GB2399545A - Trailer with a load-carrying well - Google Patents

Abstract

A vehicle trailer includes a well 3 between the front and rear sections of the trailer. A number of vertically-moveable platforms 4-6 are located in the well and may be moved between an upper position (Figure 1A) and a lower position (Figure 1D). Each platform is mounted on support members carried by the sidewalls of the well. The support members may be in the form of flexible straps. Cargo 7, such as pallets or roll cages, is loaded into the front of the trailer followed by further cargo 8 lowered into the well section. Support bars 10 are provided to enable further loading of cargo 9. The support bars extend across the width of the trailer and are supported at their ends by the walls of the trailer. The longitudinal walls of the well section may be defined by sheet members fixed together by an insulating layer to define a load-bearing laminated beam. An alternative arrangement includes a load-carrying platform located on the rear section of the trailer that may be raised on a support and displaced over the well.

Description

1 2399545

VEHICLE INCORPORATING A LOAD CARRYING WELL

The present invention relates to a vehicle incorporating a load-carrying well.

Vehicles incorporating load-carrying wells are known. For example, published International Application No. WO 01/62542 describes vehicles including trailers having a front section defining a front load-carrying floor, a rear section defining a rear load-carrying floor, and a central well section located between the front and rear sections. Arrangements are provided to enable payload to be lowered into the central well section. In use, additional payload can be loaded into the trailer by supporting payload in two layers, one lowered into the well and one located above the well.

In conventional trailers, structural strength is normally provided by a pair of beams extending along the full length of the trailer, those beams supporting a flat load- bearing floor. Clearly if a well section is provided which must be open to enable for example pallets to be lowered into it the conventional simple beam frame cannot be provided as those beams would extend across the well. Structural strength must therefore be provided by structural members extending along the longitudinal sides of the well and the above mentioned published specification shows how this can be achieved in general terms by providing beams extending along the longitudinal sides of the trailer, those beams providing the central section extending downwards at the sides of the well section. Such beam arrangements necessarily must be substantial to provide the necessary structural strength and must therefore either make a significant contribution to the overall width of the vehicle or extend beneath the well and therefore significantly limit the depth of the well.

The above published patent also describes various arrangements for lowering payload into the central well section of a trailer. These arrangements include vertically displaceable platforms which may be raised and lowered within the well section.

Although not shown in detail, the platforms are mounted on vertically extending hydraulic actuators. Such hydraulic actuators necessarily occupy a significant amount of space on either side of the well. This limits the dimensions of the well for a given outer dimension for the trailer.

Conventional trailers have been designed to comply with accepted dimensional requirements in terms of width, height and length. Payloads are generally carried on pallets the dimensions of which have been designed to fit within vehicles having standard-dimension load-carrying compartments. It would be impractical to expect users to accept a vehicle not capable of receiving standard-sized pallets and accordingly vehicle designers are constrained as to the extent to which equipment mounted on trailers can project into the standard load-carrying space. This becomes a major problem when considering thermally insulated vehicles large numbers of which are now used for the distribution of for example food products. Thus in trailers incorporating central well sections the mechanisms used for elevating load-carrying platforms within the well sections cannot project to a significant extent inwardly from the vehicle walls. Similarly, the structural integrity of the well sections must be achieved without reducing the width of the available internal space. Finally, in order for the well sections to be of sufficient depth to enable standard pallets to be stacked one above the other in the well section the depth of the well section must be as large as possible. This is a particular problem in refrigerated vehicles where generally chilled air is distributed from a front section of the trailer through the space above the payload and therefore sufficient space must be left open above the well for the efficient circulation of chilled air even if two layers of pallets are stacked one above the other in the well section.

It is an object of the present invention to provide arrangements which make it possible to manufacture trailers and other vehicles incorporating well sections capable of receiving payloads of standard dimensions.

According to the present invention, there is provided a vehicle comprising a load- carrying weld and at least one load-carrying platform which is vertically displaceable within the well to enable a payload to be lowered into the well, wherein the or each platform is mounted on support members carried by sidewalls of the well, and means are provided for moving the or each platform relative to the sidewalls on the support members.

The support members may be flexible, for example being formed from straps of the type generally used for load restraint or the like. Such support members can be relatively thin, for example only a few millimetres, and therefore do not occupy much space inside the load-carrying well. Thus by suspending a platform on such flexible support members there is no significant reduction in the available space within the well section.

The flexible support members may extend downwards from anchorage points mounted on the well sidewalls. For example the well sidewalls may be defined by sidewall plates. Each flexible member may be connected to a support plate secured to the sidewall plate, for example by arranging the support member so as to define a loop extending around the support plate. The positions of the support plates may be adjustable on the sidewalls to adjust the effective length of the flexible support members.

