AU2009100674B4

AU2009100674B4 - A ramp arrangement for a land vehicle

Info

Publication number: AU2009100674B4
Application number: AU2009100674A
Authority: AU
Inventors: Denis Di Pasquale
Original assignee: TUFF TRAILERS QLD Pty Ltd
Current assignee: TUFF TRAILERS (QLD) Pty Ltd
Priority date: 2008-11-26
Filing date: 2009-07-13
Publication date: 2010-01-14
Anticipated expiration: 2016-11-26
Also published as: AU2009100674A4; AU2008249215A1

Description

1 A RAMP ARRANGEMENT FOR A LAND VEHICLE FIELD OF THE INVENTION 5 This invention relates to a ramp arrangement for a land vehicle. This invention also extends to a vehicle having such a ramp arrangement. This invention relates particularly but not exclusively to a ramp arrangement for a trailer, e.g. a heavy duty trailer. This invention also relates particularly to a heavy 10 duty trailer or semi-trailer including the ramp arrangement. It will therefore be convenient to hereinafter describe this invention with reference to this example application. At the same time however it should be realized that the invention is capable of broader application. For example this invention could equally be applied to a ramp arrangement for a vehicle having its own motive power such as 15 a truck or the like. It does not need to be a trailer that is coupled to a prime mover. BACKGROUND TO THE INVENTION Heavy duty trailers for over the road hauling of heavy loads are a ubiquitous 20 feature of modern industrialized economies. In particular trailers can be used for transporting equipment for moving across the ground such as trucks, cars, tractors, bobcats, forklift trucks, front end loaders, bull dozers and other ground moving equipment. 25 Such ground engaging vehicles, are generally carried or supported on the deck of a heavy trailer when they are moved from one location to another. During operation it is necessary to load the vehicles on the deck of the trailer and also to unload the vehicles from the deck of the trailer. This can conveniently be done by providing a driving ramp arrangement at the tail end or rear end of the deck of the 30 trailer. The load vehicle can be driven up the ramp to load it on the deck of the trailer and can be driven down the ramp to unload it from the deck of the trailer.

2 In the prior art it has been known to provide two parallel track ramps, one towards each side of the vehicle, e.g. trailer, to form the driving ramp arrangement. One such example is shown in Fig 1 of the drawings. As shown the two parallel track ramps are operatively able to pivot between a downwardly inclined operative 5 position extending rearwards away from the vehicle in which they form a ramp up which and down which a vehicle can be moved and a vertically upstanding inoperative (stowed) position or traveling position. When the trailer is in use being towed on a road the ramps are in their inoperative 10 or traveling position. When the trailer is stationary and it is desired to offload vehicles the track ramps are pivoted from the inoperative position down into their operative position. The ramp tracks form a ramp that extends from a deck of the trailer down onto the support surface on which the trailer is supported and load vehicles can be moved off the trailer deck and down onto the support surface and 15 vice versa. A disadvantage of this driving ramp arrangement with the two track ramps is that the two track ramps project vertically upward when the trailer is driven along a road. This arrangement with the upstanding track ramps has a high drag 20 coefficient and causes a high level of drag resistance particularly when the trailer is traveling along the road at normal road traveling speeds. Yet further it requires a significant pivoting action of the bulky track ramps to change the ramp from the upstanding inoperative position to the operative position. The moment applied to the track ramps when they are being lowered into the operative position is clearly 25 substantial. In the current world environment there is a drive to reduce energy consumption and particularly fuel consumption and it would therefore be advantageous to devise a more energy efficient way of providing a trailer with a ramp arrangement 30 for loading vehicles onto the trailer and unloading vehicles from the trailer. It would also be advantageous