CA2195255C - Positive locking trailer tail - Google Patents
Positive locking trailer tail Download PDFInfo
- Publication number
- CA2195255C CA2195255C CA002195255A CA2195255A CA2195255C CA 2195255 C CA2195255 C CA 2195255C CA 002195255 A CA002195255 A CA 002195255A CA 2195255 A CA2195255 A CA 2195255A CA 2195255 C CA2195255 C CA 2195255C
- Authority
- CA
- Canada
- Prior art keywords
- trailer
- ramp
- linkage
- tail
- hydraulic cylinders
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60P—VEHICLES ADAPTED FOR LOAD TRANSPORTATION OR TO TRANSPORT, TO CARRY, OR TO COMPRISE SPECIAL LOADS OR OBJECTS
- B60P1/00—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading
- B60P1/43—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading using a loading ramp mounted on the vehicle
Landscapes
- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Vehicle Cleaning, Maintenance, Repair, Refitting, And Outriggers (AREA)
- Vehicle Body Suspensions (AREA)
- Auxiliary Methods And Devices For Loading And Unloading (AREA)
- Body Structure For Vehicles (AREA)
Abstract
There is provided a flat bed trailer including a hinged ramp tail which can be raised between a lower loading and an upper transport position. The ramp tail is raised and lowered by a linkage and extensible lifting means acting on the linkage. The advantange of the linkage of the present invention is that the extensbile liftming means - hydraulic cylinders - are retracted when the ramp is in its raised position, rather than being extended. In addition the linkage provides for an over-center lock further strengthening the ramp tail in its raised position, thus significantly lessening the amount of strain placed on the hydraulic cylinders and other mechanics as compared to that in the prior art.
Description
CA 0219s2ss 1998-10-O1 Page 2 of 23 POSITIVE LOCKING TRAILER TAIL
s This invention relates to a hydraulically operated tailgate for load supporting beds of transportation vehicles, and more particularly to a tailgate whose hydraulic lift mechanism has the effect of holding the tailgate positively locked in position when the tailgate is in its raised position, parallel and roughly planar to the main deck of the transport vehicle.
to BACKGROUND OF THE INVENTION:
Many types of trailers have previously been manufactured for the transportation of large equipment over the road. The equipment is usually loaded onto the trailer from the rearward end is of the trailer and as such an improvement which had originally emerged in the art is to provide a loading ramp of some sort attached to the rear of the trailer. It is known in the prior art to provide swingably mounted tailgates on the rear of flat deck semi-trailers and trucks, such that the tailgate can selectively be operated and used as a loading and unloading ramp for the trailer vehicle. Some examples of tailgates which selectively form loading ramps by means of folding 2o relative to a main section of the tailgate can be found in U.S. Patent
s This invention relates to a hydraulically operated tailgate for load supporting beds of transportation vehicles, and more particularly to a tailgate whose hydraulic lift mechanism has the effect of holding the tailgate positively locked in position when the tailgate is in its raised position, parallel and roughly planar to the main deck of the transport vehicle.
to BACKGROUND OF THE INVENTION:
Many types of trailers have previously been manufactured for the transportation of large equipment over the road. The equipment is usually loaded onto the trailer from the rearward end is of the trailer and as such an improvement which had originally emerged in the art is to provide a loading ramp of some sort attached to the rear of the trailer. It is known in the prior art to provide swingably mounted tailgates on the rear of flat deck semi-trailers and trucks, such that the tailgate can selectively be operated and used as a loading and unloading ramp for the trailer vehicle. Some examples of tailgates which selectively form loading ramps by means of folding 2o relative to a main section of the tailgate can be found in U.S. Patent
2,727,781 to D'Eath, U.S.
Patent 2,776,063 to Larson and U.S. Patent 2,797,960 to Endres et al. These prior art tailgates however are intended to be used by folding them into an upright position, either perpendicular Page 3 of 23 or in any event above the plane of the main portion of the truck trailer when in the raised position.
This blocks the rear of the load carrying area of the vehicle and these types of tailgates are not readily used in a substantially level load carrying position.
There have also been contemplated in the prior art telescopically extensible ramps for facilitating the loading of vehicles, such as that disclosed in U.S. Patent 460,196 to Chase and U.S. Patent 2,611,466 to Biggert et al. A telescopically extensible loading ramp however is limited in utility insofar as when it is in its retracted position the ramp cannot be used as a portion of the load carrying bed.
to It has been contemplated in the prior art as well then, to provide swingably movable sections of the rear of a load carrying bed trailer, such that the swinging section can be lowered to the ground, thus forming a ramp to allow for the loading of the truck, and then raised into a position parallel and approximately planar to that of the main load carrying bed such that the ramp itself is in its raised position provides additional length on the trailer on which the load can be distributed or carried. An example of a trailer with a hinged ramp tail is disclosed in U.S. Patent 5,215,426 to Bills, Jr.
Hydraulic power actuation of the raising and lowering of the ramp section of the trailer is known 2o in the art. A hydraulic fluid pressure cylinder has in the past been used to lift the ramp section of such a trailer by pushing out/extending the piston rod of the cylinder to raise the ramp section, such hydraulic cylinder operating either individually, or along with some type of linkage Page 4 of 23 mechanism used to decrease the angle from which the hydraulic cylinder needs to operate in order to lift the ramp section. A push hydraulic would be used to elevate such a ramp section, and then by releasing the hydraulic cylinder the weight of the ramp would cause the piston rod to retract inside the hydraulic cylinder and lower the ramp section into its loading position. The problem with hydraulic mechanisms such as this used to raise and lower such a trailer ramp to and from a planar load-bearing position is that the piston rod is extended into its extended position to raise the ramp to its upper position and hold it there. The piston rod of the hydraulic cylinder then ends up bearing a great deal of weight transferred thereto through whatever type of linkage mechanism is used, and the rod can be weakened or bent by the combination of such weight and to additional shocks created by road conditions as the trailer is moved.
One solution to attempt to relieve the considerable strain on the extended piston rod of the hydraulic cylinder holding the ramp section in its raised position has been to add a mechanical locking device which can be locked into place to firmly anchor the ramp section in position once is it is raised. For example, U.S. Patent 4,305,694 to Chan, wherein the hydraulic actuating mechanism displacing the ramp extension simultaneously mechanically locks the tailgate to the frame of the semi-trailer vehicle. However, in that case the hydraulic piston which is used to actuate the mechanical lock is in its extended position when the lock is engaged, and as such there is the potential that mechanical forces could be communicated back to that piston rod again. As 2o well, this very concept of a separately actuated lock requires additional equipment to be added to the trailer, increasing the cost and complexity of manufacture and maintenance.
Page 5 of 23 Another method of hydraulically raising and lowering the ramp section of the trailer is disclosed by Bills Jr. The Bills, Jr. apparatus is operated by the hydraulic shifting of the rear axle of the trailer, moving that axle back and forth beneath the hinged section of the trailer tail. It is the purpose of that invention as claimed to allow for the redistribution of the weight carned on the trailer by the positioning of the rear axle at varying spacings behind the first axle on the trailer.
