Patent Application
20080001130
The present invention relates to load handling apparatus and more particularly to such apparatus including a bag that may be inflated for controlled movement (e.g. lifting) of loads. It also relates to an inflatable bag for use with such load handling apparatus. Moreover, it relates to trailers and vehicles and more particularly to trailers and vehicles incorporating a load-carrying platform.
It is known to use inflatable bags to lift heavy loads such as large vehicles or load-carrying platforms. The pressure of the inflating fluid (e.g. air) applies a force that is distributed evenly over the surface of the bag. The lifting capacity of the bag is proportional to the contact area of the bag with the load or platform. In many designs the bag is initially flat with one side disposed on a base and the other side placed under a load or a load-carrying platform. Inflating the bag increases its height and forces the platform to move away from the base so as to move the load. The base and platform may be arranged, for example, such that they are separated in a vertical direction or, alternatively, they may be pivotally connected such that the inflation of the air bag serves to increase the angle of inclination between them. During inflation the air column (represented by the bag) and therefore displacement distance increases but there is a tendency for the contact surfaces of the bag to balloon into a generally convex shape such that the contact between the bag and the platform decreases and so the lifting capacity decreases.
Bags of this kind are generally flexible but resistant to being stretched and are impervious. They are typically manufactured from one or more sheets comprising a woven synthetic fibre, such as an aramid or a para-aramid (e.g. Kevlar®) that is coated or impregnated with a rubber or flexible plastics material such as neoprene or polyurethane. In a single sheet design the sheet is folded and the overlapping edges at its perimeter are secured by gluing or heat (e.g. radio frequency) welding. In a design with two sheets, the sheets are overlaid and perimeter edges are secured in a similar fashion. The perimeter seams, and in particular the bag corners, are areas of weakness as there is a tendency for them to peel apart under high bag pressures. Moreover, if a glue is used it can deteriorate and fail with age. Often steps are taken to strengthen the bags by adding one or more layers in the weak areas but this adds to the manufacturing costs.
It is known to employ several bags in a vertical stack in order to increase the potential vertical displacement of the load. Moreover, it is generally possible to achieve a higher pressure with multiple bags as compared to a single bag with an equivalent air column without increasing the wall stress. The bags may be separately inflatable or, alternatively may be in fluid communication with one another and inflated from the same source. Arrangement of the bags into stacks can render the lifting apparatus unstable as there is a tendency for the bags to shift relative to one another and it is possible for one or more bags of the stack to slide out from under the load. It is therefore necessary to employ suitable tethering arrangements to avoid this problem. This again adds to the manufacturing costs.
UK patent application no. GB 2206158 describes an inflatable bag used to raise a load-carrying platform and WO 01102281 describes an airbag that is used to operate the extension or collapse of a scissor lift.
Conventional trailers provide an enclosable space into which cargo can be loaded for carriage. Such trailers are usually provided with a rectangular frame, and a number of solid panels attached to the rectangular frame. Such trailers are mounted on a chassis comprising suitable running gear, to allow connection of the trailer to a tractor unit for haulage purposes.
In order to maximise the carrying capacity of the known trailer, it is known to lower the base of the trailer between the rear axle and the front hitch of the trailer so as to form a well. Such a modification generally allows additional goods to be stacked within the trailer on top of one another.
International Patent Application No. PCT/GB01/00279, publication No. WO 01/62542 (Insulated Structures Ltd et al) describes various mechanisms for loading a trailer. However, each of the mechanisms described in this document is suitable only for loading pallets using a forklift truck, not for carrying roll cages which are often used to carry cargo in trailers, nor for loading pallets using a manually operated pallet-barrow.
Our co-pending International Patent Application No. PCT/GB2004/000602 describes a trailer having a load-carrying well and at least one displaceable platform on to which goods are loaded. In one embodiment there is one or more vertically displaceable platforms disposed in the well and a rear displaceable platform disposed at the rear of the trailer. The latter platform has a lower portion that moves in a vertical direction and an upper portion that can translate in a generally horizontal direction. Once the well platform is loaded the rear platform is loaded with cargo and displaced first vertically and then horizontally over the well thereby increasing the load capacity of the trailer. One of the lifting mechanisms described for elevating the platforms is a scissor jack and air bag combination (illustrated in
This type of mechanism is described in International patent application WO 01/02281 (McNiven) and is comprised of wedge-shaped multiple compartment airbags disposed between inclined limbs of the scissor jack. The airbags are inflatable to extend the scissor jack and raise a load.
It is an object of the present invention to provide an improved inflatable bag for use in a load handling apparatus.
According to a first aspect of the present invention there is provided an inflatable bag for use in a load handling apparatus comprising a tube, one end of the tube being joined to the other end of the tube so as to form an endless loop, the endless loop defining an inner volume, the bag comprising inlet means arranged to allow admission of fluid into the inner volume.
