Abstract:
A load carrying vehicle body with a chassis is provided which has a forward support and a rearward support, and which is able to accommodate a load. The rearward support includes a pair of support members each with at least one wheel mounted to one side of a support member. The support members are movable on the chassis between a first position at which the wheels are located within the tracking width of the vehicle and at which the wheels are aligned with the direction of travel of the vehicle, and a second position at which the wheels are displaced laterally from the tracking width to provide access to the rear of the chassis. A first lock is provided between the support members which is able to be interengaged when the support members are in the first position to maintain the wheels in the first position and to enable the support members to cooperate with each other in accommodating the stresses and load exerted thereon when in the first position.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a load carrying vehicle. 
     A particular application of the vehicle relates to one which can be used for the transportation of heavy loads and which facilitates the loading of those heavy loads onto the vehicle. 
     Throughout the specification the term “tracking width” shall be taken to mean the usual width of the vehicle in its movement over the ground. 
     BACKGROUND 
     In the transportation of large heavy loads such as earthmoving equipment it is conventional practice to use low loader trailer vehicles which are supported on a multiplicity of tyres. The tyres are of necessity of small diameter in order for them to be able to fit beneath the platform. In this regard it is quite common to use 32 wheels arranged in 4 rows of eight. In such an arrangement a complex control system for load-equalisation interconnects the wheels to ensure that the load is spread as evenly as possible over all of the wheels over a range of uneven road conditions for each wheel set. Such a practice has presented a number of disadvantages which include the feature that the control system cannot function effectively over a sufficient range of wheel travel to be able to accommodate severe road irregularities which results in tyre and suspension damage. In addition the spread of support over such a large area results in severe tyre scrub during cornering which also results in damage to the tyres and the suspension components. In addition the use of a large number of wheels which are each provided with their own suspension system and in many cases their own braking system presents a significant maintenance problem. In addition the use of a large number of small brakes leads to problem of uniform application. Furthermore the braking systems that are used are generally unsuited to continuous application on downgrades since they overheat quickly and it is a common characteristic of such vehicles that they are applied continuously for lengthy periods of time, 
     As an alternative to the above arrangement there have been proposals put forward to support a low loader trailer at its forward end from the prime mover vehicle and from two sets of wheels at its rear end where the rear sets of wheels are supported to be able to pivot away from the rear of the vehicle to permit access to the trailer by a load. In such a case the wheels can be large and of a high carrying capacity since they do not have to be able be received under the vehicle. Examples of such an arrangement are disclosed in U.S. Pat. No. 5,366,336, No. 3,346,131, No. 300,523 and No. 3,119,502. However the arrangements which have been proposed in the past utilise a wheel supported to each side of a central support arm (U.S. Pat. Nos. 5,366,336 and 3,346,131) which requires the use of a multiplicity of axles or support the wheels in a cantilever fashion to one side of a support arm which requires the arm to have sufficient strength to be able to accommodate the stresses created by such cantilevered support as well as the loadings implicit as a result of the load being carried. 
     The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the priority date of the application. 
     DISCLOSURE OF THE INVENTION 
     Accordingly the invention resides in a load carrying vehicle body comprising a chassis having a forward support and a rearward support, the chassis being adapted to accommodate a load, said rearward support comprising a pair of support members each comprising at least one wheel mounted to one side of a support member, said support members being movable on the chassis between a first position at which the wheels are located within the tracking width of the vehicle and at which the wheels are aligned with the direction of travel of the vehicle and a second position at which the wheels are displaced laterally from the tracking width to provide access to the rear of the chassis, a first looking means provided between the support members, the first locking means adapted to be interengaged when the support members are in the first position to maintain the wheels in the first position and to enable the support members to cooperate with each other in accommodating the stresses and load exerted thereon when in the first position. 
     According to a preferred feature of the invention a second locking means is provided between each support member and the chassis, the second locking means being engaged when the support members are in the first position to retain the support members in the first position. According to an embodiment of the invention the second locking means also accommodates some of the stresses exerted on the support members when in the first position. 
     According to a preferred feature of the invention the mounting between the chassis and the support members is articulated to enable the rear of the chassis to be moved from a first position at which the rear end of the chassis is raised from the ground and a second position at which the rear end of the chassis is adjacent to the ground. 
     According to a preferred feature of the invention, the support members are pivotally mounted to the chassis about an upright axis to enable the wheels to be moved between the first and second position. According to one embodiment the support members each comprise an arm which extends substantially radially from the pivot axis and which support the wheels at a position spaced from the pivot axis. 
     According to a further preferred feature, two or more wheels are mounted to said one side of each support member. According to one embodiment the at least one wheel is located to the side of each member which is remote from the other support member. 
     According to a further preferred feature of the invention, said load carrying vehicle body comprises a trailer wherein the forward support comprises a mounting adapted to be supported from a towing vehicle. 