if an elegant engineering solution could be devised 3 that provided a ramp that was easy and quick to move between the operative and inoperative positions. SUMMARY OF THE INVENTION 5 According to one aspect of this invention there is provided a trailer vehicle that includes: a main load support having a load bearing surface; and a ramp arrangement having a ramp body defining a traverse surface, including 10 one ramp part that is pivotally mounted about a transverse pivot axis towards a rear end of the main load support so that the ramp body is pivotally displaceable about the pivot axis between an operative position in which the traverse surface inclines downwardly away from the main load support and a traveling position in which the traverse surface extends generally in the same plane 15 as the load bearing surface, wherein the one ramp part includes a transversely extending ramp support wall extending down from the ramp body for supporting the ramp platform body on a vehicle support surface when the ramp body is in the operative position; and another ramp part mounted on the one ramp part, wherein the other ramp 20 part undergoes sliding translational displacement relative to the one ramp part in one direction to an extended position to increase the traverse surface of the ramp body whereby to enable the ramp body to extend down to a support surface on which the trailer vehicle is mounted, and wherein the other ramp part undergoes sliding translational displacement in an opposite direction to a retracted position to 25 decrease the traverse surface. The one ramp part may include a generally rectangular ramp platform body, and a hinging arrangement for mounting the ramp platform body about a transverse hinge axis such that it is hingedly displaceable about the hinge axis between said 30 operative position and said traveling position. The one ramp part may further include a ramp platform drive means in the form of at least one hydraulic actuator having a hydraulic housing mounted on the main load support and a ram movably mounted on the hydraulic housing that is drivably coupled to the ramp platform 4 body whereby to pivot the hinging arrangement and the ramp platform body about the hinge axis between the traveling and operative positions. The ramp platform drive means may include two laterally spaced hydraulic actuators mounted between an undercarriage of the trailer vehicle and the ramp platform body. 5 The vehicle may include further drive means for driving the other ramp part between the retracted and extended positions in the form of a hydraulic actuator having a ram housing that is mounted on the ramp platform body, and a ram movably mounted on the ram housing, that is drivably coupled to the other ramp 10 part whereby to drive it between said retracted and extended positions. The transversely extending support wall may have a height that is selected so that the free end of the other ramp part extends down to the support surface, when said one ramp part is in the operative position and the other ramp part is in the extended 15 position, and the support wall may have a height of at least 0.4 m from its lower end up to the traverse surface at the rear end of the ramp platform body. The main load support may include a first locking formation defining a first locking aperture having an axis extending transverse to the length of the main load 20 support, and the ramp platform body may include a second locking aperture having an axis extending transverse to the length of the ramp platform body, and the second locking aperture may be arranged so that it registers with the first locking aperture when the ramp platform body is in the travelling position, and a locking pin may be arranged extending transverse to the length of the main load support and 25 displaceable into said first and second locking apertures when the ramp platform body is in the travelling position to positively lock the ramp platform body in the travelling position, and wherein the locking pin can be retracted from said first and second locking apertures to unlock the ramp platform body from the main load support, and permit the ramp platform body to be hinged downwardly to the 30 operative position. The further drive means may be actuable independently of the ramp platform drive means.

