GB2442468A

GB2442468A - Cattle Grid

Info

Publication number: GB2442468A
Application number: GB0619744A
Authority: GB
Inventors: James Mackenzie Sutherland
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-10-06
Filing date: 2006-10-06
Publication date: 2008-04-09
Anticipated expiration: 2026-10-06
Also published as: GB2442468B; GB0619744D0

Abstract

The cattle grid, particularly designed for use as a portable cattle grid, comprises a supporting platform which defines an upper supporting surface which has an at least partially arcuate profile along its length. The supporting platform is preferably latticed with the upper supporting surface having a convex profile that may have a constant or irregular radius of curvature. The upper supporting surface may merge with peripheral supporting surfaces 4 that may have a linear or curved profile. At least one tensioning element 1 may extend lengthwise along the supporting platform, which preferably comprises a number of parallel, spaced apart, laterally extending elongate elements 3 arranged on at least two parallel arciform supporting elements 2.

Description

Cattle grid The present invention relates to cattle grids and

particularly, but not exclusively, to portable cattle grids having an arcuate surface profile.

Cattle grids are well known and provide an alternative to gates in livestock fences by allowing the free passage of vehicles whilst preventing passage of livestock over the fence line. Commonly, a cattle grid comprises a plurality of elongate spaced metal members arranged in a variety of latticed patterns.

Cattle grids (hereinafter referred to as grids) are available as either fixed or portable structures. The former are usually installed largely below ground level.

Such grids have substantial subsurface structural members and are therefore generally expensive to manufacture and install.

Portable grids are generally placed on an existing road surface and, although installation costs are minimised as compared to their fixed counterparts, they are nonetheless somewhat costly to manufacture. Portable grids are generally provided with a horizontal upper surface having ramped regions at opposite ends thereof which present an inclined surface linking the horizontal surface to the surrounding road surface. Alternative constructions exist whereby the grid comprises two ramped regions which meet at an apex.

A known problem with such portable grids is that the geometry of their upper surfaces can impose a limitation on the type of vehicle and/or trailer they are able to accommodate. In particular, the underside of a vehicle having a low ground clearance and/or long wheelbase may engage with an upper surface of the grid causing damage to both the vehicle and the grid. This problem results from the angle of inclination of linear ramp surfaces relative to the surrounding road surface.

It has been proposed to solve the aforementioned problem by lengthening the linear ramp surfaces or by reducing the overall height to which the grid extends above the surrounding road surface. However, the first solution is generally undesirable due to the compromises in terms of the cost of additional materials and also the additional space requirements. The second solution results in a cattle grid which is ineffective because the latticed supporting surface lies so close to the ground as to make the passage of livestock inevitable (i.e. they learn to place their feet between the parallel bars on to the ground immediately below).

Other known portable grids have complicated combinations of resiliently hinged ramps. Grids having moving mechanical parts suffer from durability, maintenance and cost disadvantages.

According to the present invention, there is provided a cattle grid comprising a supporting platform which defines an upper supporting surface having an at least partially arcuate profile along its length.

Preferably, the supporting platform is latticed.

Preferably, the arcuate portion of the upper supporting surface is provided as a convexity.

Preferably, the arcuate portion of the upper supporting surface has a constant radius of curvature.

Alternatively, the arcuate portion of the upper supporting surface has an irregular radius of curvature.

Optionally, the upper supporting surface comprises a primary convex surface which merges into at least one peripheral supporting surface.

Preferably, the or each peripheral supporting surface has a linear profile.

Alternatively, the or each peripheral supporting surface has a convex or concave profile.

Preferably, each convex or concave profile has a constant radius of curvature.

Optionally, the primary and peripheral supporting surfaces are provided as distinct components of the cattle grid.

Optionally, the or each peripheral supporting surface overlies an end portion of said primary convex surface.

Alternatively, the respective primary and peripheral supporting surfaces are contiguous.

Preferably, at least one tensioning member extends lengthwise along the supporting platform and connects two points lying opposite said upper supporting surface.

