GB2360807A

GB2360807A - Access Cover Component and Assembly

Info

Publication number: GB2360807A
Application number: GB0007987A
Authority: GB
Inventors: David Edmonds
Original assignee: Atlanta Impex Ltd
Current assignee: Atlanta Impex Ltd
Priority date: 2000-04-01
Filing date: 2000-04-01
Publication date: 2001-10-03
Anticipated expiration: 2020-04-01
Also published as: GB0007987D0; GB2360807B

Abstract

A non-circular access cover component 10 features a plurality of strengthening members 18,19,20 on its (in use) underside. At least one of the strengthening members 18,19,20 is generally curved when viewed from an angle perpendicular to the cover plate 11. The strengthening member 18,19,20 forms an angle with the plate 11, at its centre, such that the member does not sit perpendicular to the plate, the edge of the member which is further from the plate effectively being less curved than the edge which is joined to the plate. It is preferred that the strengthening member 18,19,20 curves such that its centre is further from the edge 12,13,14 of the cover plate 11 than its two ends, and that its centre is wider in a direction perpendicular to the plane of the plate than its two ends.

Description

2360807 PATENTS ACT 1977 A10052GB - MNS/1h, Title: A cover part for a

cover and frame assembly, a cover for a cover and frame assembly and a cover and frame assembly

Description of Invention

This invention relates to a cover part for a cover and frame assembly, a cover for a cover and frame assembly and to a cover and frame assembly.

The cover and frame assembly to which this invention relates in broad terms (hereinafter referred to as being of the kind specified) comprises a frame which in use is positioned in the ground above an opening such as a manhole, access or ventilation shaft or the like, and a cover associated and engageable with the frame which is operative to prevent or allow access to the opening.

More specifically, the cover to which this invention relates in broad terms is of the kind which comprises two generally triangular cover parts, each cover part having frame engagement portions at or near each corner so as to enable a three point contact, and hence non-rock, assembly to be obtained.

Such covers are in common use in many countries, with the so-called "D40W load class of covers having to meet a number of statutory requirements such as load bearing capacity, case of removal, and resistance to rocking and distortion.

In order to provide covers which comply with the various strength requirements, but which are not unduly difficult to remove from their frame, the covers are usually provided with one or more strengthening means on their (in use) underside, and it is an object of the present invention to provide an improved cover part for a cover and frame assembly of this general kind. It is also an object of the present invention to provide an improved cover of this general kind, and an improved cover and frame assembly of the kind specified.

According to a first aspect of the present invention, there is provided a cover part for a cover and frame assembly of the kind specified, the cover part 2 having a substantially planar cover member and a plurality of generally elongate strengthening members attached to or integral with the cover member, at least one of the strengthening members being generally curved when the cover part is viewed in a direction generally perpendicular to the plane of the cover member.

A strengthening member may be provided adjacent each side edge of the cover member, and the ends of the strengthening members may be positioned at or closely adjacent the ends of the side edges.

Preferably, the strengthening members are generally arcuate when the cover part is viewed in a direction generally perpendicular to the plane of the cover member.

The arcuate strengthening members may bow inwardly from the respective side edges of the cover member.

The strengthening members may extend substantially at right angles to the plane of the cover member.

As least one strengthening member may be provided with a flange or lip on its distal edge. Thus, at least one strengthening member may be generally Lshaped when viewed in cross-section.

Alternatively, the flange provided on the distal edge of the strengthening member may be such that the strengthening member is generally T-shaped in cross-section.

As a further alternative, or in addition, at least one strengthening member may taper towards the cover member. Thus, the distal thickness of the or each strengthening member may be greater than the thickness of said strengthening member where the or each strengthening member contacts the cover member.

At least one strengthening member may extend from the plane of the cover member in a non-perpendicular manner.

3 Thus, at least one strengthening member may form an included angle with the plane of the cover member of between 75' and 90'. Conveniently, the included angle is between 80' and 88% desirably about 84'.

At least one strengthening member may be curved when viewed in crosssection.

The height of the strengthening members (i.e. the distance between a distal edge thereof and the cover member) may be substantially even throughout the length of the strengthening members.

Preferably, however, the height of at least one strengthening member increases towards a central portion thereof. Conveniently, the or each said strengthening member is curved when viewed in elevation, such that the height thereof increases towards said central portion in a generally symmetrical manner.

The height of the strengthening member at said central portion may be approximately twice the height of the strengthening member at the ends thereof. All the strengthening members may be curved in elevation.

According to a second aspect of the present invention there is provided a cover for a cover and frame assembly of the kind specified, the cover comprising two mutually inter-fitting cover parts in accordance with any one of the preceding ten paragraphs.

In accordance with a third aspect of the present invention, there is provided a cover and frame assembly of the kind specified comprising a frame and a cover in accordance with any one of the preceding eleven paragraphs.