5 The main load support may include an elongated load support body having a generally rectangular flat load bearing surface defined longitudinally between a leading end and a trailing end of the load support body and transversely spaced lateral long sides of the body. 5 The one ramp part may include a ramp platform body defining a generally rectangular flat ramp platform traverse surface between its leading end and its trailing end and between transversely spaced lateral sides. Also, the one ramp part may include a hinging arrangement for mounting the ramp platform body about a 10 transverse hinge axis towards the rear end of the elongated load support body, so that the ramp platform body may be hingedly displaceable about the hinge axis between an operating position in which the ramp platform traverse surface inclines downwardly away from the rear end of the load bearing surface, in a rearwards direction, and another traveling position in which the ramp platform traverse surface 15 extends generally horizontally away from the load bearing surface. The ramp platform support may be formed integrally with the ramp platform body. That is it may be formed as a part of the structure of the ramp platform body. 20 The ramp platform support may support the ramp body at a point intermediate the main load support and the free end of the other ramp part, e.g. to suitably support the ramp body when vehicles are loaded onto the trailer and unloaded from the trailer.

6 The ramp platform support may be a static or stationary fixed support that does not need to be moved into an operative position when it is used. That is it does not have to be moved between operative and inoperative positions by a folding action or the like. It depends below the ramp platform body in the transport or 5 traveling position and when the ramp platform body is pivoted into the inclined or loading position, the downwardly depending ramp platform support is lowered into contact or engagement with the support surface. The transverse support wall towards the rear end of the ramp platform body may 10 be sized to support the rear end of the ramp platform body in a position in which the rear end of the ramp platform traverse surface is spaced above from the vehicle support surface when the ramp platform support abuts the vehicle support surface. The ramp support wall may be sized to support the rear end of the ramp platform traverse surface at least 0.4 m above the vehicle support surface when 15 the ramp support surface abuts the vehicle support surface. Further, the hinging arrangement for mounting the ramp platform body toward the rear end of the main load support may be arranged so as to permit it to pivot relative to the main load support through at least 10 degrees between the traveling 20 position and the loading position, e.g. to pivot through a range of 13 to 17 degrees. The other ramp part may include two laterally spaced elongated ramp track members defining track traverse surfaces between leading ends and trailing ends and transversely spaced long sides thereof. The ramp track members may be 25 displaceable into an extended position by translational movement in a direction rearward away from the one ramp part for increasing the effective traverse surface of the ramp body in a rearwards direction. The ramp track members may be received within the ramp platform body in a 30 retracted position in which the track traverse surfaces overlap substantially completely with the ramp platform traverse surface. The ramp track members may be operatively able to be displaced by translational movement in a direction 7 rearward away from the ramp platform body to increase the effective traverse surface of the ramp body. The ramp track members may be sized to project rearwards away from the ramp 5 platform body so that the track traverse surfaces extend in a generally planar fashion between the rear end of the platform traverse surface and the vehicle support surface when the ramp platform body is in its inclined position. The ramp platform body may include a ramp track support over which the ramp 10 track members are displaceable when displaced between the retracted and extended positions. The ramp track support may include two parallel transversely spaced sliding support surfaces over which the two ramp track members are slidingly displaceable when displaced between the retracted and extended positions. 15 The ramp platform body may include a guiding arrangement for guiding the displacement of the ramp extension members between the retracted and extended positions. The guide arrangement may include transversely spaced guide formations and vertically spaced guide formations defining between them a track 20 traveling path along which the displacement of the ramp extension members is guided between the retracted and extended positions. The guide formations may be sized and shaped to be complementary to the outer sides of the ramp track members for snug sliding fitment of the ramp track 25 members in the guide passages. The other ramp part may include a bridging member extending transversely between the ramp track members for holding the ramp track members together in a fixed spaced relationship to each other. Each ramp track member may include 30 an elongated generally flat substantially box-shaped body having a longitudinally tapered rear end portion defining a transverse taper end portion face at a taper 8 angle that enables the taper end portion face to lie flat on the vehicle support surface, in use. The ramp arrangement may include a ramp platform drive means for driving the 5 ramp platform pivotally about the hinge axis between the traveling and operative positions. The ramp platform drive means may include a hydraulic drive means, e.g. in the form of two laterally spaced hydraulic actuators, mounted between an undercarriage of the trailer vehicle and the ramp platform body, for displacing the ramp platform pivotally about the hinge axis. 10 Similarly, the trailer may include a ramp track member drive means for displacing the ramp track members towards and away from the ramp platform body between the extended and retracted positions along the ramp track member traveling path. The ramp track member drive means may include a hydraulic actuator mounted 15 between the ramp platform body and the bridging member extending transversely between the ramp track members. The ramp track member drive means may be actuable independently of the ramp platform drive means. 20 The trailer vehicle may also include a locking arrangement for locking the ramp platform body in the operative position in which the ramp platform traverse surface inclines downwardly away rewards from the rear end of the load bearing surface and locking the ramp platform body in the traveling position in which the ramp 25 platform traverse surface extends horizontally generally planar with the load bearing surface. The locking arrangement may include at least two vertically offset transversely open apertures defined by a rear end of the undercarriage of the vehicle and that 30 are associated with the inclined operative position and the horizontal traveling position of the ramp platform body respectively, and a locking pin transversely retractably displaceable into the apertures at the respective positions for positively 9 locking the ramp platform body relative to the undercarriage of the vehicle in either one of said operative and traveling positions. The trailer vehicle may include at least one user controller unit interfaced with a 5 hydraulic system of the trailer vehicle for controlling the hydraulic actuators and the locking arrangement. Yet also, the undercarriage of the trailer vehicle may include two transversely space parallel elongated support beams extending longitudinally between a rear 10 end and a front end of the main load support body. The elongated load support body may also include a raised support body portion toward a leading end of the load support body. 15 The trailer vehicle may be a heavy duty trailer and may include a coupling arrangement for coupling to a fifth-wheel hitch of a tractor vehicle. According to another aspect of this invention there is provided a ramp arrangement for a vehicle having a main load support, the ramp arrangement 20 including: a ramp platform that is pivotally mounted about a lateral pivot axis towards a rear end of the main load support, the ramp platform being pivotally displaceable between an operative position in which it inclines downwardly away from the main load support and a travelling position in which it extends generally horizontally; 25 and a ramp extension member having a ramp platform end and a free end mounted on the ramp platform, the ramp extension member being translationally displaceable between a retracted position in which it substantially overlaps with the ramp platform and an extended position in which it substantially projects out of the ramp platform in a rearward direction. 30 The ramp arrangement may include any one or more of the features of the ramp arrangement defined in the first aspect of the invention above.