The ramp is lowered into the loading position by retracting the rear axle all the way into its position right behind the front axle of the trailer. The ramp lowers, the trailer is loaded, and the rear axle is pushed back into a position somewhere beneath the ramp portion of the trailer for transport of the load. In the case of this trailer, however, the unloaded weight of the trailer itself to is high, due to the additional steel structure which is used to slide the rear axle of the trailer back and forth. In addition, the number of moving parts in the actuating mechanism and accompanying superstructure make the trailer harder to manufacture, and more difficult and more costly to maintain.
is Hydraulic actuation of load-bearing ramp tails is preferred to manual or other methods of raising and lowering such trailer ramps. The load bearing aspect of the ramp tail is important as it increases the available length of the trailer to haul longer or larger pieces of equipment, as compared to those trailers with telescoping ramps or ramps which fold into an upright position.
The problem which the present invention seeks to overcome is the load strains placed on the 2o hydraulic mechanisms used in the prior art.
Page 6 of 23 SUMMARY OF THE INVENTION:
It is the object of the present invention to provide a trailer with a ramp tail with an improved hydraulic lifting mechanism to move the ramp tail between its upper and lower positions.
It is a further object of the present invention to provide an apparatus in which the hydraulic cylinders used to raise and lower the ramp tail are in their stronger retracted position while the ramp tail is in its load carrying upper position.
to It is the further object of the present invention that this hydraulically actuated ramp tail be held positively locked in its raised planar position by the lifting linkage itself, rather than by additional mechanical pins or the like such as has been contemplated in the prior art.
It is the further object of the present invention that in order to hold the raised ramp in positively is locked position with minimal stress on the hydraulic mechanism including the hydraulic cylinders used therein, the hydraulic cylinders be in their retracted positions when the ramp is in its raised position and the linkages between the trailer, the ramp and the hydraulic cylinders be such that a maximum of the load-bearing downward forces exerted on the ramp under load be communicated from the ramp into the trailer frame, and a minimum of such forces exerted on the 2o hydraulic cylinders used to raise and lower the ramp.
The invention accomplishes these obj ects comprising substantially a frame, having rearward and Page 7 of 23 forward ends, with attachment means on the forward end of the frame for connecting the trailer to a prime mover; one or more ground-engaging axle assemblies attached to the frame; a ramp tail having rearward and forward ends, the forward end of the ramp tail being hingedly connected to the rearward end of the frame such that the ramp tail is selectively moveable between an upper position wherein the ramp tail is approximately horizontal, and a lower position wherein the ramp tail is inclined downward and rearward towards the ground; two or more bending linkages, each said bending linkage comprising two linkage arms pivotally joined together in a linkage joint, each said bending linkage pivotally attached at one end to the trailer at a trailer attachment point between the ground and the point of attachment of the ramp tail to the frame and at the other end to to the ramp tail at a ramp tail attachment point and wherein the distance between the trailer attachment point and the ramp tail attachment point when the ramp tail is in its upper position is the ramp hypotenuse and said bending linkages when in alignment are longer than the ramp hypotenuse; one or more hydraulic cylinders attached such as to exert force on the linkage joints so as to bend said bending linkages, oriented such that by retracting the hydraulic cylinders the is ramp tail is raised to its upper position and an over-centre lock is created by the bending linkages, and by extending the hydraulic cylinders the ramp tail is moved to its lower position, said ramp tail first raising slightly above the horizontal as the linkage arms come into alignment and the over-centre lock is overcome.
2o The over center lock is acheived by the bending linkages and linkage arms being of dimensions such that the linkages themselves in their 'straight' or 'aligned' position are longer than the ramp hypotenuse. The ramp tail is raised by retracting the hydraulic cylinders, and lowered by Page 8 of 23 extending them.
A linkage cross brace could be added joining the linkage joints, while still allowing the linkage joints to bend, so that the movement of the linkages was mirrored.
One or more hydraulic cylinders could also be used. In embodiments employing more than one hydraulic cylinder, the cylinders could be controlled in tandem to further stabilize and strengthen the operation of the device. The hydraulic cylinders could be pivotally attached at their one end to the ramp tail and at their free end to the linkage joints, or in the case of an embodiment with to more than one linkage and a linkage cross brace, the hydraulic cylinders could be attached at their free end to the linkage cross brace. Offset hydraulic attachment flanges could also be added, to allow for the pivotal attachment of the hydraulic cylinders to the bending linkages at a point offset below the alignment axis of the bending linkage.
is One or more axles might be used on the trailer.
DESCRIPTION OF THE DRAWINGS:
2o While the invention is claimed in the concluding portions hereof, preferred embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with Page 9 of 23 like numbers, and where:
Figure 1 is a side view of the present invention, showing the ramp tail in its upper position;
s Figure 2 is a top view of the frame and structural elements of the invention;
Figure 3 is a close-up side view of the ramp tail in its lower position;
to Figure 4 is a close-up side view of the ramp tail in its upper position;
and Figure 5 is a top view of the mechanical means of the invention, used to raise and lower the ramp tail.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:
The present invention is a flat deck trailer with a hinged ramp tail, the hinged ramp tail being raised and lowered via a bending linkage that provides an over-center locked position when the 2o ramp tail is in its raised transport position.
Turning first to Figure 1, which shows the general profile of the preferred embodiment. The Page 10 of 23 present invention involves a hydraulically actuated ramp tail 1 attached to the rearward end of a trailer 2, said trailer 2 having a flat trailer deck 3 for the loading and hauling of heavy equipment and the like. Located in position on the underside of the goose neck portion 6 of the trailer is a hitch pin 4 for attachment to a standard fifth wheel power unit.
To turn to Figure 2, and the structural characteristics of the trailer 2. The trailer 2 consists of two main frame members 7, which in this case display toward their forward ends 8 a jog which forms the common goose neck feature displayed in the drawings and as illustrated in Figure 1. Attached across the forward ends 8 of the frame members is the trailer front beam 10, which forms the to front edge of the trailer 2. Similarly attached across the rearward ends 9 of the frame members is the trailer end beam 13. Attached to the frame members 7 in positions between the trailer deck supports 11 and underneath the trailer deck surface 12 are one or more axle assemblies 17 with suspension, wheels, tires and brakes to be in contact with the ground surface and to carry the trailer and load.
Extending downward from the trailer end beam 13 is the rear face plate 14.
Across the bottom edge of the rear face plate 14 is welded the rear face cross member 15, which in the preferred embodiment is square steel tubing. Welded back from the rear face cross member 15 to the bottom face of each trailer frame member 7 is a rear cross member brace 16, for additional 2o support. The trailer end beam 13, the rear face plate 14, the rear face cross member 15 and the rear cross member brace 16 form a solidly reinforced trailer attachment surface, to which the ramp tail 1 can be hingably secured and the mechanical means for raising and lowering the ramp Page 11 of 23 tail 1 can be operatively attached. It will be understood that the invention could be practiced on trailers of other basic construction without departing from the intent of the present invention and as such the details of the trailer offered here should not be interpreted in a limiting, but rather in a specifically illustrative, sense. The essential basics of the trailer itself is that it have a frame, s attachment means and one or more ground-engaging axle assemblies.
