SAME

The present invention relates to a dump tray for a bulk material transport truck having a suspended floor, which may comprise steel membrane or an clastomeric mat.

An ongoing objective in mining operations is to minimise equipment and vehicle maintenance by maximising service life, so as to keep operating costs per tonne as low as possible. To this end, mining vehicles and equipment are generally designed to be strong and durable to withstand the riggers of mining operations.

One particular item of mining equipment subjected to significant ongoing stress and wear is a dump tray. There is a need in the art for dump tray designs which provide adequate strength and durability but reduced weight and/or a suitability for differing mining operations.

According to a first aspect of the present invention, there is provided dump tray for a bulk material transport truck, comprising:

a front wall, opposed side walls and a floor; and

a frame which supports the front wall, side walls and floor, the frame defining a chassis of the tray ("the tray chassis"), via which the tray is pivotally attachable to a chassis of the truck, and comprising opposed longitudinal members disposed laterally outward of the tray chassis on opposite sides thereof, each longitudinal member being positioned at a higher level than the tray chassis, and transverse members interconnecting the tray chassis and longitudinal members,

wherein:

the floor is secured to the longitudinal members such that it is suspended over the tray chassis;

the transverse members comprise laterally outwardly divergent branches; and the longitudinal members are fixed to laterally outer ends of the branches. The floor may comprise one of an elastomeric mat and a steel membrane. In one embodiment of the invention, the floor comprises the elastomeric mat, which can be interchanged with the steel membrane. In another embodiment of the invention, the floor comprises the steel membrane, which can be interchanged with the floor comprising the elastomeric mat.

The dump tray according to a preferred embodiment of the first aspect has parts which comprise:

a structure comprising the front wall, opposed side walls and frame; and the elastomeric mat or steel membrane and components which secure it to the structure; preferably, which components preferably comprise ones to secure the elastomeric mat or steel membrane to the frame.

According to a second aspect of the. present invention, there is provided a dump tray for a bulk material transport truck, the dump tray comprising a front wall, opposed side walls, a floor, and a frame which supports the front wall and side walls, defines a chassis of the tray (''the tray chassis"), via which the tray is pivotal ly attachable to a chassis of the truck, and supports the floor whereby it is suspended over the tray chassis, the dump tray including an elastomeric mat or a steel membrane. In one embodiment of the invention, the floor comprises the elastomeric mat and is interchangeable with the floor comprising the steel membrane. In another embodiment of the invention, the floor comprises the steel membrane and is interchangeable with the floor comprising the elastomeric mat.

The dump tray according to a preferred embodiment of the second aspect has parts which comprise:

a structure comprising the front wall, opposed side walls and frame; and

the elastomeric mat or steel membrane and components which secure it to the structure, which components preferably comprise ones to secure the elastomeric mat or steel membrane to the frame.

According to a third aspect of the present invention, there is provided a system of parts for assembly of a dump tray for a bulk material transport truck, the dump tray having a chassis ("the tray chassis"), via which the tray is pivotally attachable to a chassis of the truck, and a floor which is suspended over the tray chassis, wherein the parts comprise:

a structure comprising a front wall of the dump tray, opposed side walls of the dump tray and a frame which supports the front wall and side walls;

an elastomeric mat;

a steel membrane; and

components to secure the elastomeric mat and steel membrane to the structure, whereby the floor can comprise the elastomeric mat or the steel membrane.

Preferably, the system is configured such that ones of said components secure the elastomeric mat and steel membrane to the frame.

Preferably, the system is configured such that the floor comprising the elastomeric mat and the floor comprising the steel membrane are interchangeable.

According to a fourth aspect of the present invention, there is provided a dump tray assembled from parts of the system according to the third aspect, the dump tray comprising said structure and one of the elastomeric mat and steel membrane secured to the structure by ones of said components such that said floor is suspended over the tray chassis. Preferably, said one of the elastomeric mat and steel membrane can be replaced with the other of the elastomeric mat and steel membrane, and said other of the mat and membrane is securable to the structure by ones of said components of the system such that said floor instead comprises it.

