Title

Trench Cover Field of the Invention

The present invention relates to trench covers of the type used to temporarily cover a trench formed in a path or road. Background

It is well know that pathways or roads may require the digging of a trench. During the periods when the trench is formed it is desirable to provide for a temporary covering of that trench. Trench covers such as those described in my earlier application WO02084033, are known for this purpose.

While such trench covers are suitable for a wide variety of trenches there are problems where the camber of the surface is such that the cover, when placed over the trench cannot engage with the ground on which it is placed and therefore has a tendency to rock. For these reasons and others there is a need for an improved trench cover.

Summary

These problems and others are addressed by a trench cover provided in accordance with the invention. Such a cover includes a pair of ground engaging portions bridged by a central trench covering portion, at least one of the ground engaging portions or the trench covering portion having an arcuate surface.

By providing at least one of the ground engaging portions or trench covering portion with an arcuate surface, multiple possible points of contact between the trench cover and the ground are provided so as to assist in provision of a stable trench cover which does not rock when placed over the trench, irrespective of the camber of the surface of the road or pathway. Such trench covers are particularly useful for linear runs where a trench has been provided along the main axis of the road or path.

Desirably at least one of the ground engaging portions is provided with an arcuate surface. The central trench covering portion is desirably also provided with an arcuate lower surface- the lower surface being that surface of the cover which in use is closest to the ground. The curve of the central trench covering portion is desirably opposite to that of the ground engaging portions.

Accordingly the invention provides a trench cover according to claim 1. Advantageous embodiments are provided in the claims dependent thereto.

These and other features of the present invention will be better understood with reference to the drawings which follow which are provided to assist in an understanding of the teaching of the invention and are not to be construed as limiting in any fashion.

Brief Description Of The Drawings

The present invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a side view of a trench cover provided in accordance with the teaching of the present invention. Figure 2 is a view from below of the cover of Figure 1.

Figure 3 is a perspective view from above and one side of the trench cover.

Detailed Description Of The Drawings

The teaching of the present invention will now be described with reference to exemplary embodiments thereof which are provided to assist with an understanding of the invention and are not to be construed as limiting in any way. It will be appreciated that modifications can be made to the exemplary arrangements which follow without departing from the scope of the invention

which is only to be limited insofar as is deemed necessary in the light of the appended claims.

Figure 1 is a side view of a trench cover 100 provided in accordance with the teaching of the present invention. The cover 100 includes a pair of ground engaging portions 105, 110 bridged by a central trench covering portion 135. In use the ground engaging portions 105, 100 will be on either side of a trench 120 formed in a road or pathway 125. Each of the ground engaging portions is provided with an arcuate or curved surface 130 which in use is in contact with the ground 125. It will be appreciated that by providing a curved surface that multiple points of contact between the ground engaging portions 105, 110 and the ground are provided, the specific points of contact being dependent on the actual camber of the surface on which the trench cover is used. In this way the contact between the trench cover and the ground can be distributed depending on the camber thereby ensuring that when the cover is located over a trench that it will not rock on the trench.

It will be understood that as there are multiple points of contact between the contacting surfaces of the trench cover and the ground, these points of contact being on either side of the trench which is being covered, that there is a minimisation of rocking of the trench cover on the road.

To provide the multiple possible points of contact it is necessary for the ground engaging portions to have a convex surface presented to the ground.

The central trench covering portion has an upper 135 and a lower 140 surface, the lower surface being that surface which is proximal to the trench when the cover is in use. The lower surface may also be arcuate or curved, but in contrast with the ground engaging portions, it is desirable that where curved, that the lower surface present a concave surface to the ground. In this way any debris which has accumulated around the perimeter of the trench 145 is cleared

by the trench cover, the concave surface increasing the clearance height 150 between the lower surface of the covering portion and the ground 125.

The trench cover may include first and second wings 155A, 155B, which are located at the sides of the trench cover adjacent to the ground engaging portions 105, 110. Desirably, if provided these wings are pivotable relative to the central trench covering portion. Each of the wings has a ground engaging portion proximal portion 160 and a ground engaging portion distal portion or tip 165. The pivoting of the wing relative to the central trench covering portion effects a change in the relative orientation of the central trench covering portion to the tip 165 of the wing. Once the trench cover is in location relative to the trench, the pivoting of the wing enables the tip 165 to be brought into contact with the ground 125, to provide a ramp along each side of the trench cover 100.