The ramp tail itself is similarly constructed to the remainder of the trailer, having two ramp tail frame members 19 to which are attached a ramp tail front beam 23 and the ramp tail end beam 25. Again the particular construction of the ramp, insofar as it does not affect the operation of to the bending linkages and hydraulic cylinders, is non-essential to the invention and it will again be understood that modifications thereto would not depart from the scope and intent of the claimed invention.
The ramp tail 1 is hingably attached to the trailer 2 such that the ramp tail 1 is selectively is moveable between upper and lower positions, said ramp tail 1 being substantially horizontal and roughly co-planar to the trailer deck 3 when in its first said upper position and inclined downwardly and rearwardly with respect to the trailer deck 3 when in its second said lower position. In this case the ramp tail 1 is connected to the trailer end beam 13 at the ramp trailer attachment point 26 with a commonly known pin hinging mechanism.
Bending linkages are used to join the trailer and the ramp tail and raise and lower the ramp tail.
Each bending linkage consists of a first linkage arm 30 and a second linkage arm 31, which in the Page 12 of 23 present embodiment are equal in length, pivotally joined at a linkage joint 34. Each said bending linkage is pivotally attached at one end to the trailer at a trailer attachment point between the ground and the point of attachment of the ramp tail to the frame and at the other end to the ramp tail at a ramp tail attachment point and wherein the distance between the trailer attachment point and the ramp tail attachment point when the ramp tail is in its upper position is the ramp hypotenuse RH and said bending linkages when in alignment are longer than the ramp hypotenuse RH.
The size of the bending linkages, namely that the bending linkage when the two linkage arms 30, l0 31 are straight and in alignment is larger than the ramp hypotenuse RH, provides for a positive over-centre lock of the bending linkages when the ramp tail is in its upper transport position. The bending of the bending linkages in the opposite direction then results in the linkage arms 30, 31 coming into alignment and then overcoming the over-centre lock to lower the ramp tail to the ground, after first raising it slightly above the horizontal as the bending linkages are first aligned.
is This is best illustrated in Figures 3 and 4. The only point at which the joined first and second linkage arms 30, 31 can reach their fully aligned straight span, which for the purpose of this disclosure will be referred to at that point as the center line, is above the horizontal position of the ramp tail 1 as that is shifted between positions. When the ramp tail 1 is in its lower position the first and second linkage arms 30, 31 are below center line, and when the ramp tail 1 is in its zo upper position the first and second linkage arms 30, 31 are slightly above center, creating the over-center lock.
Page 13 of 23 The present embodiment shows two bending linkages, although it will be understood that any number of bending linkages could be used, depending on the strength of manufacture of each bending linkage and on the specification and load to which the trailer and ramp tail are to be put.
In this case the first linkage arm 30 and second linkage arm 31 are manufactured out of hollow structural steel tube.
One or more hydraulic cylinders are used to exert force on the linkage joints so as to bend the bending linkages, oriented such that by retracting the hydraulic cylinders the ramp tail is raised to its upper position and an over-centre lock is created by the bending linkages, and by extending to the hydraulic cylinders the ramp tail is moved to its lower position, said ramp tail first raising slightly above the horizontal as the Linkage arms come into alignment and the over-centre lock is overcome. The hydraulic cylinders could be attached directly to the linkage joints in a pivotal manner, or could be attached elsewhere in such a manner as to move the bending linkages via the linkage joints.
is A linkage cross brace is also shown in this embodiment. 'The linkage cross brace 35 is used to hingably join the first linkage arm 30 and second linkage arm 31 of each of the number of bending linkages, with each bending linkage attached to the linkage cross brace 35 in its appropriate position for use. In this case, the two bending linkages are attached at opposite ends of the 20 linkage cross brace 35. The first linkage arm 30 and second linkage arm 31 are joined through their respective linkage juncture holes 34 by the linkage cross brace 35, which is round and fits snugly through the linkage attachment holes 34. In this manner, with all of the bending linkages Page 14 of 23 joined by the linkage cross brace 35, movement initiated in relation to the linkage cross brace 35 will move each pair of linkage arms 30, 31 simultaneously and in the exact same path and manner.
The first linkage arm 30 and second linkage arm 31 are placed onto the linkage cross brace 35 side by side, as is shown in Figure 5. It will be understood, however, that the first linkage arm 30 and second linkage arm 31 of each bending linkage could be spaced apart from each other along the linkage cross brace 35, with the positioning of the linkage trailer attachment flanges 36 and the linkage ramp attachment flanges 38 adjusted accordingly, and that would be contemplated to within the scope of the present invention.
Also attached to the linkage cross brace 35 are one or more linkage cylinder attachment flanges 40, one flange for each hydraulic cylinder 44 used in the mechanical means. In the case of the present embodiment, two hydraulic cylinders are used and therefore two linkage cylinder is attachment flanges 40 are used as well. In this case each linkage cylinder attachment flange 40 has a round linkage flange hole 41. The linkage cylinder attachment flanges 40 are attached to the linkage cross brace 35 spaced between the attached first and second linkage arms 30, 31. The linkage cylinder attachment flange 40 is manufactured and attached to the linkage cross brace 3 5 such that the linkage flange hole 41 is below the first linkage arm 30. This positioning of the 20 linkage cylinder attachment flange 40 and linkage flange hole 41 is shown in Figures 3 and 4. By offsetting the linkage attachment flanges below the center line of the bending linkage when in its aligned position, the behavior of the bending linkages can be further improved.
Page 15 of 23 Attached along the inside surface of the ramp tail front beam 23 in corresponding positions to the linkage cylinder attachment flanges 40, such that the hydraulic cylinders 44 can be installed between them and in parallel to each other, are the ramp cylinder attachment flanges 42. Each ramp cylinder attachment flange 42 has a round ramp cylinder hole 43. There is to be one ramp cylinder attachment flange 42 installed for each hydraulic cylinder 44 to be used, so again in the present embodiment two ramp cylinder attachment flanges 42 are used.
Attached to the trailer attachment surface along its bottom edge, and specifically attached to the rear face cross member 15, is one linkage trailer attachment flange 36 for each first linkage arm l0 30 used in the mechanical means - in the case of the present embodiment, two. The linkage trailer attachment flanges 36 are attached to the rear face cross member 15 at positions to be joined the first linkage arms 30. Each linkage trailer attachment flange 36 actually consists of two flanges extending outward from the trailer attachment surface, each having a round trailer flange hole 37.
These two flanges are spaced apart by the thickness of the first linkage arm 30, the trailer flange is holes 37 being in alignment and at the end of the flange 36 some distance away from the trailer attachment surface.