In a preferred embodiment of the second, third or fourth aspect of the invention, the frame includes opposed longitudinal members disposed laterally outward of the tray chassis on opposite sides thereof, each longitudinal member being positioned at a higher level than the tray chassis, and transverse members interconnecting the tray chassis and longitudinal members, and the floor is secured or securable to the longitudinal members. Preferably, the transverse members comprise laterally outwardly divergent branches and the longitudinal members are fixed to laterally outer ends of the branches. Preferably, the number of branches which each transverse member comprises is two.

Preferably, the side walls are coupled to the frame via the longitudinal members.

Either or each transverse member may comprise a first section, which extends laterally outwardly from the tray chassis, and second sections, which diverge laterally outwardly from a laterally outer end of the first section and define the branches. Preferably, the number of second sections in the/each transverse member is two. Either or each transverse member may comprise a bifurcated support member defined by the first and second sections thereof.

Preferably, the transverse members curve upwardly from the tray chassis. Preferably, the number of transverse members interconnecting the tray chassis and each of the longitudinal members is two.

Preferably, the floor is suspended over the transverse members. Preferably, the chassis comprises a pair of laterally spaced apart longitudinal beams. Preferably, the transverse members comprise I-beam sections.

In a preferred embodiment of the invention, the components comprise brackets configured to hold lateral edge sections of the steel membrane floor to the frame. Preferably, the brackets comprise hook-shaped members. Preferably, in that embodiment, the components further comprise longitudinal ribs at lateral edge portions of the steel membrane to be received by the hook-shaped members. Preferably, the ribs are attached to an underside of the membrane and the hook-shaped members are upwardly opening for downward receipt of the ribs therein. The ribs may comprise round bar or tube sections, which may be welded to the membrane. In a preferred embodiment of the invention, the components comprise spaced apart pins arranged along opposite sides of the structure, and lateral edge portions of the elastomeric mat are configured with holes to receive the pins such that the mat is attached to the structure. Preferably, the pins project upwardly such that the holes are downwardly receivable thereover. Preferably, the pins are arranged on the longitudinal members. Preferably, the pins are fixed to upper walls of the longitudinal members.

In a preferred embodiment of the invention, the components comprise clamping members configured to clamp edge portions of the floor against the structure. Preferably, the clamping members comprise ones to clamp lateral edge portions of the floor against structure - preferably against the frame, and more preferably against the longitudinal members. Preferably, the clamping members comprise ones to clamp a front edge portion of the floor against the structure - preferably against the frame or front wall.

Preferably, the clamping members are configured to conceal the clamped edge portion(s). Preferably, the clamping members comprise wear plates. Preferably, the clamping members comprise first portions which are arranged for receipt against said edge portion(s) and second portions which project upwardly from the first portions to . be fixed to the structure at positions remote from the edge portion(s). Preferably, the components further include fasteners, such as bolts, to secure the clamping members to the frame and/or side walls. Preferably, the fasteners are received or receivable through the second portions to secure the clamping members at said positions, which fasteners may comprise, for example, bolts.

In a preferred embodiment of the invention, the parts include flexible elongate members configured to hang from the structure - preferably the frame - to support the mat from beneath. The flexible elongate members are configured to hang from the structure whereby a supportive bed comprising the flexible elongate members underlies the elastomeric mat.

Preferably, the flexible elongate members comprise ropes or cables. Preferably, the flexible el ^' ongate members are elastomeric.

In a preferred embodiment of the invention, the flexible elongate members are configured such that each extends from one lateral side of the tray to the other, preferably such that they are generally parallel.

Preferably, the parts include said supportive bed comprising the flexible elongate members and a sheet secured to them so as to support a part of the mat from beneath. Preferably, the sheet is arranged to support a central part of the mat from beneath. Preferably, ones of the flexible elongate members extend through the sheet to support the sheet.