10 According to yet another aspect of this invention there is provided a road going vehicle including: a main load support; and 5 a ramp arrangement including a ramp platform that is pivotally mounted about a lateral pivot axis towards a rear end of the main load support, the ramp platform being pivotally displaceable between an operating position in which it 11 inclines downwardly away from the main load support and a traveling position in which it extends generally horizontally; and a ramp extension member having a ramp platform end and a free end mounted on the ramp platform, the ramp extension member being translationally displaceable between a retracted position 5 in which it substantially overlaps with the ramp platform and an extended position in which it substantially projects out of the ramp platform in a rearward direction. The load support and the ramp arrangement may include any one or more of the features of the ramp arrangement defined in the first aspect of the invention 10 above. The vehicle may have its own motive means for driving it on a road. The vehicle may be a truck. The truck may have a flat load platform or the truck 15 may have a utility tray. Instead the vehicle may be a utility vehicle with a utility tray. Yet further the vehicle may be a trailer for being towed by a car or a truck. For example the trailer may be a small trailer. 20 The road going vehicle may have an enclosed goods carrying compartment and it is not required to be open to the outside air. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 25 A trailer vehicle and a ramp arrangement in accordance with this invention may manifest itself in a variety of forms. It will be convenient to hereinafter describe at least one embodiment of the invention in detail with reference to the accompanying drawings. The purpose of providing this detailed description is to 30 instruct persons having an interest in the subject matter of the invention how to carry the invention into practical effect. However it is to be clearly understood that 12 the specific nature of this detailed description does not supersede the generality of the preceding broad description. In the drawings: Figure 1 is a three dimensional view of a trailer vehicle with a ramp arrangement 5 according to the prior art; Figure 2 is a three dimensional view of a trailer vehicle having a ramp arrangement in accordance with one embodiment of the invention; 10 Figure 3 is a side view of the trailer vehicle having the ramp arrangement shown in Figure 2 in a raised traveling position; Figure 4 is a side view of the trailer vehicle with the ramp arrangement shown in Figure 2 in a lowered operative position for enabling vehicles to be driven onto or 15 driven off the trailer vehicle; Figure 5 is a top plan view of a ramp platform body forming part of the ramp arrangement shown in Figure 2; 20 Figure 6 is a sectional side view of the ramp platform body of Figure 5, the section being taken along the line VI-VI in Figure 5; Figure 7 is top plan view of another part of the ramp platform body of Figure 5 showing its attachment to chassis support beams of the trailer vehicle; 25 Figure 8 is a sectional side view of part of the ramp platform body of Figure 5 along line VIII-VIII in Figure 7; Figure 9 is a bottom plan view of ramp track members forming part of the ramp 30 arrangement shown in Figure 2; Figure 10 is a sectional side view of one of the ramp track members in Figure 9 taken along line X-X; 13 Figure 11 is a sectional side view of a rear end portion of the trailer vehicle having the ramp arrangement shown in Figure 2; 5 Figure 12 is a rear end view of the ramp platform body of Fig 5; Figure 13 is another sectional side view of a rear part of the trailer vehicle having the ramp arrangement shown in Figure 2; 10 Figure 14 is a transverse sectional view of the rear part of the trailer vehicle including the ramp arrangement of Figure 13 taken along line XIV-XIV; Figure 15 is a bottom plan view of the vehicle and the ramp arrangement of Figure 13 showing a locking arrangement for the ramp arrangement; 15 Figure 16 is a side elevation of a rear end part of a chassis support beam; Figure 17 is a cross sectional view of the rear end part of the chassis support beam of Figure 16 taken along line XVII-XVII; and 20 Figure 18 is a side elevational view of a rear end of the trailer and the ramp arrangement of Figure 2 showing controls mounted on a side of the ramp platform body. 25 In Figure 1 reference numeral 10 refers generally to a prior art trailer vehicle for a heavy duty truck for over the road hauling of heavy loads. The trailer vehicle 10 includes a loading deck 16 that can be used for transporting load vehicles such as cars, tractors, bobcats, forklift trucks, front end loaders, bull dozers 30 and other ground moving equipment. These ground engaging load vehicles or pieces of equipment as described above, need to be loaded onto and unloaded from the loading deck 16. Conveniently the 14 trailer vehicle 10 includes a driving ramp arrangement, generally indicated by reference numeral 14, at the tail of the trailer 10 over which the load vehicle can be driven to both load it on the trailer 10 and unload it from the trailer 10. 5 The driving ramp arrangement 14 includes two parallel ramp track members 18, 20 having traverse surfaces, one towards each side of the vehicle 10. As shown the two parallel ramp track members are operatively able to pivot (see arrows 22) between a downwardly inclined operative position extending rearwards away from the vehicle 10 and a vertically upstanding inoperative stowed position or traveling position. 10 In the stowed position the two ramps tracks 18, 20 project substantially vertically upward from the trailer 10 when the trailer 10 is driven along a road, so that traverse surfaces of the ramp tracks 18, 20 face in a forward traveling direction. This creates a high drag coefficient and causes a high level of drag resistance particularly when the 15 trailer 10 is traveling along the road at speed. Figure 2 shows a trailer vehicle 22, in accordance with one embodiment of the invention. 20 The trailer vehicle 22 is for a heavy duty truck having a tractor (not shown) for towing the trailer vehicle 22 over a vehicle support surface such as a road. The trailer 22 has a main load support in the form of a loading deck, generally indicated by reference numeral 24 and a trailer undercarriage. 25 The trailer 22 also includes a ramp arrangement 12 having a ramp body 30 including at least two parts 32, 34 that together define a traverse surface 36. The loading deck 24 includes an elongated and generally rectangular flat load bearing 30 surface or floor 28 defined longitudinally between a leading end and a trailing end of the loading deck 24 and transversely spaced lateral long sides of the loading deck 24.