     The invention will be more fully understood in the light of the following description of several specific embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The description is made with reference to the accompanying drawings of which: 
     FIG. 1 is a schematic side elevation of a trailer according to the first embodiment where the trailer is supported from a towing vehicle and the chassis is in the raised position; 
     FIG. 2 is a schematic side elevation of the trailer and towing vehicle of FIG. 1 with the chassis in the lowered position; 
     FIG. 3 is a plan view of the trailer with the support members in the first position; 
     FIG. 4 is a side elevation of the trailer and towing vehicle of FIGS. 1 and 2 showing the support members in the second position; 
     FIG. 5 is a plan view of the trailer of the first embodiment showing the support members in the second position; 
     FIGS. 6.1,  6 . 2 ,  6 . 3 ,  6 . 4  and  6 . 5  are a schematic illustrations of the step by step procedure involved in loading the trailer vehicle according to the first embodiment; 
     FIG. 7 is a side elevation of the third embodiment with the trailer in the raised position; 
     FIG. 8 is a side elevation of the third embodiment with the trailer in the lowered position; 
     FIG. 9 is a partial plan of the third embodiment showing one set of wheels in the tracking position; 
     FIG. 10 is a partial plan of the third embodiment showing one set of wheels in the loading position; and 
     FIG. 11 is a partial isometric view of one of the wheel mountings according to the third embodiment. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The first embodiment as shown at FIGS. 1 to  6  is directed to a trailer vehicle  11  which is adapted to be towed behind a towing vehicle  12  which takes the form of a prime mover. The trailer is provided with a chassis  13  which provides a load carrying platform. The chassis is provided at its forward end with a substantially conventional goose-neck portion  14  which is adapted to be mounted to a substantially conventional hitch such as a fifth wheel  15  provided on the towing vehicle  12 . The rear of the chassis  13  is supported from pair of rear supports  16 . 
     Each rear support  16  comprises a pair of support arms  17  located to each side of the rear end of the chassis  13 . The support arms are mounted to the chassis  13  through an upright pivot  18  which allows the arms  17  to be able to pivot about an upright axis between a first position as shown at FIG. 3 at which they extend in a substantially parallel relationship from the rear of the chassis  13  to a second position as shown at FIG. 5 which they extend to each side of the chassis  13  in opposed relation to each other. 
     Each support arm  17  supports a pair of wheels  19  which are supported from a common axle extending laterally from the side of the respective arm which is remote from the other arm side of the support arm  17 . The sides of the arms which are proximate each other are each provided with an extension  25  which each extend laterally from the respective arm. The outer ends of the extensions are provided with a first and second locking members which are adapted to be lockingly interengagable with each other when the support arms  17  are in the first position and to provide a rigid interconnection between the support arms  17  when they are in the first position in order that the interconnected extensions  25  can accommodate at least some of the torsional loads exerted on the arms as a result of the cantilevered support provided to the wheels by the arms. 
     In order to facilitate movement of the support arms between the first position as shown at FIG.  3  and the second position as shown at FIG. 5 a suitable extension means such as a hydraulic ram is mounted between the chassis  13  and each of the support arms  17 . In addition, the mounting between the support arms  17  and the chassis  13  is articulated about one or more transverse axes to provide a hinged connection therebetween. A suitable extension means or drive means is provided in association with the articulated mounting to control the hinged movement of the chassis  13  with respect to the support arms  17 . As a result of the articulated mounting and the drive means associated with it, the chassis  13  can be lowered from the normal substantially horizontal load carrying position as shown at FIG. 1 to a lowered position shown at FIG. 2 at which the rear end is close to the ground or is supported upon the ground. When the chassis is in the lowered position and the support arms  17  are in their second position as shown at FIGS. 4 and 5, the rear end of the chassis is accessible by a vehicle to enable a load to be deposited onto the chassis  13 . 
     FIGS. 6.1 to  6 . 5  illustrate the manner in which the trailer body according to the first embodiment can be loaded to support a mobile load in the form of a piece of earthmoving equipment  27 . In use the rear end of the load support chassis  13  is lowered from the normal transport position shown at FIG. 6.1 to a lowered position at which it is close to the ground or is in engagement with the ground as shown at FIG. 6.2 by activation of the extension or drive means associated with the articulated mounting between the chassis  13  and the support arm  17 . The extensions are then disconnected from each other and the support arms  17  are caused to be moved to their second position as shown at FIG. 6.3 which provides clear access to the rear edge of the support chassis  13 . A load can then be moved onto the support chassis  13  over the rear edge platform as shown at FIG. 6.4. Once the load is in position, the support arms  17  are then caused to be moved to the first position, the extensions  25  are then lockingly interconnected and the chassis  13  is raised as shown at FIG. 6.5. The trailer vehicle together with its load  27  can then be towed by the towing vehicle  12 . 