The flexible support members may be coupled to means carried by the platform for drawing the flexible members into a space beneath the platform. For example, each flexible member may extend around a roller carried by the platform and may be connected to a hydraulic actuator carried by the platform, the hydraulic actuator being extensible in a direction parallel to an upper surface of the platform. Hydraulic fluid may be supplied to the platform actuator by a piston and cylinder coupling one end of which is mounted on the platform and the other end of which is mounted on the well.

Arranging hydraulic actuators in the floor of the platform results in a very efficient utilisation of the available space. This in turn makes it possible to lower a payload into the well to a depth such that there is still plenty of space above the payload for the circulation of chilled air in a refrigerated trailer.

Each platform may support projections received within vertical guide tracks fitted to the well walls. The guide tracks ensure the appropriate positioning of the platform within the well. In addition, means may be provided for obstructing upper ends of the guide tracks so that, after a platform has been raised to an elevated position, the guide tracks may be obstructed so that the platform will be prevented from moving downwards from the elevated position. Thus an inherently safe mechanical structure is provided which will protect against accidental lowering of the platforms in the event for example of hydraulic failure.

The present invention also provides a vehicle comprising a front section defining a load-carrying front floor, a rear section defining a loadcarrying rear floor, and a well section located between the front and rear sections, the well section including a thermally insulated well floor, thermally insulated transverse sidewalls extending downwards from the front and rear floors to the well floor, and thermally insulated longitudinal sidewalls extending between the well floor and the front and rear sections, wherein at least an upper portion of each longitudinal sidewall comprises inner and outer load-bearing sheet members separated by an insulating layer, the sheet members being fixed to the insulating layer to define a load-bearing laminated beam extending between the front and rear sections.

The load-bearing laminated beam can provide great structural strength without occupying a large space in the horizontal direction and whilst maintaining the integrity of the thermally insulated wall in which the laminated beam is incorporated.

Once again therefore this arrangement ensures that the space within the well into which payload can be lowered is not restricted.

Each longitudinal sidewall may include a rectangular outer frame formed from sheet members, at least an upper part of that frame being fixed to the insulating layer to define the load-bearing laminated beam. Of course other sections of the rectangular outer frame may also be assembled to form laminated beams as desired.

The sheet members may be secured by screws driven into the insulating layer, the screws on opposite sides of the insulating layer being offset relative to each other to ensure their separation by a material forming the insulating layer. Thus the insulating characteristics of the beam are not compromised as a result of the screws forming thermal bridges through the insulating layer. The insulating layer may include a layer of polycarbonate into which the screws are driven.

The front and rear sections of the vehicle may comprise longitudinally extending frame beams connected to transverse frame beams, the transverse frame beams being secured to the transverse sidewalls of the well section. The transverse frame beams may be connected to an inner transverse wall of the well by thermally insulating connectors, for example connectors defined by spaced apart plates extending from the transverse frame beam and the well wall, the plates being interconnected by a bolt passing through the apertured plates, and the bolt being thermally insulated from the plates.

The present invention also provides a vehicle comprising a first section defining a load-carrying front floor, a rear section defining a rear floor, a well section located between the front and rear sections, and means for lowering payload into the well section, wherein a support platform is vertically displaceable above the rear floor between raised and lowered positions, and the support platform carries a 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.

Thus a simple and robust mechanism is provided which enables payload to be lifted up and moved over the well section. This is achieved by using low-profile supports in the sidewalls, avoiding any significant reduction in the internal width of the vehicle available for receiving payload.

Rollers may be interposed between the support platform and the loadcarrying platform and between the sidewall support and the load-carrying platform. For example, the load-carrying platform may support rollers along its longitudinal edges which run on tracks extending along longitudinal edges of the support platform. The sidewall supports may include rollers on which formations on the longitudinal edges of the loadcarrying platform roll. The sidewall support rollers may be mounted on plates defining inner sidewalls of the well section.