In a preferred embodiment of the invention, the flexible elongate members are provided with fittings to secure them to opposite sides of the structure, preferably to the frame, and more preferably to the longitudinal members. Preferably, the fittings comprise ones which are adjustable such that the tension in the elongate members can be varied. Preferably, the fittings are configured to engage laterally outer walls of the structure, and the structure is formed with spaced apart holes arranged along opposite sides thereof to receive ends of the elongate members therethrough such that the fittings so engage the laterally outer walls. Preferably, the fittings are adjustable at positions exterior of the tray. Preferably, a front edge portion of the floor is secured to the frame and/or front wall. Preferably, the dump tray/set additionally comprises further components configured to secure the front edge to the frame and/or front wall. Preferably, the further components comprise clamping members configured to clamp the front edge portion of the floor against the frame and/or front wall. Preferably, those clamping members are configured to conceal the front edge portion. Preferably, those clamping members comprise wear plates. Preferably, those clamping members comprise first portions which are arranged for receipt against the front edge portion and second portions which project upwardly from the first portions to be fixed to the frame and/or front wall at positions remote from the front edge portion. Preferably, the further components further include fasteners, such as bolts, to secure the clamping members to the frame and/or front wall. Preferably, the fasteners are received or receivable through the second portions to secure the clamping members at said positions, which fasteners may comprise, for example, bolts.

Preferred embodiments of the invention provide a dump tray having a steel body and a floor suspended by the body and comprising either of a rubber mat and a steel membrane, which may be interchangeable without modification of the body design.

Owing to the combination of the frame and suspended floor, the overall weight of the dump tray can be considerably lower than that of conventional dump trays. The noise and vibration caused by loading impact on the dump tray floor can be reduced considerably thank to the provision of the elastomeric mat floor.

According to a fifth aspect of the present invention, there is provided a tray for carrying bulk material in mining operations, the tray comprising:

a floor which comprises a steel membrane or a rubber wear mat;

a chassis comprising two main lengthwise central beams;

a pair of side beams from which the floor is supported; and

a pair of transverse beams interconnecting the chassis and the pair of side beams. Preferably, the transverse beams comprise divergent beam sections. In the preferred embodiments of the invention, the chassis, side beams and transverse beams define a skeleton steel frame via which the floor is supported. The tray may carry bulk material from an exploration pit to an extraction plant. Preferably, the floor which comprises the steel membrane and the floor which comprises the rubber wear mat are interchangeable. Preferably, the transverse beams interconnect with the side ^" beams via toeholds. Preferably, the tray includes a front wall comprising five straight sections which are arranged at varying angles to approximate a curve. Preferably, the tray includes a curved canopy at an upper end of the front wall. Preferably, the canopy comprising sections of plate of varying thickness, a thickest one of which is anchored to the front wall. Preferably, the canopy includes a gusset structure which restricts oscillation of the canopy relative to the front wall. Preferably, the floor is secured via clamps and bolts. In a preferred embodiment of the invention, the floor is the rubber wear mat floor and the tray includes synthetic suspension ropes which extend between opposed side walls of the tray and support the floor from beneath. The rubber wear mat floor may comprise rubber, rubber with steel reinforcement, rubber with a reinforcive steel backing, and may be provided with elastic bands, polymer resins or nylon (which may constitute the suspension ropes). The rubber wear mat floor may provide outstanding noise reduction, impact absorption and vibration attenuation owing to its being elastic and flexible.

According to a sixth aspect of the present invention, there is provided a dump tray for a bulk material transport truck, which is mountable to a chassis of the truck to be pivotable, about the chassis, between a level orientation, for carrying the bulk material, and a tilted condition, for the dumping the bulk material, the dump tray including a canopy an upper side of which is upwardly convergent or generally convex in an upward direction. Preferably, the upper side is curved.

According to a seventh aspect of the present invention, there is provided a dump tray for a bulk material transport truck, which is mountable to a chassis of the truck to be pivotable, about the chassis, between a level orientation, for carrying the bulk material, and a tilted condition, for the dumping the bulk material, the dump tray including a front wall which is generally convex in a forward direction. Preferably, the front wall comprises a panel structure and bracing members attached to an exterior side of the panel structure. Preferably, the panel structure comprises generally flat panel sections arranged side-by- side whereby the panel structure has a generally convex configuration in the forward direction.

