Abstract:
A knockdown ramp construction has a plurality of quadrangular platform members of uniform length, width, and height arranged in adjacent stacks of different heights. Vertically adjacent platform members are coupled to one another by removable couplers which preclude relative horizontal movement between adjacent platform members. An inclined riser member atop the uppermost platform member of each stack provides a smoothly inclined upper surface for the ramp. Separable connectors connect adjacent stacks of platform and riser members to one another, thereby precluding relative movement of the stacked members in directions away from one another.

Description:
[0001]    This invention relates to a knockdown ramp construction composed of a plurality of uniform platform and riser members removably connected to one another to form a smooth, inclined surface between two different levels.  
         BACKGROUND OF THE INVENTION  
         [0002]    There are many instances in which a temporary ramp is desirable to facilitate transition from one elevation to another. For example, a ramp to facilitate movement of a wheeled object, such as a wheel chair, between different levels is desirable in those instances in which the need for the wheeled object is temporary. Many temporary ramp constructions have been proposed, but not all of them have been satisfactory for a number of reasons. For example, it is not uncommon for the known ramp constructions to be composed of a fairly large number of different size and different shape components, thereby requiring considerable skill in forming and assembling the components to construct a suitable ramp. In addition, it is not uncommon for the components of a ramp to become separated from one another fairly easily, thereby resulting in unacceptable instability of the ramp.  
           [0003]    An object of the invention is to provide a knockdown ramp construction which overcomes the disadvantages referred to above.  
         SUMMARY OF THE INVENTION  
         [0004]    A ramp constructed in accordance with the invention is composed of relatively few, modular components which are usable to form ramps of virtually any length and height and composed of components which provide rigidity and stability for the completed ramp. The components comprise uniform platform members and uniform riser members, the platform members having substantially planer, parallel upper and lower surfaces and the riser members having planar lower surfaces and upper inclined surfaces which rise a distance corresponding to the thickness or height of a platform member.  
           [0005]    The platform members are vertically stackable and are stabilized against relative lateral movement by coupling members. The riser members correspond in width to that of each platform member and may be connected to an underlying platform member by coupling members of the same kind used to join vertically adjacent platform members.  
           [0006]    The lowermost platform member of each stack of platform members may be connected to the lowermost member of an adjacent stack by a connector which prevents relative movement of adjacent stacks in a direction away from one another.  
           [0007]    The uppermost platform member at the higher end of the ramp may be topped by an uppermost riser member and the shorter end of the ramp may be constituted by one of the riser members. It thus is possible to provide a ramp having a smoothly inclined surface from one end of the ramp to the other.  
           [0008]    Although the riser members have a width corresponding to that of each of the platform members, the length of a riser member may be either the same as or less than that of a platform member. This makes it possible to provide a ramp having considerable lateral stability, but minimizes the width of the inclined surface to that which is needed.  
           [0009]    Each of the platform members is of uniform thickness and the upper and lower horizontal surfaces thereof are joined by smooth, vertical side and end walls of uniform thickness. The platform members therefore can be positioned one atop another to form a stack of selected height. To prevent inadvertent lateral movement of adjacent platform members separable coupling members are provided which include sockets in the lower surface of each platform member and comprise a generally cylindrical body capable of removable accommodation in a socket in the lower surface of an upper platform member, the body terminating at its opposite end in lugs which interlock with cross bars provided in the upper surface of the adjacent lower platform member thereby providing security against relative lateral movement of vertically adjacent platforms.  
           [0010]    The lowermost platform members of adjacent stacks are connected to one another in such manner as to prevent movement of one stack relative to another in a direction that would separate the adjacent stacks. The connector includes a base above which retainer fingers project, the fingers being spaced from one another a distance corresponding to twice the thickness of a vertical wall of the platform members. The arrangement is such that, when the side or end walls of two adjacent platform members abut one another, the fingers of the connector will straddle the two walls and restrain the platform members against separation.  
           [0011]    Each riser member is of wedge configuration and has a lower, horizontal surface and an inclined upper surface. The inclination of the upper surface is such that, at the thicker edge of the riser, there is a vertical wall which corresponds in height and thickness to a sidewall of a platform member. Thus, when a riser member is placed atop a platform member there will be a smooth, inclined surface from that edge of the riser which abuts the platform to the opposite edge of the riser.  