     The first embodiment provides a trailer vehicle which when under load has a substantially conventional tracking width but which can be loaded from the rear end without the need for any ancillary plant or equipment. In addition the use of a common axle to support each set of wheels from the support arm and the interengagement between the arms through the extensions  25  when in the transport position can result in a reduction in the tare weight of the vehicle. 
     According to a second embodiment (not shown), the movement of the support arms  17  between the first position as shown at FIG.  3  and the second position as shown at FIG. 5 can be effected by movement of the trailer vehicle  11  under the control of the towing vehicle  12 . In order to move the support arms  17  between the first position as shown at FIG.  3  and the second position as shown at FIG. 5, the support arms  17  are unlocked from engagement with the chassis  13 . In addition the extensions  25  are disengaged. The trailer vehicle is then moved rearwardly which will cause the support arms  17  to rotate about the pivots  18  until they occupy the second position as shown at FIG. 5 at which time the rearward movement of the vehicle can then cease. In order to move the support arms from the second position to the first position the trailer vehicle is moved forwardly which causes the support arms to pivot about the pivots  18  until they trail behind the chassis to occupy the first position. 
     A third embodiment of the invention is shown at FIGS. 7,  8 ,  9 ,  10  and  11  comprises a trailer vehicle of the same form as that of the first embodiment. 
     In the case of the third embodiment the support arm  117  comprises an elongate arm which is pivotally supported at one end from a pivot  118  located at the respective side of the trailer body whereby the support arm  117  is able to pivot between a position lying closely adjacent to and parallel to the rear face of the trailer and a position extending substantially perpendicularly from the rear face of the trailer body. The support arm  117  is provided with a perpendicularly extending pivot arm  121  which is pivotally supported from a longitudinally directed pivot pin provided at an intermediate position along the length of the support arm  117  such that it pivots about a substantially horizontal axis. The pivotal movement of the pivot arm  117  about the upright pivot axis  118  is effected by means of a first hydraulic cylinder  123  which extends between the side of the trailer body  113  and a radial arm provided on the upright pivot  118  whereby on the retraction and extension of the first hydraulic cylinder  123  the support arm  117  is caused to move between its tracking position as shown at FIG.  9  and its loading position as shown at FIG.  10 . 
     The support arms  117  have extensions fixedly disposed at second ends of said support arms  117 , said extensions being of a length such that when the pivot arms are in their tracking position as shown at FIG. 9 the free ends of each of the extensions are interengaged and the first and second locking members provided at those ends can be locked into such interengagement by means of a suitable locking pin. In addition, a further locking means is provided between the chassis  113  and each of the support arms  117 . Said locking means comprises a third and a fourth locking member  130  disposed on said chassis  113 . The 3rd locking member  130  is lockingly engagable with the second end of one support arm  117 , and the 4th locking member  130  is lockingly engagable with the second end of the other support arm  117 . The 3rd and 4th locking members  130  each comprise a support bracket or lug on the chassis which are engaged by the respective second ends on each respective support member. Therefore, when the support arms are in their tracking position, the second end of each support arm  117  is engaged with a corresponding support bracket or lug provided on the chassis  113  and are lockingly engaged with that lug or bracket such that the arms are fixed in position relative to the trailer body  113 . 
     In order to control the pivotal movement of the rear face  120  of the trailer body relative to the ground a second hydraulic cylinder  124  is provided between the support arm  117  and the pivot arm  121  whereby extension or retraction of the second hydraulic cylinder will cause pivotal movement of the pivot arm  121  on the support arm  117  in order to effect the lowering or raising of the rear end of the trailer body  113  as desired. 
     The third embodiment provides a means for positively effecting the transposition of the support arm  117  from its tracking position to its raised position and also controlling the lowering and raising of the trailer body  113 . 
     It is anticipated that in utilisation of the third embodiment it may be appropriate to initially retract the second hydraulic cylinders  124  in order to lower the rear end of the trailer body into contact with the ground and to relieve at least some if not almost all of the weight from the wheels  119 . The first hydraulic cylinders  123  can then be retracted in order to effect the pivotal movement of the support arms about the upright pivot axis  118  to move the support arms to their loading position as shown at FIG.  10 . 
     According to a further embodiment of the invention the support arms may be mounted to the trailer body in the manner described in relation to each of the above embodiments. However, in order to be able to pivot about an upright axis there is no means for effective pivotal movement between the wheels and the support arm about a horizontal axis, The effect of such is that the rear end of the trailer body cannot be lowered. In order to effect loading of the embodiment the trailer body is provided with appropriate ramps to effect the transfer of a load from the ground onto the rear of the trailer body when the wheels are in the loading position. 
     A further embodiment of the invention comprises a variation of the first embodiment in which the extension means which causes the movement of the arms between the first and second position is mounted between each of the support arms  17 . 
     Throughout this specification (including the claims if present), unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. 
     It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiments described above.