Attached along the front face of the ramp tail center beam 24 are a similax number of linkage ramp attachment flanges 38, attached in positions to be joined the second linkage arms 31. Each 20 linkage ramp attachment flange 38 actually consists of two flanges extending outward and forward from the ramp tail center beam 24, each having a round ramp flange hole 39. These two flanges are spaced apart by the thickness of the second linkage arm 31, the ramp flange holes 39 Page 16 of 23 being in alignment and at the end of the flange some distance away from the ramp tail center beam 24.
It will be understood that the use of flanges or other means of pivotal attachment of the hydraulic cylinders to the trailer and the linkage joints or linkage cross brace, as well as the attachment of the bending linkages to the ramp tail or the trailer, could be varied to use different attachment methods without departing from the intent of the present invention and as such are contemplated within the scope of the present invention.
to Standard hydraulic cylinders would be used. It will be understood that various attachment means could be provided on the ends of the hydraulic cylinders and that such attachment means and necessary modification to the attachment of the cylinders to the device are contemplated within the scope of this invention. It will also be understood that other extensible means other than hydraulic cylinders could be used.
is Where more than one hydraulic cylinder is used they can be linked in tandem so that they all operate identically.
The bending linkages and hydraulic cylinders are mounted in place to operatively interconnect the 2o ramp tail 1 with the trailer 2 as follows. Each of the first linkage arms 30 is attached to the corresponding linkage trailer attachment flange 36 by the use of a pin or the like placed through the trailer flange hole 37 on one side, through the first linkage attachment hole 32, and out the Page 17 of 23 trailer flange hole 37 on the other side. Each first linkage arm 30 would be similarly attached to the trailer attachment surface in this manner. Each of the second linkage arms 31 is attached to the corresponding linkage ramp attachment flange 38 by the use of a pin or the like placed through the ramp flange hole 39 on one side, through the second linkage attachment hole 33, and s out the ramp flange hole 39 on the other side. Each second linkage arm 31 would be attached to the ramp tail center beam 24 in this manner. The hydraulic cylinders 44 would then be installed similarly in position, with pins or the like, with the hydraulic cylinder attachment end 46 attached to the ramp cylinder attachment flange 42 through the ramp cylinder hole 43 and the flange holes on the hydraulic cylinder attachment end 46. T'he flange holes on the piston rod attachment end l0 47 would be attached to the linkage flange hole 41 on the corresponding linkage cylinder attachment flange 40, again with a pin or the like. With the attachments having been made at these four operative points, the actuating mechanism for the raising and lowering the ramp tail 1 is ready to operate.
is The hydraulic cylinders are operated by pressurized fluid from a suitable source under control of suitable control valves (not shown) all of which is generally well known in the art.
One of the major problems experienced in the prior art was that of the hydraulic cylinders used to actuate such a ramp tail being in their extended position and the piston rods therefore subj ected 2o to extreme loads and stress while the ramp tail was in its raised position, while the hydraulic cylinder would be in its stronger retracted position while the ramp tail was lowered to the ground and no strain was placed on or support was required from the hydraulic cylinder. The present Page 18 of 23 invention reverses this - the hydraulic cylinders are extended to their full stroke when the ramp tail 1 is in its lower position, and are fully retracted when the ramp tail 1 is in its raised position.
This causes less stress on the hydraulic cylinders while the trailer 2 is under load.
With the attachment point of the hydraulic cylinders 44 to the linkage cross brace 35 being below the first linkage arm 30, the downward force of the loaded ramp tail communicated onto the hydraulic cylinder is minimized, with the remainder traveling through the first linkage arm 30 and being communicated into the trailer 2 and its stronger frame and suspension.
In addition, with the hydraulic cylinder 44 in its retracted position any force that is communicated through the to hydraulic cylinder 44 is easily handled without strain by the cylinder which is in its strongest position when retracted.
To lower the ramp tail 1 to the ground the hydraulic cylinders 44 are extended, which in turn through movement of the linkage cross brace 35 moves the joined first and second linkage arms is 30, 31 down below their center line and the attached ramp tail 1 is lowered to the ground. When operated to raise the ramp tail 1, the piston rods of the hydraulic cylinders 44 are pulled in, thus moving the linkage cross brace 35 and the linkage arms 30, 31 back up past the center line and into the above described locked position.
zo While the current embodiment speaks of a hitch pin 4 being used on the lower surface of the gooseneck to attach the trailer 2 to a power unit, it will be understood and is contemplated within the scope of this invention that modifications could be made to the front end of the trailer Page 19 of 23 including the use of a different hook up apparatus or the like to adapt the trailer for use with a different power unit, without altering the substance of the invention claimed.
The trailer of the illustrated embodiment has two ground-engaging axle assemblies.
s While the invention in this embodiment comprises a trailer of common goose neck variety, it will be understood that a foreseeable variation would be to use a conventional flatbed trailer configuration without a gooseneck configuration and that this is contemplated within the scope of the invention - that is to say the trailer 1 being of constant sufficient height from front to rear to to allow for the proper placement of the hitch pin or other power attachment method. This would result in a higher trailer which would merely mean that the ramp tail would come down at a steeper angle in its lower position, or could be lengthened to provide a lengthier loading slope.
Thus it can be seen that the invention accomplishes at least all of its stated objectives. Since is various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.
Patent 2,776,063 to Larson and U.S. Patent 2,797,960 to Endres et al. These prior art tailgates however are intended to be used by folding them into an upright position, either perpendicular Page 3 of 23 or in any event above the plane of the main portion of the truck trailer when in the raised position.
This blocks the rear of the load carrying area of the vehicle and these types of tailgates are not readily used in a substantially level load carrying position.
There have also been contemplated in the prior art telescopically extensible ramps for facilitating the loading of vehicles, such as that disclosed in U.S. Patent 460,196 to Chase and U.S. Patent 2,611,466 to Biggert et al. A telescopically extensible loading ramp however is limited in utility insofar as when it is in its retracted position the ramp cannot be used as a portion of the load carrying bed.
to It has been contemplated in the prior art as well then, to provide swingably movable sections of the rear of a load carrying bed trailer, such that the swinging section can be lowered to the ground, thus forming a ramp to allow for the loading of the truck, and then raised into a position parallel and approximately planar to that of the main load carrying bed such that the ramp itself is in its raised position provides additional length on the trailer on which the load can be distributed or carried. An example of a trailer with a hinged ramp tail is disclosed in U.S. Patent 5,215,426 to Bills, Jr.