The support platform may carry a drive motor for displacing the loadcarrring platform over the well. The drive motor may drive a roller which rotates above an axis transverse to the vehicle, which projects above an upper surface of the support platforms and which frictionally engages the surface defined by the load-carrying platform such that rotation of the roller drives the load carrying platform relative to the support platform.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures IA to ID illustrate the loading of pallets into a first trailer embodying the present invention which is intended to transport standard British pallets loaded onto the trailer by a forklift truck; Figures 2A to 2F illustrate the loading of standard European pallets onto a trailer embodying the present invention; Figure 3A to 3F illustrate the loading of roll cages onto a trailer embodying the present invention; Figures 4A to 4F illustrate the loading of standard British pallets onto a further trailer embodying the present invention; Figures 5A and 5B illustrate a mechanism for adjusting the floor level of a rear trailer section in an embodiment of the present invention; Figures 6 to 15 illustrate details of a rolling and vertically moveable platform which may be embodied in a trailer in accordance with the present invention; Figure 16 illustrates sub assemblies which may be incorporated in a trailer embodying the present invention; Figures 17, 18 and 19 illustrate details of one subassembly shown in Figure 16; Figures 20 to 34 illustrate details of a well subassembly shown in Figure 16; Figures 35 to 38 illustrate details of bracing and guide assemblies incorporated in the well shown in Figure 16; Figures 39 to 42 illustrate details of platforms which may be raised and lowered within the well; Figures 43 and 44 illustrate platform suspension arrangements used within the well; Figures 45 to 47 illustrate a hydraulic supply connection for coupling hydraulic fluid to actuators within the platforms; Figures 48 to 51 illustrate details of platform support arrangements in the sidewalls of the well structure; and Figures 52 to 55 illustrate support bar assemblies which may be clipped to the sidewall arrangements illustrated in Figure 48.

Referring to Figures lA to ID, this illustrates the loading of cargo on pallets into a trailer in accordance with a first embodiment of the present invention. A front section of the trailer supports a conventional towing hitch 1 and a rear section of the trailer supports three axles each carrying wheels 2. A well 3 is defined between the front and rear sections of the trailer and three platforms 4, 5 and 6 may be moved vertically within the well between an upper position as shown in Figure 1A and a lower position as shown in Figure 1 D. As shown in Figure 1A, initially cargo is loaded into the trailer so that four pairs of pallets 7 occupy the front section of the trailer. A further pair of pallets 8 are then loaded onto the platform 4. The platfonn 4 is then lowered into the well 3, and a further pair of pallets 9 are mounted on support bars 10 inserted above the pallets 8, the support bars extending across the width of the trailer and being supported at each of their ends by the walls of the trailer. A further pair of pallets 11 are then loaded onto platform 5 to result in the configuration shown in Figure 1B.

The platform 5 is then lowered and a further pair of pallets 12 are mounted on support bars 13 extending across the width of the trailer. A further pair of pallets 14 are then loaded onto the platform 6. The result is illustrated in Figure 1 C. To complete the loading process, the platform 6 is lowered into the well, two pairs of pallets 15 and 16 are mounted above the pallets 14 on support bars 17, and five further pairs of pallets 18 are loaded into the rear section of the trailer. The assembly is then fully loaded.

In an alternative embodiment of the invention illustrated in Figures 2A to 2F, once again the illustrated trailer comprises a front section and a rear section separated by a well 3 within which three vertically moveable platforms 4, 5 and 6 are located.

Initially the platforms 4, 5 and 6 are aligned with the floor of the front section of the trailer and with an upper surface of a vertically and horizontally moveable platform 19 supported in the rear section of the trailer. The platform 19 is mounted on a support platfonn 20, the support platform 20 being moveable in the vertical direction so as to elevate the platform 19, and the platform 19 being displaceable in the horizontal direction after the support platform 20 has been elevated.

As shown in Figure 2B, initially ten pairs of pallets 21 are loaded into the trailer. The platforms 4, 5 and 6 are then lowered as shown in Figure 2C, and the support platform is elevated as shown in Figure 2D. The platform 19 is then rolled forward onto supports provided in the trailer walls and the platform support 20 is lowered so that an upper surface defined by the platform is aligned with a short floor surface 22 at the entry end of the trailer. Further pallets 23 are then loaded into the rear section of the trailer.

Figures 3A to 3F illustrate an arrangement similar to that of Figures 2A to 2F but in which only two platforms 24 and 25 are provided within well 3. The illustrated configuration is appropriate for the loading of roll cages rather than pallets. As in the case of the embodiment of Figures 2A to 2F, platforms 24 and 25 are initially elevated and the trailer is filled with roll cages. The platforms 24 and 25 are then lowered (Figure 3C) and roll cages loaded into the rear section of the trailer are then raised and moved forward over the platforms 24 and 25. The final loading of the trailer is then completed by loading roll cages into the rear section of the trailer.

Referring now to Figures 4A to 4F, this shows an arrangement very similar to that illustrated in Figures 2A to 2F, but whereas the arrangement of Figures 2A to 2F is appropriate for carrying pallets of standard European dimensions the arrangement of Figures 4A to 4F is designed for carrying pallets having the dimensions of standard British pallets. Once again, in the embodiment of Figures 4A to 4F pallets initially loaded in the rear section of the trailer are raised and pushed forwards over previously loaded pallets which have been lowered into the well 3.