15 The one ramp part 32 is pivotally mounted on the loading deck 24 for pivoting the traverse surface 36 of the ramp body 30 relative to the load bearing surface 28 of the loading deck 24. The other ramp part 34 is mounted on the one ramp part 32 and is displaceable relative to the one ramp part 32 for increasing or decreasing the effective 5 traverse surface 36 of the ramp body 30. The one ramp part 32 includes a generally rectangular ramp platform body 38 defining a generally flat ramp platform traverse surface 36.1 extending between its leading end and trailing end and between transversely spaced lateral sides. The one ramp part 32 10 also includes a hinging arrangement 40 for mounting the ramp platform body 38 about a transverse hinge axis 42 towards the rear end of the loading deck 24. Thus, the ramp platform body 38 is hingedly displaceable about the hinge axis 42 between an operative position in which the ramp platform traverse surface 36.1 inclines (see Figures 2 and 4) downwardly in a rearward direction away from the rear end of the 15 loading deck 24 and a traveling position in which the ramp platform traverse surface 36.1 extends generally horizontally (see Figure 3) such that it is in plane with the load bearing surface 28 of the loading deck 24. In this embodiment, the hinging arrangement 40 mounts the ramp platform body 38 20 on the loading deck 24 in such a way that it permits the ramp platform body 38 to pivot relative to the loading deck 24 through at least 10 degrees between the inclined operative position and the horizontal traveling position. Typically the ramp platform body 38 pivots through a range of 13 to 17 degrees. The hinging arrangement 40 includes hinge pins 48 and cooperating hinge sleeves 50 shown in Fig 8 that are 25 mounted towards upper adjacent edges of the ramp body 38 and the chassis support beams 52 of the trailer undercarriage. The one ramp part 32 includes a ramp support 44 towards its rear end for supporting the ramp platform body 38 on the vehicle support surface when the ramp platform 30 body 38 is hingedly displaced to the operative position in which the ramp platform traverse surface 36.1 inclines downwardly rearwards away from the rear end of the load bearing surface 28. The ramp support 44 includes a transverse support wall towards the rear end of the ramp platform body 38 that projects away from the ramp 16 platform body 38 and has a base 40 at its free end for engaging the vehicle support surface. The support wall 44 is formed integrally with the ramp platform body 38 as a part of the structure of the ramp platform body 38 so it depends down below the ramp platform body 38. The support wall 44 is permanently fixed in position and does not 5 need to be moved when it is used to support the ramp platform body 38. The transverse support wall 44 towards the rear end of the ramp platform body 38 is sized to have a vertical height so that, when the ramp platform body 38 is supported on the vehicle support surface by the support wall 44, the ramp platform traverse 10 surface 36.1 is positioned spaced above the vehicle support surface, e.g. at least 0.4 m above the vehicle support surface. The other ramp part 34 includes two laterally spaced elongated ramp track members 52, 54 defining track traverse surfaces 36.2 between leading ends and trailing ends 15 and transversely spaced long sides thereof. The ramp track members 52, 54 are displaceable in a translational fashion rearward away from the ramp platform body 38 for increasing the effective traverse surface 36 of the ramp body 38 in a rearwards direction. 20 Thus, the track traverse surfaces 36.2 of the ramp track members 52, 54 overlap the platform traverse surface 36.1 when the ramp track members are retracted into the ramp platform body 38, and are exposed when the ramp track members 52, 54 are displaced rearwards away from the ramp platform body 38 into an extended position to increase the effective traverse surface 36. The effective traverse area is thus the 25 sum of the platform traverse surface 36.1 and the portion of the track traverse surface 36.2 that projects out of the ramp platform body 38. The ramp platform body 38 is generally box-shaped and includes an interior defined between a top wall and transversely spaced side walls. The ramp track members 52, 30 54 are received within the interior of the ramp platform body 38 when 17 it is retracted so that the track traverse surfaces 36.2 overlap substantially completely with the ramp platform traverse surface 36.1. The ramp track members 52, 54 are operatively able to be displaced from a retracted position, in a translational fashion, rearward away from the ramp platform body 38 to an 5 extended position for increasing the effective traverse surface 36 of the ramp body 30 The ramp platform body 38 includes a guiding arrangement, generally indicated by reference numeral 56, for guiding the displacement of the ramp track members 52, 10 54 between their retracted and extended positions. The guide arrangement 56 includes transversely spaced guide formations and vertically spaced guide formations formed by structural parts of the ramp platform body 38. The guide formations define guide passages forming ramp track member travel paths (see arrow 58) along which the displacement of the ramp track members 52, 54 are 15 guided between the retracted and extended positions. The guide formations have rearward openings 60 through which the ramp track members pass when displaced between the retracted and extended positions. To this end, the guide formations 56 are sized and shaped to be complementary to lateral outer sides of the ramp track members 52, 54 for snug sliding fitment of the ramp track members 20 in the guide passages 58. The ramp platform body 38 includes a ramp track support surface, for vertically supporting the ramp track members, over which the ramp track members 52, 54 are displaceable when displaced between the retracted and extended positions. 25 The ramp track support surface is formed by the guide formations over which the two ramp track members 52, 54 are slidingly displaceable when displaced between the retracted and extended positions. Each ramp track member 52, 54 includes an elongated generally flat box-shaped 30 body 62 having a longitudinally tapered rear end portion 66 defining a transverse taper portion face 64 at a taper angle that enables the taper end portion face 64 to lie flat on the vehicle support surface, in use.

