Abstract:
A multi-section ramp hinged longitudinally end-to-end uncurls from a portable mode into an arc of hinged sections in open, or operational mode, each adjacent section pair limited in opening rotation at less than 180 degrees as adjacent section ends come into abutment. In its folded position, more upper ramp sections nest in respective adjacent next lower ramp sections, in a stacked nesting configuration resulting in a tightly compact, mobile unit easily storable in a small volume and transported by hand. Each section comprises a runway in the form of a plate with vertical panels on each runway lateral side extending downward from the runway and with vertical end members on each runway longitudinal end, forming an inverted open box. Longitudinal strengthening ribs run between end members and pass into aligned slots in more inner runway sections upon ramp folding so inner sections can nest more within the larger sections without impacting the ribs.

Description:
BACKGROUND 
   1. Field of the Technology 
   This invention relates to ramps for loading and unloading from a first level to a second level and to ramps serviceable as temporary bridges. More specifically, the invention relates to a foldable ramp with successively nesting ramp sections hinged together end-to-end in moving between a compact mobile package and an open operational runway. 
   2. Prior Art 
   Loading wheeled vehicles, such as motorcycles, small utility vehicles, and lawnmowers, onto larger vehicles, such as pickups or flatbed trucks have been difficult for some time. Ramps for such loading and unloading of vehicles have been proposed but remain inadequate, typically being inconveniently large and heavy or not conveniently storable away from the truck. Perhaps because of the weight and large folded size, ramps have often been integrated into the vehicle, such as a substitute for or integrated with a truck tailgate. 
   Various types of foldable ramps have been disclosed. It is common for sections to be hinged end to end, such as with ramps with two longitudinal sections connected by a transverse hinge folded in face-to-face opposition, as in U.S. Pat. No. 6,009,587 by Beeman and U.S. Pat. No. 4,761,847 by Savage et al. or such as in ramps with more than two sections that fold together in a “Z” or accordion arrangement, such as in U.S. Pat. No. 5,062,174 by DaSalvo and U.S. Pat. No. 4,944,546 by Keller. These ramps are serviceable but remain unduly large and inconvenient to transport. With the accordion style folding, the ramp load capacity is also necessarily limited by whatever mechanism is employed to keep the upward oriented hinge joint from opening under load. A lightweight portable and compact ramp remains an unresolved requirement. 
   SUMMARY 
   It is the object of the present invention to provide a portable ramp particularly suitable as a runway for small-wheeled vehicles such as motorcycles and even wheelchairs and small utility vehicles. (For purposes herein, the term portable is meant to indicate an ability to be moved independent of a platform to which it may be temporarily connected or associated during use.) It is another object that the ramp be compact for ease of storage and transport. It is a further object that the ramp be of lightweight design. It is a still further object that all of the ramp hinge joints be urged into compressive union under load, inherently increasing load capacity. 
   These objects are achieved in a multi-section ramp hinged longitudinally end to end that uncurls from a portable mode into an arc of hinged sections in open, or operational mode with longitudinal adjacent section ends abutted at less than 180 degrees. In its folded position, more upper ramp sections nest in respective adjacent next lower ramp sections, in a stacked nesting configuration. For purposes within, stacked nesting is meant to describe one section within a second section which in turn is within a third section, etc. 
   The ramp comprises a plurality of sections, typically four, and for ease of description, the ramp is described as having four sections. However, it should be understood that the ramp could conceivably comprise more than four sections without deviating from the disclosure of the invention. Such ramps with more than four sections are to be deemed included in this invention. 
   Each section comprises a runway in the form of a plate with panels on each runway lateral side and with end members on each runway longitudinal end, forming an inverted open box. Longitudinal strengthening ribs run between end members and pass into aligned slots in first and second runway sections so these sections can nest within the larger sections without impacting the longitudinal ribs. Shallow transverse strengthening ribs run between panels, interrupted only by said slots in first and second sections. Thus, all sections fold into close face-to-face, parallel opposition with another ramp section spaced apart from the section runway only by the shallow transverse ribs. The resulting folded ramp then presents a tightly compact, mobile unit easily stored in a small volume and transportable by hand. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is perspective side view of the ramp of the present invention in unfolded, operational position, shown with a pair of wheels on which the ramp can roll when folded. Also shown are two upper sections with slots dividing the sections into section portions, the slots provided to receive strengthening ribs of the lower sections when the upper sections fold compactly into the larger lower sections. 
