AU2010257358B2

AU2010257358B2 - Haulage Vehicle

Info

Publication number: AU2010257358B2
Application number: AU2010257358A
Authority: AU
Inventors: Robert J. Nash
Original assignee: ABAKAY Pty Ltd
Current assignee: ABAKAY Pty Ltd
Priority date: 2002-11-12
Filing date: 2010-12-22
Publication date: 2012-09-13
Anticipated expiration: 2023-11-12
Also published as: AU2003275781A1; WO2004043736A1; AU2010257358A1

Abstract

Abstract A haulage vehicle (10) having a load carrying body (12) adapted to hold a load, the vehicle (10) being supported on at least three pairs of opposed wheel assemblies (24, 26, 28) located on opposite sides of the central longitudinal extent of the vehicle (10), the load carrying body (12) having a closable discharge opening (40) at a lower extent thereof for selectively discharge the load, and extending substantially along the entire central longitudinal extent of the load carrying body (12), the lower extent of the load carrying body (12) and closable discharge opening (40) are disposed in the region between at least a central pair of opposed wheel assemblies (24, 26, 28), each of the pairs of opposed wheel assemblies (24, 26, 28) incorporate, in self-contained manner, a motor, to allow discharge of load unimpeded between the pairs of opposed wheel assemblies (24, 26, 28) while the vehicle (10) is in motion. In an other embodiment the vehicle (10) includes a spreader disposed behind, the spread discharged load in a single pass and obviate the need for a separate grading operation. -- --- IT C-4 tj' La

