Patent Application
20050220595
This invention relates to trailers with tail end ramps and particularly to such trailers in which the tail ramp can be raised to a level deck surface for added carrying capacity or load distribution.
Convertible ramp trailers, sometimes called dovetail trailers, are useful for carrying extended loads because the tail end structure can be raised from a downwardly tilted position, which enables ease of loading, to an upper position level with the trailer deck for carrying the load on the rear portion of the trailer. Some trailers have sloping rear tail sections, but this area is generally unusable to carry loads. Others trailers, such as shown in U.S. Pat. No. 6,186,734, have a sloping tail end surface with a fold-out ramp which engages the ground, and enables a vehicle to be driven upwardly and on the trailer deck. While the use of fold-out ramps and sloping tail ends for loading a wheeled vehicle is common, far less common are those trailers in which a tilted ramp can be raised to a flat position. U.S. Pat. No. 6,394,734 is one the few that discloses repositioning of a downwardly inclined tail section upward to a level transport position. The '734 patent discloses a bulky, cumbersome and expensive tail assembly in which the whole of the assembly is hingedly connected to the trailer main deck and swings up or down upon actuation of hydraulic lift mechanisms.
The principal objects of the invention are: to provide a trailer having a tail end which is convertible from a sloping loading ramp to a level load surface; to provide such a trailer which enables carrying an object on the load ramp in a level position; to provide such a trailer which is inexpensive to produce and is low or no maintenance; and to provide such a trailer which is well adapted for its intended purpose.
A trailer has a deck terminating in a sloping dovetail end for loading. The dovetail end has an underlying fixed supporting frame structure and a platform structure on the supporting frame. The platform structure is hingedly mounted so as to lower against the supporting frame and to raise to a level position which is an extension of the trailer deck. The invention is provided in two embodiments. In a first embodiment, the platform extends across the entire ramp frame and is movable between a lowered position on the ramp frame, which facilitates loading, and a raised position providing a level surface, coincident with the trailer deck for carrying the object. Separate ramps are carried by the trailer in the second embodiment which are deployed to span the gap between the ground surface and the termination of the platform when in the lowered position. These ramps can be carried in pockets longitudinally under the trailer ramp frame. In the second embodiment, the platform is a center section bounded by left and right side ramps which are hingedly connected and fold outwardly from the ramp frame to provide extensions. When the center section platform is lowered to its full down position, a vehicle can be wheeled, winched or driven up the ramps without interference from the lowered center section. Thereafter, the left and right side ramps can be swung back to the folded position and the center section raised on the support frame so as to provide a level surface for carrying the article.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.
The reference 1,
One embodiment of the dovetail trailer is shown in
In the whole platform embodiment shown in
The dovetail platform 15 consists of a generally rectangular frame of side rails 17 and 18 and forward and rear end rails 19 and 20. The rails 17-20 are generally channel beams. A deck top center section 22 is longitudinally mounted and connected between the end rails 19 and 20. The deck top center section has opposite side rails 23 and 24 and a plate top 25, preferably with a non-skid pattern. Drive ramps 27 and 28 are on either side of the center section 22 and are formed of short lengths of angle beams with the angle upwardly so as to provide good traction for a vehicle being driven upwardly on the dovetail platform 15. Support legs 30 extend downwardly from hinged mounts 31 positioned on the bottom of the side rails 7 and 8 and spaced a short distance forwardly of the end rail 9. These support legs 30 prevent the trailer 1 from tilting upwardly as heavy vehicles are driven onto the ramp 6. The support legs 30 are stowed by folding forwardly and secured by a latch 33.
To raise and lower the dovetail platform 15 relative to the ramp frame 6, a raising structure extends between the tail end ramp frames 6 and the platform 15 to swing the platform structure upwardly to form a level extension of the trailer deck 4. In the illustrated example,
When the dovetail platform 15 is in the fully lowered position, there is still a lip extending above a ground surface such that short ramps are necessary for a vehicle to drive on to reach the edge of the dovetail platform 15. These ramps 42 are contained in pockets 44 through the end rail 9. The ramps 42 have hook ends that fit over the rear end rail 20 of the dovetail platform 15.
An alternative form of a dovetail trailer 50 is shown in connection with
The alternative embodiment 51 includes a center section 66 which forms a dovetail end platform which moves up and down relative to the ramp frame 6. The center section 66 is simply a platform 67 hinged 69 at a front end and with the rear end swingable up and down relative to the underlying ramp frame 6. Structure 70 such as a toggle arrangement 72 enables the center section 66 to raise up and down with upper and lower link arms 73 and 74 and a center hinge pin 75 rotated by a level arm 77. The center hinge pin 75 is arranged so it is secured one of the link arms 73 or 74 with the other freely revolving so that when the lever arm 77 is thrown, the toggle arrangement 72 rotates into an over-center position
The center section 66 has at the lower position for the toggle arrangement 72 a hinge bar 78 with spring assist 79 toward the raised position.
The alternative embodiment 50 acts substantially the same as the first embodiment wherein when raised, the center section 66 and the side ramps 54 and 55, when swung forwardly, combine to create a level extension of the trailer deck 4 so that a vehicle may be loaded on the trailer and then positioned rearwardly for the most effective balance and control of the trailer.
The forms of the invention described above are to be used as illustration only and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as herein above set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention.
The inventors hereby state their intent to rely on the doctrine of equivalence to determine and access the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.