       FIG. 2  is a perspective view of the ramp of  FIG. 1  folded into a compact portable unit, shown standing on the wheels and the distal end of the last section. 
       FIG. 3  is an underside view of the ramp unfolded, showing the longitudinal strengthening ribs aligning with slots. 
       FIG. 4  is also an underside view of the ramp shown with the first section folded against the second section with their runway bottom surfaces nested in close opposing, parallel disposition, forming a section pair. 
       FIG. 5  is a further underside view of the ramp shown with the section pair of  FIG. 4  rotated against the third section with the first section runway top surface nested in close opposing, parallel disposition to the third section bottom surface, forming a section trio. 
       FIG. 6  is a still further underside view of the ramp shown with the section trio of  FIG. 5  rotated against the fourth section with the second section runway top surface nested in close opposing, parallel disposition to the fourth section bottom surface, forming a section quartet. 
       FIG. 7  is a side view of the panel shown slightly unfolded on hinges between adjacent ramp sections hinged end to end opening downward, illustrating section ends in near abutment that prevents the sections to hinge open beyond 180 degrees and in fact less than 180 degrees to form an arc that conveys compressive forces to ramp ends under load. 
       FIG. 8  is a side view of the first section panel. 
       FIG. 9  is a side view of the second section panel. 
       FIG. 10  is a side view of the third section panel. 
       FIG. 11  is a side view of the fourth section panel. 
       FIG. 12  is a side view of the panel partially folded illustrating the nature of folding as an approximate curl of the collective panel sections. 
       FIG. 13   a  is a plan view of a typical section outer box component showing side panels, end longitudinal end members, and supporting ribs before the panels and end members are folded to form an inverted open box. 
       FIG. 13   b  is a plan view of a typical section inner box component showing side panels, end longitudinal end members, and supporting ribs before the panels and end members are folded to form an inverted open box. 
       FIG. 13   c  is a plan view of the section outer box component of  FIG. 13   a  a perforated runway. 
       FIG. 14  is an exploded view of a typical section formed by three component inverted open boxes of  FIGS. 13   a–c , shown with a spacer to establish section slots. For sections without slots, the spacers are omitted and the boxes are assembled side by side. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to the figures, and particularly to  FIG. 1 , the foldable ramp  10  of the present invention comprises a plurality of ramp sections  12 , typically four, hinged end to end, disposed such that all adjacent sections rotate on hinges  30  only inward as shown in  FIG. 3 , that is, with section bottom surfaces  14  rotating toward each other during folding and away from each other during opening, in respective curling and uncurling motions in an approximate spiral path with each more upper section folding first and curling to nest within a larger, next lower section. So nested, runway top surfaces  15  and bottom surfaces  14  lie in close, parallel opposition. 
   Each upper section  12   u  is dimensioned slightly smaller than its next lower adjacent section  12   l  both longitudinally and transversely such that upon folding the upper section  12   u  with its runway  16 , panels,  17 , end members  18  and strengthening ribs  20  is nested within the lower section  12   l . For ease of description, each section above an adjacent section is deemed to be smaller than its adjacent lower section. However, it should be understood that it is deemed equivalent to have a lower section smaller than and folding into a larger adjacent upper section. Also, it is understood that use of terms such “nesting” and “fitting within” and other similar terms are meant to convey a smaller section fitting within the another section into which it nests; that is between the lateral side panels and end members  18  and in close face-to-face opposition to the underside of each section runway. It does not necessarily require that those side panels and/or end members extend from the respective runways beyond an inner section nested within. For ease of description, sections may be designated numerically, such as first section, second section, third section, and fourth section etc. This nomenclature is for convenience of description only and should not be construed as limiting the number of sections. 
   The ramp sections  12  open fully to an operational mode with adjacent section end members  18  abutting, inherently preventing adjacent sections from opening beyond 180 degrees. Section end members  18  are disposed transversely on adjacent ramp section longitudinal ends at less than 90 degrees from runway  16 , each end member with an abutting surface  19  facing outward from its respective section end with its normal (line perpendicular to its face) longitudinal with the ramp, the runway ending at the end members  18 , so that end members  18  of adjacent sections  12   u  and  12   l  abut longitudinally face to face with their respective runways meeting at less than 180 degrees creating an arc along the ramp runway. Thus, under load the ramp section end members  18  abut under compressive forces, urging them together with stability increasing under increasing load. 
   The ramp sections  18  are strengthened by the side panels  17  (shown in  FIGS. 8–11 ) depending vertically downward from the section runway  16  along each section lateral side  22  and longitudinal strengthening ribs  20  running longitudinally between section longitudinal ends  24 , between and parallel to side panels  17  and terminating in longitudinal abutment with said end members. Shallow transverse strengthening ribs  26  extend between panels  17  and longitudinal strengthening ribs  20  and between pairs of strengthening ribs  20 . 
   Turning to the hinges  30  and referring primarily to  FIG. 1  and  FIG. 12 , it is helpful to describe the hinge configuration in relation to upper and lower adjacent sections  12   u  and  12   l . It has been described that for each pair of adjacent sections, one will be smaller than the other so that the smaller can nest within the larger. Consistent with the assumed nomenclature herein, in describing the hinge  30 , the smaller adjacent section will be referred to as the upper section  12   u  and the larger adjacent section will be referred to as the lower section  12   l . Similarly, an upper element will indicate in the direction of the smaller section and a lower element will indicate in the direction of the larger element. Continuing, hinge ears  32  on lower ends  34  of each of the side panels  17  and lower ends  36  of the longitudinal strengthening ribs  20  (except the last or lowest section) extend below and beyond an upper section  12   u  reaching under the adjacent lower section  12   l . A hinge plate  36  extends vertically downward under the runway lower surface  16   a  of the lower section  12   l  inward from a lower section end member  18  on a lower section first end  38 , that is, longitudinally between the section end members at an upper end of said lower section. A hinge bar  40  passes through a hinge plate hole  42  aligned with a hole  44  in the hinge ears  32  on the ribs  20  below the ribs  20  of the lower section  12   l  and on each section lateral side  22  forming the hinge  30  between the adjacent upper and lower sections  12   u  and  12   l , longitudinally. Thus, when the upper section  12   u  pivots on the hinge  30 , it folds fully under the adjacent lower section  12   l , inward of the lower section end member  18 . 
   As also shown in  FIG. 3 , ramp hinges  30  between adjacent sections  12   u  and  12   l  are below the ramp runway  16  enabling the ramp  10  to fold in the general nature of a crude spiral path  46  as shown in  FIG. 12 . With ramp hinges  30  below the abutting end members  18 , load forces are absorbed as compressive forces through the abutting member ends  18  and the ramp load is transferred to ramp end members  18  largely as if the ramp were a single unit. Beyond the abutting sections, the ramp load limit is derived from the stress transferred to the ramp hinges  30  located below the abutting end members  18 . It is understood that as compressive forces act at the abutting end members, tension forces act below those end members, which are absorbed by the hinge. Provided the sections have sufficient support strength greater than the hinge strength, the ramp load capacity is then limited only by the hinge strength. 
   To accommodate longitudinal strengthening ribs  20  as the two upper most sections  121  and  122  nest together, the rib ears  32  of the upper most, or first, section  121  connect pivotably to the hinge bar  40  outside of the ears  32  of the next lower, or second, section  122 , also folding together in face-to-face opposition in scissor-like fashion. The scissor-like closing of the strengthening ribs  20  and panels  17  assures that the sections  12  do not bind during folding but remain fully aligned. Respective side panels  17  of nesting sections slide in scissor-like fashion into opposing face-to-face disposition with the runway bottom surface  14  of the two sections also in opposing close parallel face-to-face disposition. 
   The two upper sections  121  and  122 , or first and second sections, rotate on their hinge  301  into a folded configuration with their runway bottom surfaces  141  and  142  in close parallel opposition forming a section pair  52 , as shown in  FIG. 4 . 