Details of the structures and mechanisms which make it possible to manufacture trailers capable of the operations described with reference to Figures I to 4 are given in the following description. The first detail to be described with reference to Figures 5A and 5B is that which enables the combination of platform 19 and support platform of Figures 2A to 2F to be initially positioned so that the upper surface of platform 19 is aligned with floor section 22 (see Figure 2A) and then for the upper surface of support platform 20 to be aligned with floor section 22 (Figure 2E).

Referring in detail to Figures SA and 5B, the rear section of the trailer comprises beams 26 supporting an insulated floor 27 and extending between insulated sidewalls 28. The support platform 20 (see Figures 2A to 2F) is mounted on vertically displaceable support beams 29 above the floor 27 such that the support platform 20 can be moved in the direction indicated by arrows 30. Two pairs of blocks 31 are supported on a slide above the floor 27 and coupled to a hydraulic actuator 32 so as to be displaceable from the position shown in Figure SA to a position (not shown) in which the blocks are located vertically beneath the beams 29.

When the platform 19 is in its initial position as shown in Figure 2A, the blocks 31 are in the position shown in Figure SA so that the beams 29 can be lowered into contact with the floor 27. After the support platform 20 has been raised and the platform 19 has been displaced over the well of the trailer, the blocks 31 are moved to the left in Figure SA until they are located beneath the beams 29. The support platform 20 is then lowered until the beams 29 rest on the blocks 31. As a result the upper surface of the support platform 20 now assumes the vertical position initially assumed by the upper surface of the platform 19, that is aligned with the surface 22 (Figure 2E). Thus a simple mechanism is provided which ensures that the surface onto which a forklift truck or the like has to be driven is vertically aligned with the edge of the trailer floor adjacent the entry end of the trailer.

Vertical displacement of the support platform 20 may be achieved using hydraulic actuators (not shown) extending vertically beneath the floor 27, or any other convenient means, for example and arrangement similar to that described below which is used to vertically displace platforms within the well section of the trailer.

Referring now to Figures 6 to I S. details of one arrangement for enabling the platform 19 of Figures 2A to 2F to be pushed forward within the trailer will be described.

Figure 6 shows the upper horizontally displaceable platform 19 after it has been pushed forward partially relative to the lower support platform 20. Each edge of the platform 19 carries a row of rollers 33 (Figure 13) which are aligned with a flat roller track 34 extending along a respective edge of the support platform 20. The rollers 33 are carried in a support beam 35 connected to an outwardly projecting angle 36. The lower edge of angle 36 is intended to run on rollers provided in the sidewalls of the trailer above the well. The support platform 20 is reinforced by side beams 37 located beneath the tracks 34.

Figure 11 shows one edge of the platform 19 after it has been displaced from its initial position above the support platform 20 onto supports provided on the trailer walls. A plate 38 secured to an inner wall of the trailer carries rollers 39 which are located behind a cover plate 40. A series of rollers is provided along each side of the trailer wall above the well so as to provide a roller track onto which the angle 36 supported by the platform 19 can be displaced. When the platform 19 is fully supported on the rollers 39 the rollers 33 carried by support beams 35 are not in contact with any support surface.

Various mechanisms may be provided for applying a force to the platform 19 so as to displace it on and off the support platform 20. Simple motor and chain drive assemblies could be provided in the support platform 20 but an alternative arrangement is illustrated in Figures 6 to 10 in the form of a motor 41 driving a wheel 42 which projects upwards through an aperture in the support platform 20 as shown in Figure 8. The wheel 42 is positioned at the front edge of the support platform 20 so as to bear against the underside of a beam 43 extending along the length of the platform 19. The beam 43 supports a rubber strip 44 against which the wheel 42 bears. There is good frictional engagement between the wheel 42 and the strip 44 and thus simply by driving the motor 41 the platform 19 can be driven as appropriate on to and off the support platform 20.

Referring now to figure 16, this illustrates the structure of the frame which supports the components of the trailer illustrated in for example Figures 2A to 2F. A front subassembly 45 is coupled to a well assembly 46 which in turn is coupled to a rear subassembly 47 carrying the running gear. To assist understanding, the subassemblies 45 and 47 are shown spaced from the well assembly 46 in Figure 16 but it will be appreciated that the three main components will be united as indicated by arrows 48.

Details of the front subassembly 45 as shown in Figure 16 are illustrated in Figures 17, 18 and 19. The front subassembly comprises a pair of beams 49 of I section which are welded to a box section beam 50, the box beam 50 in turn being connected to vertically extending angle members 51. The towing hitch 1 will be connected in the position shown in Figure 18 to an appropriate support structure extending between the beams 49, that support structure not being shown in Figure 17.

