MATERIAL

The present invention relates to an apparatus for laying track and recovering ground covering material.

Conditions often arise where vehicle passage across a ground surface is substantially hindered either as a result of the ground being, for example, water logged or sandy such that traction between the vehicle wheels and the ground surface becomes inadequate and/or the ground surface itself cannot adequately support the weight load of the vehicle.

A known system for rninimising the effect of such conditions utilises a ground covering material in the form of a prefabricated track which is layed across the land surface to allow for transport of vehicles. One particular form of track consists of aluminium alloy extrusions having a length of 3.35 metres and a width of 0.229 metres, interlinked in a side by side manner to form a track about 30 metres long.

The system for laying the track utilises a vehicle 1 having a tray 2 which supports a pivotable cradle 3 which in turn supports an axle 4 of a spool 5 carrying a roll 6 of track 7, as shown in Figure 1. In operation, the vehicle 1 is driven to a desired location and the cradle 3 pivoted into the position shown in Figure 2. The track is then manually lifted from the spool 5, over a frame 8 above a cabin 9 of the vehicle 1, onto the ground surface 10. The track is unrolled by driving the vehicle forward over the track. The system has a number of significant disadvantages in that the forward view of a driver of the vehicle is obstructed by the track 7 and the spool 5 is itself not controlled such that if the driver stops the vehicle 1 , the spool 5 will continue to rotate, resulting in the track unwinding behind the vehicle 1. Additionally, for retrieval after use, the track must be hand-cranked back onto the spool which is labour intensive and time consuming. Further, the system is not readily adapted for deployment of more than one roll per vehicle without the use of a crane or the like to lift and interchange the spools.

It is an object of the present invention to provide an apparatus for laying and recovering ground

covering material, which addresses one or more of the above described disadvantages of the known system of laying track.

In accordance with the present invention, there is provided an apparatus for laying and recovering ground covering material, such as track, including a main body structure having support means for supporting an axle of a spool arranged to carry the material, and an attachment member adapted for releasable attachment of the apparatus to a vehicle, wherein the structure is provided with a drive assembly for driving the spool, the drive assembly being adapted to be operably linked with the vehicle for actuation of the assembly.

Preferably the drive assembly includes a hydraulic motor which is adapted to couple into a hydraulic circuit of the vehicle.

Preferably the attachment member is adapted to secure the apparatus to a conventional front end loader vehicle, and the apparatus further includes hydraulic lines to couple the hydraulic motor with to hydraulics of the front end loader, via existing attachments on the vehicle, such that no modification of the front end loader is needed.

Preferably, the support means include a bearing block arranged to either side of the spool, each block including a base component and a cap component wherein one of the components of each block is removable to allow for removal or introduction of the axle of the spool.

Preferably, the drive assembly includes a chain drive extending between a drive shaft of the motor and a drive sprocket attached to the axle of the spool, the assembly also including a tensioning sprocket slidably mounted to the body structure for adjusting the tension of the chain.

Preferably, the apparatus includes a second drive assembly as above described, each drive assembly being arranged to drive the spool from opposite ends of the axle.

Preferably the apparatus further includes support legs which are adapted to pivot between a storage position, when the apparatus is mounted to the vehicle, and an extended position for

supporting the apparatus in an elevated condition relative to a ground surface when the apparatus is released from the vehicle.

In another aspect, there is provided a vehicle incorporating the above described apparatus Preferably, the vehicle is a front-end loader type vehicle.

Preferred embodiments of the invention are further described, by way of non-limiting example only, with reference to the accompanying drawings in which:

Figures 1 and 2 diagrammatically represent a known system for laying track;

Figure 3 is a rear view of an apparatus in accordance with the present invention;

Figure 4 is a side view of the apparatus of Figure 3;

Figure 5 is a diagrammatic representation of the apparatus secured to a front end loader,

Figure 6 is a schematic drawing of a hydraulic circuit used to drive hydraulic motors of the apparatus; and

Figure 7 is a diagrammatic representation of a preferred procedure for retrieving a previously layed track using the apparatus of the present invention.

The apparatus 11 shown in Figures 3 and 4 includes a main body structure 12 arranged to support an axle 13 of a spool 14 carrying track 7, as above described (shown in phantom lines in Figure 4) The body structure 12 includes an attachment member 15 in the form of a bracket 16 which is adapted to receive a locking plate of a front end loader (see Figure 5). Two drive assemblies 17 are provided at either side of the structure for driving the axle 13 of the spool 14

The structure 12 includes an elongate frame 18 having lateral support means 19, for carrying the spool 14, in the form of side frames 20, 21, each of which comprise a horizontal member 22, a

reinforcing member 23 and a bearing block 24 adjacent the junction of the members 22, 23. Each bearing block 24 includes a base component 25 and a releasable cap component 26.