   In continuing the compact folding process, as shown in  FIG. 5 , the section pair  52  pivots as a unit on the next lower hinge  302 , between the second and third sections  122  and  123 , such that the pair  52  nests into the third section  123  (counted from the top, or smallest section) with the first section runway top surface  151  folding into face-to-face opposition and parallel to the third runway bottom surface  143 , forming a trio  54  of sections with the third section panels  173  and member ends  183  around the section pair  52 . In thus folding into the third section  123 , the panels  172  of the second section  122  fold in scissor-like fashion into face-to-face opposition with the panels  173  of the third section  123 . 
   To accommodate the ribs  203  of the third section  123  as the section pair  52  nests into the runway underside  143  of the third section  123 , the first section runway top surface  151  includes longitudinal slots  601  aligned with the ribs  203  of the third section  123  such that as the section pair  52  rotates into its fold position, nesting within the third section side panels  173  and end members  183 , the third section ribs  203  move into the first section slots  601 . 
   Further in continuing the compact folding process, as shown in  FIG. 6 , the section trio  54  pivots as a unit on the next lower hinge  303 , between the third and fourth sections  123  and  124 , such that the trio  54  nests into the fourth section  124  with the upper runway surface  152  of the second section  122  folding into face-to-face close parallel opposition to the runway bottom surface  144  of the fourth section  124 , forming a section quartet  56  with the fourth section panels  174  and end members  184  around the section trio  56 . As before, the panels  173  of the third section  123  fold in scissor-like fashion into face-to-face opposition with the panels  174  of the fourth section  124 . 
   In similar manner as above, to accommodate the ribs of the fourth section  124  as the trio  56  nests into the underside  154  of the fourth section  124 , the second section runway top surface  152  includes longitudinal slots  602  aligned with the longitudinal ribs  204  of the fourth section such that as the trio  56  rotates into its fold position, nesting within the fourth section side panels  174  and end members  184 , the fourth section ribs  204  move into the second section slots  602 . 
   As shown in  FIG. 3 , the slots  601  and  602  of the first and second sections comprise strengthening ribs  201  and  202  on each side of the section slots, respectively. Thus the slots divide these sections into three section portions  12   a ,  12   b  and  12   c  with a central portion  12   b  separated from the outer portions  12   a  and  12   c  by a spacer  12   d  on the hinge bars  40  between central and outer sections on each section end that defines the slot  60  by separating the section portions, as further illustrated in  FIG. 14 . The inner portion  12   b  may comprise a porous plate or a mesh  12   e  to minimize weight of the section runway while still accommodating riding of a wheeled vehicle thereon, such as a motorcycle. The outer section portions  12   a  and  12   c  may comprise a solid plate  12   f  that facilitates a person safely walking alongside the motorcycle. 
   As shown in  FIG. 14 , the sections may comprise boxes  70  open at their bottoms as section components. With the end member  18  comprising a plurality of end member portions, longitudinal ends  72  of boxes  70  collectively comprise a section end portion  73  bridging adjacent lateral sides therein closing each box circumference. Section tops  15  comprise a plurality of segments  71  that respectively are box tops. Outer lateral sides  74  of outer boxes  70   o  comprise section panels  17 . Inner lateral sides  76  of boxes  70  comprise section longitudinal strengthening ribs  20 . With the boxes  70  spaced apart by spacers  12   d  they form section slots  60 . When assembled together without spacers, adjacent box sides together form a single longitudinal rib  20 . 
   In folded configuration, the two lowest and largest sections  123  and  124  thus enclose the remaining smaller sections  121  and  122  nested between them. A wheel  80  on the upper end  82  of each panel  17   c  of the third, or next to last section  123  enables the folded unit to conveniently roll. The pivot bar  40  between the last two sections  123  and  124  serves as a convenient handle in directing the folded unit on its wheels. Further, the distance of the pivot bar  40  to the wheel contact with the ground is equal to that distance from that pivot bar  40  to the last section distal end  84  such that the folded unit stands supported on one side on the wheels  80  and on the other side on the last section distal end  84 .