Vehicle ladders find a variety of applications. Permanently or temporarily fixed ladders have been used to form vehicle tracks on soft or unprepared road bases. For example, over soft sand or other soft terrain the National Parks authority forms tracks using laterally fixed timer lengths, so called"timber corduroy tracks". Similar constructions are often used for boat ramp sand other vehicle soft or slippery paths where traction is an issue. Corduroy tracks are relatively high maintenance requiring the timber lengths to be regularly replaced. In addition, corduroy tracks require a relatively large quantity of timber, only a relatively small quantity of which is actually used to support vehicles.

Vehicle ladders also find use as recovery equipment for providing improved traction in a form that can be placed in front of a vehicles tyre to enable the vehicle to extricate itself from mud or soft sand. Examples of recovery ladders include sand ladders formed from lengths of aluminum with holes pierced therethrough. This type of sand ladder is generally heavy and difficult to place in front of a tyre. In addition, in muddy terrain these ladders provide little or no traction.

Other metal ladders have been formed from expanded mesh such as is used to form high grip walkways. However, such expanded mesh is generally deformed when used for the recovery of a large 4WD. This is generally because in order for such a ladder to have sufficient strength to support a 4WD repeatedly it needs to be of a gauge that would render it too heavy for ready positioning in front of the wheels of a vehicle.

Fibreglass gratings have also been used. However, wheel spin on plastic grating generally results in the grating being heat effected, either in melting by friction the top surface of the grating or causing the grating to plastically deform.

An articulated series of plastic ribbed members that is light weight has been dried but provides little support for the vehicle.

We have now found a ladder for supporting a vehicle and providing traction that is light weight an cost effective or at least provides the user with a useful or commercial choice. According to the present invention there is provided a vehicle ladder comprising a stiff vehicle support and a multiplicity of traction members wherein the traction members are mounted on at least one driving surface of the

vehicle support and wherein the traction members are formed of metal and comprise one or more projections for enhancing the traction of the vehicle.

The vehicle ladder of the present invention may find use in fixed or temporary applications. Fixed applications include the vehicle paths on soft ground.

For example, in sandy terrain the vehicle ladder of the present invention may be used to form a track by fixing lines of spaced apart vehicle ladders corresponding to the distance between the wheels of the vehicles using the track. Other fixed applications include boat ramps and the like.

Temporary applications of the vehicle ladder of the present invention preferably include vehicle recovery whereby the vehicle ladder is placed under or in front of a wheel of a vehicle whereby the wheel can gain traction on the ladder and advance the vehicle. Other temporary applications of the vehicle ladder include providing a temporary ramp for a vehicle to traverse, so that an approach angle or departure angle can be reduced to within the range of the vehicle.

The vehicle ladder of the present invention comprises a stiff vehicle support. It will be understood that the term"stiff"is used herein to refer to the ability of the vehicle support to bear the weight of the vehicle without undue deformation. It will be appreciated that the vehicle support may flex to a limited degree and not be completely rigid but that the vehicle support should be sufficiently stiff so that the vehicle support does not simply deform about the wheel of the vehicle or to the shape of the terrain.

The vehicle support of the present invention may be dimensioned to any suitable size and is based upon the intended application. In fixed applications the vehicle support is preferably of sufficient width to enable a variety of vehicles to traverse the ladder. Each vehicle support that may be spaced apart to form a track should be sufficiently broad in size to enable a variety of vehicles to traverse the ladder, with its left and right wheels supported upon the ladders. The length of the vehicle support in a fixed applications maybe any convenient length as such applications will be generally constructed with machinery that will enable the lifting and manipulation of substantial sections and weight is not a critical problem.

Preferably the length of the vehicle support will be selected so that the vehicle ladder is can be used to form tracks having a desired curvature.

In the temporary applications such as a vehicle recovery, the vehicle

ladders are used individually and it is preferred that the width of the vehicle support is at least the width of the vehicle tire and preferably less than twice the width of the vehicle tire. The length of the vehicle support is preferably selected such that the weight of the vehicle ladder is manageable by a single person and we have found that a suitable length is between 1.2 m and 2 m. Preferably the length of the vehicle support is about 1.75 m.