Each drive assembly 17 includes a hydraulic motor 27, a chain drive 28 and a drive sprocket 29 keyed to the axle 13. The motors 27 are coupled to the frame 18 via a respective bracket 30 such that a drive shaft 31 associated with each motor 27 extends through a side flange 37 of the frame 18. Each shaft 31 includes a sprocket 33 fitting thereto for driving the chain drive 28 which passes around the drive sprocket 29 to thereby provide controlled rotation of the axle 13 of the spool 14. A tensioning sprocket 34 is provided in an intermediate member 35, which extends between the members 22, 23 of the side structure, for varying the tension of the chain drive 28, as required.

Foldable legs 36 are provided at an underside 37 of the apparatus. The legs 36 are arranged to pivot about couplings 38, between a storage position and the extended position, as shown.

In operation, the apparatus 11 is mounted to a front end loader vehicle 39 by means of an engaging plate 40 of the vehicle being interlocked with the bracket 16, as shown in Figure 5. Hydraulic lines (not shown) for the motors 27 may then be connected directly to the hydraulics of the front end loader vehicle 39, via pre-existing attachments 41 on the vehicle, such that a hydraulic circuit shown in Figure 5 is established.

In order to mount the spool 14 to the apparatus 1 1, cap components 26 of the bearing blocks 24 may be removed and the apparatus 1 1 positioned such that the axle 13 of a spool 14 rests in the base component 25 of the blocks 24. The cap component 26 is then fastened back onto the base component 25 to lock the spool 14 in rotational engagement with the apparatus 11. The drive sprockets 29 are then slidably mounted on the opposite ends 42, 43 axle 13 and keyed in place. The chain drive of each drive assembly is then passed around the respective sprockets 29, 33 and suitably tensioned by the tensioning sprockets 34. A suitably shaped chain guard can then be positioned in place over each drive assembly. After attaching the spool 14 to the apparatus 11, the vehicle 39 may be driven to a suitable location and the drive motors 27 engaged to rotate the spool 14 and deploy the track 7 whilst driving the vehicle in a forwardly direction. Once the

track has been fully unwound, the track is detached from the spool 14 and the apparatus 39 fitted with another spool or, alternatively, the vehicle 39 may be provided with a new apparatus, already with a spool in place. An additional length of track may then be layed, as required.

For retrieval, the end of the track 7 is simply reconnected with the spool, the vehicle 39 reversed slightly, and a revolution of the track wound onto the spool 14. A preferable mode of operation then involves reversing the vehicle 39 about 10 to 15 meters back along the track 7, without winding the spool, so as to produce a large loop 44 in the track, as shown diagrammatically in Figure 7. The track may then be wound onto the spool using the drive motors 27. Such a procedure provides two advantages in that vibrational motion is imparted to the track while the vehicle reverses which helps to shake sand and gravel from the track 7 and the friction resulting from the looped section of the track engaging the underlaying section 45 of the track ensures that the trackway is wound onto the spool under tension.

Connection of the apparatus directly to a pre-existing vehicle, particularly the utilisation of the vehicle hydraulics for powering the hydraulic motors of the apparatus, means that the vehicle itself need not be reconfigured from its conventional structure. Accordingly, after deployment of the track, the vehicle may still serve its original function as, in the described embodiment, a front end loader. It is, however, envisaged that the apparatus may be permanently affixed to a purpose built vehicle.

In addition, the present invention allows for speed of deployment and recovery of the track as well as minimisation of personnel required, as compared with the above described conventional system. In one particular trial, an apparatus was constructed, having a length dimension L of 3.645m, a height H of 1.73m (including a leg height h of 0.8m) and a width dimension W of about 1.6m, to carry a spool of conventional track, the spool having an axle length of 4.15m. The overall weight of the apparatus and spool was in the order of 4,400kg, with the apparatus being 900kg. The apparatus was constructed specifically for attachment to an Hitachi LX 120-2 wheeled front end loader, having a hydraulic operating pressure of 2850 Psi. Such a configuration, with a drive ratio between the drive shaft 31 and axle 13 of 5: 1, allowed for a 50.3 metre track to be fully deployed in 78 seconds and retrieved in 3 to 4 minutes. As can be

appreciated, this provides significant advantages over the system described with reference to Figures 1 and 2, as regards operational efficiency. The visibility afforded to the vehicle driver whilst laying or recovering the track is also maximised, as is the control of the spool

As can be also appreciated, the apparatus is readily adapted for interchange of spools and the spools themselves may be arranged to carry any form of ground covering material and need not be limited to the aluminium track described above. Further, it is also envisaged that the hydraulic motors may be replaced with any other suitable drive mechanism such as, for example, electric motors which are coupled into electrical circuits of the vehicle and actuated thereby via controls in the vehicle.

Finally, it is to be understood that various alterations, modifications and/or additions may be incorporated into the various constructions and arrangements of parts without departing from the spirit or ambit of the invention.