Hydraulic power actuation of the raising and lowering of the ramp section of the trailer is known 2o in the art. A hydraulic fluid pressure cylinder has in the past been used to lift the ramp section of such a trailer by pushing out/extending the piston rod of the cylinder to raise the ramp section, such hydraulic cylinder operating either individually, or along with some type of linkage Page 4 of 23 mechanism used to decrease the angle from which the hydraulic cylinder needs to operate in order to lift the ramp section. A push hydraulic would be used to elevate such a ramp section, and then by releasing the hydraulic cylinder the weight of the ramp would cause the piston rod to retract inside the hydraulic cylinder and lower the ramp section into its loading position. The problem with hydraulic mechanisms such as this used to raise and lower such a trailer ramp to and from a planar load-bearing position is that the piston rod is extended into its extended position to raise the ramp to its upper position and hold it there. The piston rod of the hydraulic cylinder then ends up bearing a great deal of weight transferred thereto through whatever type of linkage mechanism is used, and the rod can be weakened or bent by the combination of such weight and to additional shocks created by road conditions as the trailer is moved.
One solution to attempt to relieve the considerable strain on the extended piston rod of the hydraulic cylinder holding the ramp section in its raised position has been to add a mechanical locking device which can be locked into place to firmly anchor the ramp section in position once is it is raised. For example, U.S. Patent 4,305,694 to Chan, wherein the hydraulic actuating mechanism displacing the ramp extension simultaneously mechanically locks the tailgate to the frame of the semi-trailer vehicle. However, in that case the hydraulic piston which is used to actuate the mechanical lock is in its extended position when the lock is engaged, and as such there is the potential that mechanical forces could be communicated back to that piston rod again. As 2o well, this very concept of a separately actuated lock requires additional equipment to be added to the trailer, increasing the cost and complexity of manufacture and maintenance.
Page 5 of 23 Another method of hydraulically raising and lowering the ramp section of the trailer is disclosed by Bills Jr. The Bills, Jr. apparatus is operated by the hydraulic shifting of the rear axle of the trailer, moving that axle back and forth beneath the hinged section of the trailer tail. It is the purpose of that invention as claimed to allow for the redistribution of the weight carned on the trailer by the positioning of the rear axle at varying spacings behind the first axle on the trailer.
The ramp is lowered into the loading position by retracting the rear axle all the way into its position right behind the front axle of the trailer. The ramp lowers, the trailer is loaded, and the rear axle is pushed back into a position somewhere beneath the ramp portion of the trailer for transport of the load. In the case of this trailer, however, the unloaded weight of the trailer itself to is high, due to the additional steel structure which is used to slide the rear axle of the trailer back and forth. In addition, the number of moving parts in the actuating mechanism and accompanying superstructure make the trailer harder to manufacture, and more difficult and more costly to maintain.
is Hydraulic actuation of load-bearing ramp tails is preferred to manual or other methods of raising and lowering such trailer ramps. The load bearing aspect of the ramp tail is important as it increases the available length of the trailer to haul longer or larger pieces of equipment, as compared to those trailers with telescoping ramps or ramps which fold into an upright position.
The problem which the present invention seeks to overcome is the load strains placed on the 2o hydraulic mechanisms used in the prior art.
Page 6 of 23 SUMMARY OF THE INVENTION:
It is the object of the present invention to provide a trailer with a ramp tail with an improved hydraulic lifting mechanism to move the ramp tail between its upper and lower positions.
It is a further object of the present invention to provide an apparatus in which the hydraulic cylinders used to raise and lower the ramp tail are in their stronger retracted position while the ramp tail is in its load carrying upper position.
to It is the further object of the present invention that this hydraulically actuated ramp tail be held positively locked in its raised planar position by the lifting linkage itself, rather than by additional mechanical pins or the like such as has been contemplated in the prior art.
It is the further object of the present invention that in order to hold the raised ramp in positively is locked position with minimal stress on the hydraulic mechanism including the hydraulic cylinders used therein, the hydraulic cylinders be in their retracted positions when the ramp is in its raised position and the linkages between the trailer, the ramp and the hydraulic cylinders be such that a maximum of the load-bearing downward forces exerted on the ramp under load be communicated from the ramp into the trailer frame, and a minimum of such forces exerted on the 2o hydraulic cylinders used to raise and lower the ramp.
The invention accomplishes these obj ects comprising substantially a frame, having rearward and Page 7 of 23 forward ends, with attachment means on the forward end of the frame for connecting the trailer to a prime mover; one or more ground-engaging axle assemblies attached to the frame; a ramp tail having rearward and forward ends, the forward end of the ramp tail being hingedly connected to the rearward end of the frame such that the ramp tail is selectively moveable between an upper position wherein the ramp tail is approximately horizontal, and a lower position wherein the ramp tail is inclined downward and rearward towards the ground; two or more bending linkages, each said bending linkage comprising two linkage arms pivotally joined together in a linkage joint, each said bending linkage pivotally attached at one end to the trailer at a trailer attachment point between the ground and the point of attachment of the ramp tail to the frame and at the other end to to the ramp tail at a ramp tail attachment point and wherein the distance between the trailer attachment point and the ramp tail attachment point when the ramp tail is in its upper position is the ramp hypotenuse and said bending linkages when in alignment are longer than the ramp hypotenuse; one or more hydraulic cylinders attached such as to exert force on the linkage joints so as to bend said bending linkages, oriented such that by retracting the hydraulic cylinders the is ramp tail is raised to its upper position and an over-centre lock is created by the bending linkages, and by extending the hydraulic cylinders the ramp tail is moved to its lower position, said ramp tail first raising slightly above the horizontal as the linkage arms come into alignment and the over-centre lock is overcome.
2o The over center lock is acheived by the bending linkages and linkage arms being of dimensions such that the linkages themselves in their 'straight' or 'aligned' position are longer than the ramp hypotenuse. The ramp tail is raised by retracting the hydraulic cylinders, and lowered by Page 8 of 23 extending them.
A linkage cross brace could be added joining the linkage joints, while still allowing the linkage joints to bend, so that the movement of the linkages was mirrored.
One or more hydraulic cylinders could also be used. In embodiments employing more than one hydraulic cylinder, the cylinders could be controlled in tandem to further stabilize and strengthen the operation of the device. The hydraulic cylinders could be pivotally attached at their one end to the ramp tail and at their free end to the linkage joints, or in the case of an embodiment with to more than one linkage and a linkage cross brace, the hydraulic cylinders could be attached at their free end to the linkage cross brace. Offset hydraulic attachment flanges could also be added, to allow for the pivotal attachment of the hydraulic cylinders to the bending linkages at a point offset below the alignment axis of the bending linkage.
is One or more axles might be used on the trailer.
DESCRIPTION OF THE DRAWINGS:
2o While the invention is claimed in the concluding portions hereof, preferred embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with Page 9 of 23 like numbers, and where:
Figure 1 is a side view of the present invention, showing the ramp tail in its upper position;
s Figure 2 is a top view of the frame and structural elements of the invention;
Figure 3 is a close-up side view of the ramp tail in its lower position;
to Figure 4 is a close-up side view of the ramp tail in its upper position;
and Figure 5 is a top view of the mechanical means of the invention, used to raise and lower the ramp tail.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:
The present invention is a flat deck trailer with a hinged ramp tail, the hinged ramp tail being raised and lowered via a bending linkage that provides an over-center locked position when the 2o ramp tail is in its raised transport position.