The invention will now be described in greater detail, but by way of example only, by reference to the accompanying drawings, wherein:

FIGURE 1 is an underneath plan view of a cover part in accordance with the invention, FIGURE 2 is an underneath perspective view of the cover part of Figure 1, 4 FIGURE 3 is a cross-section on the line III-III of Figure 1, FIGURE 4 shows an alternative form of strengthening member, also in crosssection, FIGURE 5 is an elevational view in the direction of arrow A of Figure 2, and FIGURE 6 is a top plan view of a cover and frame assembly incorporating two mutually inter-fitting cover parts of the kind shown in Figures 1 to 5.

Referring first to Figure 1, there is shown a cover part 10 of a cover and frame assembly of the kind specified, the cover part 10 comprising a generally triangular and planar cover member 11 having side edges 12, 13 and 14, with the edges 12 and 13 being about 60Omm in length and with the edge 14 being about 850mm in length, in accordance with standard requirements. Side edges 12 and 13 are provided with recesses 15 and 16 adapted to receive a cover removal tool (not shown) so as to facilitate leverage of the cover from an associated frame of the general kind shown in Figure 6.

The cover member is also provided with a generally centrally located keyway 17 adapted to receive a cover removal tool, in generally conventional manner. It will be appreciated that the keyway could alternatively be positioned elsewhere to facilitate removal of the cover member. Thus, the keyway could be positioned further towards the corners of the cover member, if desired.

On the underside of the cover member 11 are provided three generally arcuate strengthening members 18, 19 and 20, with the strengthening members 18 and 19 extending generally perpendicularly to the plane of the cover member 11, i.e. out of the paper of Figure 1. The ends of each strengthening member are integral with or positioned closely adjacent engaging formations 21, 22 and 23, which are configured to locate in or abut with similarly configured receiving formations disposed at corners of the associated ftaine, in conventional manner, so as to achieve the required "non-rock" configuration.

As shown in Figure 3, the strengthening member 20, in contrast to the strengthening members 18 and 19, does not up-stand perpendicularly to the plane of the cover member 11 throughout its length. In contrast, the strengthening member 20 is provided at its distal edge 24 with a flange 25 which extends towards the respective side edge 14 of the cover member 11, thus giving the strengthening member 20 a somewhat inverted L-shape when viewed in cross-section. In addition, a support part 26 of the strengthening member 20 forms an included angle a of about 84' with the cover member 11.

It has been found by the applicants that the use of a strengthening member having such a cross-section shifts the neutral axis of the strengthening member towards the cover member 11 (i.e. into the paper of Figure 1), thus apparently reducing the stress forces which are present in the strengthening means at the position furthest ftom the point of load application, which approximates to the distal edge 24. This, it has been found, improves the mechanical properties of the cover part, and reduces its susceptibility to progressive weakening.

The applicants have also found that similar beneficial mechanical effects may also be obtained where the flange 25 extends either side of the distal edge 24 thus giving the strengthening member a T-shaped cross- section.

If desired, the strengthening members 18 and 19 could also be configured with a similar L or T-shaped flange arrangement.

Figure 4 shows an alternative construction of the strengthening member, shown in cross-section in a manner allied to that of Figure 3, in which the distal thickness td of the strengthening member 20 is greater than the thickness tc.. of the strengthening member at the point where it contacts the cover member. This configuration, which is somewhat easier to mould or cast than the UTshaped arrangements described in relation to Figure 3, also provides 6 considerable mechanical strength benefits by virtue of the increased amount of stress absorbing material which is present in the strengthening member at a position remote from the point of load application. It can also been seen from Figure 4 that the strengthening member 20, when viewed in cross-section, is somewhat displaced from the vertical, forming instead an included angle of about 840 with the cover member 11. As illustrated by Figure 4, both side walls 26a and 26b of the support part 26 are off-set from the vertical, with side wall 26a being more offset than side wall 26b.

It has also been found by the applicants that where the strengthening members are curved (i.e. generally C-shaped) in cross-section, with the strengthening members thus having a concave (dish-like) configuration when viewed from their respective (nearest) side edge of the cover member, the load absorbing properties of the cover part are even further improved.

Referring next to Figures 2 and 5, it can be seen that the height of the strengthening members 18, 19 and 20 (i.e. the distance between their distal edges and the cover member) increases towards the central portions thereof Whilst Figure 5 illustrates only strengthening member 20, it will be appreciated that similar considerations may apply to the strengthening members 18 and 19. Specifically, as shown in Figure 5, the height h2 of the strengthening member 20 at its central portion is substantially greater than the height of the strengthening member at its ends, with the height h, corresponding to the height of the engaging formations 21 and 22.