As shown in Figure 2, each of the ground engaging portions desirably include first 205A, 205C and second 205B, 205D feet which are located at either side of the trench cover such that feet are located at each corner of the trench cover. The feet are substantially identical, each having a curved surface of equal diameter. Indeed the visible curved surfaces of each of the feet form part of a virtual circle 170, the outline of which is visible in the side view of

Figure 1. The radius of each of the virtual circles defining each of the four feet provided at the corners of the trench cover is desirably the same. It will be appreciated that while described as separate elements to the trench cover that the feet 205 are desirably integrally formed in the trench cover. The position of the arcuate surfaces of the ground engaging portions is desirably located relative to the central trench cover portion such that a mid or centre point 200 of the virtual circle is always substantially immediately above the point of contact of the ground engaging portion with the ground.

To enable a pivot coupling of the wing to the trench cover each of the feet desirably includes an aperture provided at the midpoint 200 of the virtual circle.

First and second pins are located at either end of a cylindrical receiver 210 provided on a lower surface 215 of each wing. The receiver is desirably provided with the same radius of curvature of the virtual circles of the individual feet and is provided between each of the feet defining the ground engaging portions. The receiver also includes an aperture within which the first and second pins are force fit such that the pins do not rotate relative to the wings. The cylindrical receiver with its integrally provided aperture is desirably provided on the wing at a location such that when the wing is engaged with the trench cover, the apertures of each of the two feet and the cylindrical receiver are co- aligned. Furthermore by providing the cylindrical receiver with the same radius of curvature of the feet a substantially continuous planar surface is provided extending from a first foot 205A along the cylindrical receiver and onto the second foot 205B. A similar arrangement is provided on the other side of the trench cover but for the sake of convenience will not be described herein. It will be appreciated that the important aspect here is that the apertures of the feet and cylindrical receiver are co-aligned. The apertures provided in each of the feet desirably have a larger diameter than that of the cylindrical receiver such that the pins when located therein loosely engage with the feet and enable a relative movement of the wing to the feet.

Certain modifications to that described herein may provide for the cylindrical receiver to have a radius of curvature less than that of the virtual circles such that an arch is provided between each of the feet on the same side of the trench cover.

As will be appreciated from the top view of Figure 3 a substantially planar surface 300 is provided at upper surface in the contact region between the wing and the trench cover. This minimises the provision of any pivot point at the edge of the trench cover. The upper surfaces 305, 310 of the trench cover and wing respectively are each desirably provided in an anti-skid configuration such as may be provided by a plurality of dimples 315 upstanding on the surface.

In a manner similar to that described in our earlier application WO02084033, each of the covers may be provided with an interlink 320 on transverse sides of the cover to enable a coupling of a first cover with a substantially similar second cover to extend the length of trench that may be covered by such an trench cover arrangement. In this way the trench cover arrangement is particularly suited for linear runs.

The wings may be modified to include reflectors 325, typically provided using glass beads. These reflectors may be usefully employed during periods of darkness to identify the location of the trench cover to on-coming vehicles. To be particularly effective it will be appreciated that the trench cover should be located on the road in a direction that ensures that the reflectors are visible to on-coming traffic.

It will be appreciated that as well as increasing the cover height of the trench cover that the provision of an arcuate concave surface of the cover member also reduces the amount of material used in each trench cover. These covers are typically manufactured from iron, preferably ductile iron, which it will be appreciated is a heavy material. Any reduction in the volume of material used in the fabrication of the plate can effect a reduction in the weight of individual covers. To ensure that the strength of the cover is not affected strengthening ribs 250A, 250B, 250C may be provided on a lower surface of the trench covering portions. These ribs provided both stiffening to and strengthen the trench cover.

It will be appreciated that Figure 1 includes a scale. It will be understood that this is provided to give an indication of the typical parameters of a trench cover provided in accordance with the teaching of the present invention and it is not intended to limit the teaching of the present invention to such distances or measurement values. It will be understood that preferred embodiments of the

invention have been described with reference to a trench cover that engages with the ground through curved surfaces. In this way multiple points of contact between the ground and the cover are provided which allows the cover to be used with a variety of road or pathway surfaces and yet minimises any rocking of the cover relative to these surfaces. It will be further understood that where a trench cover has been heretofore described with reference to specific features or integers that other features or integers could equally be used without departing from the scope of the invention.

The present description relates to a trench cover that engages the ground through a curved or arcuate surface/surfaces with attendant advantages. While in the exemplary embodiment described each of the ground engaging portions comprises an arcuate surface for engaging the ground and the trench covering portion may further comprise an arcuate surface, it will be appreciated that the advantages of provision of multiple points of contact through a curved or arcuate surface may be provided by suitable alternative arrangements without departing from the scope of the invention. For example, in one alternative arrangement the trench covering portion of the trench cover may comprise an arcuate surface for contact or engaging with the ground. In a further alternative arrangement, the trench cover may comprise a trench covering portion having an arcuate surface or engaging the ground and the ground engaging portion on a first side or on both sides having an arcuate surface for contact or engaging with the ground.

The words comprises/comprising when used in this specification are to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.