TAIL BRIDGE

Abstract: The invention provides a tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail. A first plate (11) to be placed on the motor vehicle tail end is joined along a straight line at one edge to a second plate (12) making a angle of from 12 to 20 degrees with the first plate. An intermediate plate (14) is attached at the joint of the first and second plates and runs downwardly. A third plate (13) is attached to the lower end of the intermediate plate (14) and runs about parallel to the second plate at a distance corresponding to the thickness of a rail to be placed between the second and third plates. Bolt holes can be provided in the first and second plates for secure attachment to the motor vehicle tail end and a first end of the ramp rail. A foot piece is attached to a second end of the ramp rail to support the ramp against the road surface.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tail bridge that provides a bridge between the tail part of a motor vehicle and a support rail. 2. Brief Description of the Background of the Invention Including Prior Art United States Patent 2,594,425 to Hymen Greenberg teaches a removable runway. United States Patent 1,568,303 to W.E. Webster teaches a freight skid. United States Patent 3,580,373 teaches a portable ramp. United States Patent 749,595 to H. Van Doorn teaches a wharf drop. All these references teach relatively complicated devices. Some of them relate to fields completely different from a tail bridge, such as, for example, carpet edges. United States Patent 4,528,711 to Louis Parker teaches a portable wheel chair ramp. The reference employs spacer brackets 20, 21, which fix the distance between the ramps once and for all and thus render them unsuitable where different wheel distances exist for which the wheel chair ramp would be used. Further, the reference teaches use of a inner suport member 12 and outer support member 11, which have to be specially fabricated in a form stable and matching structure and which as taught are unsuitable for the rough jobs performed and truck operations. In particular the narrow channel of the support members is very limiting and awkward in situations where different wheel structures and wheel dimensions are to be employed in loading and unloading operations of trucks. SUMMARY OF THE INVENTION 1. Purposes of the Invention It is an object of the present invention to provide a simple device that allows the movement of material from ground level to the loading level of a motor vehicle. It is another object of the present invention to provide a device that avoids a step during a loading and unloading process from a motor vehicle for items to be moved along a surface. It is yet another object of the present invention to provide a structurally sound and stable means for performing loading and unloading operations from motor vehicles, and a tail bridge to be precisely positioned against the tail end of the motor vehicle. 2. Brief Description of the Invention The present invention provides a tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail. The tail bridge comprises four plates. A first plate for placing on the tail end of the motor vehicle and for running about parallel to the tail edge of the motor vehicle tail end is joined along a straight junction line to a second plate extending at an edge of the first plate and forming an angle of from about 12 to 20 degrees relative to the first plate. An intermediate section is attached between the first and second plate along the straight junction line and runs downwardly. A third plate is attached to the lower end of the intermediate section and runs substantially parallel to the second plate at a distance corresponding to the thickness of a rail to be placed between the second and third plate. The intermediate section is disposed at an angle from about 85 to 95 degrees relative to the first plate. The upper edge of the open end of the first plate and the upper edge of the free end of the second plate can be beveled. A bevel can be disposed at the lower end of the open end of the third plate, where the bevel can extend over nearly the full width of the third plate and the bevel angle can be about 30 degrees. The thickness of the first plate can be reduced by from about 40 to 60 percent between the area near the junction between the second plate and the free end. The third plate can be reduced in thickness from by about 20 to 30 percent when moving from an end near the intermediate section to the free end of the third plate. Traction lines can be provided on top of the first plate and of the second plate and can run substantially in parallel to the junction between the first and second plate. Holes having a diameter of from about 0.8 cm to about 1,3 cm can be provided near the two free corners of the first plate. Holes having a diameter of from about 0.8 cm to 2.6 cm can be disposed on the second plate and on the third plate and can be aligned in a vertical direction toward the second and third plate extension. The tail bridge can be comprised throughout of an extruded metal, which preferably is an aluminum alloy. The first plate can have an extension of from about 10 to 15 cm and where the second plate and the third plate can have an extension of from about 7 to 13 cm. The width of the plates can be from about 12 to 38 cm. The first plate can have a thickness of from about 0.35 cm to 1.3 cm, the second plate can have a thickness of from about 0.5 to 1 cm, the third plate can have a thickness of from about 0.35 to 0.8 cm