Turning first to Figure 1, which shows the general profile of the preferred embodiment. The Page 10 of 23 present invention involves a hydraulically actuated ramp tail 1 attached to the rearward end of a trailer 2, said trailer 2 having a flat trailer deck 3 for the loading and hauling of heavy equipment and the like. Located in position on the underside of the goose neck portion 6 of the trailer is a hitch pin 4 for attachment to a standard fifth wheel power unit.
To turn to Figure 2, and the structural characteristics of the trailer 2. The trailer 2 consists of two main frame members 7, which in this case display toward their forward ends 8 a jog which forms the common goose neck feature displayed in the drawings and as illustrated in Figure 1. Attached across the forward ends 8 of the frame members is the trailer front beam 10, which forms the to front edge of the trailer 2. Similarly attached across the rearward ends 9 of the frame members is the trailer end beam 13. Attached to the frame members 7 in positions between the trailer deck supports 11 and underneath the trailer deck surface 12 are one or more axle assemblies 17 with suspension, wheels, tires and brakes to be in contact with the ground surface and to carry the trailer and load.
Extending downward from the trailer end beam 13 is the rear face plate 14.
Across the bottom edge of the rear face plate 14 is welded the rear face cross member 15, which in the preferred embodiment is square steel tubing. Welded back from the rear face cross member 15 to the bottom face of each trailer frame member 7 is a rear cross member brace 16, for additional 2o support. The trailer end beam 13, the rear face plate 14, the rear face cross member 15 and the rear cross member brace 16 form a solidly reinforced trailer attachment surface, to which the ramp tail 1 can be hingably secured and the mechanical means for raising and lowering the ramp Page 11 of 23 tail 1 can be operatively attached. It will be understood that the invention could be practiced on trailers of other basic construction without departing from the intent of the present invention and as such the details of the trailer offered here should not be interpreted in a limiting, but rather in a specifically illustrative, sense. The essential basics of the trailer itself is that it have a frame, s attachment means and one or more ground-engaging axle assemblies.
The ramp tail itself is similarly constructed to the remainder of the trailer, having two ramp tail frame members 19 to which are attached a ramp tail front beam 23 and the ramp tail end beam 25. Again the particular construction of the ramp, insofar as it does not affect the operation of to the bending linkages and hydraulic cylinders, is non-essential to the invention and it will again be understood that modifications thereto would not depart from the scope and intent of the claimed invention.
The ramp tail 1 is hingably attached to the trailer 2 such that the ramp tail 1 is selectively is moveable between upper and lower positions, said ramp tail 1 being substantially horizontal and roughly co-planar to the trailer deck 3 when in its first said upper position and inclined downwardly and rearwardly with respect to the trailer deck 3 when in its second said lower position. In this case the ramp tail 1 is connected to the trailer end beam 13 at the ramp trailer attachment point 26 with a commonly known pin hinging mechanism.
Bending linkages are used to join the trailer and the ramp tail and raise and lower the ramp tail.
Each bending linkage consists of a first linkage arm 30 and a second linkage arm 31, which in the Page 12 of 23 present embodiment are equal in length, pivotally joined at a linkage joint 34. Each said bending linkage is pivotally attached at one end to the trailer at a trailer attachment point between the ground and the point of attachment of the ramp tail to the frame and at the other end to the ramp tail at a ramp tail attachment point and wherein the distance between the trailer attachment point and the ramp tail attachment point when the ramp tail is in its upper position is the ramp hypotenuse RH and said bending linkages when in alignment are longer than the ramp hypotenuse RH.
The size of the bending linkages, namely that the bending linkage when the two linkage arms 30, l0 31 are straight and in alignment is larger than the ramp hypotenuse RH, provides for a positive over-centre lock of the bending linkages when the ramp tail is in its upper transport position. The bending of the bending linkages in the opposite direction then results in the linkage arms 30, 31 coming into alignment and then overcoming the over-centre lock to lower the ramp tail to the ground, after first raising it slightly above the horizontal as the bending linkages are first aligned.
is This is best illustrated in Figures 3 and 4. The only point at which the joined first and second linkage arms 30, 31 can reach their fully aligned straight span, which for the purpose of this disclosure will be referred to at that point as the center line, is above the horizontal position of the ramp tail 1 as that is shifted between positions. When the ramp tail 1 is in its lower position the first and second linkage arms 30, 31 are below center line, and when the ramp tail 1 is in its zo upper position the first and second linkage arms 30, 31 are slightly above center, creating the over-center lock.
Page 13 of 23 The present embodiment shows two bending linkages, although it will be understood that any number of bending linkages could be used, depending on the strength of manufacture of each bending linkage and on the specification and load to which the trailer and ramp tail are to be put.
In this case the first linkage arm 30 and second linkage arm 31 are manufactured out of hollow structural steel tube.
One or more hydraulic cylinders are used to exert force on the linkage joints so as to bend the bending linkages, oriented such that by retracting the hydraulic cylinders the ramp tail is raised to its upper position and an over-centre lock is created by the bending linkages, and by extending to the hydraulic cylinders the ramp tail is moved to its lower position, said ramp tail first raising slightly above the horizontal as the Linkage arms come into alignment and the over-centre lock is overcome. The hydraulic cylinders could be attached directly to the linkage joints in a pivotal manner, or could be attached elsewhere in such a manner as to move the bending linkages via the linkage joints.
is A linkage cross brace is also shown in this embodiment. 'The linkage cross brace 35 is used to hingably join the first linkage arm 30 and second linkage arm 31 of each of the number of bending linkages, with each bending linkage attached to the linkage cross brace 35 in its appropriate position for use. In this case, the two bending linkages are attached at opposite ends of the 20 linkage cross brace 35. The first linkage arm 30 and second linkage arm 31 are joined through their respective linkage juncture holes 34 by the linkage cross brace 35, which is round and fits snugly through the linkage attachment holes 34. In this manner, with all of the bending linkages Page 14 of 23 joined by the linkage cross brace 35, movement initiated in relation to the linkage cross brace 35 will move each pair of linkage arms 30, 31 simultaneously and in the exact same path and manner.
The first linkage arm 30 and second linkage arm 31 are placed onto the linkage cross brace 35 side by side, as is shown in Figure 5. It will be understood, however, that the first linkage arm 30 and second linkage arm 31 of each bending linkage could be spaced apart from each other along the linkage cross brace 35, with the positioning of the linkage trailer attachment flanges 36 and the linkage ramp attachment flanges 38 adjusted accordingly, and that would be contemplated to within the scope of the present invention.