The thickness of the vehicle support will depend on the materials of construction thereof. We have found that a suitable thickness is in the range of from 50 mm to 120 mm. Preferably the thickness of the vehicle support will be approximately 75 mm.

The vehicle support may be formed from a variety of materials. For example, the vehicle support may be formed from timber, metal or plastic. The vehicle support is preferably formed from plastics materials in due to the ability of plastics materials to provide a lightweight yet tough support for the vehicle. The preferred and material of construction is rotationally moulded polypropylene.

Rotationally moulded polypropylene is particularly suited to forming a shell for the vehicle support. The polypropylene used may be filled or unfilled. It is preferred that a filled polypropylene is used to provide additional rigidity or stiffness in the vehicle support. The shell of polypropylene formed by a rotational moulding process is preferably filled with a further plastic material such as unfilled polypropylene or polyethylene. It will be apparent to those skilled in the art of the manufacture of moulded plastic components that other plastics may suitably be used.

The vehicle support preferably includes on the upper driving surface and the ground engagement surface thereof recesses for receiving the traction members and retaining them in the desired position. Suitably the recesses are of a shape that matches the shape of the traction members whereby their position and orientation are retained by the recesses.

The vehicle support may preferably include apertures extending the therethrough. The apertures allow any fluid that collect on top of the support to drain through the apertures. Thus friable sand can readily pass through the apertures as can water. The apertures also allow for any surface tension that might build up between the support and a muddy base to be reduced. This allows the support to be more readily extracted from muddy ground. In addition, is preferred that the upper and

lower surfaces of the support include recesses and channels that minimise any surface tension between the support and the ground and as well as facilitate the run-off of water and other fluids including sand from the upper driving surface.

The support may also include holes therethrough for fixing the support to the ground. For example, pegs such as tent pegs, may be used to retain the support in position and provide additional traction for the vehicle.

The apertures and holes through the support may provide a convenient fixing point with which to attach the vehicle support to a vehicle for transport, either on a roof rack or on a rear mounted spare wheel. In one embodiment of the present invention of the vehicle support may include mounts for attachment to a vehicle for transport, suitable mounts may include fastening toggles and the like.

The vehicle ladder for temporary positioning and the recovery of vehicles preferably includes ramped ends to readily enable the wheels of the vehicle to climb on to the supports and engage the traction members.

The vehicle ladder may be provided with an attachment for engaging a chain that allows the ladder to be fixed in position or chained to other ladders.

The traction members for use in the vehicle ladders of the present invention may be formed from any suitable metal. Suitable metals include stainless- steel, aluminium and aluminium alloys, as well as other metals and metal alloys that preferably resist corrosion.

The traction members include projections for enhancing the traction of the vehicle. The projections may be formed on the surface of the traction members or may be formed by folding the traction members to provide upstanding projections. In a preferred configuration the traction members are formed from a sheet of stainless steel that has been cut in to a polygon, preferably a square, with the apex of each corner rounded to avoid piercing the tyres of the vehicle and folded upwardly to provide traction.

Alternatively, a diecast aluminium traction member may be used. It is convenient with a diecast members to provide projections in the upper surface thereof to engage the tyres of the vehicle and enhance the traction.

It is preferred that the support include recesses for receiving the traction members and the traction members may be fixed within the recesses by a bolt or other fixing means. The bolt may project from the traction members and also assist in

providing additional traction. In a particularly preferred embodiment, the traction members include cut out sections there in for receiving lugs from the support to further assist in locating the traction members.

The vehicle support may also be provided with a ground gripping profile on its base.