The present invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Figure 1 is a rear upper perspective view of a dump tray constructed in accordance with a preferred embodiment of the invention;

Figure 2 is a bottom view of the dump tray configured with a rubber mat floor;

Figure 3 is a front view of the dump tray;

Figure 4 is a side view of the dump tray;

Figure 5 is a rear view of the dump tray;

Figure 6 A and 6B are underside perspective and front views, respectively, of a canopy of the dump tray;

Figure 7 is a plan view of the dump tray as comprising the rubber mat floor;

Figure 8 is an underside perspective view of the dump tray configured with a steel membrane floor;

Figure 9 is a perspective view showing details of wear-resistant clamping plates which secure the steel membrane floor;

Figure 10 is a perspective view showing details of an interconnection between the steel membrane floor and a frame of the dump tray;

Figures 1 1 A and 1 I B are perspective views showing how the rubber mat floor is secured to and supported from the frame;

Figure 12 is a perspective view showing an elastomeric structure mountable to the frame to support the rubber mat floor from below; and

Figures 13 A, 13B and 14 show further details of the tray as comprising the steel membrane floor and of how that floor is secured.

A dump tray 1 constructed in accordance with a preferred embodiment of the invention, shown in Figure 1. is designed to carry bulk material in mining operations, and may, for example, be used to transport such material from an exploration pit to extraction/processing plants. The tray 1 has a body structure 6 comprising a front wall 3, opposed side walls 5, between which the front wall 3 extends, and a canopy 7 which projects forwardly from a top end of the front wall 3. The walls 3, 5 and canopy 7 comprise sections of steel plate and elongate members supporting and reinforcing those sections, including upper longitudinal beams 25 which extend from rear ends of the side walls 5, along upper edges thereof, and project forwardly of the front wall 3 to form laterally outermost supports of the canopy 7, and lower longitudinal beams which extend from the side wall rear ends to the side wall front ends, adjacent lower edges of the walls 5. The tray 1 further comprises a base frame 9, which can be seen in Figures 2, 4, 5 and 8. on which the front wall 3 and side walls 5 are supported, the frame 9 comprising a pair of spaced apart axially extending central beams 1 1 , opposed longitudinal side beams 13 arranged laterally outward of the central beams 1 1 , and transverse frame members 4 interconnecting the beams 1 1 and beams 13. The beams 13 are at a higher level than the beams 1 1. The side walls 5 are secured to, and extend upwardly from, the beams 13.

The frame is provided with front 17 and rear 19 pairs of holes arranged to form clevis connections with a chassis of the truck to which the tray 1 is to be fitted, whereby to be pivotable between load-carrying and load-tipping orientations, the frame 9 thus defining a chassis of the tray 1.

Each of the front transverse members 4A comprises a first section 14, which is fixed to and extends laterally outwardly from a respective central beam 1 1 , and a pair of sections 16A fixed to and diverging laterally outwardly from a laterally outer end of the first section to define two branches. Each of the rear transverse members 4B is constituted substantially solely by a pair of sections 16B fixed to and diverging laterally outwardly from the central beams 1 1 , also defining branches. As can be seen in Figures 4, 5 and 8, the transverse members 9 curve upwardly from the chassis to the longitudinal beams 13, each of those beams being fixed to laterally outer ends of the branches 16A and 16B, whereby they are supported from the frame 9 - each at four points defined by respective branch outer ends. The frame 9 further comprises cross members 18 which interconnect the central beams 1 1. Reinforcive plates 21 are secured at the branch outer ends and fixed to outer faces of the respective beams 13. The sections 14, 16A and 16B have generally 1-shaped cross- sectional configurations.