Description

Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Abakay Pty Ltd Actual Inventor Robert J Nash Address for service is: WRAYS Ground Floor, 56 Ord Street West Perth WA 6005 Attorney code: WR Invention Title: Haulage Vehicle The following statement is a full description of this invention, including the best method of performing it known to me:- "Haulage Vehicle" Field of the Invention The present invention relates to a haulage vehicle, and in particular a haulage vehicle for handling bulk material on minesites, in road construction, and other 5 works. Background Art In the ever competitive mining and haulage industries there is always a need to reduce costs and increase productivity. While it has been understood that this goal may be achieved by the development of trucks capable of carrying larger 10 payloads, the development of larger trucks is limited by the availability of, at least in part, tyres and drive systems capable of handling the loads encountered. Today the largest known dump trucks have payload capacities typically of up to about 300 to 360 tonnes. The state of tyre technology has been a limiting factor in the design of larger trucks. A real constraint to the current development of 15 larger tracks has been the availability of tyres capable of supporting the weight required for increased truck payloads. In addition some trucks built in the past which had a higher payload capacity experienced handling and steering problems, such as the models commonly known as the "Terex 33-19 Titan" and the "Wabco Haulpak 3200B" dual rear axle trucks. 20 There is a need for a haulage vehicle that provides a useful alternative to those already known in the industry. It would be an advancement in the art to provide a haulage vehicle capable of carrying significantly more material than those of the prior art without the need to rely on advancements in tyre technology. The haulage vehicle of the present invention has one object thereof to overcome 25 substantially the above-mentioned problem associated with the prior art, or at least provide an alternative known to haulage vehicles. It is also an object to -2 provide a bulk solids haulage vehicle having features which will increase efficiency in operations in which they are utilised. The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the 5 discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia or elsewhere as at the priority date of the application. Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to 10 imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Disclosure of the Invention In accordance with the present invention there is provided a haulage vehicle having a load carrying body adapted to hold a load, said vehicle being supported 15 on at least three pairs of opposed wheel assemblies, each wheel assembly of said pair being located on opposite sides of the central longitudinal extent of said haulage vehicle, said load carrying body being equipped with a closable discharge opening at a lower extent thereof, arranged to selectively discharge said load; said closable discharge opening being characterised by extending substantially 20 along the entire central longitudinal extent of said load carrying body, and characterised in that a lower extent of said load carrying body and closable discharge opening are disposed in the region between at least a central pair of opposed wheel assemblies, and characterised in that each of the pairs of opposed wheel assemblies incorporate, in self-contained manner, a motor, to 25 obviate the need for mechanical drives extending between said pairs of opposed wheel assemblies, to allow discharge of load unimpeded between said pairs of opposed wheel assemblies while the vehicle is in motion. It should be understood that-the above described arrangement does not preclude lateral structural members being incorporated in the load carrying body, and -3 indeed these may be useful to break the impact of material being loaded to prevent material being loaded from impacting against the closable discharge opening. With this configuration a number of advantages are provided over hitherto known 5 haulage vehicle configurations. In the absence of mechanical drives extending between the pairs of opposed wheel assemblies, such mechanical drives typically including differentials and drive shafts, the lower extent of said load carrying body and said closable discharge opening can occupy the space normally occupied by such mechanical drives in conventional vehicles. With the lower extent of said 10 load carrying body and said closable discharge opening extending along the entire central longitudinal extent of said load carrying body and with the lower extent of said load carrying body and said closable discharge opening being disposed in the region between the pairs of opposed wheel assemblies, this results in the centre of gravity of the vehicle being lower than that of a vehicle that 15 might attempt to discharge around mechanical drives. This results in the vehicle having the shortest possible length and height while maximising load carrying capacity. A lower centre of gravity also assists in minimising side wall stress in the tyres of the vehicle. Preferably said haulage vehicle includes discharge rate control means for 20 controlling rate of discharge through said closable discharge opening. Preferably said closable discharge opening includes at least one pair of doors and said discharge rate control means controls the opening of and the relative disposition of said doors. Preferably said at least one pair of doors are mounted on spaced parallel axes, 25 and said closable discharge opening formed by said at least one pair of doors extends between said axes. There may be one, two, three, four, five, or six pairs of doors, preferably on common said spaced parallel axes, forming said closable discharge opening, however a practical number of pairs of doors is likely to lie between two and four, -4 with the most preferred number in the embodiment described hereafter being two. One factor that would determine that the number of pairs of doors be increased is where the load to be carried is very flowable. It should be understood that by the expression "opposed" in "pairs of opposed 5 wheel assemblies", it is meant that each pair of opposed wheel assemblies comprises a wheel assembly on each side of the vehicle; the wheel assemblies are opposed in the sense that they are on opposite sides of the vehicle. The wheel assemblies of said pairs of opposed wheel assemblies may have either one wheel or two or more wheels arranged co-axially. Thus any pair of opposed 10 wheel assemblies may have a single wheel on each side of the vehicle or two wheels (or more) on each side of the vehicle. In the most preferred embodiment, two wheels are provided on each side of the vehicle in each of said pairs of opposed wheel assemblies. Preferably, said closable discharge opening extends entirely uninterrupted (apart 15 from the presence of the closable discharge opening and any lateral structural cross-members that may be included for structural strength) substantially from between the most forward pair of opposed wheel assemblies to substantially to between the most rearward pair of opposed wheel assemblies. It should be noted that any lateral cross-members may be located well above the closable discharge 20 opening, and be provided with enlarged upper surfaces to break the impact force of material being loaded. Preferably, the load carrying body has a hopper-like configuration with sloping side portions of the load carrying body extending downward toward said closable discharge opening . 25 Preferably said the lower extent of said load carrying body and said closable discharge opening extend in proximity with the horizontal plane of the axis of the wheels, to minimise the height of the centre of gravity of the vehicle when fully loaded.

-5 Preferably the lower extent of said load carrying body and said closable discharge opening extend below the horizontal plane of the axis of the wheels, to minimise the height of the centre of gravity of the vehicle. Preferably said at least one pair of doors comprises a plurality of pairs of 5 independently operable doors located along the length of the bottom of said load carrying body , to allow staged discharge of the load to take place. The degree or extent that the doors are opened can be controlled to allow control over the rate of discharge of the load. Preferably the spatial arrangement of the load carrying body leading to the 10 closable discharge opening, its height from the ground, and its spacing from the wheels is such that under controlled discharge of the load, the load is discharged between the wheels. In this manner, the wheels do not run over the load. The haulage vehicle of the present invention may further be provided with levelling means, to level material discharged from the vehicle, the levelling means 15 being provided at the rear of the vehicle to level discharged material as the vehicle proceeds in forward motion. This allows the levelled discharged material to be driven over by a following vehicle (such as an identical haulage vehicle) without the necessity of a separate grading operation by a grader or dozer. The levelling means preferably is mounted on arms, and is provided with a height 20 adjustment apparatus to adjust the height of the levelling means with respect to the haulage vehicle. Preferably, the height adjustment apparatus includes hydraulic rams to vary the height of the levelling means with respect to the haulage vehicle (and hence the ground). While.the levelling means could be mounted for parallel movement with 25 respect to the haulage vehicle, so that the attitude of the levelling means remains constant with height adjustment, it is most preferred that the levelling means has three hydraulic rams, each operable independently of the others, to allow the height, attitude, and angle of the levelling means to be fully adjustable.