           [0012]    The riser members may be secured to underlying platform members by the same couplings that are used to secure vertically stacked platform members to one another. Further, the same connectors that are used to prevent adjacent stacks of platform members from separating may be used to prevent a riser member forming the lower end of a ramp from separating from the adjacent platform member.  
           [0013]    Since all of the platform members are uniform and all of the riser members are uniform, and since all of the vertical coupling members are uniform and all of the lateral connectors are uniform, only four different kinds of components are required to construct a ramp of any desired height and length. Since all of the couplings and connectors are removable and since all of the platform and riser members are independent of one another, a ramp can be erected and dismantled very easily and quickly.  
           [0014]    The parts from which a ramp is constructed preferably are molded from suitable plastic materials and are so constructed as to be light in weight and structurally stable. 
       
    
    
     THE DRAWINGS  
       [0015]    Apparatus constructed in accordance with the preferred embodiment of the invention is illustrated in the accompanying drawings wherein:  
         [0016]    [0016]FIG. 1 is an exploded, isometric view illustrating the manner in which a typical ramp may be constructed;  
         [0017]    [0017]FIG. 2 is an isometric, partly exploded view showing a virtually completed ramp;  
         [0018]    [0018]FIG. 3 is an enlarged, isometric, exploded view of a platform member and a riser member illustrating the manner in which they removably may be coupled to one another;  
         [0019]    [0019]FIG. 3A is a fragmentary view of two of the components shown in FIG. 3, but in inverted positions;  
         [0020]    [0020]FIG. 4 is an enlarged vertical sectional view of a portion of a ramp and illustrating how a riser member and a platform member may be connected to prevent movement of such members away from one another;  
         [0021]    [0021]FIG. 5 is a isometric, enlarged view of the connector shown in FIG. 4; and  
         [0022]    [0022]FIG. 6 is a top plan view of the connector shown in FIG. 5. 
     
    
     DETAILED DESCRIPTION  
       [0023]    A ramp constructed in accordance with the preferred embodiment of the invention is designated generally by the reference character  1  in FIG. 2 and is composed of a plurality of identical quadrangular platform members  2 , a plurality of identical wedge shaped riser members  3 , a plurality of identical vertical couplers  4 , and a plurality of identical horizontal connectors  5 .  
         [0024]    As is best shown in FIGS. 1 and 3 each platform member  2  is quadrangular and has a plurality of longitudinally and transversely extending, interconnected ribs  6  and  7 , respectively, which form a grid having a plurality of spaces  8  therein. At opposite sides of each platform  2  are vertical side walls  9  and at opposite ends of each platform member are end walls  9   a . The walls  9  and  9   a  are perpendicular to the upper and lower surfaces of the platform members. The height and thickness of each wall  9  and  9   a  are identical. Except as is set forth subsequently, each of the ribs  6  and  7  and each of the walls  9 ,  9   a  are uniform in height.  
         [0025]    At suitably spaced intervals each platform has a cylindrical socket  10  having a smooth bore and an annular wall  11 . Adjacent the upper surface of each platform member the ribs  6  and  7  span the sockets  10 , but those ribs  6  and  7  which span the sockets are of reduced height so as to enable each socket to be open and unobstructed at the lower surface of each platform  2 . The location of the sockets is such that the sockets in one platform are vertically aligned with the sockets in vertically adjacent platforms.  
         [0026]    As thus far described, the platforms  2  correspond to the platforms shown in U.S. Pat. No. 5,683,004.  
         [0027]    Each of the riser members  3  is identical and has a smooth upper surface  12  terminating at one edge in a side wall  13  and at its opposite ends in end walls  13   a . The walls  13 ,  13   a  are perpendicular to the lower surface of the riser member. The thickness of the walls  13 ,  13   a  corresponds to that of the walls  9 ,  9   a  of the platforms  2 . The surface  12  is supported from below by longitudinally and transversely extending ribs  14  and  15 , respectively, which form spaces  16 . As is shown in FIG. 3A, the ribs  14  extend the full length of the riser member  3  but the ribs  15  extend only about half the width of the riser. At suitably spaced intervals sockets  17  are formed by an annular wall  18 , and each such socket corresponds to the size and spacing of the sockets  10  which extend alongside one of the walls  9  of the platform  2 .  