and the intermediate section can have a thickness of from about 0.5 to 1 cm. Fillets with a radius of from about 0.5 to 1.5 times the thickness of the intermediate section can be provided between the first plate, the second plate and the intermediate plate. The yield strength of the tail bridge for 0.2 percent offset preferably is at least 700 kg/sq.cm, the tensile strength of the alloy employed is preferably at least 1.400 kg/sq.cm, and the Brinell hardness of the alloy preferably is at least 40. The rated stability of the device preferably is at least 150 kg maximum for each device. BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing, in which are shown several of the various possible embodiments of the present invention: Fig.1 is a sectional view of the tail bridge, Fig. 2 is a top view of the head part of the tail bridge, Fig. 3 is a sectional view of the head part of the tail bridge assembled to a wooden rail and positioned on a tailgate of a motor vehicle. Fig. 4 is a sectional view of a foot part of a tail bridge, Fig. 5 is a top view of a foot part of a tail bridge. DESCRIPTION OF INVENTION AND PREFERRED EMBODIMENTS In accordance with the present invention, there is provided a tail bridge comprising four plates, where the first plate 11 is to be disposed on and supported by a tail section of a motor vehicle. A second plate 12 joins the first plate at its end along a straight line 16. An intermediate plate 14 is attached to the joint of the first and second plate in a downward direction. A third plate 13 is attached to the end 18 of the intermediate plate 14. The first plate, the second plate and the intermediate plate form a strong joint at 16. The strength of the joint 16 is increased by fillets 20, 22 disposed between the first plate and the intermediate plate and between the second plate and the intermediate plate. These fillets 20, 22 can have a fillet radius of from about 0.5 to 2 times the thickness of the intermediate plate 14. The first plate 11 is conceptually positioned in a horizontal direction. Preferably, the width of the first plate 11 is larger at the end 24 where it joins the second plate 12 as compared to its free end 26. The amount of thickness reduction between the end 24 adjoining the junction to the second plate 12 and the free end 26 can be from about 30 to 60 percent. The end section is preferably provided with a bevel 28. The length of the first plate 11 can be from about 7 to 20 cm and preferably is between 10 and 15 cm, such as for example, about 12.5 cm. The free end 26 of the first plate 11 is preferably provided with a bevel 28. The bevel 28 is provided at the upper end corner 30 and preferably can cover nearly the full thickness width of the end part of the first plate. The bevel angle can be from about 20 to 45 degrees and is preferably about 25 to 35 degrees as measured relative to a plane parallel to the first plate. Furthermore, the edge at the end of the first plate 11, as well as the corresponding edges of the second and third plate to be mentioned later, are preferably provided such that these are not sharp edges but have a radius of curvature of at least 3 mm. The second plate 12 is disposed versus the first plate 11 at an angle of from about 12 to 20 degrees and preferably at an angle of from about 14 and 16 degrees, such as, for example, an angle of 15 degrees. The second plate 12 is generally shorter than the first plate 11 and is preferably from about 10 to 30 percent shorter than the first plate 11. The thickness of the second plate 12 is preferably substantially uniform, that is, uniform with variations of up to 10 percent between one end and the other. The second plate 12 is again preferably provided with a bevel 32 on its upper edge 33, which can be at an angle of from 20 to 45 degrees and preferably from about 25 to 35 degrees relative to a plane parallel to the plate. The tops of the first plate 11 and of the second plate 12 are preferably provided with friction generating elements 34, such as linear protrusions running parallel to the junction of the first and second plate, which allow, for example, tires to better grip to the tail bridge. Preferably, the surface of the first and second section is each subdivided such that each such section comprises from about 2 to 5 gripping sections with flat sections in between, where the gripping sections have a width of from about 0.8 to 1.2 times the width of the flat sections. The protrusions are preferably less than from about 1 to 10 percent of the thickness of the plates. The general shape of the cross section of the protrusions can be from about square to semicircular. The intermediate plate 14 generally extends in an angular direction that is between a perpendicular plane relative to the first plate 11 and a perpendicular plane relative to the second plate 12. More preferably, the intermediate plate 14 is in the above range within that half of the angle range that is adjacent to a perpendicular plane standing vertical to the first plate. The length of the intermediate plate 14 is such that a distance sufficient to support and hold a ramp rail is generated between the second plate 12 and the third plate 13. The length of the third plate 13 can be from about 0.8 to 1.2 times the length of the third plate 12 and is preferably from 0.9 to 1 times the length of the second plate. The free end 36 of the third plate is preferably provided with a bevel 38, where the bevel surface forms an angle of from 20 to 45 degrees with the plane of the third plate. It is important that