In order that the invention may be more fully understood and put into practice, preferred embodiments thereof will now be descried with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a vehicle ladder according to one embodiment of the present invention; Figure 2 is a perspective view of on end of the vehicle ladder shown in Figure 1; Figure 3 is a top perspective view of a vehicle ladder according to a second embodiment of the present invention; Figure 4 is a top plan view of the vehicle ladder shown in Figure 3; Figure 5 is a side plan view of the vehicle ladder shown in Figure 3; Figure 6 is a bottom plan view of the vehicle ladder shown in Figure 3; and Figure 7 is a bottom perspective view of the vehicle ladder shown in Figure 3.

Figures 1 and 2 show a vehicle ladder 1. The vehicle ladder 1 has a series of traction members 2 mounted on a vehicle support 3. The traction members 2 are seated in recesses on the upper surface of the vehicle support 3.

The vehicle support 3 has ramped ends 4, the ramped ends 4 incorporating integral traction enhancing projections 5. The ramped ends 4 enable a vehicle to mount the vehicle support 3.

The ramped ends 4 include shackles 6 to enable a chain 7 to be connected to the vehicle ladder 1. The chain 7 may be used to affix the vehicle ladder 1 in position.

The ramped ends 4 and throughout the length of the vehicle support 3 include apertures 15 for receiving pegs (not shown). The apertures enable the vehicle

ladder to be secured in a desired position.

The vehicle support 3 also includes apertures 8 for allowing any fluid materials such as water or sand to be drained from the vehicle support 3. Channels 9 also assist in the drainage of fluid from the vehicle support 3.

The traction members 2 are seated in corresponding recesses on the vehicle support 3. The traction members 2 are bolted to the vehicle support 3 by bolts 10. The bolts 10 also assist in providing traction for the vehicle. Each of the traction members 2 include for apertures 11 that receive projecting lugs 12 that extended from the vehicle support 3. The corners 13 of the traction members 2 are rounded and folded in an upward direction to provide increased traction for the vehicle.

A fastening toggle 14 enables the vehicle ladder 1 to be readily transported by mounting on the roof rack or other convenient location on a vehicle.

Figures 3,4, 5,6 and 7 show a vehicle ladder 21. The vehicle ladder 21 includes a number of traction members 22 mounted on a vehicle support 23. The vehicle support 23 is made from a rotationally moulded plastics material.

The vehicle ladder 21 includes ramped ends 24 that provide a flat profile on the bottom of the vehicle ladder 21 and a ramped profile on the top of the vehicle ladder 21. The ramped ends 24 include a set of traction members 22 mounted on both upper and lower surfaces to increase traction with the ground as well as with the vehicle tyre. The ramped ends include a series of apertures 25 extending through the ramped ends 24 which enable the vehicle ladder 21 to be readily affixed to a vehicle or pegged into the ground to increase traction. The apertures also minimise the likelihood of entrapment of air underneath the vehicle ladder in a boggy environment such that the potential of the vehicle ramp to float is minimised.

Apertures 26 on the ladder body 27 also provide for the vehicle ladder 21 to be affixed to a vehicle or for the minimisation of the likelihood of the vehicle ladder floating during positioning and/or use.

The vehicle ladder 21 is provided with a network of channels 28. The channels 28 allow materials such as water, mud and sand to be displaced from on top of the vehicle ladder 21 during use and minimise the likelihood of a vehicle losing traction with the vehicle ladder 21 due to an overwhelming build up of material on top of the vehicle ladder 21.

The vehicle ladder 21 is provided with a flange 30, which flange 30

includes apertures 29 that may be used to peg or affix the vehicle ladder 21 in position during use or retain the vehicle ladder 21 on a vehicle during transport.

The traction members 22 are essentially square shaped and formed from stainless steel. The traction members 22 include four corner lugs 31 that may be formed by folding the corners of the traction members 22 upwards for engagement with the tyres of a vehicle. The traction members 22 may be disposed in a recess on the ladder body 23 and affixed in place using a bolt or other suitable fixing method.

Persons skilled in the art will appreciate that the invention described above may be subject to improvements and modifications that will be apparent without departing from the spirit and scope of the invention described herein.