-6 Preferably, the levelling means has at least one leading face. The at least one leading face preferably is formed with a concave shape. In one form of the invention, the levelling means has two leading faces arranged to form a V-shape. In this form, the levelling means is located on the haulage 5 vehicle such that the apex of the levelling means is forward facing. Preferably both of the leading faces are concave and the concave faces are forward facing. The apex of the V-shape is preferably centrally located with respect to a longitudinal axis of the vehicle. The levelling means may be further provided with a third, rearward face, providing 10 a blade to level when the vehicle is reversing. The rearward face also provides structural rigidity to the levelling means. The rearward face can be used to level material often spilled during previous loading operations, as the vehicle reverses into position to receive a new load, obviating the need to provide a separate bulldozing operation on the site. 15 Preferably said levelling means extends substantially across and preferably beyond the entire width of the haulage vehicle. Preferably, the haulage vehicle is further provided with laser levelling equipment interfaced with said height adjustment apparatus. Preferably, each wheel assembly of said pairs of opposed wheel assemblies is 20 attached via suspension means to the haulage vehicle. Preferably, each wheel assembly incorporates said motor in the form of an electric motor, preferably in the form of an AC electric motor. The most preferred form of the haulage vehicle according to the invention has three said pairs of opposed wheel assemblies, although in an alternative 25 arrangement the haulage vehicle may be provided with four pairs of opposed wheel assemblies comprising a forward pair of opposed wheel assemblies, a rearward pair of opposed wheel assemblies and two further pairs of opposed -7 wheel assemblies located in spaced relation between said forward and rearward pairs. Preferably at least said forward and rearward pairs of opposed wheel assemblies are provided with steering means. The steering means is preferably controlled 5 electrically or hydraulically by an electronic control circuit. Preferably, all of said pairs of opposed wheel assemblies are provided with steering means controlled by said electronic control circuit which selectively allows controlled steering and/or crabbing of said haulage vehicle. Preferably, the haulage vehicle has an integral bulk solids containing body and 10 chassis. The haulage vehicle may further have a rollover protective structure extending over the cab. Preferably the cab is centrally located with respect to a longitudinal axis of the vehicle. Brief Description of the Drawings The present invention will now be described by way of example only in the 15 following description of one preferred embodiment thereof, made with reference to the accompanying drawings, in which: Figure 1 is frontal view of a haulage vehicle in accordance with the present invention; Figure 2 is a side view of the haulage vehicle of Figure 1; 20 Figure 3 is a first rear view of the haulage vehicle of Figure 1; Figure 4 is a second rear view of the haulage vehicle of Figure 1; Figure 5 is a third rear view of the haulage vehicle of Figure 1; Figure 6 is a top plan view of the levelling means of the bulk solids haulage vehicle of Figure 1; Figure 7 is an upper perspective view of an alternative embodiment of the levelling means for a bulk solids haulage vehicle of the invention; Figure 8 is an upper perspective view of a wheel assembly used in the bulk solids haulage vehicle of Figure 1; 5 Figure 9 is a top plan view of the wheel assembly used in the bulk solids haulage vehicle of Figure 1; and Figure 10 is a cut away view of the wheel assembly of the haulage vehicle of Figure 1. Best Mode(s) for Carrying Out the Invention 10 In Figures 1 to 5 there is shown a haulage vehicle 10 having an integral load carrying body 12, upper chassis 14 and lower chassis 16. A roll over protective structure 18 extends over a cab 20 in which the driver sits, the roll-over protective structure being provided to protect a driver in the event of an accident. An engine bay 22 located under the cab provides an area for twin diesel engines and 15 alternators to provide electrical power for the vehicle. The diesel engines are MTU 4 cycle units, model 16V-4000, having 64 litre displacement V16 configuration, and developing 2,500 BHP at 1,900 RPM. The alternators are General Electric units, model GE GTA 41. The vehicle 10 is provided with three pairs of opposed wheel assemblies, being a 20 rearward pair of opposed wheel assemblies 24, a central pair of opposed wheel assemblies 26 and a forward pair of opposed wheel assemblies 28. The pairs of opposed wheel assemblies 24, 26, 28 each have two wheel assemblies 24a and 24b, 26aand 26b, and 28a and, 28b respectively, 24a, 26a, 28a on the right hand side of the vehicle and 24b, 26b, 28b on the left hand side of the vehicle. In turn, 25 each wheel assembly has two wheels 30 31 arranged adjacently and co-axially. Each wheel 30 31 has a removeable rim on which is mounted a tyre.

-9 The load carrying body 12 is topped with downwardly outwardly extending spill guards 34 extending along each side of the load carrying body. These spill guards deflect material away from the wheels 30, 31, that may spill during the loading process. The load carrying body 12 extends to a position down partly 5 between the wheels 30 31, and further has a lower extent in the form of a load discharge passage 38 which is centrally disposed along the longitudinal axis of the vehicle 10. The load discharge passage 38 extends between opposed wheel assemblies 24a and 24b, 26a and 26b, and 28a and 28b, on either side of the vehicle 10 and forward of the axis of the most rearward opposed wheel 10 assemblies 24a and 24b, particularly from this axis to the axis of the most forward opposed wheel assembly 28. Control over discharge of load in the load carrying body 12 and in the load discharge passage 38 is provided by four bottom opening doors 40 provided as two pairs, mounted about parallel spaced apart longitudinal axes 41a and 41b. 15 The doors 40 are hydraulically operated by hydraulic rams 42 and are controlled from the cab 20 by the driver of the vehicle 10. The doors 40 are part of a closable discharge opening 43. In Figure 3, the doors 40 are shown in the closed position and in figure 4 the doors 40 are shown in the fully open position . The degree or amount that the doors are opened is controlled by control of the 20 hydraulic rams 42, to control the rate of discharge of the load. The hydraulic rams are also used to control which of the two pairs doors 40 are opened, being either the forward pair or rearward pair, to further control discharge of the load. The rate of discharge would be varied with the speed that the vehicle is travelling, to achieve an even rate of discharge. 25 The load discharge passage 38 can be considered conceptually as a structure integral with the load carrying body 12, which leads to the discharge opening 43. The load discharge passage 38 is, in effect, a narrowing of the load carrying body 12, leading to the discharge opening 43. Referring to Figures 2, 5, and 6 , the vehicle 10 has a levelling means in the form 30 of a V-shaped spreader 46 for levelling material discharged from the load carrying body 12. The spreader 46 is provided disposed behind the rear 48 of the vehicle -10 10, supported on attachment arms 50 from the lower chassis of the vehiclelO. The attachment arms 50 are mounted to the spreader 46 and to the lower chassis on pivotable ball trunnion joints 51. The spreader 46 has height adjustment means in the form of three hydraulic rams 52. The combination of the pivotable 5 ball trunnion joints 51 and the three hydraulic rams 52 allow the height, angle, and attitude of the spreader 46 to be fully adjustable. The spreader 46 has two leading faces 56, 58 which are supported from behind by a central fillet 59 on which the mounting point 52a for the centre/forward hydraulic ram 52 is located, and supported further by a horizontal support strut 60. The horizontal support 10 strut 60 which provides support against collapse during a grading operation for the front faces 56 58. The horizontal support strut also provides mounting locations for the lower pivotable ball trunnion joints 51 to which the attachment arms 50 attach, and mounting points 52b for the two rear hydraulic rams 52.. The two leading faces 56, 58 are concave about a horizontal axis, and swept back 15 from the forward apex 62 of the spreader, so that the discharged material being spread, curls along the faces 56 58, assisting in even spreading of the material. The leading faces 56, 58 are taller at the apex 62, tapering in height with increasing distance from the apex 62, as the height of the spread discharge load reduces as the spreader proceeds. 20 Referring to figure 7, an alternative embodiment of a spreader 46 is illustrated, having a rear face 64. The rear face 64 is also slightly concave, and is provided to perform a grading/dozing/spreading operation when the vehicle is reversed into a loading station. The loaders in a loading station often spill material, so the provision of the rear face 64 on the spreader 46 allows the vehicle to be reversed 25 without the need for a separate bulldozing operation to prepare the way for the vehicle. The wheel assemblies 24, 26, 28 are each attached via a king pin 65 and clevis 66 arrangement to suspension formed by swing arms 67 connected to the lower chassis 16 and formed by a shock absorbing strut 68 connected to the upper 30 chassis 14 of the vehicle 10. The king pin 65 and clevis 66 arrangement allows each wheel to be steered by controlled movement about a vertical axis formed by - 11 the king pin 65. The king pin 65 and clevis 66 assembly also includes a pair of load bearings 69. Steering of each wheel assembly is effected through two hydraulic rams 70 which work in tandem, one pushing while the other pulls. One of the hydraulic rams 5 connects to a left hand (viewed from the inside) steering arm 71 while the other hydraulic ram connects to a right hand steering arm 72. The hydraulic steering is controllable electrically from the cab 20 by the driver of the vehicle 10 to both steer the vehicle and to allow it to crab. This arrangement provides a high degree of manoeuvrability which is desirable on a mine site. 10 Referring to figure 10, each wheel assembly 24, 26, 28 is powered by an AC electric motor 74 driving the wheels and tyres 30, 31 through a reduction gearbox 76. The wheel assemblies are General Electric GE150AC motors fitted with 44/80 R57 radial ply tyres. The tyres have a weight capacity of 67,000kg each, giving a total weight capacity of 804,000kg. 15 The unladen weight of the vehicle is approximately 250,000kg, and rated load is 500,000kg. This is achieved in a vehicle having an overall length of 18m, width of 10.5m, and height of 6m. In comparison with other vehicles, the Unit Rig MT 5500 is perhaps one of the largest capacity trucks presently available, having an unladen weight of 216,000kg and rated load of 326,531kg, with an overall length 20 of 14.78m, width of 9.45m, and height of 7.67m (with tipper lowered). Another vehicle having a high capacity is the Liebherr T282 having an unladen weight of 203,300kg and rated load of 363,000kg, with an overall length of 14.5m, width of 8.7m, and height of 7.4m (with tipper lowered, but excluding load height). The haulage vehicle of the present invention offers a number of advantages over 25 the dump trucks of the prior art. The vehicle does not rely on the development of larger tyres in order to carry payloads larger than the trucks of the prior art. The vehicle is able to be fitted with tyres adapted for dump trucks with approximately 50 % the payload of the vehicle of the present invention. For example, a vehicle in accordance with the present -12 invention with a payload of 450 tonnes, will be able to utilise tyres currently used for dump trucks with payloads of 240 tonnes. This is due to the load carried on a greater number of tyres than a conventional truck. In addition, with the arrangement of wheels and tyres, greater handling and riding characteristics are 5 provided. The design of the vehicle allows a portion of the payload to be carried between the wheel assemblies thereby giving the vehicle a lower centre of gravity which in effect reduces the overload rating for each tyre as there is less sidewall pressure which results in increased tyre life and the weight and speed rating for each tyre. 10 Furthermore, the lower centre of gravity should provide the vehicle with improved handling characteristics when carrying a full load. The individual hydraulic steering systems are centrally controlled by electric or hydraulic means. The steering system differs from conventional systems as there is no tracking bar linking the two steering wheels together. As each wheel is 15 steered independently, the central control system is able to provide the optimum tracking for each wheel, thereby providing superior handling qualities and decreased tyre wear compared to the trucks of the prior art. Furthermore, there is no lateral drive train to occlude the load being discharged. A benefit of the AC electric drive configuration on all wheels is the ability to handle higher ramp 20 speeds and increased ramp grades with improved retarding and braking abilities. An advantage of the configuration as disclosed herein is that it is not necessary for the vehicle to stop, reverse to a dumping face and raise its tray in order to discharge its load. The nature of the means for discharging loads should provide significant reductions in cycle times thereby providing the haulage vehicle 10 of 25 the present invention with significant advantages over the dump trucks of the prior art. Furthermore, the self-levelling system means that material is able to be discharged in a manner that will eliminate the requirement to doze or rehandle material to batter the dumps to final environmental standards required in 30 rehabilitation. With the vehicle being capable of dumping and grading in a single -131 - 13 pass, the ground in its wake is immediately left ready for the next vehicle to drive over. It is envisaged that the haulage vehicle may have many applications outside the haulage of ore and waste material in the mining industry. For example, it may be 5 used in underground applications when fitted with ejector trays or in road and tailings dam construction. Due to its ability to carry such massive weights, the vehicle may also have military applications. It should be appreciated that the scope of the invention is not limited to the particular embodiment that is described herein, and that modifications and 10 variations such as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.

Claims

1. A haulage vehicle having a load carrying body adapted to hold a load, said vehicle being supported on at least three pairs of opposed wheel assemblies, each wheel assembly of said pair being located on opposite 5 sides of the central longitudinal extent of said haulage vehicle, said load carrying body being equipped with a closable discharge opening at a lower extent .thereof, arranged to selectively discharge said load; said closable discharge opening being characterised by extending substantially along the entire central longitudinal extent of said load carrying body, and 10 characterised in that a lower extent of said load carrying body and closable discharge opening are disposed in the region between at least a central pair of opposed wheel assemblies, and characterised in that each of the pairs of opposed wheel assemblies incorporate, in self-contained manner, a motor, to obviate the need for mechanical drives extending between said pairs of 15 opposed wheel assemblies, to allow discharge of load unimpeded between said pairs of opposed wheel assemblies while the vehicle is in motion.

2. A haulage vehicle as claimed in claim 1 wherein said closable discharge opening includes at least one pair of doors mounted on spaced parallel axes, and said closable discharge opening formed by said at least one pair 20 of doors extends between said axes.

3. A haulage vehicle as claimed in claim 2 wherein a discharge rate control means is provided for controlling rate of discharge through said at least one pair of doors by controlling the opening of and the relative disposition of said doors. 25

4. A haulage vehicle as claimed in claim 2 or 3 wherein there are provided two pairs of doors on common said spaced parallel axes.

5. A haulage vehicle as claimed in any one of the preceding claims wherein each wheel assembly of said pairs of opposed wheel assemblies has two wheels arranged co-axially. -15

6. A haulage vehicle as claimed in any one of the preceding claims wherein said closable discharge opening extends entirely uninterrupted, apart from the presence of the closable discharge opening and any lateral structural cross-members that may be included for structural strength, substantially 5 from between the most forward pair of opposed wheel assemblies to substantially to between the most rearward pair of opposed wheel assemblies.

7. A haulage vehicle as claimed in any one of the preceding claims wherein the load carrying body has a hopper-like configuration with sloping side portions 10 of the load carrying body extending downward toward said closable discharge opening

8. A haulage vehicle as claimed in claim 7 wherein said the lower extent of said load carrying body and said closable discharge opening extend in proximity with the horizontal plane of the axis of the wheels, to minimise the height of 15 the centre of gravity of the vehicle when fully loaded.

9. A haulage vehicle as claimed in claim 7 wherein the lower extent of said load carrying body and said closable discharge opening extend below the horizontal plane of the axis of the wheels, to minimise the height of the centre of gravity of the vehicle. 20

10. A haulage vehicle as claimed in any one of the preceding claims further including levelling means provided at the rear of the vehicle to level discharged material as the vehicle proceeds in forward motion, said levelling means extending substantially across and preferably beyond the entire width of the haulage vehicle. 25

11. A haulage vehicle as claimed in claim 10 wherein said levelling means preferably is mounted on arms, and is provided with a height adjustment apparatus to adjust the height thereof. -16

12. A haulage vehicle as claimed in claim 11 wherein the height adjustment apparatus includes three hydraulic rams, each operable independently of the others, to allow the height, attitude, and angle of the levelling means to be fully adjustable. 5

13. A haulage vehicle as claimed in any one of claims 10 to 12 wherein the levelling means has two leading concave faces arranged to form a V-shape with the apex forward facing and centrally located with respect to the longitudinal axis of the vehicle.

14. A haulage vehicle as claimed in claim 13 wherein the levelling means is 10 provided with a third, rearward face, providing a blade to level when the vehicle is reversing.

15. A haulage vehicle as claimed in any one of the preceding claims having three said pairs of opposed wheel assemblies, with at least said forward and rearward pairs of opposed wheel assemblies provided with hydraulically 15 controlled steering means.

16. A haulage vehicle as claimed in claim 15 wherein all of said pairs of opposed wheel assemblies are provided with said steering means controlled hydraulically by a control circuit which selectively allows controlled steering and/or crabbing of said haulage vehicle. 20

17. A haulage vehicle substantially as herein described, with reference to the drawings..