specifically, the drive chain  34  will remain securely mounted to the vertical support member  18  by the engagement of the locking tines  78  within the openings of the drive chain  34 . On the other hand, if the chain lock block  50  were to fail, for example by the severing of the locking tines  78 , the lift platform assembly would be maintained in a level position by the drive chain&#39;s  34  connection to the mounting bracket  48  through the chain clevis  54 . Therefore, it is apparent to one skilled in the art that the security assembly  15  provides redundant means of support to the lift platform assembly while maintaining its ability to provide a platform leveling and height adjustment means.  
         [0044]    Although each of the foregoing embodiments has been described, it should be apparent that variations of embodiments are also contemplated and, therefore, are within the scope of the present invention. As a non-limiting example, the chain lock block may be fastened directly to the vertical support member  18 , and not to the mounting bracket  48  as illustrated, thereby providing a redundant means of support in the event the mounting bracket securing bolts  52  fail.  
         [0045]    Although terminology such as vertical, horizontal, right, and left were used in describing the illustrated embodiment of the present invention for clarity, it should be apparent to those skilled in the art that these terms are descriptive, and not limiting.  
         [0046]    While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.