The tray 1 further comprises a floor 30, shown generically in Figure 1 , secured at lateral edges thereof to the beams 13 and at a front edge thereof to a lower end of the front wall 3, as will be described in further detail later, whereby the floor is suspended from the tray body 6, over the frame 9. The provision of an open frame structure and a floor suspended thereabove, instead of a conventional integral steel floor, results in significantly reduced overall weight of the tray 1 . Advantageously, owing to the transverse members' comprising laterally outwardly divergent branches, the amount of frame material required to support the beams 13 adequately at spaced apart positions along their length is significantly less than is the case where separate sections extend, parallel to each other, from those positions to the beams 1 1.

The. tray 1 is assembled from a system of parts which is such that the suspended floor 30 may be one which comprises a rubber wear mat 60 or instead one which comprises a steel membrane 50. More particularly, the parts consist of a main structure 40, comprising the frame 9 and body 6 supported thereon, a steel membrane floor 50, an elastomeric mat floor 60 and an associated bed structure 70 for supporting the mat from below, and components for securing the elastomeric mat and steel membrane to the structure 40, as will be described in further detail shortly. *

Referring in particular to Figures 8, 10. 1.3 A and 1 3B, the steel membrane floor 50 comprises a curved section of steel plate or sheet 52 and longitudinal ribs 54 each of which is defined by steel rod or pipe and attached, preferably via longitudinal fillet welds, to the underside of the membrane 52 adjacent a respective side edge thereof and extending substantially the entire length of the membrane 52.

The components for securing the membrane floor 50 to the structure 40 comprise brackets 56 welded to, or otherwise fixed (e.g. releasably, such as via bolts) against, laterally inner faces 14 of the beams 13. The brackets 56 define axially spaced apart hooks which project laterally inwardly from the beams 13, and are arranged substantially throughout the entire lengths of the beams 13. The hooks along each beam 1 are positioned to catch over respective ribs 54 when the floor 50 is lowered onto the beams 13, whereby the membrane 52 hangs from the beams 13 via the brackets 56, which distribute the load exerted by the floor on the beams 13 along the lengths of those beams. When the membrane 52 is so positioned, its front edge is received on a ledge 2 defined at, and extending along, a lower edge of the front wall 3. The components for then securing the membrane floor 50 to the structure 40 comprise wear-resistant clamping plates 58, in the form of liners having L-shaped cross-sections, which are arranged side-by-side along the lateral edges of the membrane 52 and fasteners, in the form of bolts (omitted from the drawings for clarity), which are received through holes 59 formed through upper sections of the members 58, and thence through holes 23 formed through the walls 5, to receive, at their outer ends, nuts whereby the upper sections 58A are fixed against inner upright faces of the walls 5 and the membrane side edges are thus clamped between lower sections 58B of the members 58 and generally upwardly facing surfaces of the beams 13, laterally outward of the ribs. Rearmost ones 58' of the members 58 are configured with additional holes 59', and the securing components include additional fasteners, in the form of bolts 57, which are received through the holes 59', holes 53 formed through rear portions of the membrane side edge sections (which align with the holes 59'), and holes 23' which are formed through rear portions of the beams 13 and aligned with the aligned holes 59' and 53. Ends of the fasteners 57 which thus project from lower faces of the beams 13 receive nuts such that the rear side edge sections of the membrane 52 are secured not only by engagement between the ribs and hooks and the clamping engagement between the members 58' and beams 13, but also by the fasteners 57' which force the lower sections of the members 58' into particularly tight engagement with the membrane side edge rear portions and additionally form an interlock with those edge portions by virtue of their being received therethrough. A rear section of the membrane floor 50, which is generally- subjected to particularly high stress when the tray 1 is loaded, is thus very robustly secured to the structure 40.

Referring to Figures 9, 10, 13 A, 13B and 14, the components for securing the membrane floor 50 to the structure 40 additionally include further wear-resistant clamping members 58", which are also in the form of liner plates having L-shaped cross-sections, and arranged side-by-side along the front edge of the membrane 52, whereby that edge is clamped between the lower sections 58B" thereof and the ledge 2, and the upper sections 58A" are received against the front wall 3. The members 58" are secured to the wall 3 by fillet welding, along their upper edges, though may, alternatively or additionally, be secured to that wall via fasteners, such as bolts, through the upper sections 58A" and thence through the wall 3. The lower sections 58B" of laterally outermost ones of the clamping members 58" are configured with holes 59" therethrough, which holes align with respective holes 53' formed adjacent front corners of the membrane 52 and which, in turn, align with holes through the ledge 2, and bolts 57" are received through the aligned holes and fitted at ends thereof with nuts such that the lower sections 58B" clamp the membrane front corners particularly tightly against the beams 13 and those corners are additionally held last by the interlock formed between the corners and the fasteners 57" received therethrough, A front section of the membrane 52, which can also be subjected to particularly high stresses when the tray is loaded, is also thus very robustly fixed to the structure 40.