18 The other ramp part 34 also includes a bridging member 68 in the form of a brace extending transversely between the ramp track members 52, 54 for holding the ramp track members 52, 54 together in a fixed spatial relationship to each other. The brace 68 includes a mounting flange 70 projecting forwardly from a position 5 intermediate transverse ends of the brace 68. The trailer 22 also includes a ramp platform drive means 72 for driving the ramp platform body 38 pivotally about the hinge axis 42. The ramp platform drive means 72 includes two laterally spaced hydraulic actuators or rams 74 mounted 10 between mounting brackets 76 provided on the undercarriage of the trailer vehicle 22 and mounting brackets 78 provided on the ramp platform body 38, for displacing the ramp platform body 38 pivotally about the hinge axis. Further, the trailer 22 includes drive means 80 for the ramp track members 52, 54 15 in the form of a hydraulic actuator or ram for displacing the ramp track members 52, 55 along the ramp member traveling path between the extended and retracted positions. The ramp platform body includes two forwardly projecting transversely spaced arms 82, 84 and a brace member 86 extending there between. The hydraulic actuator 80 is mounted between the associated brace member 86 and 20 mounting flange 70 projecting from the brace 68 of the ramp track members 52, 54. The trailer 22 includes a user control arrangement 88 for independently controlling the activation of the drive means 72 and the drive means 80 , so that the ramp 25 track members 52, 54 and the ramp platform body 38 are controllable independently from each other. The control arrangement 88 includes control pendants 90 that are interfaced with the hydraulic system of the trailer and that are carried on a side of the trailer 22 near the rear thereof. 30 The trailer 22 further includes a locking arrangement, generally indicated by reference numeral 92, for releasably locking the ramp platform body 38 in either 19 one of the inclined or horizontal positions. The locking arrangement 92 includes two vertically offset transversely open apertures 94 defined by a rear end of the support beams 52 of the trailer 22 that are associated with the inclined position and the horizontal position of the ramp platform body 38 respectively. The ramp 5 platform body 38 includes vertically extending locking brackets 39 that define an aperture 98 there through and that are displaceable with the ramp platform body 38 for registering with either one of the apertures 94 in the inclined or horizontal positions, as the case may be. The locking arrangement also includes a locking pin 100 for passing through the registering aperture 98 in the bracket and the 10 aperture 94 in the beams 52. The locking pin 100 is controlled by retraction or extension from a hydraulic booster unit 102 for positively locking the ramp platform body 38 relative to the undercarriage of the trailer 22. In another embodiment that has not been illustrated the locking arrangement 92 is 15 designed only to lock the ramp platform body to the main load support in the traveling position. In the operative position with the ramp platform body extending down the ramp platform body is supported by the transverse support wall resting on the support surface. Further when the further ramp part is extended fully it also bears against the support surface on which the trailer vehicle is positioned and 20 provides some support. Consequently in this embodiment the ramp platform body is mounted on the support surface in the operative position and is not locked in this position by mechanically locking the ramp platform body to the main load support. 25 In this embodiment the locking arrangement 92 includes a transversely open aperture 94 defined on a rear end of the support beams 52 of the trailer 22 that is associated with the horizontal traveling position of the ramp platform body 38. The ramp platform body 38 includes a vertically extending locking bracket 39 that defines an aperture 98 there through and that is displaceable with the ramp 30 platform body 38 for registering with the aperture 94 in the horizontal traveling position. The locking arrangement also includes a locking pin 100 for passing through the registering aperture 98 in the bracket and the aperture 94 in the 20 beams 52. The locking pin 100 is controlled by retraction or extension from a hydraulic booster unit 102 for positively locking the ramp platform body 38 relative to the undercarriage of the trailer 22. 5 The trailer vehicle 22 also includes a raised support body portion 104 towards a leading end of the load support body 24. This includes a fifth wheel for pivotally mounting over the rear axle of a towing rig in the usual way. In use, if a user whishes to load a ground engaging load vehicle such as a 10 earthmoving machine on the loading bed 24 of the trailer 22, a user selects the appropriate control from the controls 90. This retracts the pin 100 out of the locking pin apertures 98, 94 so that the platform body 38 is free to pivot about the hinge axis 42 relative to the loading deck 24. 15 The user then actuates the hydraulic rams 74 of the ramp body drive arrangement 72 (using the controls 90) for displacing the ramp platform body 38 from the traveling to the operative position. To do this the ramp platform body 38 is pivoted towards the vehicle support surface until the base 46 of the support wall 44 engages the vehicle 20 support surface. At this stage, the associated locking pin apertures 94, 98 register with each other and the locking pin 100 is inserted into the registering holes for holding the ramp platform body 38 in its inclined position. The ramp platform traverse surface 36.1 of the ramp platform body now inclines rearwards from the load bearing surface 28. However the ramp platform traverse surface 36.1 remains spaced above 25 the vehicle support surface or ground. The user then selects the appropriate control 90 and activates the hydraulic ram of the track member drive arrangement 80 which causes the ramp track members 52, 54 to be displaced in a translational fashion out of the ramp platform body 38. The track 30 members 52, 54 are displaced away from the ramp body 38 until their wedge portions 66 and particularly the faces 64 thereof reach the ground.