According to a second aspect of the invention, there is provided
A method of making an inflatable bag comprising the steps of:
Providing a sheet of suitable bag material,
Folding the sheet of bag material into a tube such that one side edge of the sheet overlaps the opposite side edge of the sheet, joining the folded tube along the overlapping side edge so as to form an elongate tube with opposite ends and an overlapping seam running longitudinally thereof,
Folding the elongate tube so that one end thereof is tucked inside the other end thereof to form an overlap region, the folded elongate tube defining an endless loop having an inner volume, and
Forming a seam which seals off the inner region, the seam being formed in the overlap region.
According to a third aspect of the present invention there is provided load handling apparatus comprising a base, a movable platform on to which goods can be loaded and at least one inflatable bag defining an internal inflation chamber and disposed between the platform and the base such that upon inflation of the bag the platform is moved relative to the base, wherein the bag is folded so as to define a plurality of superposed bag portions such that the chamber is divided into a plurality of interconnected and stacked sub-chambers.
The load handling apparatus provides for a simple structure that is relatively easy to manufacture and use. The stacked sub-chambers provide for a stable arrangement with improved displacement distance and enable lower inflation pressures to be used for a given load.
The bag is preferably elongate.
In one preferred embodiment of the third aspect, the bag is configured such that the inflation chamber is in the form an endless loop. The bag may be substantially tubular in cross-section with ends of the tube being joined to form the chamber into said endless loop.
The ends of the tube preferably overlap and are bonded at the overlap.
Such a bag is of a unitary structure and free of peripheral seams that are prone to failure and leakage under pressure. The bag can thus be inflated to higher pressures and the limitation is the tensile strength of the bag material rather than the strength of the seams.
In another preferred embodiment of the third aspect, the bag has at least one sealed end formed by a seam that is formed by overlapping bag portions configured such that when the bag is inflated the portions are loaded in shear. The bag may be in the form of a flattened tube defining opposed major walls with the seam being formed by the end being in turned and opposed in-turned portions being bonded together and bonded to an interior surface of one of the major walls. This arrangement ensures that the seam becomes part of the wall of the bag when inflated so that it is loaded in shear only. This enables the bag to be inflated to significantly higher pressures without risk of leakage.
The superposed bag portions may be arranged so as to be coterminous.
The bag portions preferably comprise first and second sub-chambers of a first length and at least one pair of third sub-chambers interposed between said first and second sub-chambers and are arranged to be in a side-by-side disposition. Each of the third sub-chambers may be substantially half the length of the first and second sub-chambers so that in combination they equal said first length.
The bag may be folded into a convoluted configuration which may define a chamber that is substantially sinuous.
The bag is ideally substantially tubular in cross-section with ends of the tube being joined to form the chamber into said endless loop. The ends of the tube may overlap and be joined at the overlap by fixing means.
There may be an extensible linkage between the platform and the base. One preferred example is a scissor linkage. The scissor linkage may comprise a pair of beams interconnected at a pivot. The retaining member may be connected to the pivot. The retaining member may be in the form of a bar extending in parallel to the pivot axis and spaced therefrom. The retaining member is ideally received in a fold of the bag such that the bag is prevented from unfolding during inflation.
A bag-retaining member may be provided for retaining the bag in the folded configuration during inflation or deflation. The bag may be folded around the retaining member such that it cannot unfold during inflation. Such a retaining member may be fixed to the pivot shaft of the scissor linkage. Alternatively the retaining member serves to hold two folded parts of the bag adjacent to each other and is otherwise free from connection to the apparatus. This arrangement allows the bag to flex and its portions to move over one another by rolling or sliding without putting undue strain on other parts of the apparatus. The retaining member may be in the form of a loop.
The bag-retaining member may be in the form of a bar extending in parallel to the pivot axis and spaced therefrom.
Preferably there are provided paced panels that are disposed between the platform and base. The bag may be disposed between said panels. The bag may be folded around at least one of said spaced panels. The panels may be connected to the linkage. In one preferred embodiment they are fixed to the elongate members of the linkage and are inclined to one another.
The panels are preferably disposed in parallel to the platform and base and the elongate members of the scissor linkage are connected thereto by a coupling arrangement that permits relative movement between the limbs and the panels.
The superposed portions of the bag are ideally joined to one another.
The bag may be constructed from a single sheet of material which may be folded and joined at overlapping edges to form a tubular construction. Fixing means for joining the overlapping edges may be, for example, glue, crimping or a heat or r.f. weld or a combination thereof.
The bag ideally has an inlet port for receipt of inflating fluid and a pressure relief valve.
In one preferred embodiment there is provided an intermediate panel and two inflatable bags one disposed between the platform and the intermediate panel and the other disposed between the intermediate panel and the base.
An inflating fluid conduit for connection to a source of inflating fluid is preferably provided with the conduit defining separate outlet branches for connection to each bag. This enables simultaneous inflation or deflation of the two bags and an equalisation of the pressure between them. The conduit is preferably disposed at least in part within the intermediate panel.
The intermediate panel may be pivotally disposed on the pivot of the scissor linkage. This accommodates movement of the bags relative to the platform and base.
The surface of the bag material is treated with a low friction finish so as to permit the superposed bag portions to slide over one another. This may be achieved by applying an embossed finish on the bag surface.