The steel from which the membrane 52 is made has a yield strength of 650 to 700 MPa, conferring good strength, a nominal hardness of 450 HBW, conferring good wear resistance, an elongation percentage exceeding 10%, and a Charpy value of 27J/-20°C, conferring good impact resistance.

The selectability and interchangeability of the steel membrane floor 50 and rubber mat floor 60 allow the superficies of the tray floor to be optimised according to operational requirements. For example, the rubber mat floor 60 is particularly well suited for extreme conditions, and may be employed to minimise noise resulting from impact of rocks against the tray during loading, and/or to reduce or eliminate "carryback", whereas the steel membrane floor 50 may be employed where the bulk material to be carried by the truck has is relatively non-abrasive or has a relatively low density, e.g. comprises coal, whereby the payload and ease of maintenance of the tray can be maximised.

Referring to Figures 1 1 A and 1 IB, the elastomeric mat floor 60 is similarly configured to be fixed against the beams 13 and ledge 2 so as to be suspended over the frame 9. The rubber mat 62 is configured with spaced apart holes 64 along each of its side edges, and the components for securing it to the structure 40 include spaced apart studs 65 arranged along each beam 13 and projecting upwardly to be received in respective ones of the holes 64, thereby holding the mat 62 to the beams 13. Referring also to Figure 12, the supportive bed structure 70, which is configured to underlie the mat 62 so as to support it from below, comprises parallel elastomeric ropes 72 and a centrally disposed longitudinally extending strip of rubber 74 through which the ropes 72 pass. The ropes 72 are configured with loops 73 at their ends and are provided with screw-tensionable connectors 68 receivable through the loops 73. The rope ends are receivable in respective ones of axially spaced apart holes in the beams 13, each hole being defined by a respective sleeve 69 attached to opposite side walls of the respective beam 13 and having an inner end which extends through a respective cutout in the beam inner side wall. Each connector 68 comprises a clevis fitting 68A received through the respective eye and a bolt 68B threadingly engaged with the fitting 68A and received through a respective aperture through the beam outer wall to secure the fitting 68A, and thus the respective rope end, to the beam 13. Advantageously, each bolt head can be engaged, on the outside wall of the respective beam 13 whereby the bolt can be turned to increase or reduce the effective length of the respective rope, whereby a nominal spacing between the mat 62 and the frame 9 over which it is thus suspended can be easily maintained or altered, and the tension through each rope adjusted.

Each rope comprises a core formed from polyester fibres and a rubber sheet which surrounds the core.

·

The mat 62 is configured with a thickened section 61 at its rear end, which section occupies about a third of the length of the mat 62, so as to be resistant to particularly high impact and wear realised at that end. Referring to Figure 1 IB, the components for securing the mat floor 60 to the structure 40 additionally include the clamping members 58 which attach to the structure 40 in the manner already described and thus clamp the side edges of the mat 62 against the beams 13, concealing those edges along their entire lengths and thus protecting them from wear and impact damage. Those components also comprise either the clamping members 58" shown in Figures 13A and 13B, which also attach to the structure 40 in the manner already described and thus clamp the front edge of the mat 62 against the ledge 2, concealing it along its entire length and thus protecting it from wear and impact damage, or may instead comprise wear-resistant blocks 80, shown in Figures 1 and 7, attached to the structure 40 so as to clamp the mat front edge against the ^' ledge, thereby similarly concealing and protecting it.