the second and third plate are constructed such that a good fit is provided to the ramp rail surfaces. Upon load, the ramp rail is preferably supported on the ground at its one end. Such fixture then results in a compression between the rail and the tail bridge against the area of the intermediate plate under load. In addition, preferably the support rail 40 is bolted to the second and third plates, as is illustrated in Fig. 3. It is necessary that the surfaces of the rail are essentially flush against the surfaces of the second and third plates so as to achieve a strong connection between tail bridge and rail. Furthermore, bolt holes 51 - 54 are to be provided in the second 12 and third plate 13 which are aligned perpendicularly to the extension of these plates such that bolts 43 can be employed and tightened to hold a rail in place between the second and third plate. The bore holes can have diameters from about 0.6 cm to about 2.6 cm and preferably have diameters of 0.9 to 1.6 cm. In general, these bore holes are shown in the drawing designated as 51, 52, 53 and 54. The second rail can have a thickness of from about 0.35 cm to 0.8 cm and the thickness is preferably about 0.65 cm. The intermediate plate 14 can have a thickness of from about 0.35 to 1 cm and is preferably between 0.5 and 0.8 cm such as near 0.63 cm. The third plate 13 adjoins the intermediate plate 14 and has a length of from about 0.7 to 1 times the length of the first plate 11. Preferably the end 18 of the third plate 13 and the end 16 of the second plate are vertically aligned relative the second 12 and third plate 13 surfaces. The third plate is provided with a bevel at its lower end that can be disposed at an angle of from about 20 to 45 degrees and preferably at an angle of from about 25 to 35 degrees relative to the third plate plane. The width of the bevel can be about 1/5 to 1/10 of the length of the third plate and is preferably from about 1 to 1.5 cm. Furthermore, the first plate 11 is preferably provided with holes 55 that can have a diameter of from 0.6 to 1.3 cm and that can to provide an attachment means for attaching and securing the first plate 11 on the tail end 42 of a load platform of a motor vehicle. The device of the present invention is preferably produced as an integral piece by metal extrusion. Preferred metals employed include alloys of aluminum such as alloy 6061-T6. Other materials useful for producing the invention device include formed metals such as formed steel. The steel employed can be in the form of a T beam, where one upper arm of the T is bent off at an angle of from about 12 to 18 degrees and where the lower part of the T is bent off and formed to provide the intermediate plate and the third plate. Alternatively, the tail bridge could be welded together by employing various welding processes for T joints or corner joints. Useable weld types included bead, groove, fillet and weave. The overall dimensions of the device are preferably less than 75 cm and more preferably less than about 60 cm, and these dimensions can be those dimensions running in the directions of a three dimensional coordinate system. The width of the device can be from about 12 to 50 cm and preferably is between 15 and 25 cm, such as, for example, about 20 cm. This width is appropriate for matching dimensional lumber pieces such as material stock of nominal "2X10 inches". The distance between the second plate and the third plate also is to set such that it closely matches the thickness dimensions of dimensional lumber pieces. For example, a thickness of 37.5 mm is appropriate for nominal "2-inch" lumber material. The present invention provides the advantage that the tail bridge is suitable for moving heavy equipment with ease onto a loading platform of a motor vehicle. In view of the compression forces resulting upon loading a ramp and the tail bridge, substantial stability is provided and rated weights of 150 kg and more can be obtained. The tail bridge provides a relatively smooth but nevertheless friction providing support for wheels that have to be transported onto a loading level of a motor vehicle or of a trailer. The bolt attachment that can be provided on both the vehicular end side and on the side with ramp rail ensures a secure support for the materials to be moved onto the loading level. The invention device has further applications in providing a scaffolding support for masons such that a staging on an upper level can be achieved and wheel barrows can be moved upward from level to level. In particular, bumps are avoided and a secure attachment is present. A further application of the tail bridge can be for temporary installation of ramps for wheel chairs, which ramps can be disposed on top of stairways. The first plate can be easily installed at the top of a stairway, and the two ramp rails would still allow intermediate space for a person to mount the stairs as they originally existed while at the same time allowing a wheel chair to be moved upward. Of course, the relative angles between the first plate 11 and the second plate 12 would be adjusted to the rise angle of the stairway, such as, for example, from about 35 to 50 degrees. Also the dimensions of the plates could be adapted to the specific stair parameters. According to the invention, there is also provided a foot part for the tail bridge. The foot part comprises an overall V-shaped section plate 101 which expands on the inside to about the width of the piece of lumber to be inserted. The lower section plate 103 of this expansion is preferably a rounded section. The angle of the tip 105 can be from about 30 to 70 degrees and is preferably between about 35 and 55 degrees. The radius of curvature of the rounded section plate 103 can be from about 2 to 5 times the thickness of the lumber piece used and the radius of curvature is preferably from about 2.5 to 4 times the thickness of the lumber piece used. Each arm 103, 107 of the about V-shaped section plate is extended by a straight section plate. Preferably, the straight section plates are about parallel to each other and their plane forms an angle of less than 20 degrees and preferably of less than 5 degrees with the bisector of the angle of the V. The length of the two straight section plates 113, 115 adjoining the respective V-shaped section plates 103, 107 can be from about 0.5 to 2 times the length of the V-shaped section plates (Fig. 4). Preferably, within the center third of the two straight extended section plates, a hole 117, 119 is provided for a countersunk screw, both on the upper part 115 and on the lower part 113 of the straight extension plate. The diameter of the holes 117, 119 can be from about one to two times the thickness of the plate. The rounded section is preferably provided with grooves and ridges on the outside of the V-shaped section plates which allow a solid footing of this piece on the ground. The grooves 109 are preferably disposed running in parallel to the intersection line of the V-shaped section plates. There can be from about 10 to 50, and preferably from about 20 to 30, about uniformly spaced grooves and ridges on the curved section plate 103 for providing stability of the support. The grooves 119 can further be located on the upper section plate 107 for providing frictional support to wheels of a carriage. The grooves and ridges on the straight upper section plate can be grouped as from about 5 to 10 and can have an intermediate space between the groups, which extends in transport direction to 0.5 to 2 times the width of a group of grooves and ridges. The depth of the grooves can be from about 0.5 to 1 times the separation distance of neighboring grooves. The size of the grooves can be from about 0.05 to 0.3 of the thickness of the base material, and is preferably from about 0.1 to 0.2 of the thickness of the base material. The thickness of the plate for clamping the lumber beam can be from about 0.1 to 0.2 of the thickness of the beam to be held and is preferably from about 0.15 to 0.18 of the thickness of the beam. The length of the curved section and of the straight section joining at an angle can be from about 1.1 to 1.5, and preferably is from about 1.2 to 1.4, of the thickness of the lumber beam to be held. The width of the foot section corresponds to that of the lumber beam and of the head part of the tail bridge. It is preferably from about 15 to 25 cm. A bevel section 121, 123 can be provided at the outside ends of the straight extension plates and can extend over 0.2 to 0.4, and preferably over 0.25 to 0.3, of the extension of the straight extension plates in transport direction. The bevel angle can be from about 10 to 30 degrees relative to the transport direction. Preferred materials for these elements include aluminum, in particular extruded aluminum, stainless steel, steel, and plastic materials having a high strength and toughness.

Claims: A tail bridge for bridging a tail end (42) of a motor vehicle and the ground with a ramp rail (40), comprising: a first plate (11) to be placed on said tail end (42) for running substantially parallel thereto, a second plate (12) rigidly joined to the first plate (11) along a straight uninterrupted junction line (16) and extending at the edge of the first plate (11) and forming an angle relative to the first plate (11), and means (51-54,43) for mounting the ramp rail (40) to the second plate (12), characterized in that the tail bridge comprises only one ramp rail (40), an intermediate section (14) is rigidly joined between the first (11) and second (12) plate substantially along the straight junction line (16) and extending downwardly, a third plate (13) is rigidly joined to the lower end of the intermediate section (14) and running substantially parallel to said second plate (12) and spaced therefrom a distance corresponding to the thickness of the ramp rail (40) to be placed between the second (12) and the third (13) plate, the angle between the first (11) and the second plate (12) is from about 12 to 20 degrees, and the intermediate section (14) is disposed at an angle from about 85 to 95 degrees relative to the first plate (11). The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to claim 1 further comprising a bevel at the upper edge of the open end of the first plate (11). The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims further comprising a bevel disposed at the upper edge of the free end of the second plate (12). The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims further comprising a bevel disposed at the lower end of the open end of the third plate (13), where the bevel extends over nearly the full width of the third plate (13) and where the bevel angle is about 20 to 40 degrees. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims wherein the thickness of the first plate (11) is tapered and being reduced by from about 40 to 60 percent between the area near the junction of the first plate (11) and the second plate (12) and the free end. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims wherein the third plate (13) is tapered and being reduced in thickness from by about 20 to 30 percent when moving from an end near the intermediate section (14) to the free end of the third plate (13). The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims further comprising traction lines on top of the first plate (11) and on top of the second plate (12), which traction lines run substantially in parallel to the junction between the first (11) and second (12) plate. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims further comprising holes (55) having a diameter of from about 0.6 cm to about 1.3 cm displaced near the two free corners of the first plate (11). The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims further comprising holes (51) having a diameter of from about 0.6 cm to 2.5 cm disposed on the second plate (12) and on the third plate (13), which are aligned in a vertical direction toward the second (12) and third (13) plate extension. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims where the device is comprised throughout of an extruded metal. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to claim 10 wherein the extruded metal is an aluminum alloy. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims wherein the first plate (11) has an extension of from about 10 to 15 cm and where the second plate (12) and the third plate (13) have an extension of from about 7.5 to 12.5 cm. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims wherein the width of the plates (11, 12, 13) is from about 12 to 38 cm and wherein the first plate (11) has a thickness of from about 0.35 cm to 1.3 cm, wherein the second plate (12) has a thickness of from about 0.5 to 1 cm, wherein the third plate (13) has a thickness of from about 0.35 to 0.75 cm, wherein the intermediate section (14) has a thickness of from about 0.5 to 1 cm, and wherein fillets (20, 22) are provided between the first plate (11), the second plate (12) and the intermediate plate (14) and where the radius of the fillet (20, 22) is from about 0.5 to 1.5 the thickness of the intermediate section. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims wherein the yield strength for 0.2 percent offset is at least 700 kg/sq.cm, wherein the tensile strength of the alloy employed is at least 1.400 kg/sq.cm, wherein the Brinell hardness of the alloy is at least 40, and wherein the rated stability of the device is at least 150 kg maximum for each device. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to one of the preceding claims a foot part for the tail bridge including a lower section plate (103) to be placed on the ground for supporting the tail bridge; an upper section plate (107) solidly joined to the lower section plate (103) to provide an about V-shape with the apex of the V to be disposed remote relative to the ramp rail; an upper extension plate (115) joined to the end of the upper section plate (107) remote from the apex of the V along a straight uninterrupted junction line and extending at an edge of the upper section plate (107) and forming an angle of from about 30 to 70 degrees relative to the upper section plate (107); a lower extension plate (113) joined to the end of the lower section plate (103) remote from the apex of the V such that the upper extension plate (115) and the lower extension plate (113) are about parallel with an angle of less than about 5 degrees between them and where the middle plane between the upper extension plane and the lower extension plane forms an angle of less than about 20 degrees with the bisector of the V and such that a second end of the ramp rail can be placed between the upper and the lower extension plates; a hole (119) in the upper extension plate; a hole (117) in the lower extension plate such that a bolt can be placed jointly through the hole in the upper section plate and in the lower extension plate for solidly attaching the ramp rail to the lower extension plate (113) and to the upper extension plate (115). The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to claim 15 further comprising ridges and grooves disposed on the lower section plate (103) toward the ground running about parallel to the junction line between the lower section plate (103) and the upper section plate (107) for frictionally engaging ground and lower section plate (103); ridges and grooves disposed on the upper section plate (107) toward the ground running about parallel to the junction line between the lower section plate (103) and the upper section plate (107) for frictionally engaging a wheel of a transport vehicle; wherein the lower section plate (103) is convex relative to the upper section plate (107); and wherein the upper section plate (107) and the lower section plate (103) form an angle of from about 35 to 55 degrees at the apex (105) of the V. The tail bridge for bridging a tail end of a motor vehicle and the ground with a ramp rail according to claims 1 to 14 a foot part for the tail bridge including a lower section plate (103) to be placed on the ground for supporting the tail bridge; an upper section plate (107) solidly joined to the lower section plate (103) to provide an about V-shape with the apex of the V to be disposed remote relative to the ramp rail; a lower extension plate (113) joined to the end of the lower section plate (103) remote from the apex of the V such that a second end of the ramp rail can be attached to the lower extension plate.

Inventors: SMITH, EDWARD R.
Applicants: SMITH, EDWARD R.
Application year: 1988
Main classification: B65G69
IPC codes: B65G69, B60P1