The sheet is preferably folded to form a tubular construction with a single seam parallel to the longitudinal axis of the tube.
The bag ideally has an inlet and an outlet port.
According to a fourth aspect of the present invention there is provided a inflatable bag for handling a load, the bag defining an internal inflation chamber, wherein the bag is configured so that the inflation chamber is in the form an endless loop, the bag being folded so as to define a plurality of superposed bag portions such that the chamber is divided into a plurality of interconnected and stacked sub chambers.
According to a fifth aspect of the present invention there is provided an inflatable bag for handling a load, the bag defining an internal inflation chamber, the bag having at least one sealed end formed by a seam that is formed by overlapping bag portions, the seam being configured such that when the bag is inflated the portions are loaded in shear, the bag being folded so as to define a plurality of superposed bag portions such that the chamber is divided into a plurality of interconnected and stacked sub-chambers. The bag may be in the form of a flattened tube defining opposed major walls with the seam being formed by the end being in-turned and opposed in-turned portions being bonded together and bonded to an interior surface of one of the major walls.
The bag material is preferably flexible but substantially inelastic.
According to a sixth aspect of the present invention, there is provided a trailer defining a floor extending from a first end, and comprising at least one first displaceable platform on to which goods can be loaded from the first end of the trailer, the platform being supported on the floor by a lifting mechanism, the lifting mechanism comprising at least one scissor linkage movable between collapsed and extended positions, a pair of vertically spaced panels each coupled to the scissor linkage at a position between the floor and the platform by a coupling arrangement that permits relative movement between the linkage and the panels during movement of the linkage between the collapsed and extended positions, and an inflatable bag comprising a plurality of compartments in fluid communication with one another, the bag being disposed between the panels such that inflation of the bag causes the panels to be forced apart so that the scissor linkage is moved to the extended position and the platform raised.
It is to be understood that the term “trailer” is used in this context to include a vehicle with an enclosable space into which cargo is loaded. The lifting mechanism provides for a compact arrangement that does not compromise the loading capacity of the trailer. The scissor linkage ideally comprises first and second elongate members interconnected at a pivot. The elongate members of the scissor linkage each have first and second ends and the panels are ideally coupled to the elongate members intermediate said first and second ends.
The coupling arrangement preferably comprises a projection defined on either the linkage or the panel, and a slot defined on the other of the linkage or the panel, the projection being received in the slot and being moveable relative to said slot in both translation and rotation. The projection may be in the form of a pin or, alternatively may be in the form of a bar that extends across the panel.
The slot may be defined on the panel and the projection may be defined on an elongate member of the scissor linkage.
A first end of the first elongate member is preferably pivotally connected to the platform at a fixed location and a second end of the first elongate member is free to translate over the floor. A first end of the second elongate member may be pivotally connected to the floor at a fixed location and the second end of the second elongate member may be free to translate over the underside of the platform.
A roller or, alternatively, a sliding member may be connected to each of the second ends of the first and second elongate members. Each roller or sliding member may be received in a respective guide track connected to the platform or the floor.
The platform may be supported by first and second scissor linkages, one being disposed on each side. The first and second scissor linkages are preferably connected by a common pivot that may be in the form of a shaft disposed between the floor and the platform.
The underside of the platform preferably has at least one recess to accommodate at least part of the inflatable bag and/or the scissor linkage and/or the panels when in the collapsed position.
There may be provided at least one recess in the panels to accommodate at least part of the inflatable bag and/or the scissor linkage when in the collapsed position. The bag compartments are ideally arranged in a superposed relationship.
The bag preferably has an inlet valve and an outlet valve.
An additional bag may be provided intermediate an upper one of said panels and said platform.
The additional bag may have multiple compartments in fluid communication with one another.
Ideally there is provided a source of fluid connected to said bag or bags The trailer may define a well, the displaceable platform being located in said well.
The trailer may comprise a first section defining a load-carrying front floor, a rear section defining a rear floor, a well located between the front and rear sections, the displaceable platform being disposed in said well.
Alternatively the trailer may comprise a first section defining a load-carrying front floor, a rear section defining a rear floor, a well located between the front and rear sections, wherein the displaceable platform is vertically displaceable above the rear floor between raised and lowered positions, and the support platform carries the load carrying platform which is horizontally displaceable over the well when the support platform is in the raised position, the load-carrying platform being displaceable from the support platform onto supports mounted on sidewalls of the vehicle.
According to a seventh aspect of the present invention there is provided a displaceable platform on to which goods can be loaded, the platform being supported by a lifting mechanism, the lifting mechanism comprising at least one scissor linkage movable between collapsed and extended positions, a pair of vertically spaced panels each coupled to the scissor linkage at a position between a surface on which the mechanism is supported and the platform by a coupling arrangement that permits relative movement between the linkage and the panels during movement between the collapsed and extended positions, and an inflatable bag comprising a plurality of compartments in fluid communication with one another, the bag being disposed between the panels such that inflation of the bag causes the panels to be forced apart so that the scissor linkage is moved to the extended position and the platform raised.
Specific embodiments of the various aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:
FIGS. 1 to 3 show the construction of an airbag in accordance with the first and second aspects of the present invention;
a to 23f are longitudinal sectional views of a trailer in accordance with the present invention and illustrate the steps on loading the trailer with cargo;
FIGS. 38 to 41 are similar to that of
FIGS. 48 to 51 are partial end views of the trailer showing the rear platform arrangement movement sequence with
Referring now to FIGS. 1 to 3 of the drawings, the exemplary airbag for use in load handling apparatus of the present invention is constructed from a single elongate sheet of flexible, impervious material 1 whose long side edges 2, 3 are folded inwardly (in the direction of the arrows shown in
Since the bag 10 is constructed from a single sheet of material 1 it is cheaper to manufacture. Moreover, the lack of peripheral seams is advantageous as these are areas of weakness during inflation at high pressures. The longitudinal seam 4a and the loop seam 8 provided at the end portions are both provided by overlapping surfaces of the sheet material. This means that, in use, inflation of the bag causes the seams to be loaded in shear rather than being peeled apart as in the case of a peripheral seam (known as a “peel weld”) generally present in conventional bag designs. Such seams (often referred to as “shear welds”) are generally around four times as strong as a conventional peel weld. The bag of the present invention is thus more resistant to leakage than current bag designs and can therefore be used at higher inflation pressures. It is preferred that the tube is folded into the bag 10 so that the longitudinal seam 4a is on the inner face of the endless loop.
It will be appreciated that the strength of the seam is determined by the width of the overlap of the two portions of sheet material and the consequent surface area of bond.
It is to be appreciated that the sheet 1 and the final closed bag 10 can be of any suitable shape for use in the present invention but generally an elongate form is most practical.
The sheet 1 is constructed from any suitable material that is impervious so as to prevent air leakage, flexible to allow easy inflation and deflation, sufficiently strong so as not to burst or puncture easily under pressure, durable so that it may be reused and generally inextensible. One example of such a material is a synthetic woven structure such as an aramid or para-aramid yarn (e.g. Kevlar®) that is impregnated or coated with a suitable rubber or rubber-like material (e.g. neoprene) or a plastics material such as polyurethane.
The bag 10 described above may be used as part of load handling apparatus to displace a load by inserting it between a fixed base 11 (which may be the floor, the ground or a plate) and a movable platform 12 on which the load is to be carried or otherwise supported. Such an arrangement is shown schematically in
When the bag 10 is inflated the platform 12 is urged away from the base in the direction of the arrow in
The two vertically stacked sub-chambers 13 of the bag can generally be inflated to higher pressures compared to a single bag offering the same vertical column, contact area and tensile strength on the basis that each bag has a side wall with a smaller radius than the single bag. For a thin-walled pressure vessel the hoop stress in the wall is proportional to the radius of that wall and the internal pressure in the vessel. Replacing a single chamber with multiple chambers 13 each with side walls of reduced radius allows a greater pressure to be used without increase in hoop stress in the wall. This is made possible by designing the bag such that there are not peripheral seams that are prone to peeling and therefore leakage. Moreover, the arrangement is more stable in comparison to using separate stacked bags.
Using multiple stacked bag sub-chambers means that a given lift height can be achieved by inflating each chamber to a fraction of the overall height. This is beneficial in comparison to a single airbag as each chamber is not inflated to a point where its surfaces tend to balloon outwards and thus reduce the contact area between adjacent chambers and between the chambers and the base or platform. The result is that the bag of the present invention can be inflated to lower pressures in comparison to a single bag in order to achieve any given lift height.
In order to prevent the bag 10 from shifting laterally relative to the platform 12, it can be disposed around a retaining member 14, which is shown schematically in
Exemplary load handling apparatus in the form of lifting mechanisms of the present invention are illustrated in
The lifting mechanism of both
On each side of the pivot shaft 24 there is fixed relative thereto a parallel bag retaining bar 14 spaced therefrom to define a clearance 16 (see
The first beam 22 of each linkage is provided at one end with a roller 25 mounted on a shaft 26 and designed to bear against the underside surface of the platform 20 or, alternatively, against a bearing surface (not shown) fixed to the underside of the platform. In another version of the design, a channel-shaped member may be connected to the underside of the platform to provide a guide track in which the roller 25 travels. The other end of the beam 22 is pivotally connected to the base 11 at a fixed location 27. The second beam 23 is similarly connected but in reverse with one end 28 being pivotally connected to the underside of the platform and the other end having a roller 29 so as to allow it to traverse over the floor 11. Again a guide track may be provided. Thus the beams 22, 23 of each linkage are able to pivot between collapsed and extended positions so as to lower or elevate the platform 20 as will be described below.
In the embodiment of
The lift mechanism 8 is actuated by two inflatable bags 40 that are folded into the configuration shown in
Each bag 40 has an inlet port 41 (shown on one bag only in the figures) with valve for connection to a source of compressed air or other suitable inflating fluid. The inlet ports are ideally connected to the same source to ensure simultaneous inflation. For example the source may be connected to a manifold that supplies the inflating fluid to branch conduits that are each connected to a respective inlet port 41.