Also attached to the linkage cross brace 35 are one or more linkage cylinder attachment flanges 40, one flange for each hydraulic cylinder 44 used in the mechanical means. In the case of the present embodiment, two hydraulic cylinders are used and therefore two linkage cylinder is attachment flanges 40 are used as well. In this case each linkage cylinder attachment flange 40 has a round linkage flange hole 41. The linkage cylinder attachment flanges 40 are attached to the linkage cross brace 35 spaced between the attached first and second linkage arms 30, 31. The linkage cylinder attachment flange 40 is manufactured and attached to the linkage cross brace 3 5 such that the linkage flange hole 41 is below the first linkage arm 30. This positioning of the 20 linkage cylinder attachment flange 40 and linkage flange hole 41 is shown in Figures 3 and 4. By offsetting the linkage attachment flanges below the center line of the bending linkage when in its aligned position, the behavior of the bending linkages can be further improved.
Page 15 of 23 Attached along the inside surface of the ramp tail front beam 23 in corresponding positions to the linkage cylinder attachment flanges 40, such that the hydraulic cylinders 44 can be installed between them and in parallel to each other, are the ramp cylinder attachment flanges 42. Each ramp cylinder attachment flange 42 has a round ramp cylinder hole 43. There is to be one ramp cylinder attachment flange 42 installed for each hydraulic cylinder 44 to be used, so again in the present embodiment two ramp cylinder attachment flanges 42 are used.
Attached to the trailer attachment surface along its bottom edge, and specifically attached to the rear face cross member 15, is one linkage trailer attachment flange 36 for each first linkage arm l0 30 used in the mechanical means - in the case of the present embodiment, two. The linkage trailer attachment flanges 36 are attached to the rear face cross member 15 at positions to be joined the first linkage arms 30. Each linkage trailer attachment flange 36 actually consists of two flanges extending outward from the trailer attachment surface, each having a round trailer flange hole 37.
These two flanges are spaced apart by the thickness of the first linkage arm 30, the trailer flange is holes 37 being in alignment and at the end of the flange 36 some distance away from the trailer attachment surface.
Attached along the front face of the ramp tail center beam 24 are a similax number of linkage ramp attachment flanges 38, attached in positions to be joined the second linkage arms 31. Each 20 linkage ramp attachment flange 38 actually consists of two flanges extending outward and forward from the ramp tail center beam 24, each having a round ramp flange hole 39. These two flanges are spaced apart by the thickness of the second linkage arm 31, the ramp flange holes 39 Page 16 of 23 being in alignment and at the end of the flange some distance away from the ramp tail center beam 24.
It will be understood that the use of flanges or other means of pivotal attachment of the hydraulic cylinders to the trailer and the linkage joints or linkage cross brace, as well as the attachment of the bending linkages to the ramp tail or the trailer, could be varied to use different attachment methods without departing from the intent of the present invention and as such are contemplated within the scope of the present invention.
to Standard hydraulic cylinders would be used. It will be understood that various attachment means could be provided on the ends of the hydraulic cylinders and that such attachment means and necessary modification to the attachment of the cylinders to the device are contemplated within the scope of this invention. It will also be understood that other extensible means other than hydraulic cylinders could be used.
is Where more than one hydraulic cylinder is used they can be linked in tandem so that they all operate identically.
The bending linkages and hydraulic cylinders are mounted in place to operatively interconnect the 2o ramp tail 1 with the trailer 2 as follows. Each of the first linkage arms 30 is attached to the corresponding linkage trailer attachment flange 36 by the use of a pin or the like placed through the trailer flange hole 37 on one side, through the first linkage attachment hole 32, and out the Page 17 of 23 trailer flange hole 37 on the other side. Each first linkage arm 30 would be similarly attached to the trailer attachment surface in this manner. Each of the second linkage arms 31 is attached to the corresponding linkage ramp attachment flange 38 by the use of a pin or the like placed through the ramp flange hole 39 on one side, through the second linkage attachment hole 33, and s out the ramp flange hole 39 on the other side. Each second linkage arm 31 would be attached to the ramp tail center beam 24 in this manner. The hydraulic cylinders 44 would then be installed similarly in position, with pins or the like, with the hydraulic cylinder attachment end 46 attached to the ramp cylinder attachment flange 42 through the ramp cylinder hole 43 and the flange holes on the hydraulic cylinder attachment end 46. T'he flange holes on the piston rod attachment end l0 47 would be attached to the linkage flange hole 41 on the corresponding linkage cylinder attachment flange 40, again with a pin or the like. With the attachments having been made at these four operative points, the actuating mechanism for the raising and lowering the ramp tail 1 is ready to operate.
is The hydraulic cylinders are operated by pressurized fluid from a suitable source under control of suitable control valves (not shown) all of which is generally well known in the art.
One of the major problems experienced in the prior art was that of the hydraulic cylinders used to actuate such a ramp tail being in their extended position and the piston rods therefore subj ected 2o to extreme loads and stress while the ramp tail was in its raised position, while the hydraulic cylinder would be in its stronger retracted position while the ramp tail was lowered to the ground and no strain was placed on or support was required from the hydraulic cylinder. The present Page 18 of 23 invention reverses this - the hydraulic cylinders are extended to their full stroke when the ramp tail 1 is in its lower position, and are fully retracted when the ramp tail 1 is in its raised position.
This causes less stress on the hydraulic cylinders while the trailer 2 is under load.
With the attachment point of the hydraulic cylinders 44 to the linkage cross brace 35 being below the first linkage arm 30, the downward force of the loaded ramp tail communicated onto the hydraulic cylinder is minimized, with the remainder traveling through the first linkage arm 30 and being communicated into the trailer 2 and its stronger frame and suspension.
In addition, with the hydraulic cylinder 44 in its retracted position any force that is communicated through the to hydraulic cylinder 44 is easily handled without strain by the cylinder which is in its strongest position when retracted.
To lower the ramp tail 1 to the ground the hydraulic cylinders 44 are extended, which in turn through movement of the linkage cross brace 35 moves the joined first and second linkage arms is 30, 31 down below their center line and the attached ramp tail 1 is lowered to the ground. When operated to raise the ramp tail 1, the piston rods of the hydraulic cylinders 44 are pulled in, thus moving the linkage cross brace 35 and the linkage arms 30, 31 back up past the center line and into the above described locked position.
zo While the current embodiment speaks of a hitch pin 4 being used on the lower surface of the gooseneck to attach the trailer 2 to a power unit, it will be understood and is contemplated within the scope of this invention that modifications could be made to the front end of the trailer Page 19 of 23 including the use of a different hook up apparatus or the like to adapt the trailer for use with a different power unit, without altering the substance of the invention claimed.
The trailer of the illustrated embodiment has two ground-engaging axle assemblies.
s While the invention in this embodiment comprises a trailer of common goose neck variety, it will be understood that a foreseeable variation would be to use a conventional flatbed trailer configuration without a gooseneck configuration and that this is contemplated within the scope of the invention - that is to say the trailer 1 being of constant sufficient height from front to rear to to allow for the proper placement of the hitch pin or other power attachment method. This would result in a higher trailer which would merely mean that the ramp tail would come down at a steeper angle in its lower position, or could be lengthened to provide a lengthier loading slope.
