BACKGROUND OF THE INVENTION Goods such as aluminium ingots are modularised for transport.

Aluminium ingots and other goods may be bundled according to USLM (Unit Strap Lifting Method) practice. Other types of modularisation (such as palletising) are also known. The Applicant's Australian Petty Patent No 689,431 (45,243/97) illustrates methods and apparatus for transporting modularised loads.

The present invention seeks to simplify or streamline known methods of transport and provides a trailer vehicle for achieving this aim. It is ari object of the invention to provide methods and apparatus for transporting goods.

SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a trailer vehicle including a frame body having side walls and a centre grab lift mounted between the side walls. At least some of the wheels of the trailer vehicle are automatically steerable to follow the swept path of a tractor which tows the trailer vehicle.

In a further preferred embodiment, the trailer vehicle comprises an offset goose neck which is adapted to maintain the trailer vehicle and load in a level orientation.

In yet another embodiment of the invention, all of the trailer vehicle wheels are automatically steerable to follow the swept path of a tractor which tows the trailer vehicle.

In a preferred embodiment of the invention individual wheels in a dual- wheel group are mechanically coupled so that an upward movement of one wheel causes a downward displacement of the other wheel in the group.

In another embodiment of the invention, each wheel group is rotated by a pair of hydraulic cylinders, each cylinder having a piston which includes a rack gear, the two rack gears acting on a sun gear of a planetary reduction gear box.

In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings in which:- Fig. 1 is a perspective view of a trailer vehicle according to one embodiment of the present invention being pulled by a tractor, Fig. 2 is a schematic plan view of the trailer vehicle shown in Fig. 1, (for clarity, the top or roof girders are not shown), Fig. 3 is a perspective view of a trailer vehicle according to another embodiment of the present invention, being pulled by a tractor.

Fig. 4 is a perspective view of a trailer vehicle according to the teachings of the present invention, Fig. 5 is a side elevation of the device depicted in Fig. 1, Fig. 6 is a side elevation of the trailer vehicle depicted in Fig. 2, Fig. 7 is a top plan view of the device depicted in Fig. 3, Figs. 8 and 9 are end elevations of the trailer depicted in Figs. 3 and 4, Fig. 10 is an end elevation of a trailer according to the present invention, Fig. 11 is a perspective view of a wheel group affixed to a movable

plate, Figs. 12 and 13 are perspective views of a suspension for a dual- wheel group, Fig. 14 is a side view of a suspension, Fig. 15 is a perspective view of the hydraulic cylinders and planetary reduction gear box associated with a wheel group, Fig. 16 is a perspective view of the interior of a planetary gear box, Figs. 17 (a)- (d) illustrate the hydraulic cylinder and the rack gear associated with each cylinder, Fig. 18 is a perspective view of an axle assembly, Fig. 19 is an elevation of the internal workings of an axle assembly illustrating the coupling between axles in a wheel group.

Fig. 20 is a perspective view from one side of a trailer according to a third embodiment of the invention, Fig. 21 is a perspective view of the trailer shown in Fig. 20 from the other side, Fig. 22 is an enlarged perspective view of the goose neck end of the trailer shown in Figs. 20 and 21, Fig. 23 is a plan view of the trailer shown in Figs. 20 and 21, Fig. 24 is an enlarged front view of the trailer shown in Figs. 20 and 21, Fig. 25 is a view similar to Fig. 23 with the goose neck off-set Fig. 26 is a perspective view of an alternative mechanism for retracting and extending each wheel group, Fig. 27 is a view similar to Fig. 26 with the main plate in its fully extended position, Fig. 28 is a view similar to Fig. 26 with the main plate in its central

position, Fig. 29 is a view similar to Fig. 26 with the main plate in its fully retracted position, and Fig. 30 is a cross-sectional view of the retracting and extending mechanism shown in Fig. 26.

As shown in Figs. 1,2 and 3, a trailer vehicle 10 includes a frame body 11. The frame body 11 is fabricated from girders or the like and has an open rear 12. The sides of the frame 13 together with the open rear 12 define a passage which can receive, by end loading, a unitised load. Within the frame body 11, several top grab lift devices 14 are positioned over the passage.

Roof beams or girders 15 connect the two sides 13.

In this example, three top grab lift devices 14 are used. Each comprises a hydraulic cylinder 16 located above the passage and generally parallel to the roof girders 15 of the frame body 11. The ends of the hydraulic cylinders 16 are pivotally affixed to the upper ends of the lifting beams or arms 17 of the top grab lift. The lifting arms 17 pivot around a central bearing 18 so that the simultaneous action of the cylinders 16 is converted to an opening and closing of a pair of opposed, parallel lifting tine spars 19.

The three top grab lift devices 14 are preferably equally spaced from one another and all located forward of the rear axle group 20. This allows the tine spars 19 to be opened further without interfering with the frame or wheels.

In some instances, the spar tines 19 must be openable to about 250 mm wider than the load presented for pick up. It follows that the grab lift devices are preferably located rearward of the forward axle group 21 for the same reason.

In this way, a load which is grabable from the bottom and which can be backed over by the trailer, can be lifted by the tine spars. Where the load is, for example, two rows of ingots separated by a longitudinal gap, the centre grab

lift can (when driving the tine spars together) also bring the rows of ingots together thus closing the gap.

To accommodate the tine spars, the lower extremity of the load should form or have a slot or ledge or lip along most or all of its length. Such loads are known in palletised loads, A-frame loads for glass and bulk transport or super packs of aluminium ingots. In fact any goods may be transported in this way if packed onto a cooperating pallet, for example with parallel slots or ledges or lips along most or all of its length along the ground.

In one embodiment of the invention shown in Figs. 1 to 3, the overall length of the trailer vehicle is between 17 and 19 metres with a 6.5 metre load space between the axle groups. The overall trailer vehicle width is nominally under 3 metres so that it can operate at all hours without a pilot vehicle. The overall height will preferably be less than 3.2 meters so that it can enter most industrial doorways. The overall height should not exceed 4.3 metres.

Once the trailer has backed over the load and the load is positioned under the centre grab lift devices, the tine spars 19 are brought together by the hydraulic cylinders 14. This first requires that the suspension of all of the trailer vehicle wheels be lowered so that the tine spars 19 are at the same height as tine spar engaging portion of the load. Once the load is engaged, the suspension of all of the wheels of the trailer vehicle is raised, thus lifting the load off the ground.

In the preferred embodiments of the invention, all of the wheels of the trailer vehicle are also steerable. It is preferred that the steering of the trailer vehicle wheels be automatic and synchronised with the tractor steering. One such known system maintains at least the rear wheels in the swept path of the tractor wheels in either the forward or reverse direction. Such a system is provided for example, by Stockton River Pty Limited, 19 Speedwell Street,

Somerville, Victoria, 3912, Australia. This steering system is powered from the tractor and operatively connected to the fifth wheel turntable from which the steering system derives angular displacement data. The lifting suspension may be hydraulic or pneumatic and also powered from the tractor.

So that the underside of the trailer vehicle does not interfere with the steerable trailer wheels, a clearance of about 700 mm between the road and the underside of the trailer vehicle is provided. With respect to the invention depicted in Figs. 1 to 3, the travelling height of the grab lift arms is preferably 350-400 mm from the ground. It will be noted that the invention as it relates to the trailer vehicle is not limited to any particular combination of driving and driven wheels on the tractor or trailer vehicle.

For design purposes of this example (Figs. 1 to 3) a Gross Combination Mass of 55 tonnes is estimated based on a 32 tonne payload, an 11 tonne trailer vehicle mass (with centre grab lift devices), a tractor mass of 10 tonnes and a 2 tonne variance.

The trailer vehicle's goose neck 30 must also be capable of height adjustment and goose necks of this type are known. This is desired for optimising the weight distribution and towing geometry of the trailer vehicle and tractor or prime mover.

Service labour costs are reduced because straddle carriers are not required to load goods onto roadable transport vehicles. When transporting aluminium ingots in bulk, binding straps may be eliminated. Further, ingots may be transported directly from the smelter pad to the storage yard or from the lifting table area to the storage area. In addition, direct pick up from the storage yard to the wharf area is possible, with waiting times being reduced at each end of the cycle. In general the system and trailer vehicle reduce the idle time during which ordinary vehicles are waiting to be loaded and unloaded.

As shown in Figs. 4 to 7, another embodiment of the invention reveals a trailer 110 comprising a rigid frame having parallel sides 111 and 112. The two sides 111,112 are rigidly interconnected at the front of the trailer 113 and also braced by a hollow"U"shaped cross beam 114 located at the rear of the trailer. As shown in Figs. 6 and 7 an additional transverse brace 115 may be provided forward of one of the two top grab lifts 116 which are used to elevate and restrain the trailer's cargo. Each side 111,112 of the trailer supports a number of dual-wheel wheel groups 120. In the examples suggested by Figs.

4 to 7 each side carries six dual-wheel groups for a total of 24 road contacting wheels.

As shown in Figs. 8 and 9 the opening and closing of the top grab lift 116 is controlled by a horizontal disposed hydraulic cylinder 121. Raising and lowering of the lift 116 is accomplished by vertically oriented cylinders disposed to either side of the lift. The vertical arms 122 of the lift 116 are pivoted with respect to a vertical brace 123 so that the tines 124 open when the cylinder 121 is contracted and closed when the cylinder 121 is extended.

Note in Fig. 8 that the wheel groups 120 do not interfere with the operation of the lift 116 because they have been extended away from the centre line 130 of the trailer. When the wheel groups are extended (as shown in Fig. 8) the arms 122 of the lift 116 are free to open or close but the stance or distance 131 between the outer extremities of a pair of dual-wheel wheel groups is excessive for normal roads.

Fig. 9 illustrates that when the lift 116 is raised high enough, the opposing wheel groups 120 in a pair can be brought closer together. The stance 131 in Fig. 9 is therefore less than the stance depicted in Fig. 8.

As shown in Fig. 11, the adjustment of the stance or distance between wheel groups in a pair is accomplished by mounting the wheel group 120 on a

rigid plate 141. The plate is about 20mm thick and fabricated from a high strength allow steel having an approximate 100,000 mpa yield strength. The plate is restrained between two pairs of bearings 142, each bearing consists of a channel 143 which carries a high strength, low friction polymeric or reinforced polymeric bearing surface 144. The plate 141 is therefore capable of reciprocal motion when influenced by the pair of hydraulic cylinders 145,146.

The hydraulic cylinders 145,146 form a triangle. The cylinders 145,146 are attached at one end 148 to the rigid frame or chassis of the trailer. The associated hydraulic pistons 149,150 converts to a closely spaced pivot mount 151. This arrangement provides for a great deal of strength in a compact space. In the alternative, the reciprocating motion of the plate 141 may be achieved with a single cylinder oriented along the mid-line 400 of the plate. It can be seen in Fig. 11 that the plate 141 carries a bolt circle 152 which is used to mount a planetary gear reduction unit 160. The gear reduction unit 160 allows the wheel group 120 to rotate under the plate 141. This rotation affects the steering of the wheel group as well as permitting the wheel group to be oriented perpendicular to the trailer axis, as shown in Fig. 11, when the stance of the vehicle is being adjusted. It is obviously desirable to have the wheels oriented in their direction of travel.

Figs. 12 to 14 illustrate a suspension mechanism 170 for the wheel groups 120. Each suspension 170 comprises a"Z"link mechanism 171 restrained at each end by a rigid suspension frame 172. Motion in the"Z"link mechanism is dampened by a pneumatic or hydraulic cylinder 173 which is attached at one end to the rigid suspension frame 172 and at the other end to one of the links 174 in the"Z"mechanism. The cylinder 173 is also capable of lifting and lowering the suspension, under load. The suspension is adapted to

be lifted about 600mm so that the wheels are in ground contact on ramps or rough terrain.

A planetary reduction gear box 160 is rigidly mounted to the top of each suspension frame 172. As shown in Fig. 13, a pinion 175 extending from the sun gear 176 of the planetary gear box extends down through the suspension frame 172 where it is acted upon by a pair of opposed, double acting hydraulic cylinders 176,177. When the pinion 175 is rotated by the hydraulic cylinders 176,177 the sun gear 180 rotates, effectively causing the tyre's suspension to pivot under the rigid plate 141 to which the outer flange 182 of the planetary reducer is mounted.

As shown in Figs. 15 and 17, the hydraulic cylinders 176,177 each comprise an elongated cylindrical case 190 within which travels a reciprocating piston which is integral with a rack gear 191. Openings 192 in the cyrindrical cases 190 allow the pinion 175 to be located between the adjacent cylinders 176,177. As shown in Fig. 17 (b) the opening 192 in the case 190 allows the teeth 193 of the rack gear to contact the pinion 175. The cylinders 176,177 always act in opposition to one another to cause rotation of the pinion 175, the combined action of the cylinders 176,177 thus causes the suspension and wheel group to rotate, even under heavy loads and when the trailer is not moving.

Fig. 18 illustrates the centre link 100 of the"Z"link mechanism of the suspension 170. This centre link 200 comprises a main casting 201 which is bored to receive a pair of partially rotatable bosses 202. Each boss 202 carries a stub shaft 203 which in turn carries a wheel hub 204. Each boss 202 includes a helical groove 205, the two helical grooves 205 are interconnected by a shuttle 210. The shuttle 210 has protrusions or teeth 211 at each end that are machined to fit into the grooves. The shuttle 210 is prevented from rotating

by a key way 212 formed in the casing 201. Thus, because the two helical grooves 205,205 (a) are anti-sense and because the shuttle 210 is prevented from rotating, a rotation of one boss 202 causes a rotation of the other boss 202 in an opposite direction. Accordingly, when one wheel in a group 120 experiences a force which tends to lift it, the lifting force is translated into a rotation of its boss 202 which is in turn translated into an opposite directed displacement of the other wheel in the group. This has the effect of distributing a vertical load which otherwise would be borne by only a single wheel in a group 120.

In one embodiment of the invention the wheel groups 120 may be steered automatically and without any direct input from the driver of the trailer.

This is accomplished (as shown in Fig. 7) by providing proximity sensors 210 along the inside wall of the sides 111,112 of the trailer 10. Each of the proximity sensors 210 delivers an electrical signal which is interpreted by a microprocessor as indicative of the distance between the sensor and the load.

The sensors 210 may be provided as opposing pairs 211,212 so that the signals provided by each sensor may be compared or interpreted as an indication of vehicle position relative to the load. Thus, discrepancy in the signals provided by a pair of sensors 211,212 can be translated into a corrective steering command. The steering command can then be provided to a wheel group controller, the controller providing command input to the wheel groups until the signals provided by the pair 211,212 are equal.

As shown in Fig. 20, a third embodiment of the invention comprises a trailer vehicle 300 having hollow parallel sides 301 interconnected by"U" shaped beams 302. Thus, each of the lifting cylinders 307 penetrates through the hollow side in which it is mounted. The sides 301 and cross beams 302 are formed from high strength steel plates (such as HARDOX tm tempered and

quenched alloy steel) which are welded into box sections so as to provide strong and rigid sections which are light weight. In this example, two"U" shaped cross beams are provided at the rear 303 of the trailer and a single "U"shaped cross beam is provided at the front 304. The cross beams 302 and the sides 301 form a chassis which is supported above the ground by a plurality of wheel sets 305. The wheel sets 305 each comprise a pair of wheels and are of the type described with reference to Figs. 11 to 19. Each side 301 is equipped with at least two but up to eight such sets of wheels 305. This particular example is adapted to be supported above 14 wheel sets, seven under each side. In this embodiment, the load lifting is done by he lifting devices 306, but the wheel sets are still capable of about 600mm travel to accommodate uneven terrain.

The chassis retains a pair of hydraulic lifting devices 306. Eacfi lifting device 306 comprises opposed pairs of hydraulic cylinders 307 which act in concert to elevate and lower a pair of parallel tracks 308. The tracks 308 support a pair of carriages 309, each of which carries a descending grab arm 310. The carriages 309 and grab arms 310 in a pair move toward each other, and away, under the influence of a pair of hydraulic cylinders (not shown) mounted within the carriage 309. The cylinders are attached at one end to a rigid end plate 380 (see Fig. 22) and at their other end to the inner extremity 381 of the carriage 309. Both grab arms on a side are affixed to a carry plate 311. The carry plate 311 extends along the length of the trailer and may be used to organise and compact a load prior to lifting as well as to create a frictional engagement with a load which is being carried. The carry plate 310 includes a full length ridge or tine 310 and a reinforcing box beam 313 which rigidises the tine 312 and also extends the bottom edge of the lifting plate 311.

The parallel tracks 308 are rigidised and reinforced by an interconnecting web 320. The web 320 inhibits the flexing of the tracks 308 under load. The pairs of hydraulic lifting cylinders 307 are also stabilised by a central hollow box beam stabiliser 321 which slides within a similarly shaped opening 322 formed in each side between each pair of lifting cylinders 307.

The hollow sides 301 are tapered at each end 303,304. In preferred embodiments of the invention, a ground contacting cylinder 322 is carried within each hollow stabiliser 321. As the stabiliser 321 rises with the hydraulic cylinders 307, the ground contacting cylinder 322 can be made to descend.

The bottom portion or foot 323 of each ground contacting cylinder 322 may be brought into engagement with the ground so as to remove excessive load from the wheel sets 305 so that they may be rotated or moved into position under the trailer or steered as required.

As shown in Figs 22 to 25 the front"U"shaped cross beam 302 carries an offset goose neck 305. Mounted forward of the front"U"shaped cross beam 302 is a mounting box 351. The mounting box 351 is generally hollow and carries hinges at each end 352, which hinges allow the mounting box 351 to pivot along a horizontal axis with respect to the front beam 302. The mounting box 351 has extended tabs 380 on each side which pivotally engage with similar tabs mounted on the front cross beam 302 so that sufficient clearance 381 is created between the front beam 352 and mounting box 351 for the purpose of allowing the mounting box 351 to pivot without interference.

The pivoting motion is accomplished through the extension and retraction of a pair of hydraulic cylinders 353 mounted on opposite side edges of the box 351.

A goose neck 354 is pivotally mounted to the mounting box 351, by vertically oriented pivots 355. The pivots 355 and the pivot axis 356 (Figs. 24 and 22) are displaced from the central longitudinal axis 357 of the trailer 300.

Movement of the goose arm 354 about its pivoting axis 356 is accomplished by an offset hydraulic cylinder 357. In this way, the point of contact and coupling (fifth wheel) 360 with the prime mover can be offset to one side (Fig. 25) and maintained in this position so that the trailer 300 can be driven forward over a load as well as backed into a load. As shown best in Fig. 24, the fifth wheel or coupling 360 is shifted to one side by the hydraulic cylinder 357. Because the pivots 355 are no lower than the bottom surface 370 of the front beam 302 and because this lower surface is high enough not to interfere with a load which is going to be picked up, the goose neck 350 does not interfere with the load on the ground when it is in the offset position depicted in Fig. 24. A descending portion of the goose neck 371 brings the fifth wheel 360 low enough to engage with a conventional prime mover.

An alternative mechanism for extending and retracting the wheel groups is shown in Figs. 26 to 30. As in the embodiment of Fig. 11, each wheel group is mounted on a main plate 141 which is constrained between and slidable within the two bearings 142. Extending between the two bearings 142 there is a cross slide 400 which receives on its underside a sliding block and big end bearing 401 at the outer end of an arm 402 fixed to the rotatable plate 403 that rotates in an aperture in the main plate 141. A releasable locking pin 404 on the underside of the lockable plate can be locked to the wheel group so that turning of the wheel group rotates the plate 403 and the action of the big end bearing and sliding block 401 within the cross slide 400 causes the main plate 411 to move from side to side.

The main plate 141 is shown in Fig. 27 in its extended position with the big end bearing and sliding block 401 in the centre of the cross slide 400. In Fig. 28, the main plate 141 is in its central position with the big end bearing and sliding block 401 at the right hand end of the cross slide 400. In fig. 29 the

main plate 141 is in its fully retracted position with the bid end bearing and sliding block 401 in the middle of the cross slide but with the arm 402 in the opposition disposition to that shown in Fig. 27.

As shown in Fig. 30, strengthening ribs 405 on the underside of the main plate 141 support a plate 406 which is the attachment point for the wheel groups. The upper plate 407 of the bearing 142 are attached to the underside of the main trailer beams.

To extend the wheel group from the retracted or travelling position, the trailer vehicle is stopped, the locking pin is engaged with the wheel group and the wheels turned inwards so that rotation of the rotatable plate 403 is translated into outward movement of the main plate 141 to the position shown in Fig. 27. To retract the wheels, the trailer vehicle is stopped, the locking pin 405 engaged and the wheels turned outwards so that rotation of the rotatable plate 403 is translated into inward movement of the main plate 141 to the position shown in Fig. 29. The mid position of the main plate 141 is shown in Fig. 28 and in Fig. 26, the main plate is midway between the central position shown in Fig. 28 and the fully extended position shown in Fig. 27.

Various other modifications may be made in details of design and constructions of the trailer vehicle without departing from the scope and ambit of the invention.