Preferably, the supporting platform comprises a plurality of laterally extending linear elongate members, each being connected in spaced parallel arrangement on at least two parallel arcform supporting members each extending perpendicularly with respect to said elongate members.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which: Fig. 1 illustrates a problem associated with prior art cattle grids with regard to vehicles having low clearance and/or a long wheelbase; Fig. 2 illustrates a problem associated with prior art cattle grids with regard to vehicles towing long and/or low trailers; Fig. 3 illustrates a problem associated with prior art cattle grids with regard to vehicles having large front and/or rear overhangs; Fig. 4a is an end elevation of a cattle grid according to the present invention; Fig. 4b is a sectional side elevation of a similar cattle grid to that shown in Fig. 4a in-situ on an existing road surface; Fig. 4c is a plan view of a similar cattle grid to that shown in Figs. 4a and 4b; Fig. 5 shows a side elevation of an alternative form of cattle grid according to the present invention in situ on an existing road surface; and Fig. 6 shows a side elevation of an alternative arrangement of a cattle grid according to the present invention in situ partially below a surrounding road surface.

Figs. 4a-c show a cattle grid comprising a series of parallel elongate members (3) mounted at regular spaced intervals on two parallel arciform members (2) each of which extend perpendicularly with respect to the elongate members. The respective members (2, 3) may be formed of rolled steel or any other material having the appropriate strength and durability characteristics. The respective members (2, 3) are connected together by any suitable means such as welding or fasteners. Together, the respective members (2, 3) define a latticed supporting platform having an upper surface for supporting vehicles. The upper supporting surface has an overall convex arcuate profile having a substantially constant radius of curvature to form a shallow arch having a gradual change of incline along its length relative to the surrounding road surface.

Fig. 4b shows the grid in-situ on an existing road surface and having peripheral approach ramps (4) serving to provide a continuous upper supporting surface which meets the surrounding road at its opposite ends. The approach ramps may be formed of compacted hard core materials or any other material having the appropriate strength and durability characteristics.

Linear tensioning members (1) extend horizontally below the arcitorm members (2) and are attached to opposite ends of the arciform members (2), which are in turn attached to retaining members (5). The retaining members (5) also serve as a means of connecting the peripheral approach ramps (4) to the central portion of the grid. The purpose of the tensioning members (1) is to strengthen the arciform portion of the cattle grid at minimal cost, making it particularly suitable for the carriage of heavier vehicles. It will be appreciated that the tensioning members (1) can be omitted from cattle grids designed to carry light-weight vehicles.

The radius of curvature of the arc is balanced against its overall length such that the upper supporting surface of the grid protrudes above the surrounding road surface by a height and gradient which are each sufficiently low to allow the unobstructed passage of target vehicles whilst being sufficiently high to remain effective for its intended purpose of preventing the passage of livestock.

One non-limiting example of a cattle grid which allows the passage of farm pick-up vehicles has the following dimensions: the radius of curvature is 8 metres; the length of the arciform portion is 3.1 metres; the maximum height it protrudes above its chord (which connects the opposite ends of its upper supporting surface) is 150mm (i.e. this is its maximum height above its chord at its mid-point); the width of the grid is 2.0 metres. Of course, it will be appreciated that the above measurements (particularly the radius of curvature and width) can each be varied to accommodate different types of traffic. It should be noted that when the cattle grid is in situ, the chord will normally be arranged horizontally at a height of at least 200mm above the road surface (or the base of a recess formed in the road). Accordingly, the cattle grid's upper supporting surface protrudes above an underlying surface (i.e. the road surface or the base of a recess formed in the road) by at least 350mm at its highest point. This is the minimum height required to prevent livestock stepping through the cattle grid.

Typically, the cattle grid presents a "vehicle window" width of 2.45 metres to allow the passage of farm pick-up vehicles whilst minimising the use of materials. This is because its side flakes (which are a standard feature of all grids acting to prevent livestock bypassing the grid along its edges) are set slightly wide of the edge of the grid and are slightly further apart at their top than at their foot. Again, this dimension can be varied to accommodate or exclude particular sizes of vehicles as required.

Fig. 5 shows an alternative arrangement of a grid which is installed on an existing road surface (A). The arciform members (2) connect to the retaining members (5) at their lower ends to define recesses at opposite ends of the grid. Peripheral members (6), each having parallel elongate members (3) are shaped such that they can be fitted into each recess and overlie the ends of the arciform members (2). The upper surfaces of the retaining members (5) and the peripheral members (6) present a continuous upper supporting surface which merges with the peripheral approach ramps (4). The extent to which the grid protrudes above the level of the surrounding road surface is minimised by presenting only a shallow rise in the roadway. This extent of protrusion is controlled by varying the position of the connection of the arciform members (2) on the retaining members (5). The alternative arrangement of Fig. 5 is a special case which requires modification in order to ensure that its upper supporting surface protrudes above an underlying surface by at least 350mm. This is achieved by providing deeper retaining members (5) combined with longer approach ramps (4) when the grid is installed on top of an existing road surface. When installed partially below the level of the surrounding road surface, the grid is provided with deeper retaining members (5) and located in a deeper recess in the road.

Fig. 6 shows a further alternative arrangement of a grid which is installed partially below the surrounding road surface. In this arrangement, the arcitorm members (2) connect to the retaining members (5) at their upper ends in a similar manner to that in the embodiment of Fig. 4b such that the upper surface of cattle grid merges with the surrounding road surface (A).

The grids described above may be manufactured and sold as a pre-assembled unit or as a self-assembly flat pack. The latter alternative substantially reduces manufacturing, packaging and transport costs. The simple construction of the grids of the present invention in terms of the reduced amount of materials used and the reduced manufacturing time result in further cost savings.

Modifications and improvements may be made without departing from the scope of the present invention. For example, although the sub-surface grid of Fig. 6 does not require approach ramps or peripheral members to enable a smooth transition to and from the road surface, this could also be achieved on a grid which is positioned on an existing road surface by extending the latticed supporting surface to road level at its opposite ends.

Although the grid shown in Fig. 5 is shown in situ on an existing road surface, this design is particularly suitable for instaHation partially below the surrounding road surface whereby its minimal projection above the road surface will be especially effective in allowing the passage of low ground clearance vehicles.

Claims

1. A cattle grid comprtsing a supporting platform which defines an upper supporting surface having an at least partially arcuate profile along its length.

2. A cattle grid as claimed in claim 1, wherein the supporting platform is latticed.

3. A cattle grid as claimed in claim 1 or 2, wherein the arcuate portion of the upper supporting surface is provided as a convexity.

4. A cattle grid as claimed in any preceding claim, wherein, the arcuate portion of the upper supporting surface has a constant radius of curvature.

5. A cattle grid as claimed in any of claims 1 to 3, wherein the arcuate portion of the upper supporting surface has an irregular radius of curvature.

6. A cattle grid as claimed in any preceding claim, wherein the upper supporting surface comprises a primary convex surface which merges into at least one peripheral supporting surface.

7. A cattle grid as claimed in claim 6, wherein the or each peripheral supporting surface has a linear profile.

8. A cattle grid as claimed in claim 7, wherein the or each peripheral supporting surface has a convex or concave profile.

9. A cattle grid as claimed in claim 8, wherein each convex or concave profile has a constant radius of curvature.

10. A cattle grid as claimed in any of claims 6 to 9, wherein the primary and peripheral supporting surfaces are provided as distinct components of the cattle grid.

11. A cattle grid as claimed in any of claims 6 to 10, wherein the or each peripheral supporting surface overlies an end portion of said primary convex surface.

12. A cattle grid as claimed in any of claims 6 to 9, wherein the respective primary and peripheral supporting surfaces are contiguous.

13. A cattle grid as claimed in any preceding claim, wherein at least one tensioning member extends lengthwise along the supporting platform and connects two points lying opposite said upper supporting surface.

14. A cattle grid as claimed in any preceding claim, wherein the supporting platform comprises a plurality of laterally extending linear elongate members, each being connected in spaced parallel arrangement on at least two parallel arciform supporting members each extending perpendicularly with respect to said elongate members.

15. A cattle grid as substantially hereinbefore described with reference to Figs. 4a, 4b, Ic, 5 and 6.