21 An earthmoving machine to be loaded on the trailer can now be driven up the ramp arrangement 12 over the effective traverse surface 36 onto the loading deck 24. Once the earthmoving machine is loaded onto the deck 24, the user can retract the hydraulic ram 80 so that the ramp track members 52, 54 are retracted into the ramp 5 platform body 38. The locking pin 100 is then retracted and the ramp platform body 38 is displaced hingedly to its horizontal traveling position. Thereafter the locking arrangement is activated by the user, to lock the ramp platform body 38 in its horizontal position. The above steps are repeated when the time comes to offload the earthmoving machine. 10 In the other embodiment that has been described above the ramp platform body is supported in the operative position by the support wall 44 resting on the support surface. Thus in this embodiment it is not necessary to withdraw the locking pin 100 from the passages before the ramp platform body 38 is pivoted up to the traveling 15 position. An advantage of the trailer 22 is that the ramp track members 52, 54 are stowed generally horizontally, either projecting rearwards or retracted within the ramp platform body 38. This way, the ramp track members 52, 54 do not stand up vertically and 20 face in a forward direction of the trailer vehicle. Thus they do not cause any significant drag resistance particularly when the trailer 12 is traveling along the road at normal road traveling speeds. A further advantage of having the ramp members stowed in a generally horizontally 25 extending orientation is that the rear end of the trailer is unobstructed. It is therefore possible to place a load on the load bearing surface that projects rearward out of the back of the trailer. This would not be possible with the trailer shown in Figure 1 as the upwardly projecting ramp parts would be in the way. 30 A further advantage is that the ramp arrangement can be easily and efficaciously moved from the inoperative to the operative positions in use by activating hydraulic rams. Further the mechanical load on the rams is less than with the prior art arrangement shown in Fig 1. Yet further the actual extent of movement required to 22 change the ramp arrangement between the operative and the traveling positions is not very great. A further advantage of the arrangement described above with reference to the 5 drawings is that the transverse extending platform support wall is engineered to provide load bearing support for a load, such as an earthmoving machine, when it travels over the ramp, at a point intermediate the rear end of the main load support and the free end of the ramp extension member. The wall is rigid and fixed in position and does not need to be folded out or extended when the ramp platform body is 10 moved from the traveling to the operative position. It therefore does not require a drive mechanism to extend it when it is required to support the ram platform body. The static nature of this feature enables it be formed integrally with the ramp platform body and to be built with sufficient strength to provide appropriate mechanical support for the ramp intermediate the ends of the traverse surface when it is in the operative 15 position. It also acts to relieve the moment applied to the rear end of the main load support, in use A further advantage of the embodiment described above with reference to the drawings is that it has a controller arrangement for controlling operation of the locking 20 arrangement to lock the ramp arrangement to the main load support in the traveling position. This enables locking and unlocking actions to be performed by an operator using the controller arrangement. A yet further advantage is that the drive systems for driving the ramp platform body 25 between the inclined operative and horizontal traveling positions can be received internally within the ramp arrangement as can the drive arrangement for driving the ramp track members and they do not occupy much space. They are also mounted inconspicuously on the vehicle. 30 It will of course be realized that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto, as would be apparent to persons skilled in the art, are deemed to fall within the broad scope and ambit of the invention as is herein set forth.