Figure 20 to 34 illustrate the structure of the well assembly 46 of Figure 16.

Figure 20, 21 and 22 illustrate the construction of an underlying well frame from eight lengths of angle, comprising lengths 52 which extend along the lower side edges of the well, lengths 53 which extend along front and rear lower edges of the well, and lengths 54 which extend upwards from each of the four corners of the rectangular frame. The framework of Figures 20, 21 and 22 is then supplemented by an assembly of plates shown in Figure 23 and 24, the angles 52, 53 and 54 being shown in broken lines in Figures 23 and 24. The assembly of plates comprises a relatively wide upper plate 55, vertically extending side plates 56 and lower plate 57.

The outer frame structure described with reference to Figures 20 to 24 receives an inner well wall structure as illustrated in Figures 25 to 30. The underside of the floor of the inner well structure comprises a Imm thick steel sheet 58 (Figures 28 and 30) which overlaps the inwardly extending edge of the frame that is made up from the angles 52 and 53 (Figure 20). A 4mm thick layer of ply 59 is laid on the sheet 58, then a three layer section of insulating Styrofoam is laid on the ply 59, the three sheets being labelled 60, 61 and 62. The foam layers 60 to 62 extend across the full width of the base of the well between timber spacers 63 resting on the frame members 52, 53.

A cover layer in the form of a further lmm thick steel sheet 64 and a further 4mm thick ply sheet 65 extends over the upper layer 62 and over the timber spacers 63.

Mounted on the steel sheet 64 is a further frame made of angle 66 the upwardly extending parts of which support a steel plate 67 which is 6mm thick.

As shown in the longitudinal section of Figure 27, the front and rear inner well plates 67 extend vertically upwards to end flush with the level of the front section of the trailer floor. In contrast, as shown in the transverse section of Figure 29, the plates 67 which extend along the sidewalls of the well extend above the level of the trailer floor the position of which is represented by the broken line 68 in Figure 29 and by the upper surface 69 of the front floor section 70 of the trailer as shown in Figure 27.

The sidewalls of the well are covered with a lmm thick sheet of steel 71 as best indicated in Figure 31. The laminated assembly shown in Figure 31 provides structural strength to the well such that the well can support the loads transmitted through it between the front and rear trailer sub frame assemblies 45 and 47 (see Figure 16). Figure 31 shows that the upper plate 55 (Figures 24) is covered by the steel sheet 71 and defines a large number of counter sunk holes through which screws 72 extend. Similarly, the vertically extending steel sheet 6 defining a sidewall of the well defines a series of countersunk holes receiving screws 73. Sandwiched between the plates 67 and 55 is a three-layer body of thermal insulation made up from a 20mm thick layer 74 of high density load bearing Styrofoam, a lOmm thick layer 75 of polycarbonate, and a further 20mm thick layer 76 of high density load bearing stryofoam. The screws 72, 73 ensure that the multi-layer assembly is locked together without the screws providing a thermal bridge between the inner and outer skins of the well. Thus thermal insulation is maintained whilst at the same time the assembly provides the necessary structural strength to the overall trailer frame.

As can be appreciated best from Figure 29, the sidewalls of the well which extend above the trailer floor level indicated by line 68 are made up in part of a vertical extension of the lOmm thick polycarbonate layer 75 shown in Figure 31. The detail of this upper section of the well sidewalls is shown in Figure 32. Again in Figure 32 the broken line 68 indicates the trailer floor level.

The polycarbonate 75 is sandwiched between a 20mm thick layer 77 of high density load bearing Styrofoam and a 9mm thick sheet of plywood 78. A further layer 79 of 20mm thick high density load bearing Styrofoam is located on the outside of the ply 78 and inside a lmm thick outer skin 80 of the trailer.

Referring to Figures 33 and 34, this shows the interconnection between the well assembly and the rear subassembly 47 (see also Figure 16). The rear subassembly 47 comprises longitudinally extending beams 81 which are secured to a box section cross beam 82 from the ends of which angles 83 extend vertically downwards. The beam 82 is connected to the frame of the well assembly 46 by connectors 84 details of which are shown in Figure 34.

Referring to Figure 34, spaced apart stainless steel brackets 85 are mounted on the well frame. A stainless steel bracket 86 is mounted on the cross beam 82. The brackets 85 and 86 define apertures which received insulating collars 87 through which a bolt 88 extends. Insulating washers 89 maintain separation between the brackets 85, 86 and the bolt 88. Thusthe well frame and rear subassembly 47 are securely interconnected but thermally insulated from each other. Similar connectors 84 are provided between the well frame and front sub frame 45 (see figure 16). In addition the angles 51 and 83 are bolted to the well frame. As a result the overall assembly is extremely robust and well able to cope with the bending moments that will be applied to the trailer frame in use.

Within the well assembly as described above additional components are provided for guiding and separating the vertically moveable platforms which are received within the well. In the described embodiment there are three vertically moveable platforms in which case there are guide structures at both the front and rear ends of the well and two guide structures spaced apart along the length of the well. Figures 35, 36 and 37 illustrate one of the two structures which are spaced apart along the length of the well.

Each of these structures provides additional strength to the well as it in effect forms a brace extending across the width of well.

Referring to Figures 35 to 37, the bracing sections comprise bottom plates 90 which will be welded to the inner skin of the well floor, upstanding plates 91 which extend a short distance vertically from the plates 90, and side members each made up from an assembly of four box sections 92, 93, 94 and 95. Slots 96 are defined between the box sections 94 and 95 to provide guides for adjacent vertically moveable platforms.

The box sections 92 and 93 will when installed be welded to the inner skin of the well body. Bracing frames comprising horizontal beams 97, diagonal beams 98 and vertical plates 99 provide appropriate bracing to the assembly. Plates 100 provide a surface to which a cross plate (not shown) can be bolted so as to define a narrow section of the trailer floor between adjacent moveable platforms when the platforms are flush with the front and rear sections of the trailer floor.

Referring to Figure 38, this shows a guide structure one of which is located inside both the front and rear walls of the well. It also shows a platform locking mechanism which will secure the platforms in the raised position even in the event of the failure of the associated control system. In Figure 38, vertically extending components similar in structure to the box sections 92 to 95 of Figure 36, define vertically extending slots 101 which serve as guides for projections extending from the adjacent moveable platform. At the top of each of these slots there is a spaced-apart pair of plates over which is slideable a locking member 102 carried by a locking bar 103 the position of which is controlled by a hydraulic actuator 104. The configuration at the upper end of each slot 101 is thus the same as the configuration at the top of each slot 96 of the intermediate bracing assemblies shown in Figure 35. With the locking members 102 in the position shown in Figure 38, projections on an adjacent platform can be carried upwards to a position above the locking member 102, at which point the actuator 104 can be energised so as to move the locking member 102 over the top of the slot 101. Thereafter the platform cannot be lowered until the locking bar 103 has been retracted to the position shown in Figure 38. It will be appreciate that a locking mechanism equivalent to that shown in Figure 38 is provided at each end of the well and on each of the intermediate bracing assemblies such as that shown in Figure 35.

Referring now to Figures 39 to 41, this shows the configuration of one of the three platforms which is vertically displaceable within the well. Each platform comprises an upper plate 105 which when the platform is in its locked raised position is aligned with the front and rear sections of the trailer floor. The upper plate is connected by reinforcing plates 106 to cross members 107 the ends of which support projections in the form of plates 108 with bracing members 109. The projections 108 are located so as to run in the slots 101 in the end guide members (see Figure 38) or the slots 96 in the intermediate bracing members (Figures 35).

Referring now to Figures 42 to 44, this illustrates the mechanism used for elevating one of the three platforms received within the well. As shown in Figure 39, each platform incorporates six reinforcing plates between which five elongated spaces 110 to 114 are defined. The central space 112 is shown in Figure 42 as being empty but in fact receives a hydraulic connection assembly to be described below. The two outer most spaces 110 and 114 receive hydraulic actuators which are used to control the elevation of one side of the platform, whereas the two spaces] 1] and 113 receive hydraulic actuator assemblies which control the elevation of the other side of the platform. Each of the four hydraulic actuator assemblies is connected to a flexible strap which extends from the hydraulic actuator around a respective roller 115 and upwards across the inner face of the inner wall of the well to an anchorage point] 16 above the vehicle floor level which is indicated by a line 1] 7.

With the actuators fully extended as shown in Figure 43, the platform is suspended a short distance above the base of the well. If the actuators are then energised so as to pull the actuators inwards, thereby dragging the straps progressively further into the moveable platform, the platform is pulled up until it assumes the position shown in Figure 44. Thus all of the active hydraulic components are carried within the platform and there are no complicated mechanical linkages. The suspension of the moveable platform in this manner in combination with the simple guide channels engaged by the projections]08 of Figure 39 ensure that the platforms can be reliably raised and lowered. The locking mechanism described with reference to Figure 38 ensures that once the platforms have been raised they can be locked in the raised position without requiring continuing energisation of the hydraulic actuators.

It is of course necessary to deliver hydraulic fluid to the actuator shown in Figure 42.

This is achieved by the mechanism illustrated in Figures 45 to 46 which is received in the space 112 beneath the platform.

Referring to Figure 45, this shows a bottom mounting plate 118 which in practice would be secured to the inside of the inner floor of the well assembly. A hydraulic feed 119 delivers pressurised hydraulic fluid to a pivotally supported t-connector 120 in communication with the inside of a hydraulic cylinder 121 and from that cylinder through a piston 122 to a further hydraulic t-connector 123. The hydraulic t- connector 123 is mounted on a plate 124 fixed to the moveable platform in the space 112 (Figure 42). With the platform in the lowered position (Figure 43) a side view of the assembly of Figure 45 is as represented in Figure 46. As the platform rises, the plate 124 is pulled upwards with the platform so that the assembly assumes the configuration shown in Figure 47. The piston and cylinder arrangement 121, 122 is arranged such that no axial force is delivered by the hydraulic assembly of Figures 45 to 47 which therefore simply acts a mechanism for delivering pressurized hydraulic fluid to the actuators mounted on the platform.

Referring now to Figures 48 to 51, Figure 48 is an elevation of a steel plate which defines the inner sidewall of the well, anchorage points for the straps which support the three platforms, and recesses for receiving the ends of support bars to be described below. Thus the plate shown in Figure 48 corresponds to the plate 67 shown in Figure 30.

Referring to Figure 48, the plate 67 defines six apertures 125 edges of which define rows of offset screws holes 126 to which strap supports 127 can be secured. The strap supports 127 are in use inserted in permanent loops formed in the ends of the platform straps. As shown in Figure 50, the supports 127 also define offset apertures 128. The apertures 126 and 128 are provided to enable the positioning of the supports 127 at different locations along the length of the apertures 125 so as to compensate for any manufacturing tolerances when the straps that are used to support the platforms are manufactured. The pitch between the apertures 128 is twice the offset between the sets of apertures on opposite sides of the support, the same relationship applying to the offset between the apertures 126 on opposite sides of the same aperture 125. This means that by appropriate reversal of the supports 127 the vertical position of the supports 127 can be adjusted by half the pitch of the spacing between adjacent apertures 128. Thus when the movable platforms are being installed the platform support straps are pulled tight and the support plates 127 are fitted in as high a position as is possible given the length of the associated straps. Appropriate distribution valves will also be required in the hydraulic circuits (assuming that all the hydraulic actuators and the platforms are driven from a single hydraulic source) so as to ensure that the platforms remain substantially horizontal as they are elevated.

The plate 67 also defines apertures 129 across each of which is welded a plate 130.

Thus the plates 130 extend across a lower section only of the apertures 129.

Insulation immediately behind the apertures 129 is also cut away to enable a support bar end to be pushed a short distance through the aperture 129.

Figures 52 to 55 illustrate the manner in which a cargo support bar may be engaged with the plates 130 extending partially across the apertures 129. Figure 52 shows a support bar 131 which is a simple square box section and supports a hook member on each of its ends. The hook member is defined by an end plate 132 which closes off the end of the box section, a spacer plate 133, and a hook plate 134, the hook plate 134 being secured to the space plate 133 so as to define a slot 135 with the end plate 132. The hook assembly shown in Figure 52 is intended to be insertable through the section of an aperture 129 as shown in Figure 53 above one of the plate 130 which partially closes off the aperture 129.

Figure 54 illustrates the positioning of a support bar as shown in Figure 52 so that the support bar extends across the well between two of the apertures 129 on opposite sides of the well. Sides of the well are indicated by broken lines 136 and the recess located behind the apertures 129 is indicated by the broken line 137. Initially the support bar is positioned with both of its ends extending into the facing recesses above the plates 130 as shown in Figure 54. The support bar is then pulled downwards to the position shown in Figure 55 so that the hook plates 134 engage over and in effect lock relative to each other the plates 130 which are located on opposite sides of the wells. Not only does the positioning of a support bar in this manner enable the positioning of cargo on the support bars in the manner described with reference to Figures 1A to ID, but in addition the support bars provide further bracing between opposite sides of the well assembly.

It will be appreciated that in embodiments of the invention in which cargo can be loaded onto a platform such as the platform 19 of Figure 2 for subsequent movement over the well it will not be necessary to provide support bars. However in some circumstances it may be advantageous to fit a trailer with a platform such as the platform 19 of Figure 2 and also provide the facility to receive support bars such as those illustrated in Figures 52 to 55 so as to provide maximum flexibility to a vehicle operator.

Claims (27)

1. A vehicle comprising a load-carrying well and at least one loadcarrying platform which is vertically displaceable within the well to enable a payload to be lowered into the well, wherein the or each platform is mounted on support members carried by sidewalls of the well, and means are provided for moving the or each platform relative to the sidewalls on the support members.