Referring to Figures 2 and 4, as mentioned previously, the bed structure 70 supports the rubber mat 62 from below. More particularly, the strip 74 forms an "undcrmat" against which a central longitudinal portion of the mat 62 rests, whereby that section is provided with a relatively high degree of support. Advantageously, dynamic loads exerted by the load on the tray 1 , such as during loading of the tray or transportation of the load in the tray, are significantly dampened by the rubber floor 60 and bed structure 70 which underlies it, and noise and vibration considerably reduced also. The rubber mat floor 60 also provides for an improved and more efficient filling of the tray 1 and acts to limit spillage of load during transportation.

The flexible elongate members may be formed from other materials; e.g., they may comprise elastic bands, cores and/or coating formed of alternative polymers. Moreover, the mat may be one which is reinforced, either with internal reinforcement or a reinforcive backing, which reinforcement may comprise steel, nylon or another suitable material.

The elastomeric floor 60 and support bed 70 may be configured and adjusted such that, when the tray 1 is loaded, they stretch sufficiently so as to rest against parts of the frame 9, e.g., the transverse members thereof, whereby those parts of the frame take up some of the load exerted on the tray 1 by the load, so that the tension in the ropes is less than it would be where the floor 60 and structure 70 to remain clear of the frame 9 when the tray is loaded. Owing to the provision of the elastomeric floor assembly, the tension in the floor is decreased in comparison to a traditional suspended dump body floor, and loading through the beams 13 will similarly be reduced as compared with the side beams in a dump body having a traditional suspended floor. Referring to Figures 6A and 6B, the canopy 7 includes a frame structure 10 comprising transversely spaced apart gussets 12 which project forwardly from the front wall 5, and axially spaced apart cross members 4 fixed to the gussets 12 and extending substantially the width of the canopy 7. The canopy 7 further comprises an outer panel 17 comprising steel plate which is fixed to the frame 10, including to the cross members 4, so as to assume an upwardly convex or curved configuration corresponding to a camber of the cross members 4. The canopy 7 further comprises a curved elongate web 8 attached to the front end of the panel 17 to provide stiffening thereto. Owing to the curvature of the canopy 7, there is, advantageously, a reduced or eliminated tendency for payload material to gather on the canopy 7. The canopy frame 10 forms a main support which restricts or eliminates oscillation of the canopy 7 relative to the front wall 3.

The steel membrane floor is lighter than the elastomeric floor assembly comprising the floor 60 and support structure 70, and the steel membrane itself is thinner than the rubber mat.

Moreover, the system is configured such that the membrane or mat side edges are arranged with a grade with the horizontal of about 21 % to about 25, which is less than the angle of such edges in traditional suspended dump tray floors, whereby the floor assumes a relatively flat dished configuration and may thus be arranged closer to the chassis.

The front wall 3 comprises forwardly convex, transverse beams 27 which are generally parallel and each extend substantially the width of the front wall 3. The front wall 3 further comprises an arrangement of substantially flat panel sections arranged side-by-side and fixed to the cross members 27 to form the inner surface of the wall 3, the sections comprising a central section 3A, intermediate sections 3B at opposite lateral sides of the section 3 A, and outer sections 3C at laterally outer sides of the intermediate sections 3B. Adjacent edges of the sections are welded together, and laterally outer edges of the sections 3C are welded to the panels of the side walls 5. Upper edges of the side-by-side sections are appropriately angled to align with a rear edge of the canopy panel, and are each welded to that edge. Lower edges of the sections are welded to the ledge 2. The front wall 3 thus has a generally forwardly convex configuration by which configuration is defined by a plurality of flat panel sections, whereby it has improved load-bearing capacity when the tray 1 is loaded.

The frame in other embodiments may comprise a different arrangement of transverse members, dependent on the tray dimensions and intended application. For example, the transverse members may include ones each of which consists of a single beam section extending from a central beam 1 1 to the respective laterally outer beam 13, with the remainder of the transverse members comprising the laterally outwardly divergent branches. Alternatively or additionally, the transverse members may comprise ones each of which has more than two (e.g., three) branches.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.