As can also be seen from Figure 1, the strengthening member 20 is curved when viewed in elevation, with this assisting in removal of the cover parts 10, as described further in relation to Figure 6. In a particularly favourable embodiment, the height 112 may be approximately 10Omm, whereas the height h, may be just 53min. It will however be appreciated that other combinations of heights h, and h2 are envisaged.

7 Whilst the applicants do not wish to limit in any way the protection which is sought, it is believed that the use of arcuate strengthening members (when viewed in plan) improves the strength of the associated cover part by virtue of the strengthening members' tendency to attempt to "straighten" when a downward load is applied. It is understood that during the straightening process, a degree of the applied load is absorbed laterally, thus reducing the effective downward force which is applied to the cover part. In addition, it will be appreciated that as the arcuate strengthening members protrude farther towards the centre section of the cover part than would linear strengthening members which extend generally parallel to the side edges, a greater degree of support is provided in this centre section, thus reducing the so-called "diaphragm effecf' which might otherwise result in downward deformation of the upper surface of the cover member.

These advantages are increased when other of the previously described features are incorporated into the strengthening members.

It will also be appreciated that the improved strength characteristics mean that cross-braces, extending between the strengthening members, are not required, and this has the effect of reducing the overall weight of the cover part by a considerable degree. In particular, whilst a "standard" cover part formed from ductile iron typically weighs about 27 kilograms, the applicants have found that a cover part made in accordance with the present invention need weigh only about 21 kilograms, whilst still meeting the various performance requirements such as the "13400" load class referred to above. Thus, the reduced weight greatly facilitates removal of the cover parts from a roadway, and thus ensures that the covers pails comply with the various health and safety 4Cone man" removal requirements.

It has also been found that the inwardly bowed configuration of the strengthening members, in conjunction with their curved configuration when viewed in elevation, renders the cover parts far more suitable for diagonal 8 "slide-ouf 'removal (i.e. in the direction shown by arrow B in Figure 6) from an associated frame 30, by virtue of the interaction between the strengthening members 18, 19 and 20 with the associated support ledges (not shown) which are provided on the inner edges 31 of the frame 30.

In brief, the gradually increasing height of the strengthening members towards their centres enables them to "ride" over the ledges.

The cover part may be formed (e.g. cast) from a metal such as ductile iron, although other materials and manufacturing methods may also be suitable.

In the present specification "comprise" means "includes or consists of' and "comprisinj means "including or consisting of'.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

9 CLAIMS:

1. A cover part for a cover and frame assembly of the kind specified, the cover part having a substantially planar cover member and a plurality of generally elongate strengthening members attached to or integral with the cover member, at least one of the strengthening members being generally curved when the cover part is viewed in a direction generally perpendicular to the plane of the cover member.

2. A cover part according to claim 1 wherein a strengthening member is provided adjacent each side edge of the cover member, and wherein the ends of the strengthening members are positioned at or closely adjacent the ends of the side edges.

3. A cover part according to claim 1 or claim 2 wherein the or each strengthening member is generally arcuate when viewed in a direction generally perpendicular to the plane of the cover member.

4. A cover part according to claim 3 wherein the or each strengthening member bows inwardly from the respective side edge of the cover member.

5. A cover part according to any one of the preceding claims wherein the or each strengthening member extends substantially at right angles to the plane of the cover member.

6. A cover part according to any one of the preceding claims wherein at least one strengthening member is provided with a flange or lip on its distal edge.

7. A cover part according to claim 6 wherein the or each strengthening member is generally L-shaped in cross-section.

8. A cover part according to claim 6 wherein the or each strengthening member is generally T-shaped in cross-section.

9. A cover part according to any one of claims 1 to 4 wherein the or each strengthening member forms an included angle with the plane of the cover member of between 75' and 90'.

10. A cover part according to claim 9 wherein the or each strengthening member forms an included angle with the plane of the cover member of about 80' to 88'.

11. A cover part according to any one of the preceding claims wherein the or each strengthening member tapers towards the cover member.

12. A cover part according to any one of the preceding claims wherein the height of the or each strengthening member increases towards a central portion thereof.

13. A cover part according to any one of the preceding claims wherein the or each strengthening is curved when viewed in elevation.

14. A cover part according to any one of claims 1 to 4, or any one of claims 6, 11 or 13 when dependent on any one of claims 1 to 4, wherein the or each strengthening member is generally curved when viewed in crosssection.

11

15. A cover part substantially as hereinbefore described and/or as shown in the accompanying drawings.

16. A cover for a cover and firame assembly of the kind specified, the cover comprising two cover parts according to any one of claims 1 to 15.

17. A cover substantially as hereinbefore described andlor as shown in the accompanying drawings.

18. A cover and frame assembly of the kind specified comprising a frame and a cover according to claim 16 or claim 17.

19. A cover and frame assembly substantially as hereinbefore described and/or as shown in the accompanying drawings.

20. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.