         [0028]    The couplings  4  correspond to those disclosed in U.S. Pat. No. 5,683,004 and each coupling comprises an annular body or insert  19  of such size as removably and snugly to be accommodated in any one of the sockets  10  and  17 . The body  19  is open at one end and, at its other end, has a wall supporting a pair of spaced lugs projections  20  each of which is provided with a shoulder  21 . The space between the projections  20  is sufficient to accommodate the rib  6  which traverses a socket  10  and the projections  20  are of such size as to enter the spaces on opposite sides of the rib  6 . When two of the couplings  4  are accommodated in two of the sockets of either of the members  2  or  3 , the couplings restrain relative movement horizontally between such members.  
         [0029]    The apparatus thus far described makes it possible to construct a ramp  1  wherein a plurality of platform members  2  are arranged in vertically ascending stacks adjacent one another with each adjacent stack having a height different from the next adjacent stack. In the ramp shown in FIG. 2, there is one platform  2  at the lower end of the ramp, two stacked platforms adjacent the single platform, three stacked platforms  2  adjacent the pair of stacked ramps, and four platforms  2  at the higher end of the ramp. Positioned atop the uppermost platform  2  in each stack is a riser member  3 . Adjacent the lower end of the ramp is a single riser member  3 . In the ramp shown in FIG. 2 each of the platform members  2  is of uniform length, width, and height and each of the riser members corresponds to the length and width of each platform member. However, since each riser member is of wedge configuration it has only one side wall  13  which extends the full length of the riser and has a height corresponding to the height of the side wall  9  of the adjacent ramp member. The surface  12  of the riser is inclined at such an angle to the horizontal as to provide a smoothly inclined surface from one end of the ramp to the other.  
         [0030]    Each of the stacks of platform and riser members is stable in all horizontal directions because of the coupling members  4  which couple the stacked platform members to one another and the riser members to the uppermost platform member of each stack. However, each stack of such members could move transversely relative to one another since none of the couplings  4  connects any of the platform members or riser members to corresponding members of adjacent stacks. The ability of adjacent stacks of members to move transversely relative to one another is overcome by the provision of the connectors  5 .  
         [0031]    Each connector  5  comprises a base  22  having two pairs of upstanding retainer fingers  23  and  24 . Between each pair of fingers  23  and  24  is a space  25  which is twice the thickness of each wall  9  and  13  of each platform  2  and riser  3 , respectively. This spacing makes it possible for any two adjacent walls  9  of two ramp members  2  or any two adjacent walls  9  and  13  of adjacent ramp members  2  and riser members  3  to be accommodated snugly in the space  25  and thereby enable adjacent platforms and risers to be restrained against relative horizontal movement.  
         [0032]    The walls  9  and  9   a  of the platform members  2  are provided with notches  27  and the walls  13  and  13   a  of the riser members  3  are provided with similar notches  28  along their lower edges of such depth as to accommodate the base  22  of a connector  5 , thereby ensuring that the majority of the lower edges of the walls of the members  2  and  3  will bear upon the surface on which such members rest. The notches preferably are formed in all of the side and end walls of the platform member  2  and in the side and end walls  13 ,  13   a  of the riser members.  
         [0033]    The length of the platform and riser members may be uniform as is shown in FIGS. 1 and 2. However, the length of the riser members could be shorter than that of the platform members as is shown in FIG. 3. If the riser members are shorter than the platform members, the riser members may be positioned at either end of a stack of platform members or at the center thereof. It thus is possible to provide a ramp which has a portion of its width smoothly inclined and another portion of its width in stair-step form.  
         [0034]    [0034]FIG. 2 discloses a ramp wherein a riser member  3  is in position to be placed atop the uppermost platform member  2 . If it is desired to provide a horizontal surface at the upper end of the uppermost, or any other upper platform member, the riser member simply need not be applied to the upper end of a selected stack.  
         [0035]    The disclosed embodiment is representative of a presently preferred form of the invention, but is intended to be illustrative rather than definitive thereof. The invention is defined in the claims.