A pressure relief valve 42 is also provided to prevent over-inflation.
In operation the air (or other fluid) ingresses through the inlet ports 41 and serves to inflate all the chambers of the bags 40. As the bags inflate they impart a force to the panels 30, 31 such that the latter move apart in a vertical direction. This movement is transferred to the scissor linkages via the pins 33 such that the linkage is forced to extend and thereby elevate the platform 20. As the linkages extend the rollers 25, 29 at the ends of the beams 22, 23 translate over the surfaces of the platform 20 and base 11. The slots 32 in the panels 30, 31 allow the pins 33 to translate and rotate relative to the beams 22, 23 thereby allowing relative movement between the panels 30, 31 and the linkage beams 22, 23. It will be understood that in an alternative embodiment the slots 32 could be provided along the beams 22, 23 and the pins 33 on the panels 30, 31. The mechanism is shown fully extended in
In order to lower the platform 20 the process is reversed by opening an outlet valve. This allows the bags to deflate and the scissor linkages to move to the collapsed position under the weight of the platform 20 and any load carried by it.
During inflation the compartments of the bags 40 inflate substantially simultaneously so as to provide a stable and controlled lifting movement. The bags 40 are designed to withstand high pressures.
In the alternative exemplary embodiment of
Inflation of the bags 55, 56 causes them to expand against the panels 50 to 53 and adopt a general wedge shape. This action forces the panel pairs 50 and 51, 52 and 53 to move apart such that the angle between them (and therefore the beams to which they are fixed) increases thereby extending the scissor linkages to raise the platform 40.
The embodiment of
The apparatus again comprises a base 100 and a platform 101 between which the scissor linkage extends and parallel intermediate panels 102, 103 to which the beams of the scissor are connected in the same manner as that described above in relation to
The provision of an endless loop inflatable chamber 108 divided into multiple superposed sub-chambers that are vertically stacked and supported by the central plate 104 and intermediate panels 102, 103 ensures greater stability in comparison to the multiple bags of the prior art lifting arrangements. As indicated above the use of an endless loop chamber provides for a much stronger bag without peel welds and the arrangement of multiple sub-chambers can result in reduced inflation pressures for a given lift height.
The use of a central plate and intermediate panels provide stability in that the bag can be supported on and/or folded around them. This permits the employment of more bags or the division of a bag into more sub-chambers thereby providing a higher lift capacity and/or a reduced inflation pressure for a given height. In tests by the application it has been established that the arrangement of the present invention was able to lift a given load through a given height at 7 psi which compares to an inflation pressure of 30 psi using a prior art bag design.
By using a large radius bag, for example 50 cm, the inflation pressure required to lift a load can be substantially reduced to below 3 psi for normal loads.
The pivotal mounting of the central plate 104 ensures that bag movement can be accommodated without applying stress to the scissor linkage.
The retaining loops 109, 110 are designed to retain the bags in the folded configuration whilst allowing relative rolling and/or sliding movement of adjacent bag surfaces during inflation or deflation. An example of one such loop is shown in
The embodiment of
Upper and lower bags 207, 208 are disposed between the platform 200 and central plate 203 and the base 201 and central plate 203 respectively. Each bag again defines a single chamber 209 in the form of an endless loop and is folded so as to define a plurality of vertically superposed sub-chambers 209a to 209h as in the embodiments described previously. In particular, each bag is folded inwardly at opposed locations of the loop to define a convoluted chamber. The bag chamber is divided into upper and lower sub-chambers 209a, 209f that extend substantially along the length of the lifting apparatus and two pairs of intermediate sub-chambers 209b,c and 209d,e. The sub-chambers of each pair 209b,c and 209d,e extend half way across the length of the apparatus and combine to be substantially coterminous with the upper and lower chambers 209a and 209f. The folded configuration of the bag is supported by retaining loops 210 that are disposed between the two pairs of subchambers. The design of the retaining loops 210 is the same as that described above in the embodiment of
It will be appreciated that in another embodiment (not shown) the bags may be folded around intermediate panels disposed between those bag portions that define the uppermost or lowermost sub-chamber 209a or 209f and the adjacent pair of intermediate sub-chambers.
An outlet of the source of inflating fluid is connected to a manifold 211 that directs the inflating fluid to a pair of branch conduits 212, 213 each conduit supplying an inlet of a respective bag. The manifold is located, in part, within the central plate with one branch directed upwardly to connect to the lowermost sub-chamber of the upper bag and the other directed downwardly to connect to the uppermost subchamber of the lower bag. This arrangement ensures that the bags are inflated simultaneously and that the bag pressures are equalised at all times thus reducing the stress on the scissor linkage in the event of failure of one of the bags. It will be appreciated that the manifold can be used in any configuration where there is more than one bag.
In any of the embodiments described, the scissor linkage could be dispensed with altogether providing an appropriate guiding arrangement is provided for the platform 20, 101, 200 as will be described later.
The arrangement ensures that the bag surfaces in contact with the floor and platform are maximised so that the bag pressure and therefore tensile stress can be reduced for a given load and lifting height.
The bag surface may be embossed to allow the surfaces of the overlying portions to slide over each other during inflation or deflation. It will be appreciated that other kinds of finishing treatments to the bag surface may be applied in order to achieve this purpose.
An alternative bag configuration in accordance with the invention is shown in FIGS. 15 to 18. This bag may be used in any of the load handling apparatus designs described above instead of the endless loop chamber bag. The alternative bag configuration is elongate in the form of a flattened tube as before but does not define an endless loop chamber. Instead the bag has sealed ends that are designed such that the seams are not in the form of “peel welds” but are rather shear welds. The bag may be folded in the same configurations as the endless loop chamber bag described above and differs only in that the ends are not joined together. It has all the advantages of afforded by the endless loop chamber bag as described above.
In this invention it is important that the two halves 305a, 305b of the in-turned portion 305 not only bond together but that they are bonded to the interior surface of only one of the walls 306 of the flattened bag. The material is prevented from fusing to the other wall 307 by inserting a thin blank 309 of suitable material between the relevant wall 307 and the in-turned portion 305b. The blank material has a different dielectric loss index or a higher thermal capacity such that it does not fuse to the bag material on each side when subjected to the electric field. The resulting seam, illustrated in
The inlet to the endless loop 10 may be formed in a similar way to that shown in
The bag may contain a mesh of thin plastics or other material that extends substantially along the full interior length of the chamber. This assists in ensuring that the inflating fluid is distributed from the inlet port along the full length of the bag more efficiently. A mesh could be used in the endless loop chamber bag described above. Any kind of reticulated membrane may be used in place of the mesh. The load handling apparatus of the kind described above is particularly suitable for use in raising and lowering cargo-carrying platforms in articulated trailers or other vehicles. Examples are described in International Patent Application nos. PCT/GB01/00279 and PCT/GB04/000602.
It will be appreciated that numerous modifications to the above described design may be made without departing from the scope of the invention as defined in the appended claims. For example, the airbag may be folded any convenient number of times to provide multiple stacked chambers. Moreover, it is to be understood that the bags may be used with any suitable type of load handling apparatus. Finally in the embodiments using a scissor lift it is to be understood that any number of linkages may be used for any given platform.
a to 23f show a trailer 400 having three rear axles supporting wheels 410 and a front hitch 412 (which may also be referred to as a king pin, and which typically is received in the fifth wheel of the tractor unit). It can be seen that a central part of the floor of the trailer between the wheels 410 and the front hitch 412 is lower than front and rear floor sections, so as to allow additional cargo to be carried in the lower part of the trailer which is hereinafter referred to as a well 414. It can be seen that, in this example, the well 414 is provided with a vertically moveable platform 416 which can be raised and lowered by the action of a lifting mechanism 418 (shown in schematic form in
In the embodiment shown in
Referring to
Referring to
It will be appreciated from the foregoing description that the present invention allows space usage within the trailer 400 to be optimised, given that the pallets 428 are carried on a platform 424 located above the pallets 428 in the well 414. Furthermore the present invention is advantageous, because all loading positions can be accessed using a manually operated pallet barrow without the need for a forklift truck. However, it will be appreciated that the invention can be used with a forklift truck if desired. Additionally, the invention can be used with roll cages, if it is desired to carry cargo in this way. Also, although the up-and-over platform arrangement has been shown in a trailer, it will be apparent that this arrangement may also be used with advantage in cargo-carrying vehicles with no detachable trailer.
Furthermore, the lifting and forwardly extending double-platform arrangement may provide advantages in cargo carrying vehicles and trailers that do not possess wells, although when used in conjunction with load carrying wells the arrangements are particularly advantageous.
In these illustrations a generic load-carrying platform is designated by the reference numeral 20 and parts corresponding to parts in
The first beam 22 of each linkage is provided at one end with a roller 25 mounted on a shaft 26 and designed to bear against the underside surface of the platform 20 or, alternatively, a bearing surface fixed to the underside of the platform. In another version of the design, a channel-shaped member may be connected to the underside of the platform to provide a guide track in which the roller 25 travels. The other end of the beam 22 is pivotally connected to the floor at a fixed location 27. The second beam 23 is similarly connected but in reverse with one end 28 being pivotally connected to the underside of the platform and the other end having a roller 29 so as to allow it to traverse over the floor F. Again a guide track may be provided. Thus the beams 22, 23 of each linkage are able to pivot between collapsed and extended positions so as to lower or elevate the platform 20 as will be described below.
The scissor linkages support upper and lower vertically spaced panels 30, 31 that are disposed between the floor F and the platform 20 and occupy planes parallel to the floor and the platform. Each of the panels 30, 31 comprises a pair of planar sheets of steel or other suitable material that are joined by reinforcing webs as necessary. The side edges of the panels that face the beams 22, 23 of the linkages have longitudinal slots 32 for receipt of pins 33 that are fixed to the beams and extend in a direction perpendicular to the longitudinal axes of the beams. Each pin 33 moves with the beam 23, 23 to which it is fixed and is thereby able to translate and rotate in its slot 32 so as to permit movement of the linkages between the collapsed and extended positions whilst still supporting the panels 30, 31.
The lift mechanism is actuated by two inflatable bags 40 that are interposed in a side-by-side relationship between the upper and lower panels 30, 31. The bags 40 each comprise multiple compartments that are each defined by a single sheet of material that is folded over, bonded at its peripheral edges and bonded to an adjacent bag compartment. The bag material is constructed from an impervious flexible material. An example of a suitable material is a synthetic woven fabric such as Nylon® or Kevlar® based fabric that is coated or impregnated with polyurethane but it is to be appreciated that other materials may be used. The peripheral edges and the facing surfaces of adjacent bags may be bonded by, for example, heat welding. Alternatively, a bag as described in FIGS. 1 to 7 could be used.
In the example shown, the lowermost compartment of each bag 40 has an inlet port 41 (one only shown) with valve 42 for connection to a source of compressed air or other suitable inflating fluid. Each of the bag compartments are in fluid communication with the others by means of passages 43 which are represented in dotted line in the bag on the left hand side only of
In order to lower the platform 20 the process is reversed by opening an outlet valve. This allows the bags to deflate and the scissor linkages to move to the collapsed position (see
During inflation the compartments of the bags 40 inflate substantially simultaneously so as to provide a stable and controlled lifting movement. The bags 40 are designed to withstand high pressures. Restricting the vertical dimension of the bags to that between the panels 30, 31 provides improved stability as the height (and footprint) of the bags is reduced in comparison to a bag that extends between the floor and the platform. Moreover, the vertical distance through which the linkages and therefore the platform can travel is not compromised.
The advantage of the scissor lift arrangement is that it can collapse to a very flat configuration, and so takes up a small volume in the trailer/vehicle. The mechanism is shown approaching the fully collapsed position in
A modified version of the lift mechanism is illustrated in
It is to be appreciated that numerous modifications to the above described design may be made without departing from the scope of the invention as defined in the appended claims. For example, the pair of scissor linkages may be replaced with a single linkage. Moreover, the rollers at the end of the linkage beams can be replaced by sliders of any suitable low friction material.
The trailer shown in FIGS. 24 to 51 is similar in many respects to that shown in
In
Behind the well 514, the trailer has a rear platform arrangement 520 similar to that of
The well platform lifting apparatus 518 and the rear platform lifting apparatus 526 are similar and only the operation of the rear platform lifting apparatus 526 will be described in detail.
The rear platform arrangement is lifted and lowered by the rear platform lifting apparatus 526 which comprises four inflatable bags 10 of the type described in FIGS. 1 to 7, and particularly
Each bag 10 comprises an endless loop made by rolling a flat sheet into an elongate tube and sealing the tube along a longitudinal seam. The tube is then folded into an endless loop and the overlapping ends are joined to form a seal around the hoop radius of the loop.
Each bag 10 has an air inlet tube (not shown in FIGS. 24 to 26) which is connected to a regulator valve which regulates, automatically, the inlet/outlet of compressed air into and out of the respective bag 10. An air compressor, such as the vehicle cab air compressor or an independent trailer mounted compressor supplies the compressed air to the regulator valves.
The operation of the lifting apparatus will be described in more detail below.
In
In that condition, the gates 534,536 are closed so that they extend transversely across the trailer and are latched by means of respective locking latches 538 to the side wall of the trailer opposite to the wall on which they are mounted. The gates partition off sections of the trailer and prevent the pallets stacked on the rear horizontally moveable platform 524 and the rear vertically moveable platform 522 from moving forward to damage pallets stacked further forward under heavy braking.
FIGS. 31 to 37 illustrate the drive mechanism 542 for the rear horizontally moveable platform 524. The drive mechanism comprises carriages 544 on each side of the trailer which run along respective rails 546 and which are driven by means of a cable and pulley system 548 driven, in turn, by a motor 550 (see
As shown in
One of the carriages 544 is shown in more detail in
The runner portion 552 comprises a runner plate 556, through which are located a series of runner axles 558. Runners 560 are mounted on respective runner axles 558. Each runner 560 comprises an annular body with a circumferential groove 562 formed around the outer circumference thereof. The groove 562 is dimensioned to be a snug, running fit around the rail 546.
The rail 546 comprises a lower rail part 564 and an upper rail part 566 spaced from the lower rail part, both of which are attached to the trailer wall. The lower rail part 564 comprises an upstanding rail 568 and a bracket part 570 for mounting the upstanding rail 568 to the trailer wall. The upper rail part comprises a depending rail guide 572 carried by a bracket part 574. The upstanding rail 566 is a snug running fit with the runner 560. The depending rail guide 572 is a loose fit with the runner 560 and is intended simply to prevent the runner 560 from being pulled off the rail by the weight of the platform.
A long carriage plate 576 extends downwardly from the runner plate 556 and the hook portion 554 is formed at the lower end of the carriage plate 576. The hook portion 554 kicks out away from the trailer wall from the base of the carriage plate 576. The hook portion comprises a hook 578 at the lower end thereof and a slider plate 580 which extends below the hook into a lower slide rail 582 mounted to the trailer wall.
The motor 550 drives the cable 584 one way so that the carriage 544 is pulled forward along the rail 546 and the other way to pull the carriage rearwardly along the rail 546. The hook 578 of the hook portion 554 supports the horizontally moveable rear platform, as will be described in more detail below.
FIGS. 38 to 41 illustrate the loading process for the trailer 500. Reference will also be made to other figures which show the details of certain steps.
When the trailer 500 is completely unladen, the well load platform 516 lies at the base of the well 514 and the gates 534, 536 (see FIGS. 27 to 30) are arranged in their open position, i.e. that shown in
When it is desired to load the trailer, the well lifting apparatus 518 is activated to inflate the airbags 10 which support the well load platform 516. Airbags 10 are inflated so that the upper surface of the well load platform 516 is flush with the floor of the trailer forward of the well and the upper surface of the horizontally moveable rear platform 524 and the rear floor 532. Pallets 528 can then be loaded either using a forklift truck or a manually operated pallet barrow. Alternatively, in place of pallets, roll cages may be wheeled over the rear floor 532, the horizontally moveable rear platform 524, the well load platform 516 onto the floor of the trailer forward of the well 514. When that area is fully loaded, the gate 534 is moved to the closed position shown in
Further pallets 528 are then loaded onto the well load platform 516 until the well load platform is fully loaded. That configuration is shown in
Once the well lifting platform 516 is lowered to the bottom of the well, the pulley and cable system 548 is operated to move the carriage 544 along the rail 546 until it reaches its forwardmost point. The carriage 544 is dimensioned and the rail 546 is positioned so that the lower most part of the carriage 544 clears the uppermost part of the pallets 528 in the well 514. The carriage 544 is also clear of the forwardmost point of the rear platform arrangement 520. The horizontally moveable rear platform 524 is then fully loaded with pallets 528 to arrive at the configuration shown in
The rear platform lifting apparatus 526 is then operated to inflate the airbags 10 as shown in
The airbags 10 raise the rear platform arrangement 520 to a vertical position such that the underside of the horizontally moveable rear platform has a vertical clearance above the hook portion 554 of the carriage 544. The cable and pulley system 548 is then driven by the motor 550 to move the carriage 544 rearwardly of the trailer 500 along the rail 546 so that the carriage reaches the rear most part of the rail 546. In that position, the hook 578 of the hook portion 554 of the carriage 544 is arranged directly beneath a hook receiving flange 600 on the edge of the horizontally moveable rear platform 524. (see
Once the carriage 544 is arranged in the rearmost position, the rear platform lifting apparatus is operated to allow the airbags 10 to inflate which in turn, causes the vertically moveable rear platform to be lowered. That lowers the horizontally moveable rear platform until the hook receiving flange 600 is supported by the hook 578 of the hook portion 554 of the carriage 544. That configuration is shown in
When the trailer 500 is being used in a conventional way, well load platform 516 can be raised to be flush with the floor of the trailer and can be locked off in that position, as shown in
The horizontally moveable rear platform 524 and the arrangement of carriages 544 on opposite sides of the trailer wall can provide significant additional loading on the trailer walls when the platform 524 is fully laden with pallets 528. In order to accommodate that extra weight and the additional forces that it creates when the vehicle is cornering, a series of cross braces 606 are connected between the side walls of the trailer 500 and the chassis 608 of the trailer 500.
The lifting of the rear platform arrangement 520 will now be described in detail. The gallery arrangement and automatic levelling arrangement described here below can also apply equally to the well lifting apparatus and platform 518, 516.
Firstly, vertical guiderails 610 are attached to the trailer walls adjacent the corners of the rear platform arrangement 520. Each of the corners of the vertically moveable rear platform 522 are connected to a position sensor, for example a potentiometer which measure linear position. A potentiometer of the type known as the Compact String Pot SP1® sold by Celesco Transducer Products Inc. of Chatsworth, Calif., United States of America can be used to determine linear position up to a distance of 1200 mm (approx). By determining the linear displacement of each corner of the platform relative a fixed datum, for example the floor of the trailer, the regulator valves for the airbags can be controlled appropriately to ensure level elevation or descent of the platform arrangement 520. If, for some reason, one corner of the platform has ascended more slowly than the rest then the position sensor will determine whether that corner has fallen behind and the control unit which controls the regulator valves will instruct the regulator valve of the airbag beneath that corner to allow more air into that airbag, thus remedying the imbalance.
The vertically moveable rear platform 522 includes a pneumatically operated spigot 622 which in the position shown in
As shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 0419765.3 | Sep 2004 | GB | national |
| 0421670.1 | Sep 2004 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB05/03410 | 9/5/2005 | WO | 8/24/2007 |