2. A vehicle according to claim 1, wherein the or each platform is suspended on a plurality of flexible support members.

3. A vehicle according to claim 2, wherein each flexible support member extends downwards from a respective anchorage point mounted on a sidewall of the well.

4. A vehicle according the claim 3, wherein the anchorage points are defined by sidewall plates which form inner walls of the well.

5. A vehicle according to claim 4, wherein each anchorage point comprises a support plate secured to the sidewall plate, the flexible support member defining a loop extending around the support plate.

6. A vehicle according to claim 5, wherein the position of each support plate on the respective sidewall plate is adjustable to adjust the effective length of the flexible support member looped over it.

7. A vehicle according to any one of claims 2 to 6, wherein each flexible member is in the form of a strap.

8. A vehicle according to any one of claims 3 to 7, wherein each flexible member is connected to means carried by the respective platform for drawing the flexible member into a space beneath the platform.

9. A vehicle according to claim 8, wherein each flexible member extends around a roller carried by the platform and is connected to a hydraulic actuator carried by the platform, the hydraulic actuator being extensible in a direction parallel to an upper surface of the platform.

10. A vehicle according to claim 9, wherein the hydraulic actuator is connected to a hydraulic fluid supply mounted on the well through an extendible piston and cylinder coupling one end of which is mounted on the platform and the other end of which is mounted on the well.

11. A vehicle according to any preceding claim, wherein the or each platform supports projections received within vertical guide tracks fitted to the well walls.

12. A vehicle according to claim 11, wherein means are provided for obstructing upper ends of the guide tracks to lock the or each platform in an elevated position.

13. A vehicle comprising a front section defining a load-carrying front floor, a rear section defining a load-carrying rear floor, and a well section located between the front and rear sections, the well section including a thermally insulated well floor, thermally insulated transverse sidewalls extending downwards from the front and rear floors to the well floor, and thermally insulated longitudinal sidewalls extending between the well floor and the front and rear sections, wherein at least an upper portion of each longitudinal sidewall comprises inner and outer load-bearing sheet members separated by an insulating layer, the sheet members being fixed to the insulating layer to define a load- bearing laminated beam extending between the front and rear sections.

14. A vehicle according to claim 13, wherein each longitudinal sidewall includes a rectangular outer frame cornier from sheet members, at least an upper part of the frame being fixed to the insulating layer.

15. A vehicle according to claim 13 or 14, wherein the sheet members are secured by screws driven into the insulating layer, the screws on opposite sides of the insulating layer being offset relative to each other to ensure their separation by material forming the insulating layer.

16. A vehicle according to claim 13, 14 or 15, wherein the insulating layer includes a layer of polycarbonate.

17. A vehicle according to any one of claims 13 to 16, wherein the front and rear sections comprise longitudinally extending frame beams connected to transverse frame beams, the transverse frame beams being secured to the transverse sidewalls of the well section.

18. A vehicle according to claim 17, wherein the transverse frame beams are connected to an inner transverse wall of the well by thermally insulating connectors.

19. A vehicle according to claim 18, wherein each connector is defined by spaced apart plates extending from the transverse frame beam and the well wall, the plates being interconnected by a bolt passing through the apertured plates, and the bolt being thermally insulated from the plates.

20. A vehicle comprising a first section defining a load-carrying front floor, a rear section defining a rear floor, a well section located between the front and rear sections, and means for lowering payload into the well section, wherein a support platform is vertically displaceable above the rear floor between raised and lowered positions, and the support platform carries a 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.

21. A vehicle according to claim 20, wherein rollers are interposed between the support platform and load-carrying platform and between the sidewall supports and the load-carrying platform.

22. A vehicle according to claim 21, wherein the load-carrying platform supports rollers along its longitudinal edges which run on tracks extending along longitudinal edges of the support platform.

23. A vehicle according to claim 21 or 22, wherein the sidewall supports include rollers on which formations on the longitudinal edges of the loadcarrying platform roll.

24. A vehicle according to claim 23, wherein the sidewall support rollers are mounted on plates defining inner sidewalls of the well section.

25. A vehicle according to any one of claims 20 to 24, wherein the support platform carries a drive motor for displacing the load-carrying platform over the well.

26. A vehicle according to claim 25, wherein the drive motor drives a roller which rotates about an axis transverse to the vehicle, which projects above an upper surface of the support platform, and which frictionally engages a surface defined by the load- carrying platform such that rotation of the roller drives the load- carrying platform relative to the support platform.

27. A vehicle substantially as hereinbefore described with reference to the accompanying drawings.