Claims

1. A trailer vehicle that includes: a main load support having a load bearing surface; and 5 a ramp arrangement having a ramp body defining a traverse surface, including one ramp part that is pivotally mounted about a transverse pivot axis towards a rear end of the main load support so that the ramp body is pivotally displaceable about the pivot axis between an operative position in which the 10 traverse surface inclines downwardly away from the main load support and a traveling position in which the traverse surface extends generally in the same plane as the load bearing surface, wherein the one ramp part includes a transversely extending ramp support wall extending down from the ramp body for supporting the ramp body on a vehicle support surface when the ramp body 15 is in the operative position; and another ramp part mounted on the one ramp part, wherein the other ramp part undergoes sliding translational displacement relative to the one ramp part in one direction to an extended position to increase the traverse surface of the ramp body whereby to enable the ramp body to extend down to a support 20 surface on which the trailer vehicle is mounted, and wherein the other ramp part undergoes sliding translational displacement in an opposite direction to a retracted position to decrease the traverse surface.

2. A trailer vehicle as claimed in claim 1, wherein the one ramp part 25 includes a generally rectangular ramp platform body, and a hinging arrangement for mounting the ramp platform body about a transverse hinge axis such that it is hingedly displaceable about the hinge axis between said operative position and said traveling position, and further including a ramp platform drive means in the form of a hydraulic actuator having at least one 30 hydraulic housing mounted on the main load support and a ram movably mounted on the hydraulic housing that is drivably coupled to the ramp platform 24 body whereby to pivot the hinging arrangement and the ramp platform body about the hinge axis between the traveling and operative positions.

3. A trailer vehicle as claimed in claim 2, including further drive means for 5 driving the other ramp part between the retracted and extended positions in the form of a hydraulic actuator having a ram housing that is mounted on the ramp platform body, and a ram movably mounted on the ram housing, that is drivably coupled to the other ramp part whereby to drive it between said retracted and extended positions. 10

4. A trailer vehicle as claimed in claim 3, wherein the transversely extending support wall has a height that is selected so that the free end of the other ramp part extends down to the support surface, when said one ramp part is in the operative position and the other ramp part is in the extended position, and 15 wherein the support wall has a height of at least 0.4 m from its lower end up to the traverse surface at the rear end of the ramp platform body.

5. A trailer vehicle as claimed in any one of claims 2 to 4, wherein the main load support includes a first locking formation defining a first locking aperture 20 having an axis extending transverse to the length of the main load support, and the ramp platform body includes a second locking aperture having an axis extending transverse to the length of the ramp platform body, and wherein the second locking aperture is arranged so that it registers with the first locking aperture when the ramp platform body is in the travelling position, and a locking 25 pin that is arranged extending transverse to the length of the main load support and is displaceable into said first and second locking apertures when the ramp platform body is in the travelling position to positively lock the ramp platform body in the travelling position, and wherein the locking pin can be retracted from said first and second locking apertures to unlock the ramp platform body from 30 the main load support, and permit the ramp platform body to be hinged downwardly to the operative position.