Thus it can be seen that the invention accomplishes at least all of its stated objectives. Since is various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A flat bed trailer including a hinged ramp tail comprising substantially:
a) a frame, having rearward and forward ends, with attachment means on the forward end of the frame for connecting the trailer to a prime mover;
b) one or more ground-engaging axle assemblies attached to the frame;
c) a ramp tail having rearward and forward ends, the forward end of the ramp tail being hingedly connected to the rearward end of the frame such that the ramp tail is selectively moveable between an upper position wherein the ramp tail is approximately horizontal, and a lower position wherein the ramp tail is inclined downward and rearward towards the ground;
d) two or more bending linkages, each said bending linkage comprising two linkage arms pivotally joined together in a linkage joint, each said bending linkage pivotally attached at one end to the trailer at a trailer attachment point between the ground and the point of attachment of the ramp tail to the frame Page 21 of 23 and at the other end to the ramp tail at a ramp tail attachment point and wherein the distance between the trailer attachment point and the ramp tail attachment point when the ramp tail is in its upper position is the ramp hypotenuse and said bending linkages when in alignment are longer than the ramp hypotenuse;
e) one or more hydraulic cylinders attached such as to exert force on the linkage joints so as to bend said bending linkages, oriented such that by retracting the hydraulic cylinders the ramp tail is raised to its upper position and an over-centre lock is created by the bending linkages, and by extending the hydraulic cylinders the ramp tail is moved to its lower position, said ramp tail first raising slightly above the horizontal as the linkage arms come into alignment and the over-centre lock is overcome.
a) a frame, having rearward and forward ends, with attachment means on the forward end of the frame for connecting the trailer to a prime mover;
b) one or more ground-engaging axle assemblies attached to the frame;
c) a ramp tail having rearward and forward ends, the forward end of the ramp tail being hingedly connected to the rearward end of the frame such that the ramp tail is selectively moveable between an upper position wherein the ramp tail is approximately horizontal, and a lower position wherein the ramp tail is inclined downward and rearward towards the ground;
d) two or more bending linkages, each said bending linkage comprising two linkage arms pivotally joined together in a linkage joint, each said bending linkage pivotally attached at one end to the trailer at a trailer attachment point between the ground and the point of attachment of the ramp tail to the frame Page 21 of 23 and at the other end to the ramp tail at a ramp tail attachment point and wherein the distance between the trailer attachment point and the ramp tail attachment point when the ramp tail is in its upper position is the ramp hypotenuse and said bending linkages when in alignment are longer than the ramp hypotenuse;
e) one or more hydraulic cylinders attached such as to exert force on the linkage joints so as to bend said bending linkages, oriented such that by retracting the hydraulic cylinders the ramp tail is raised to its upper position and an over-centre lock is created by the bending linkages, and by extending the hydraulic cylinders the ramp tail is moved to its lower position, said ramp tail first raising slightly above the horizontal as the linkage arms come into alignment and the over-centre lock is overcome.
2. The trailer of Claim 1 wherein the number of bending linkages is two.
3. The trailer of Claim 1 further comprising a linkage cross brace joining the bending linkages by extending through the linkage joints in such a manner that the bending linkages are still able to bend.
4. The trailer of Claim 3 wherein the number of hydraulic cylinders is one.
Page 22 of 23
Page 22 of 23
5. The trailer of Claim 4 wherein the hydraulic cylinder is attached at one end to the ramp tail and the other end to the linkage cross brace.
6. The trailer of Claim 5 further comprising an offset hydraulic attachment flange attached to the linkage cross brace and by which the hydraulic cylinder is attached to the linkage cross brace at a point below the axis of the linkage arms.
7. The trailer of Claim 3 wherein the number of hydraulic cylinders is more than one.
The trailer of Claim 7 wherein the hydraulic cylinders are each attached at one end to the ramp tail and the other end to the linkage cross brace.
9. The trailer of Claim 8 further comprising offset hydraulic attachment flanges attached to the linkage cross brace and by which the hydraulic cylinders are attached to the linkage cross brace at a point below the axis of the linkage arms.
10. The trailer of Claim 1 wherein the hydraulic cylinders are fully retracted when the ramp tail is in its upper position.
11. The trailer of Claim 1 wherein the number of hydraulic cylinders is more than one, and wherein the hydraulic cylinders are controlled in tandem.
Page 23 of 23
Page 23 of 23
12. The trailer of Claim 1 wherein the number of ground-engaging axle assemblies is in the range of one to four.
13. The trailer of Claim 12 wherein the number of ground-engaging axle assemblies is two.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002195255A CA2195255C (en) | 1997-01-16 | 1997-01-16 | Positive locking trailer tail |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002195255A CA2195255C (en) | 1997-01-16 | 1997-01-16 | Positive locking trailer tail |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2195255A1 CA2195255A1 (en) | 1998-07-16 |
| CA2195255C true CA2195255C (en) | 2000-02-08 |
Family
ID=4159672
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002195255A Expired - Fee Related CA2195255C (en) | 1997-01-16 | 1997-01-16 | Positive locking trailer tail |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2195255C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI116046B (en) * | 2004-07-23 | 2005-09-15 | Hannu Leppaelae | Actuator Arrangement for Drive Bridge |
-
1997
- 1997-01-16 CA CA002195255A patent/CA2195255C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2195255A1 (en) | 1998-07-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8172248B2 (en) | Trailer with adjustable elevation | |
| US8857837B2 (en) | Trailer for transporting freight containers and method of use | |
| US4838753A (en) | Truck tractor fifth wheel-mounted lifting and towing unit | |
| US9108677B2 (en) | End dump trailer | |
| US3430792A (en) | Vehicle with tilting bed | |
| US4900055A (en) | Hydraulic retractable and extensible wheel suspension | |
| US4264262A (en) | Tow truck | |
| US5018593A (en) | High lift tag axle for trucks | |
| US20130121797A1 (en) | Container trailer | |
| CA2288483A1 (en) | Truck mounted hoist | |
| US7547178B1 (en) | Hydraulic tail trailer | |
| US4164297A (en) | Folding gooseneck for trailer | |
| US4245855A (en) | Vehicle stabilizer | |
| US5845920A (en) | Apparatus for towing a disabled truck tractor | |
| US4265463A (en) | Combination vehicle for towing, dumping and the like | |
| US9381846B2 (en) | Haul bodies and related apparatus | |
| US6561589B2 (en) | Dual acting truck hoist | |
| US20060175799A1 (en) | Utility trailer with elevating platform | |
| US5184872A (en) | Dumping semi-trailer | |
| US5494309A (en) | Self-loading piggyback-type trailer unit | |
| US6113338A (en) | Rear loading trailer and method of use | |
| CA2195255C (en) | Positive locking trailer tail | |
| US5988664A (en) | Apparatus for towing a disabled truck tractor | |
| US3977726A (en) | Double hitch tiltable trailer | |
| US4580830A (en) | Trailer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |